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1

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

2

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

3

Study of Degradation Processes in Dielectric Materials Used in Electronic Control Equipment Operated in ``Kozloduy'' NPP  

NASA Astrophysics Data System (ADS)

The electronic equipment for control of different systems of Units 5 and 6 is studied for presence of degradation processes occurring in result of continuous usage in conditions of controlled radiation background in compliance with ``Kozloduy'' NPP safety codes. Systems, operated in a continuous mode in the course of about 10 years were chosen - separate units containing different dielectric materials (varnish coating, circuit board bases, cable insulations, electro protective elements, etc.) were extrapolated. Series of test samples were prepared which were connected with flat or coaxial condensers and their characteristic parameters were measured: tg?, ?, low voltage conductivity and leak currents at voltages that exceed the working ones several times. When comparing the obtained data with the reference ones, a conclusion is made about the effectiveness of electric ageing during operation in the course of time.

Naydenov, Nayden; Popov, Angel

2007-04-01

4

Study of Degradation Processes in Dielectric Materials Used in Electronic Control Equipment Operated in 'Kozloduy' NPP  

SciTech Connect

The electronic equipment for control of different systems of Units 5 and 6 is studied for presence of degradation processes occurring in result of continuous usage in conditions of controlled radiation background in compliance with 'Kozloduy' NPP safety codes. Systems, operated in a continuous mode in the course of about 10 years were chosen - separate units containing different dielectric materials (varnish coating, circuit board bases, cable insulations, electro protective elements, etc.) were extrapolated. Series of test samples were prepared which were connected with flat or coaxial condensers and their characteristic parameters were measured: tg{delta}, {epsilon}, low voltage conductivity and leak currents at voltages that exceed the working ones several times. When comparing the obtained data with the reference ones, a conclusion is made about the effectiveness of electric ageing during operation in the course of time.

Naydenov, Nayden ['Kozloduy' NPP, Kozloduy (Bulgaria); Popov, Angel [Department of Semiconductor Physics, Faculty of Physics, University of Sofia 'St. Kliment Ohridski', 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria)

2007-04-23

5

Degradation Mechanism and Control of Silk Fibroin  

PubMed Central

Controlling the degradation process of silk is an important and interesting subject in biomaterials field. In the present study, silk fibroin films with different secondary conformations and nanostructures were used to study the degradation behavior. Silk fibroin films with highest ?-sheet content achieved highest degradation rate, different from the previous studies. A new degradation mechanism revealed that degradation behavior of silk fibroin was related to not only crystal content, but also hydrophilic interaction and crystal-noncrystal alternant nanostructures. The hydrophilic blocks of silk were firstly degraded. Then, the hydrophobic crystal blocks which were formerly surrounded and immobilized by hudrophilic blocks, became free particles and moved into solution. Based on the mechanism, which enables the process more controllable and flexible, controlling the degradation behavior of silk fibroin without sacrificing other performances such as mechanical or hydrophilic properties become feasible, and this would greatly expand the applications of silk as a biomedical material.

Lu, Qiang; Zhang, Bing; Li, Mingzhong; Zuo, Baoqi; Kaplan, David L.; Huang, Yongli; Zhu, Hesun

2012-01-01

6

Degradable polymeric materials for osteosynthesis: tutorial.  

PubMed

This report summarizes the state of the art and recent developments and advances in the use of degradable polymers devices for osteosynthesis. The current generation of biodegradable polymeric implants for bone repair utilising designs copied from metal implants, originates from the concept that devices should be supportive and as "inert" substitute to bone tissue. Today degradable polymeric devices for osteosynthesis are successful in low or mild load bearing applications. However, the lack of carefully controlled randomized prospective trials that document their efficacy in treating a particular fracture pattern is still an issue. Then, the choice between degradable and non-degradable devices must be carefully weighed and depends on many factors such as the patient age and condition, the type of fracture, the risk of infection, etc. The improvement of the biodegradable devices mechanical properties and their degradation behaviour will have to be achieved to broaden their use. The next generation of biodegradable implants will probably see the implementation of the recent gained knowledge in cell-material interactions and cells therapy, with a better control of the spatial and temporal interfaces between the material and the surrounding bone tissue. PMID:19101891

Eglin, D; Alini, M

2008-12-19

7

Hubble Space Telescope Metallized Teflon ® FEP thermal Control Materials: On-Orbit Degradation and Post-Retrieval Analysis  

Microsoft Academic Search

During the Hubble Space Telescope (HST) second servicing mission (SM2), degradation of unsupported Teflon® 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.

Jacqueline A Townsend; Patricia A Hansen; Joyce A Dever; Kim K de Groh; Bruce A Banks; Len Wang; Charles He

1999-01-01

8

Apparatus for Studying Atmospheric Degradation of Materials.  

National Technical Information Service (NTIS)

A simple, flexible test facility has been devised which is suitable for examining the effects of trace gases on the degradation of materials under conditions approximating to those of free atmospheric exposure. (Author)

K. E. Johnson A. F. Bromley

1973-01-01

9

Materials degradation caused by acid rain  

SciTech Connect

Materials Degradation Caused by Acid Rain, based on a symposium sponsored by the American Chemical Society, presents a detailed analysis of the types of materials damages that may result from acid deposition, as well as techniques for evaluating the economic impact of these damages. The 29 chapters are organized into five sections. These sections include: Measurement and Monitoring of Atmospheric Deposition; Metallic Corrosion; Degradation of Organics; and Economic Effects.

Baboian, R. (ed.)

1986-01-01

10

Mechanical degradation temperature of waste storage materials  

SciTech Connect

Heat loading analysis of the Solid Waste Disposal Facility (SWDF) waste storage configurations show the containers may exceed 90{degrees}C without any radioactive decay heat contribution. Contamination containment is primarily controlled in TRU waste packaging by using multiple bag layers of polyvinyl chloride and polyethylene. Since literature values indicate that these thermoplastic materials can begin mechanical degradation at 66{degrees}C, there was concern that the containment layers could be breached by heating. To better define the mechanical degradation temperature limits for the materials, a series of heating tests were conducted over a fifteen and thirty minute time interval. Samples of a low-density polyethylene (LDPE) bag, a high-density polyethylene (HDPE) high efficiency particulate air filter (HEPA) container, PVC bag and sealing tape were heated in a convection oven to temperatures ranging from 90 to 185{degrees}C. The following temperature limits are recommended for each of the tested materials: (1) low-density polyethylene -- 110{degrees}C; (2) polyvinyl chloride -- 130{degrees}C; (3) high-density polyethylene -- 140{degrees}C; (4) sealing tape -- 140{degrees}C. Testing with LDPE and PVC at temperatures ranging from 110 to 130{degrees}C for 60 and 120 minutes also showed no observable differences between the samples exposed at 15 and 30 minute intervals. Although these observed temperature limits differ from the literature values, the trend of HDPE having a higher temperature than LDPE is consistent with the reference literature. Experimental observations indicate that the HDPE softens at elevated temperatures, but will retain its shape upon cooling. In SWDF storage practices, this might indicate some distortion of the waste container, but catastrophic failure of the liner due to elevated temperatures (<185{degrees}C) is not anticipated.

Fink, M.C.; Meyer, M.L.

1993-05-13

11

Elastomer degradation sensor using a piezoelectric material  

DOEpatents

A method and apparatus for monitoring the degradation of elastomeric materials is provided. Piezoelectric oscillators are placed in contact with the elastomeric material so that a forced harmonic oscillator with damping is formed. The piezoelectric material is connected to an oscillator circuit,. A parameter such as the resonant frequency, amplitude or Q value of the oscillating system is related to the elasticity of the elastomeric material. Degradation of the elastomeric material causes changes in its elasticity which, in turn, causes the resonant frequency, amplitude or Q of the oscillator to change. These changes are monitored with a peak height monitor, frequency counter, Q-meter, spectrum analyzer, or other measurement circuit. Elasticity of elastomers can be monitored in situ, using miniaturized sensors.

Olness, Dolores U. (Livermore, CA); Hirschfeld, deceased, Tomas B. (late of Livermore, CA)

1990-01-01

12

Self-degradable Cementitious Sealing Materials  

SciTech Connect

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 at temperatures of {ge}200 C came in contact with water. We interpreted the mechanism of this water-initiated self-degradation as resulting from the in-situ exothermic reactions between the reactants yielded from the dissolution of the non-reacted or partially reacted sodium silicate activator and the thermal degradation of the CMC. The magnitude of self-degradation depended on the CMC content; its effective content in promoting degradation was {ge}0.7%. In contrast, no self-degradation was observed from CMC-modified Class G well cement. For 200 C-autoclaved AACMs without CMC, followed by heating at temperatures up to 300 C, they had a compressive strength ranging from 5982 to 4945 psi, which is {approx}3.5-fold higher than that of the commercial Class G well cement; the initial- and final-setting times of this AACM slurry at 85 C were {approx}60 and {approx}90 min. Two well-formed crystalline hydration phases, 1.1 nm tobermorite and calcium silicate hydrate (I), were responsible for developing this excellent high compressive strength. Although CMC is an attractive, as a degradation-promoting additive, its addition to both the AACM and the Class G well cement altered some properties of original cementitious materials; among those were an extending their setting times, an increasing their porosity, and lowering their compressive strength. Nevertheless, a 0.7% CMC-modified AACM as self-degradable cementitious material displayed the following properties before its breakdown by water; {approx}120 min initial- and {approx}180 min final-setting times at 85 C, and 1825 to 1375 psi compressive strength with 51.2 to 55.0% porosity up to 300 C.

Sugama, T.; Butcher, T., Lance Brothers, Bour, D.

2010-10-01

13

Materials Degradation in Light Water Reactors: Life After 60,???  

SciTech Connect

Nuclear reactors present a very harsh environment for components service. Components within a reactor core must tolerate high temperature water, stress, vibration, and an intense neutron field. Degradation of materials in this environment can lead to reduced performance, and in some cases, sudden failure. A recent EPRI-led study interviewed 47 US nuclear utility executives to gauge perspectives on long-term operation of nuclear reactors. Nearly 90% indicated that extensions of reactor lifetimes to beyond 60 years were likely. When polled on the most challenging issues facing further life extension, two-thirds cited plant reliability as the key issue with materials aging and cable/piping as the top concerns for plant reliability. Materials degradation within a nuclear power plant is very complex. There are many different types of materials within the reactor itself: over 25 different metal alloys can be found with can be found within the primary and secondary systems, not to mention the concrete containment vessel, instrumentation and control, and other support facilities. When this diverse set of materials is placed in the complex and harsh environment coupled with load, degradation over an extended life is indeed quite complicated. To address this issue, the USNRC has developed a Progressive Materials Degradation Approach (NUREG/CR-6923). This approach is intended to develop a foundation for appropriate actions to keep materials degradation from adversely impacting component integrity and safety and identify materials and locations where degradation can reasonably be expected in the future. Clearly, materials degradation will impact reactor reliability, availability, and potentially, safe operation. Routine surveillance and component replacement can mitigate these factors, although failures still occur. With reactor life extensions to 60 years or beyond or power uprates, many components must tolerate the reactor environment for even longer times. This may increase susceptibility for most components and may introduce new degradation modes. While all components (except perhaps the reactor vessel) can be replaced, it may not be economically favorable. Therefore, understanding, controlling, and mitigating materials degradation processes are key priorities for reactor operation, power uprate considerations, and life extensions. This document is written to give an overview of some of the materials degradation issues that may be key for extend reactor service life. A detailed description of all the possible forms of degradation is beyond the scope of this short paper and has already been described in other documents (for example, the NUREG/CR-6923). The intent of this document is to present an overview of current materials issues in the existing reactor fleet and a brief analysis of the potential impact of extending life beyond 60 years. Discussion is presented in six distinct areas: (1) Reactor pressure vessel; (2) Reactor core and primary systems; (3) Reactor secondary systems; (4) Weldments; (5) Concrete; and (6) Modeling and simulations. Following each of these areas, some research thrust directions to help identify and mitigate lifetime extension issues are proposed. Note that while piping and cabling are important for extended service, these components are discussed in more depth in a separate paper. Further, the materials degradation issues associated with fuel cladding and fuel assemblies are not discussed in this section as these components are replaced periodically and will not influence the overall lifetime of the reactor.

Busby, Jeremy T [ORNL; Nanstad, Randy K [ORNL; Stoller, Roger E [ORNL; Feng, Zhili [ORNL; Naus, Dan J [ORNL

2008-04-01

14

Degradation issues of polymer materials used in railway field  

Microsoft Academic Search

Polymer materials used in railway field are degraded by environmental factors such as thermal, oxidative, photolytic, hydrolytic, and mechanical. The expected service life of the polymer materials used in railway field is approximately 20 years that is relatively long period for the polymer material; therefore, respective degradation factors should be well considered. Some of the degradation conditions indicate similar mechanism.

Mikiya Ito; Kazukiyo Nagai

2008-01-01

15

Derivation of damage functions for atmospheric degradation of materials  

SciTech Connect

The information in the pape is directed to those who develop and use damage functions that 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 considerations associated with possible pollution control strategies. Damage functions may be derived from theoretical considerations, from controlled experiments in environmental simulation chambers, from essentially uncontrolled field experiments, or from semicontrolled field experiments. The paper discusses optimum ways of combining these methods to improve the credibility and applicability of materials damage functions for use in assessments, with reference to some of the research performed for the National Acid Precipitation Assessment Program.

Haynie, F.H.; Lipfert, F.W.

1986-05-01

16

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

17

Materials degradation caused by acid rain  

Microsoft Academic Search

This book presents the papers given at a symposium on acid rain. Topics considered at the symposium included acidification, wet deposition, dry deposition, the corrosion of metals, corrosion products, the weathering of steel, environmental effects, automotive corrosion, effects on indoor surfaces, the degradation of organics, effects on wood surfaces, effects on plants, the acid rain degradation of nylon, the legal

Baboian

1986-01-01

18

Mechanism for Degradation of Materials in Organic Devices  

NASA Astrophysics Data System (ADS)

To get insight into the mechanisms for the operational fatigue of light-related organic devices such as organic light emitting diodes, organic solar cells and electrophotography, possible mechanisms for degradation of organic materials are argued for some examples.

Tokumaru, Katsumi

19

AGING MANAGEMENT USING PROACTIVE MANAGEMENT OF MATERIALS DEGRADATION  

SciTech Connect

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. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Carpenter, C. E.; Hull, A. B.; Malik, S. N. [U.S. Nuclear Regulatory Commission, Washington D.C. 20555-0001 (United States)

2010-02-22

20

OXIDATIVE DEGRADATION OF AQUATIC HUMIC MATERIAL  

EPA Science Inventory

Experimental research on the chemical structure of aquatic humic material has been stimulated in the last decade by public health interest in possible adverse human health effects of reaction by-products of humic materials with chlorine. The purpose of the paper is to describe th...

21

Degradation of insulating materials under electrical stress  

Microsoft Academic Search

An avalanche of physical and physicochemical phenomena, often self-sustained, leads to the end of life of an insulating material. The collapse of the insulating role of a material is mostly due to the electrical field stress. The path leading from the catastrophic situation, the breakdown, back to its origin is followed in the present paper. A defect, pre-existing or created

C. Mayoux

2000-01-01

22

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

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

Materials Degradation Studies for High Temperature Steam Electrolysis Systems  

Microsoft Academic Search

Experiments are currently in progress to assess the high temperature degradation behavior of materials in solid oxide electrolysis systems. This research includes the investigation of various electrolysis cell components and balance of plant materials under both anodic and cathodic gas atmospheres at temperatures up to 850°C. Current results include corrosion data for a high temperature nickel alloy used for the

Paul Demkowicz; Pavel Medvedev; Kevin DeWall; Paul Lessing

2007-01-01

25

Solar radiation dependent degradation of solar energy related materials  

Microsoft Academic Search

Results are reported of investigations to determine the basic underlying physical causes of optical and structural degradation in solar energy related materials under high temperatures, in reactive environments and under intense solar and solar simulated irradiation. Research on problems principally in the area of solar absorbing materials are studied with specific interest in electrodeposited solar selective black chrome coatings. Experimentally

Ignatiev

1983-01-01

26

Degradation of Cellulose Acetate-Based Materials: A Review  

Microsoft Academic Search

Cellulose acetate polymer is used to make a variety of consumer products including textiles, plastic films, and cigarette\\u000a filters. A review of degradation mechanisms, and the possible approaches to diminish the environmental persistence of these\\u000a materials, will clarify the current and potential degradation rates of these products after disposal. Various studies have\\u000a been conducted on the biodegradability of cellulose acetate,

Juergen PulsSteven; Steven A. Wilson; Dirk Hölter

2011-01-01

27

A fully degradable tracheal stent: in vitro and in vivo characterization of material degradation.  

PubMed

We report on the testing of materials for a fully degradable tracheal stent. Such a stent has several advantages over currently used permanent stents made of metal or silicone polymers. However, the mode of degradation in the trachea is expected to be different from a fully submerged device, because of the uniqueness of the tracheal environment. A physical model was developed to allow an in-depth study of degradation of bioabsorbable polymers exposed to two differing media; namely 70 wt % water (gel) on one side and humidified air on the other, simulating conditions in a tracheal passage. Longitudinal microtome slices were obtained from both polymer surfaces and degradation kinetics data were derived from size exclusion chromatography. On the basis of the data obtained, it is observed that well-studied bulk-degrading polymers might show surface-eroding properties in such an environment. Generally, hydrophobic polymers retard the formation of a water concentration gradient and exhibit bulk-degradation kinetics. However, addition of specific plasticizers can influence the water uptake gradient, and force the polymer towards a pseudo "surface-eroding" behavior. In vivo studies in a rabbit model of degradable stents made from a selected polymer, demonstrate the feasibility of a fully bioabsorbable tracheal stent. This study aims to improve understanding of degradation of polymers under heterogeneous environments. PMID:22121065

Ng, Anthony H C; Ng, Nelson S P; Zhu, G H; Lim, Lynne H Y; Venkatraman, Subbu S

2011-11-28

28

Materials Degradation Studies for High Temperature Steam Electrolysis Systems  

SciTech Connect

Experiments are currently in progress to assess the high temperature degradation behavior of materials in solid oxide electrolysis systems. This research includes the investigation of various electrolysis cell components and balance of plant materials under both anodic and cathodic gas atmospheres at temperatures up to 850°C. Current results include corrosion data for a high temperature nickel alloy used for the air-side flow field in electrolysis cells and a commercial ferritic stainless steel used as the metallic interconnect. Three different corrosion inhibiting coatings were also tested on the steel material. The samples were tested at 850ºC for 500 h in both air and H2O/H2 atmospheres. The results of this research will be used to identify degradation mechanisms and demonstrate the suitability of candidate materials for long-term operation in electrolysis cells.

Paul Demkowicz; Pavel Medvedev; Kevin DeWall; Paul Lessing

2007-06-01

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

Materials Degradation in Light Water Reactors: Life After 60,???  

Microsoft Academic Search

Nuclear reactors present a very harsh environment for components service. Components within a reactor core must tolerate high temperature water, stress, vibration, and an intense neutron field. Degradation of materials in this environment can lead to reduced performance, and in some cases, sudden failure. A recent EPRI-led study interviewed 47 US nuclear utility executives to gauge perspectives on long-term operation

Jeremy T Busby; Randy K Nanstad; Roger E Stoller; Zhili Feng; Dan J Naus

2008-01-01

31

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

2013-08-18

32

Experimental characterization of material degradation of solder joint under fatigue loading  

Microsoft Academic Search

Thermal fatigue damage is a progressive process of material degradation. The objective of this study is to experimentally quantify the material degradation of solder joint in electronic BGA package under thermal fatigue loading. Elastic modulus degradation under thermal cycling, which is considered as a physically detectable quantity of material degradation, was measured by nano-indenter. It was compared with tendency of

Hong Tang; Cemal Basaran

2002-01-01

33

Physical and mechanical properties of degraded waste surrogate material  

SciTech Connect

This paper discusses rock mechanics testing of surrogate materials to provide failure criteria for compacted, degraded nuclear waste. This daunting proposition was approached by first assembling all known parameters such as the initial waste inventory and rock mechanics response of the underground setting after the waste is stored. Conservative assumptions allowing for extensive degradation processes helped quantify the lowest possible strength conditions of the future state of the waste. In the larger conceptual setting, computations involve degraded waste behavior in transient pressure gradients as gas exits the waste horizon into a wellbore. Therefore, a defensible evaluation of tensile strength is paramount for successful analyses and intentionally provided maximal failed volumes. The very conservative approach assumes rampant degradation to define waste surrogate composition. Specimens prepared from derivative degradation product were consolidated into simple geometries for rock mechanics testing. Tensile strength thus derived helped convince a skeptical peer review panel that drilling into the Waste Isolation Pilot Plant (WIPP) would not likely expel appreciable solids via the drill string.

Hansen, F.D. [Sandia National Labs., Carlsbad, NM (United States); Mellegard, K.D. [RE/SPEC Inc., Rapid City, SD (United States)

1998-03-01

34

Moving Beyond Nondestructive Examination to Proactive Management of Materials Degradation  

SciTech Connect

There is growing interest in life extensions to enable longer term operation (LTO) for both existing nuclear power plants (NPPs) and proposed new NPPs. In order to justify an initial license extension for the 40-60 year period, new non-destructive examination (NDE) approaches have been developed and deployed by NPP operators in their Aging Management Programs (AMPs). However, to achieve the goals of even longer term operation, and specifically for the USA in looking at methodologies to support subsequent license renewal periods (i.e., 60-80 years, and beyond), it is necessary to understand the capabilities of current NDE methods to detect, monitor and trend degradation and hence enable timely implementation of appropriate corrective actions. This paper discusses insights from past experience, the state-of-the-art, and current activities in the move towards providing a capacity for proactive management of materials degradation (PMMD) to support NPP LTO.

Bond, Leonard J.

2010-07-01

35

Moving Beyond NDE to Proactive Management of Materials Degradation  

SciTech Connect

There is growing interest in life extensions to enable longer term operation (LTO) for both existing nuclear power plants (NPPs) and proposed new NPPs. In order to justify an initial license extension for the 40-60 year period, new non-destructive examination (NDE) approaches have been developed and deployed by NPP operators in their Aging Management Programs (AMPs). However, to achieve the goals of even longer term operation, and specifically for the USA in looking at methodologies to support subsequent license renewal periods (i.e., 60-80 years, and beyond), it is necessary to understand the capabilities of current NDE methods to detect, monitor and trend degradation and hence enable timely implementation of appropriate corrective actions. This paper discusses insights from past experience, the state-of-the-art, and current activities in the move towards providing a capacity for proactive management of materials degradation (PMMD) to support NPP LTO.

Bond, Leonard J.

2010-07-20

36

Enhanced material classification using turbulence-degraded polarimetric imagery.  

PubMed

An enhanced material-classification algorithm using turbulence-degraded polarimetric imagery is presented. The proposed technique improves upon an existing dielectric/metal material-classification algorithm by providing a more detailed object classification. This is accomplished by redesigning the degree-of-linear-polarization priors in the blind-deconvolution algorithm to include two subclasses of metals--an aluminum group classification (includes aluminum, copper, gold, and silver) and an iron group classification (includes iron, titanium, nickel, and chromium). This new classification provides functional information about the object that is not provided by existing dielectric/metal material classifiers. A discussion of the design of these new degree-of-linear-polarization priors is provided. Experimental results of two painted metal samples are also provided to verify the algorithm's accuracy. PMID:21042363

Hyde, Milo W; Schmidt, Jason D; Havrilla, Michael J; Cain, Stephen C

2010-11-01

37

Global nuclear material control model  

SciTech Connect

The nuclear danger can be reduced by a system for global management, protection, control, and accounting as part of a disposition program for special nuclear materials. The development of an international fissile material management and control regime requires conceptual research supported by an analytical and modeling tool that treats the nuclear fuel cycle as a complete system. Such a tool must represent the fundamental data, information, and capabilities of the fuel cycle including an assessment of the global distribution of military and civilian fissile material inventories, a representation of the proliferation pertinent physical processes, and a framework supportive of national or international perspective. They have developed a prototype global nuclear material management and control systems analysis capability, the Global Nuclear Material Control (GNMC) model. The GNMC model establishes the framework for evaluating the global production, disposition, and safeguards and security requirements for fissile nuclear material.

Dreicer, J.S.; Rutherford, D.A.

1996-05-01

38

Degradation of chitosan-based materials after different sterilization treatments  

NASA Astrophysics Data System (ADS)

Biopolymers have received in recent years an increasing interest for their potential applications in the field of biomedical engineering. Among the natural polymers that have been experimented, chitosan is probably the most promising in view of its exceptional biological properties. Several techniques may be employed to sterilize chitosan-based materials. The aim of our study was to compare the effect of common sterilization treatments on the degradation of chitosan-based materials in various physical states: solutions, hydrogels and solid flakes. Four sterilization methods were compared: gamma irradiation, beta irradiation, exposure to ethylene oxide and saturated water steam sterilization (autoclaving). Exposure to gamma or beta irradiation was shown to induce an important degradation of chitosan, regardless of its physical state. The chemical structure of chitosan flakes was preserved after ethylene oxide sterilization, but this technique has a limited use for materials in the dry state. Saturated water steam sterilization of chitosan solutions led to an important depolymerization. Nevertheless, steam sterilization of chitosan flakes bagged or dispersed in water was found to preserve better the molecular weight of the polymer. Hence, the sterilization of chitosan flakes dispersed in water would represent an alternative step for the preparation of sterilized chitosan solutions. Alternatively, autoclaving chitosan physical hydrogels did not significantly modify the macromolecular structure of the polymer. Thus, this method is one of the most convenient procedures for the sterilization of physical chitosan hydrogels after their preparation.

San Juan, A.; Montembault, A.; Gillet, D.; Say, J. P.; Rouif, S.; Bouet, T.; Royaud, I.; David, L.

2012-02-01

39

Degradation, fatigue and failure of resin dental composite materials  

PubMed Central

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 degradation due to aging in different media, mainly water and water and ethanol, cyclic loading, and mixed mode loading on the flexure strength and fracture toughness. Next several selected papers will be examined in detail with respect to mixed and cyclic loading and then an examination of 3D tomography using multiaxial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection) and after that time period from secondary decay.

Drummond, James L.

2008-01-01

40

Degradation, Fatigue, and Failure of Resin Dental Composite Materials  

SciTech Connect

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 be examined in detail with respect to mixed and cyclic loading, and 3D tomography with multi-axial compression specimens. The main cause of failure, for most dental resin composites, is the breakdown of the resin matrix and/or the interface between the filler and the resin matrix. In clinical studies, it appears that failure in the first 5 years is a restoration issue (technique or material selection); after that time period, failure most often results from secondary decay.

Drummond, J.L. (UIC)

2008-11-03

41

Raw materials handling and controls  

Microsoft Academic Search

This presentation discusses some of the commonly used methods for handling raw materials prior to processing and the controls\\u000a necessary to limit deterioration of raw materials in storage. Reference is made to properties of major oil-bearing raw materials\\u000a and specific care needed in both storage and handling. Examples of typical handling and storage facilities are given.

E. H. Gustafson

1978-01-01

42

Material control and accountability alternatives  

SciTech Connect

Department of Energy and Nuclear Regulatory Commission regulations governing material control and accountability in nuclear facilities have become more restrictive in the past decade, especially in areas that address the insider threat. As the insider threat receives greater credibility, regulations have been strengthened to increase the probability of detecting insider activity and to prevent removal of a significant quantity of Special Nuclear Material (SNM) from areas under control of the protective force.

NONE

1991-08-12

43

Aerospace Materials Quality Control Presentation  

NSDL National Science Digital Library

This PowerPoint document from the Aerospace Manufacturing Education Project looks into the topic of quality control of materials used in the aerospace industry. The presentation includes 27 slides and covers why quality control is important in this field. It also includes details about aerospace QC teams and techniques, including non-destructive testing.

2012-11-16

44

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

45

Environmental Degradation of Materials for Nuclear Waste Repositories Engineered Barriers  

SciTech Connect

Several countries are considering geological repositories for the storage of nuclear waste. Most of the environments for these repositories will be reducing in nature, except for the repository in the US, which is going to be oxidizing. For the reducing repositories, alloys such as carbon steel, copper, stainless steels and titanium are being evaluated. For the repository in the US, some of the most corrosion resistant commercially available alloys are being investigated. This paper presents a summary of the behavior of the different materials under consideration for the repositories and the current understanding of the degradation modes of the proposed alloys in ground water environments from the point of view of general corrosion, localized corrosion and environmentally assisted cracking.

Rebak, R B

2006-12-24

46

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

47

Cellulosic Insulation Material I. Overall Degradation Kinetics and Reaction Heats  

Microsoft Academic Search

Kinetic studies on the thermal and oxidative decomposition of untreated cellulosic insulation have been carried out with thermal analytical techniques (TGA and DSC) to provide input parameters for smoldering studies of this material. In dry nitrogen, the weight loss proceeds in one overall step that follows a diffusion-controlled rate law with parameters: A = 1.1 × 10 min and E

F. E. ROGERS; T. J. OHLEMILLER

1980-01-01

48

Integrated control of protein degradation in C. elegans muscle  

PubMed Central

Protein degradation is a fundamental cellular process, the genomic control of which is incompletely understood. The advent of transgene-coded reporter proteins has enabled the development of C. elegans into a model for studying this problem. The regulation of muscle protein degradation is surprisingly complex, integrating multiple signals from hypodermis, intestine, neurons and muscle itself. Within the muscle, degradation is executed by separately regulated autophagy-lysosomal, ubiquitin-proteasome and calpain-mediated systems. The signal-transduction mechanisms, in some instances, involve modules previously identified for their roles in developmental processes, repurposed in terminally differentiated muscle to regulate the activities of pre-formed proteins. Here we review the genes, and mechanisms, which appear to coordinately control protein degradation within C. elegans muscle. We also consider these mechanisms in the context of development, physiology, pathophysiology and disease models.

Lehmann, Susann; Shephard, Freya; Jacobson, Lewis A.; Szewczyk, Nathaniel J.

2012-01-01

49

The RNA exosome and proteasome: common principles of degradation control.  

PubMed

Defective RNAs and proteins are swiftly degraded by cellular quality control mechanisms. A large fraction of their degradation is mediated by the exosome and the proteasome. These complexes have a similar architectural framework based on cylindrical, hollow structures that are conserved from bacteria and archaea to eukaryotes. Mechanistic similarities have also been identified for how RNAs and proteins are channelled into these structures and prepared for degradation. Insights gained from studies of the proteasome should now set the stage for elucidating the regulation, assembly and small-molecule inhibition of the exosome. PMID:23989960

Makino, Debora L; Halbach, Felix; Conti, Elena

2013-08-29

50

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

51

Damage Assessment technologies for Prognostics and Proactive Management of Materials Degradation (PMMD)  

SciTech Connect

Summary for Special Session Invited paper "The Best of NPIC&HMIT 2009" The Nuclear Regulatory Commission has undertaken the Proactive Management of Materials Degradation (PMMD) program to lay the groundwork for defining proactive actions to manage degradation of materials in light water reactors (LWRs) including nuclear power plant structures, systems and components. The PMMD program is examining LWR component materials and the degradation phenomena that affect them. Of particular interest is how such phenomena can be monitored to predict degradation and prevent component failure.

Bond, Leonard J.; Doctor, Steven R.; Griffin, Jeffrey W.; Hull, Amy; Malik, Shah

2009-04-17

52

Damage Assessment Technologies for Prognostics and Proactive Management of Materials Degradation  

SciTech Connect

The Nuclear Regulatory Commission has undertaken a program to lay the groundwork for defining proactive actions to manage degradation of materials in light water reactors (LWRs). This paper discusses the U.S. Nuclear Regulatory Commission’s Proactive Management of Materials Degradation (PMMD) program and its application to nuclear power plant structures, systems and components. The PMMD program is examining LWR component materials and the degradation phenomena that affect them. Of particular interest is how such phenomena can be monitored to predict degradation and prevent component failure. Some forms of degradation, such as stress corrosion cracking, are characterized by a long initiation time followed by a rapid growth phase. Monitoring such long-term degradation will require new NDE methods and measurement procedures. A critical analysis of all reactor components is required to determine if new inspection strategies are required to effectively manage slow degradation mechanisms that may lead to component failure. As reactor lifetimes are extended, degradation mechanisms previously considered too long-term to be of consequence (such as concrete and wiring insulation degradation) may become more important. This paper includes a review of techniques with potential for sensing and monitoring degradation in its early stages and will concisely explain the basic principles of PMMD and its relationship to in-service inspection, condition based maintenance, and advanced diagnostics and prognostics.

Bond, Leonard J.; Doctor, Steven R.; Griffin, Jeffrey W.; Hull, Amy; Malik, Shah

2011-02-26

53

Electrochemical degradation of trichloroacetic acid in aqueous media: influence of the electrode material.  

PubMed

The electrochemical degradation of trichloroacetic acid (TCAA) in water has been analysed through voltammetric studies with a rotating disc electrode and controlled-potential bulk electrolyses. The influence of the mass-transport conditions and initial concentration of TCAA for titanium, stainless steel and carbon electrodes has been studied. It is shown that the electrochemical reduction of TCAA takes place prior to the massive hydrogen evolution in the potential window for all electrode materials studied. The current efficiency is high (> 18%) compared with those normally reported in the literature, and the fractional conversion is above 50% for all the electrodes studied. Only dichloroacetic acid (DCAA) and chloride anions were routinely detected as reduction products for any of the electrodes, and reasonable values of mass balance error were obtained. Of the three materials studied, the titanium cathode gave the best results. PMID:23530352

Esclapez, M D; Díez-García, M I; Sàez, V; Bonete, P; González-García, José

54

Degradation of dental ZrO2-based materials after hydrothermal fatigue. Part I: XRD, XRF, and FESEM analyses.  

PubMed

The aim was to investigate the effect of simulated low-temperature degradation (s-LTD) and hydrothermal fatigue on the degradation of three ZrO(2)-based dental materials. Lava, IPS, and NanoZr discs were randomly assigned to (1) Control-Storage in distilled water at 37°C; (2) Aging at 134°C for 5 h (s-LTD); (3) Thermocycling in saliva for 30,000 cycles (TF). XRD revealed that ZrO(2) m phase was identified in all groups but TF increased the m phase only for Lava. Under the FESEM, Lava showed no alterations under s-LTD, but displayed corrosion areas up to 60 µm wide after TF. We conclude that TF accelerated the degradation of Lava through an increase in the m phase and grain pull-out from the material surface. PMID:22447060

Perdigão, Jorge; Pinto, Ana M; Monteiro, Regina C C; Braz Fernandes, Francisco M; Laranjeira, Pedro; Veiga, João P

2012-03-23

55

Aqueous degradation of diclofenac by heterogeneous photocatalysis using nanostructured materials  

Microsoft Academic Search

The photocatalytic degradation of diclofenac (DIC), 2-[2?, 6?-(dichlorophenyl)amino]phenylacetic acid is investigated under near UV–Vis and UV irradiation, using commercial TiO2 P25, synthesized TiO2 (anatase and rutile) and functionalized multi-walled carbon nanotube (MWCNTox): anatase (10-MWCNTox–TiO2) suspensions as catalysts. Factors affecting the kinetics of the process, such as the type and load of photocatalyst, and the presence of dissolved O2, or addition

C. Martínez; M. I. Fernández; J. A. Santaballa; J. Faria

2011-01-01

56

Main chain acid-degradable polymers for the delivery of bioactive materials  

SciTech Connect

Novel main chain acid degradable polymer backbones and drug delivery systems comprised of materials capable of delivering bioactive materials to cells for use as vaccines or other therapeutic agents are described. The polymers are synthesized using monomers that contain acid-degradable linkages cleavable under mild acidic conditions. The main chain of the resulting polymers readily degrade into many small molecules at low pH, but remain relatively stable and intact at physiological pH. The new materials have the common characteristic of being able to degrade by acid hydrolysis under conditions commonly found within the endosomal or lysosomal compartments of cells thereby releasing their payload within the cell. The materials can also be used for the delivery of therapeutics to the acidic regions of tumors and other sites of inflammation.

Frechet, Jean M. J. (Oakland, CA); Standley, Stephany M. (Evanston, IL); Jain, Rachna (Milpitas, CA); Lee, Cameron C. (Cambridge, MA)

2012-03-20

57

Electron gun control of smart materials  

Microsoft Academic Search

Smart material patches are currently an impractical choice in applications requiring fine spatial resolution or control of complex areas. The static nature of electrodes, the conventional choice for control signal application to many smart materials, makes them unsuitable in these instances. To address this issue the use of electron guns as charge sources for smart material control is investigated in

John A. Main; George Nelson; Jeffrey Martin

1998-01-01

58

The History and Future of NDE in the Management of Nuclear Power Plant Materials Degradation  

SciTech Connect

The author has spent more than 25 years conducting engineering and research studies to quantify the performance of nondestructive evaluation (NDE) in nuclear power plant (NPP) applications and identifying improvements to codes and standards for NDE to manage materials degradation. This paper will review this fundamental NDE engineering/research work and then look to the future on how NDE can be optimized for proactively managing materials degradation in NPP components.

Doctor, Steven R.

2009-04-01

59

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

60

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

61

Phosphate Ions - Does Exposure Lead to Degradation of Cementitious Materials?  

SciTech Connect

An assessment of the potential effects of phosphate ions on cementitious materials was made through a review of the literature, contacts with concrete research personnel, and conduct of a "bench-scale" laboratory investigation. Results indicate that no harmful interactions occur between phosphate ions and cememtitious materials unless phosphates are present in form of phosphoric acid.

Naus, Dan J [ORNL; Mattus, Catherine H [ORNL; Dole, Leslie Robert [ORNL

2008-01-01

62

Materials Degradation and Altering Influence on Ultrasonic Scattering by the Light Statistical Approach in Austenitic Thermal Loaded Materials  

NASA Astrophysics Data System (ADS)

Materials degradation is a complicated process including multiple phenomena. Degradation is most critical in the near surface areas. These areas contain many types of defects and material phase changes, which are also caused by the degradation of the material. The information received from those material properties are measured with special ultrasonic probe optimised for surface measurement and with a 0° longitudinal wave probe. With help of combining measured data from large area and calculating depths of interest in the sound path (RF-signal) information can be gained to improve potential estimation of degradation levels. The technique is based on combination of three factors: using back scattered ultrasonic signals and induced leaky Rayleigh wave information (1), and simple statistical data analysis (2) in combination with optimised ultrasonic transducer (3). The back scattered ultrasonic signal is a measure of the amount of geometrical reflectors such as micro-pores, inclusions, precipitations, segregations, micro-cracks and cracks as well as of back-scattering from phase boundaries during fatigue damaging and increase of degradation inside the material. The leaky Rayleigh wave component is sensitive to surface properties as known from normal Rayleigh wave probes. Especially cracks cause strong effect on leaky Rayleigh wave. If the crack is deep it cancels the leaky Rayleigh wave signal totally.

Pitkänen, J.; Kauppinen, P.; Jeskanen, H.

2004-02-01

63

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

NASA Astrophysics Data System (ADS)

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

2011-02-01

64

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

65

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

PubMed

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. PMID:21361605

Verker, Ronen; Grossman, Eitan; Gouzman, Irina

2011-02-01

66

Corrosion degradation and prevention by surface modification of biometallic materials.  

PubMed

Metals, in addition to ceramics and polymers, are important class of materials considered for replacement of non-functional parts in the body. Stainless steel 316, titanium and titanium alloys, Co-Cr, and nitinol shape memory alloys are the most frequently used metallic materials. These alloys are prone to corrosion in various extents. This review briefly discusses the important biomaterials, their properties, and the physiological environment to which these materials are exposed. Corrosion performance of currently used metallic materials has been assessed and threat to the biocompatibility from corrosion products/metal ions is discussed. The possible preventive measures to improve corrosion resistance by surface modification and to increase the bioactivity of the metallic surfaces have also been discussed. Importance of the formation of oxide layers on the metal surface, another aspect of corrosion process, has been correlated with the host response. The gap areas and future direction of research are also outlined in the paper. PMID:17143737

Singh, Raghuvir; Dahotre, Narendra B

2006-12-02

67

Under tissue conditions degradable material and a method for its manufacturing  

US Patent & Trademark Office Database

This invention relates to a material that degrades after implantation into a patient's tissue, and resorbs into the patient's body, which material is manufactured of polymer, copolymer or polymer alloy. The material has a non-crystalline, i.e., amorphous structure and is molecularly oriented and reinforced by mechanical deformation. Further, the material can be formed into surgical devices, such as screws and pins, for implantation into a patient.

2003-01-07

68

Literature review of material flow control mechanisms  

Microsoft Academic Search

We review mechanisms which control the flow or material into and within a manufacturing line. These material flow control (MFC) mechanisms address the problem of when to release material into a manufacturing line and when workcentres should be authorized to produce. The MFC mechanisms reviewed include: Kanban, CONWIP, workload regulating, starvation avoidance, BORA, maximum load limit, MRP, the base stock

ROBERT J. GRAVES; JOHN M. KONOPKA; R. JOHN MILNE

1995-01-01

69

Degradation of CIGS Devices Studied using Controlled Moisture Ingress  

NASA Astrophysics Data System (ADS)

The damp heat (DH) study at 85 C and 85% relative humidity of unencapsulated standard CIGS devices fabricated at NREL exhibited various degradation modes. In the initial 20 h of exposure there is a steep decrease in efficiency, followed by a gradual decrease until 1000 h. The devices in this study were subjected to controlled moisture ingress. Periodic light and dark current-voltage (JV), capacitance-voltage (CV) measurements were carried out before, during, and after the course of exposure. Initial trends in CV and JV data show that the decrease in the device performance correlates to the degree of degradation of the TCO and the buffer layer during the first 20 h of exposure. However, from 20-100 h of exposure the abrupt changes in CV and decrease in Voc suggest the moisture penetration deeper into the junction which might alter junction interface. This paper attempts to correlate the JV and the CV data to understand the degradation mechanism during the initial hours of DH exposure in CIGS devices.

Sundaramoorthy, Rajalakshmi; Pern, John; Li, Jian; Gessert, Tim

2011-03-01

70

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 (35wt.%) 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 22kDa 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 48h. 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 48h 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

2013-04-16

71

Non-Arrhenius behavior for oxidative degradation of chlorosulfonated polyethylene materials  

Microsoft Academic Search

We have carried out oven aging studies on eight different commercial chlorosulfonated polyethylene cable jacket materials at temperatures ranging from 80°C to 150°C utilizing ultimate tensile elongation as the degradation parameter. For each material, the elongation results were time–temperature superposed at the lowest aging temperature. When the resulting empirical shift factors were tested for Arrhenius behavior, it was found that

Kenneth T. Gillen; Robert Bernstein; Mathew Celina

2005-01-01

72

Degradation behaviour of a composite material for thermal protection systems Part III Char characterization  

Microsoft Academic Search

In the former parts of this work (J. Mat. Sci.33 (1998) pp. 3137 and 3145) the kinetic characterisation and the mathematical modelling of the behaviour of an ablative material subjected to high heat fluxes were analysed. In this work the structure and morphology of the char produced from the degradation of the same ablative material, occurring as a consequence of

L. Torre; J. M. Kenny; G. Boghetich; A. Maffezzoli

2000-01-01

73

Degradation of thermal shield materials in the space radiation environment  

Microsoft Academic Search

Changes in temperature distribution data of Experimental Technology Satellite 4 after its 3 months mission term are discussed. Analysis of the data suggested that the thermal shields loose their function in the space radiation environment. The effect of energetic particles on the shield materials was investigated. Electron beams of 500 keV and proton beams of 900 keV were irradiated on

S. Shimoji; H. Kimura; M. Koitabashi; T. Imamura; R. Kasai; M. Matsushita

1983-01-01

74

Life assessment of creep degraded super alloy materials using ultrasound  

Microsoft Academic Search

The potential of ultrasound for characterizing creep damage in superalloy materials was evaluated. Several samples of IN-738, a superalloy used in many gas turbines, were heat treated at a temperature of 1520°F under 40-kpsi stress for times ranging from 500 to 900 h. Both ultrasonic attenuation and velocity measurements using a 20-MHz transducer were employed for characterizing the samples. It

J. Saniie; B. Panda; T. Wang; D. T. Nagle

1990-01-01

75

Anaerobic rumen SBR for degradation of cellulosic material  

Microsoft Academic Search

Hydrolysis of organic particulates under anaerobic conditions is generally regarded as the rate limiting step in solid digestion processes. Rumen-based ecosystems appear to achieve very high hydrolysis rates for cellulosic organic material. This study aimed at the development and demonstration of an anaerobic sequencing batch reactor (SBR) process operating with a rumen-based microbial inoculum. Fibrous alpha cellulose was used as

S. P. Barnes; J. Keller

2004-01-01

76

Effects of C N ratio and pH of raw materials on oil degradation efficiency in a compost fermentation process.  

PubMed

Waste oil treatment was attempted using a compost fermentation process. To develop a simple method for waste oil treatment, cheap and simple materials were used as compost materials. The fermentation experiment was performed using a domestic composter to determine the optimum conditions of the fermentation. Adjustment of the pH value during the compost fermentation was also important for progression of the oil degradation. When the pH value was not controlled, the pH value decreased quickly and reached about 2 and the oil degradation was stopped. Adding caustic lime to the raw materials caused the pH value of the compost to stabilize at approximately 7. The addition of a nitrogen source had a large effect on oil degradation during the compost fermentation. The optimum value of the C N ratio of the raw materials with pH control was between 10 and 40. When the C N ratio of the materials was adjusted to 10, 20, and 40, the rate constants for oil degradation were very similar. The rate constants for NH4+ consumption were also similar. Oil degradation efficiency reached 83.5% relative to the initial oil content in the compost materials. Repeated batch operation of the compost fermentation was carried out and the compost system could maintain good efficiency for oil degradation over several repeated batch operations. Finally, the compost system was applied to the treatment of recalled mayonnaise, with favorable results being obtained. PMID:16233481

Sasaki, Naozumi; Suehara, Ken-Ichiro; Kohda, Jiro; Nakano, Yasuhisa; Yang, Takuo

2003-01-01

77

Controlling Weapons-Grade Fissile Material  

ERIC Educational Resources Information Center

|Discusses the problems of controlling weapons-grade fissionable material. Projections of the growth of fission nuclear reactors indicates sufficient materials will be available to construct 300,000 atomic bombs each containing 10 kilograms of plutonium by 1990. (SL)|

Rotblat, J.

1977-01-01

78

Porous Material Development for Boundary Layer Control.  

National Technical Information Service (NTIS)

A description is presented of the development of a new porous material that was undertaken specifically for the application of area suction boundary layer control to underwater vehicles. This material was subsequently used in the manufacture of several hy...

G. May W. B. Giles

1964-01-01

79

Histological and molecular evaluation of iron as degradable medical implant material in a murine animal model.  

PubMed

A small animal model was established to evaluate the potential of iron as a degradable implant material. After insertion into the tail of mice, the implants gradually degraded over a clinically relevant time period of several months. Histological analysis and gene expression data from whole-genome microarray analyses indicated a limited inflammatory reaction. No evidence of cellular responses to excess iron ions was detected, suggesting that the iron degradation products were metabolically inactive. Iron-rich compounds could be detected in the vicinity of the implant and in individual cells distant from the implantation site. These results demonstrate that the mouse model could be useful for the primary in vivo evaluation of novel implant materials and that iron degradation products can accumulate in diverse organs of the body. PMID:22623368

Mueller, Peter P; Arnold, Sylvia; Badar, Muhammad; Bormann, Dirk; Bach, Friedrich-Wilhelm; Drynda, Andreas; Meyer-Lindenberg, Andrea; Hauser, Hansjörg; Peuster, Matthias

2012-05-24

80

BIOBASED MATERIALS OF CONTROLLED PERFORMANCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Efforts are being made worldwide to design and develop materials from biobased polymers. Natural polymers are inherently biodegradable, however, when processed with other polymers, plasticizers and additives or when chemically crosslinked or enzymatically modified, their biodegradation behavior is i...

81

Advanced Material Handling Equipment Controls.  

National Technical Information Service (NTIS)

In order to improve the productivity, safety and reliability of Marine Corps Material Handling Equipment (MHE) in a combat environment, this investigation was divided between two specific aspects of MHE operations. The predominant of these is High Speed C...

J. A. Lusher W. V. Miller

1991-01-01

82

High temperature PD degradation characteristics in bulk and interfaces of insulating materials for power cables  

Microsoft Academic Search

In order to check the possibility of raising the service temperature of installed power cables, PD degradation characteristics in materials for cable insulation and their interfaces were investigated at high temperatures (70-110°C). With increasing temperature, the tree inception voltage of XLPE bulk decreased below 90°C and increased above 90°C. The degradation at the interfaces was also investigated and the EPR

Atsushi Maruyama; Fumitaka Komori; Yasuo Suzuoki; Tatsuki Okamoto; Tatsuya Nagata

2000-01-01

83

Tensile testing as a novel method for quantitatively evaluating bioabsorbable material degradation.  

PubMed

Bioabsorbable metallic materials have become a topic of interest in the field of interventional cardiology because of their potential application in stents. A well-defined, quantitative method for evaluating the degradation rate of candidate materials is currently needed in this area. In this study, biodegradation of 0.25-mm iron and magnesium wires was simulated in vitro through immersion in cell-culture medium with and without a fibrin coating (meant to imitate the neointima). The immersed samples were corroded under physiological conditions (37°C, 5% CO(2)). Iron degraded in a highly localized manner, producing voluminous corrosion product while magnesium degraded more uniformly. To estimate the degradation rate in a quantitative manner, both raw and corroded samples underwent tensile testing using a protocol similar to that used on polymeric nanofibers. The effective ultimate tensile stress (tensile stress holding constant cross-sectional area) was determined to be the mechanical metric that exhibited the smallest amount of variability. When the effective tensile stress data were aggregated, a statistically significant downward, linear trend in strength was observed in both materials (Fe and Mg) with and without the fibrin coating. It was also demonstrated that tensile testing is able to distinguish between the higher degradation rate of the bare wires and the lower degradation rate of the fibrin-coated wires with confidence. PMID:22847989

Bowen, Patrick K; Gelbaugh, Jesse A; Mercier, Phillip J; Goldman, Jeremy; Drelich, Jaroslaw

2012-07-30

84

Erosion induced controllable release of gliclazide encapsulated inside degradable polymeric particles.  

PubMed

The microphase inversion of water-insoluble poly(L-lactide), "poly[(L-lactide)-co-glycolide] and polylactide-block-poly(ethylene oxide)-block-polylactide from THF to water can result in narrowly distributed stable particles. Gliclazide, a commercial drug, can be encapsulated inside during the process. The formation and degradation of such particles was studied by laser light scattering. In comparison with the corrosion of a bulk material, the degradation of each particle is so fast that we only detect the decrease of the particle number, not the corrosion of individual particles. Therefore, the degradation is a "one-by-one" random process, just like the chemical reaction of molecules in solution. The disappearing rate of the particle number is nearly independent of time, ideal for the controlled release of drugs encapsulated inside. The amount of encapsulated gliclazide depends on the copolymer's hydrophobicity (composition), while the releasing rate mainly is, directly related to the disappearing rate of the particles. The correlation between the fluorescence intensity and the degradation was used to study the kinetics of gliclazide releasing. The releasing pattern is controllable with a proper choice of the drug loading, copolymer composition, pH and temperature. PMID:15468221

Zhao, Yue; Chen, Wenna; Cai, Qing; Wang, Shenguo; Bo, Jun; Wu, Chi

2004-03-15

85

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

86

Report of the Material Control and Material Accounting Task Force. Volume 2. The Role of Material Control and Material Accounting in the Safeguards Program.  

National Technical Information Service (NTIS)

The Material Control and Material Accounting Task Force defined the roles, objectives, and goals of material control and material accounting within the domestic Safeguards Program for licensed strategic special nuclear material (SSNM). The Task Force then...

F. L. Crane W. D. Altman W. B. Brown R. J. Dube J. W. Hockert

1978-01-01

87

Probabilistic material degradation model for aerospace materials subjected to high temperature, mechanical and thermal fatigue, and creep  

NASA Astrophysics Data System (ADS)

A probabilistic general material strength degradation model has been developed for structural components of aerospace propulsion systems subjected to diverse random effects. The model has been implemented in two FORTRAN programs, PROMISS (Probabilistic Material Strength Simulator) and PROMISC (Probabilistic Material Strength Calibrator). PROMISS calculates the random lifetime strength of an aerospace propulsion component due to as many as eighteen diverse random effects. Results are presented in the form of probability density functions and cumulative distribution functions of lifetime strength. PROMISC calibrates the model by calculating the values of empirical material constants.

Boyce, L.

1992-07-01

88

Degradable polyester scaffolds with controlled surface chemistry combining minimal protein adsorption with specific bioactivation.  

PubMed

Advanced biomaterials and scaffolds for tissue engineering place high demands on materials and exceed the passive biocompatibility requirements previously considered acceptable for biomedical implants. Together with degradability, the activation of specific cell–material interactions and a three-dimensional environment that mimics the extracellular matrix are core challenges and prerequisites for the organization of living cells to functional tissue. Moreover, although bioactive signalling combined with minimization of non-specific protein adsorption is an advanced modification technique for flat surfaces, it is usually not accomplished for three-dimensional fibrous scaffolds used in tissue engineering. Here, we present a one-step preparation of fully synthetic, bioactive and degradable extracellular matrix-mimetic scaffolds by electrospinning, using poly(D,L-lactide-co-glycolide) as the matrix polymer. Addition of a functional, amphiphilic macromolecule based on star-shaped poly(ethylene oxide) transforms current biomedically used degradable polyesters into hydrophilic fibres, which causes the suppression of non-specific protein adsorption on the fibres’ surface. The subsequent covalent attachment of cell-adhesion-mediating peptides to the hydrophilic fibres promotes specific bioactivation and enables adhesion of cells through exclusive recognition of the immobilized binding motifs. This approach permits synthetic materials to directly control cell behaviour, for example, resembling the binding of cells to fibronectin immobilized on collagen fibres in the extracellular matrix of connective tissue. PMID:21151163

Grafahrend, Dirk; Heffels, Karl-Heinz; Beer, Meike V; Gasteier, Peter; Möller, Martin; Boehm, Gabriele; Dalton, Paul D; Groll, Jürgen

2011-01-01

89

Correlation of electrical reactor cable failure with materials degradation  

SciTech Connect

Complete circuit failure (shortout) of electrical cables typically used in nuclear power plant containments is investigated. Failure modes are correlated with the mechanical deterioration of the elastomeric cable materials. It is found that for normal reactor operation, electrical cables are reliable and safe over very long periods. During high temperature excursions, however, cables pulled across corners under high stress may short out due to conductor creep. Severe cracking will occur in short times during high temperatures (>150/sup 0/C) and in times of the order of years at elevated temperatures (100/sup 0/C to 140/sup 0/C). A theoretical treatment of stress distribution responsible for creep and for cracking by J.E. Reaugh of Science Applications, Inc. is contained in the Appendix. 29 refs., 32 figs.

Stuetzer, O.M.

1986-03-01

90

In vivo tissue response to resorbable silica xerogels as controlled-release materials  

Microsoft Academic Search

Biodegradable, controlled-release carrier materials with non-toxic degradation products are valuable for local delivery of biologically active molecules. Previously, it was shown that room-temperature processed silica sol–gels (or xerogels) are porous, resorbable materials that can release molecules of various sizes in a controlled, time dependent manner. Previous in vitro studies also demonstrated benefits of silica xerogels as controlled-release materials for the

Shula Radin; Gehan El-Bassyouni; Edward J. Vresilovic; Evert Schepers; Paul Ducheyne

2005-01-01

91

Development of materials resistant to metal dusting degradation.  

SciTech Connect

Metal dusting corrosion has been a serious problem in the petroleum and petrochemical industries, such as reforming and syngas production systems. This form of deterioration has led to worldwide material loss for 50 years. For the past three years, we have studied the mechanism of metal dusting for Fe- and Ni-base alloys. In this report, we present a correlation between the weight loss and depth of pits that form in Ni-base alloys. Nickel-base alloys were also tested at 1 and 14.8 atm (210 psi), in a high carbon activity environment. Higher system pressure was found to accelerate corrosion in most Ni-base alloys. To reduce testing time, a pre-pitting method was developed. Mechanical scratches on the alloy surface led to fast metal dusting corrosion. We have also developed preliminary data on the performance of weldments of several Ni-base alloys in a metal dusting environment. Finally, Alloy 800 tubes and plates used in a reformer plant were examined by scanning electron microscopy, energy dispersive X-ray, and Raman spectroscopy. The oxide scale on the surface of the Alloy 800 primarily consists of Fe{sub 1+x}Cr{sub 2-X}O{sub 4} spinel phase with high Fe content. Carbon can diffuse through this oxide scale. It was discovered that the growth of metal dusting pits could be stopped by means of a slightly oxidized alloy surface. This leads to a new way to solve metal dusting problem.

Natesan, K.; Zeng, Z.

2006-04-24

92

LANL material control indicator analysis program  

SciTech Connect

The possibility of SNM diversion/theft is a major concern to organizations charged with control of Special Nuclear Material (SNM). Several methods have been put in place to deter and or detect losses of SNM. These include inventory, material control physical barriers and the use of material control indicators (MCI). This paper will discuss the multi-tier LANL review mechanism for detecting and isolating missing SNM by the use of Material Control Indicators. Los Alamos MCI include daily analysis and review of item adjustments, weekly review of item adjustments, monthly analysis and review of inventory differences by Process Status and by Material Balance Areas, and quarterly analysis and review of Propagation of Variance. This paper, by providing an introduction to a site-specific application of MCI's, assists safeguards professionals in understanding the importance of an MCI Program in detecting accumulation for subsequent diversion/theft of special nuclear material.

Roybal, G. S. (Gilbert S.)

2001-01-01

93

The effects of 1 kW class arcjet thruster plumes on spacecraft charging and spacecraft thermal control materials  

Microsoft Academic Search

Arcjet thrusters are soon to be used for north\\/south stationkeeping on commercial communications satellites. A series of tests was performed to evaluate the possible effects of these thrusters on spacecraft charging and the degradation of thermal control material. During the tests the interaction between arcjet plumes and both charged and uncharged surfaces did not cause any significant material degradation. In

A. Bogorad; D. A. Lichtin; C. Bowman; J. Armenti; E. Pencil; C. Sarmiento

1992-01-01

94

Controlling the Degradation of Covalently Cross-linked Carboxymethyl Chitosan Utilizing Bimodal Molecular Weight Distribution  

Microsoft Academic Search

Degradability is often a critical property of materials utilized in tissue engineering. Although chitosan, a naturally derived polysaccharide, is an attractive material due to its biocompatibility and ability to form scaffolds, its slow and uncontrollable rate of degradation can be an undesirable feature. In this study, we characterize chitosan derivatives formed using a combination of carboxymethylation and a bimodal molecular

Lu Guangyuan; Sheng Baiyang; Wang Gan; Wei Yujun; Gong Yandao; Zhang Xiufang; Zhang Lihai

2009-01-01

95

Hydrogen peroxide decomposition and quinoline degradation in the presence of aquifer material  

Microsoft Academic Search

Hydrogen peroxide is used as a source of oxygen for enhanced bioremediation of contaminated subsurface environments and as an oxidant in engineered systems. While a number of aspects of hydrogen peroxide chemistry are well understood, the importance and relationship between hydrogen peroxide decomposition and contaminant degradation in the presence of subsurface materials is not clear. We report on batch and

Christopher M. Miller; Richard L. Valentine

1995-01-01

96

Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository  

SciTech Connect

This paper reviews the state-of-the-art understanding of the degradation processes by the Yucca Mountain Project (YMP) with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the first 10,000-years after repository closure. This paper provides an overview of the degradation of the waste packages and drip shields in the repository after permanent closure of the facility. The degradation modes discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking, and hydrogen induced cracking of Alloy 22 and titanium alloys. The effects of microbial activity and radiation on the degradation of Alloy 22 and titanium alloys are also discussed. Further, for titanium alloys, the effects of fluorides, bromides, and galvanic coupling to less noble metals are considered. It is concluded that the materials and design adopted will provide sufficient safety margins for at least 10,000-years after repository closure.

K.G. Mon; F. Hua

2005-04-12

97

Material Control for a Reprocessing Plant.  

National Technical Information Service (NTIS)

Adequate control of special nuclear material (SNM) implies a basic knowledge of the quantities of SNM processed through or contained within a fuels processing facility with sufficient accuracy that diversion of the SNM for deleterious purposes can be dete...

D. Rundquist G. Bray S. Donelson J. Glancy T. Gozani

1976-01-01

98

Low Cycle Fatigue Evaluation of Duplex Stainless Steel with Material Degradation Effect Under Torsional Load  

NASA Astrophysics Data System (ADS)

Monotonic torsional and pure torsional low cycle fatigue (LCF) tests with artificial degradation were performed on duplex stainless steel (CF8M). CF8M is used in pipes and valves in a nuclear reactor coolant system. It was aged at 430°C for 3600 hrs. Through the monotonic and LCF tests, it is found that mechanical properties (i.e., yield strength, strain hardening exponent, strength coefficient etc.) are increased and fatigue life (Nf) is decreased with degradation of material. The relationship between shear strain amplitude (?a) and Nf was proposed.

Kwon, Jae Do; Park, Joong Cheul; Kim, Joong Hyoung

99

Role of synergy between wear and corrosion in degradation of materials  

NASA Astrophysics Data System (ADS)

Tribocorrosion is a term used to describe the material degradation due to the combination of electrochemical and tribological processes. Due to a synergetic effect, the material loss can be larger than the sum of the losses due to wear and corrosion acting separately. In this thesis, the synergy of wear and corrosion was investigated for different types of material, namely the Ti-6Al-4V alloy, the SS316L stainless steel coated with a thin film of Diamond Like Carbon (DLC), and the SS301 stainless steel coated with a thin film of chromium silicon nitride (CrSiN). A tribocorrosion apparatus was designed and constructed to conduct wear experiments in corrosive media. Sliding ball-on-plate configuration was used in this design, where the contact between the ball and the specimen is totally immersed in the test electrolyte. The specimen was connected to a potentiostat to control its electrochemical parameters, namely the potential and the current. Electrochemical techniques were used to control the kinetics of corrosion reactions, and therefore it was possible to assess separately the role of corrosion and wear in the total degradation of material, and to evaluate the synergy between them. For Ti-6Al-4V, it was found that the corrosion and tribocorrosion depend strongly on the structure of the material. The alpha-equiaxed microstructure with fine dispersed beta-phase exhibited the best corrosion resistance. The corrosion resistance was found to decrease when the basal plane was preferentially aligned parallel to the surface, which is attributed to a low resistance to charge transfer in the oxide films formed on this plane. On the other hand, when wear and corrosion were involved simultaneously, the oxide layer protecting the substrate against dissolution was mechanically destroyed leading to a high corrosion rate. It was found that the hardness was the most important factor determining the tribocorrosion behavior of the Ti-6Al-4V alloy; samples with high hardness exhibited less mechanical wear, less wear-enhanced corrosion, and less corrosion-enhanced wear. For DLC coatings, it was found that interface engineering plays a crucial role in the tribocorrosion behavior of DLC films. DLC films with nitrided interface layer (SSN3hDLC) were shown to have very poor tribocorrosion resistance; the DLC film delaminated from the substrate after 50 cycles of sliding wear at 9 N load in Ringer's solution. It should be mentioned that a previous study performed at Ecole Polytechnique de Montreal [4] has shown that the same coating resisted 1800 cycles of dry wear at 22 N without delamination. This demonstrates clearly the effect of corrosion on the wear resistance of DLC films. The use of a-SiN:H bond layer between the SS316L substrate and the DLC film improved significantly the tribocorrosion behavior of the coating. This layer acts as a barrier against corrosion reaction; the polarization resistance was 5.76 GO.cm2 compared to 27.5 MO.cm2 and 1.81 MO.cm2 for the DLC-coated SS316L with nitrided interface layer and the bare substrate, respectively. For CrSiN coatings, it was also shown that nitriding treatment of the substrate prior to deposition reduces significantly the tribocorosion resistance of the CrSiN-coated SS301 substrates. This is attributed to the peculiar morphology of the nitrided surface prior to deposition. The high relives at the grain boundaries of the substrate may be the reason for the generation, during sliding wear, of defects in the film, which makes the infiltration of the liquid easier, and consequently leads to the destruction of the CrSiN film.

Azzi, Marwan

100

Materials control and waste on building sites  

Microsoft Academic Search

The author argues that although waste occurs from many causes, it is sometimes beyond the influence of the building firm and that material control starts at design stage, as the final design should allow for the effective handling and convenient manoeuvering of materials and components of preferred sizes during construction.

Adnan Enshassi

1996-01-01

101

A Note on a Material Control Problem  

Microsoft Academic Search

In a material control problem by Hodgson and Lowe [4], an iterative algorithm is used to minimize a function which considers, for n item classes, the setup cost, inventory carrying cost, and warehouse material handling cost. We show that each subproblem in this iterative scheme can be reduced to a convex program. As a by-product of this result, we show

Siegfried Schaible; Timothy J. Lowe

1983-01-01

102

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

103

Towards Coherent Control of Energetic Material Initiation  

NASA Astrophysics Data System (ADS)

We present direct optical initiation (DOI) of energetic materials using coherent control of localized energy deposition. DOI requires depositing energy into the material to produce a critical size hot spot, which allows propagation of the reaction and thereby initiation. The hot spot characteristics needed for growth to initiation can be studied using quantum controlled initiation (QCI). Achieving QCI in condensed phase energetic materials requires optimally shaped ultrafast laser pulses to coherently guide the energy flow along desired paths. As a test of our quantum control capabilities we have successfully demonstrated our ability to control the reaction pathway of the chemical system stilbene. An acousto-optical modulator based pulse shaper was used at 266 nm, in a shaped pump/supercontinuum probe technique, to enhance and suppress the relative yields of the cis- to trans-stilbene isomerization. The quantum control techniques tested in the stilbene experiments are currently being used to investigate QCI of the explosive hexanitroazobenzene (HNAB).

Greenfield, M. T.; McGrane, S. D.; Scharff, R. J.; Moore, D. S.

2009-12-01

104

Materials for noise and vibration control  

SciTech Connect

A mini-handbook for the selection and application of commonly available noise and vibration control materials is presented. Basic information on the characteristics of sound absorptive, sound barrier, vibration damping, and vibration isolation materials are provided. Materials include: diaphragm absorbers, resonant absorbers, perforated panel absorbers, sprayon absorbers, composite barriers, cord pads, felt pads, elastomers, and metal laminates. Effects of temperature and thickness on the effectiveness of the absorbing or barrier materials are determined. Methods of estimating noise transmission loss are described. (numerous diagrams, drawings, graphs, tables)

Purcell, W.E.

1980-07-01

105

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

106

Evaluation of a degradable shape-memory polymer network as matrix for controlled drug release.  

PubMed

Degradable shape-memory polymers are multifunctional materials with broad applicability for medical devices. They are designed to acquire their therapeutically relevant shape and mechanical properties after implantation. In this study, the potential of a completely amorphous shape-memory polymer matrix for controlled drug release was comprehensively characterized according to a four step general strategy which provides concepts for validating multifunctional materials for pharmaceutical applications. Independent functionalities are thereby crucial for fully exploiting the potential of the materials. The copolyester urethane network was synthesized by crosslinking star-shaped tetrahydroxy telechelics of oligo[(rac-lactide)-co-glycolide] with an aliphatic diisocyanate. In step 1 of the four step characterization procedure, this material showed the thermal and mechanical properties, which are required for the shape-memory effect under physiological conditions. Shape recovery could be realized by a one-step or a multi-step methodology. In step 2, feasibility of drug loading of pre-formed shape-memory networks has been demonstrated with drugs of different hydrophobicities. The presence of drugs did not disturb the material's functionalities directly after loading (step 3) and under release conditions (step 4). A predictable release of about 90% of the payload in 80 days was observed. Overall, the synthesized amorphous polymer network showed three independent functionalities, i.e., a shape-memory effect combined with biodegradability and controlled drug release. PMID:19470395

Wischke, Christian; Neffe, Axel T; Steuer, Susi; Lendlein, Andreas

2009-05-24

107

Towards coherent control of energetic material initiation  

SciTech Connect

Direct optical initiation (DOI) of energetic materials using coherent control of localized energy deposition requires depositing energy into the material to produce a critical size hot spot, which allows propagation of the reaction and thereby initiation, The hot spot characteristics needed for growth to initiation can be studied using quantum controlled initiation (QCI). Achieving direct quantum controlled initiation (QCI) in condensed phase systems requires optimally shaped ultrafast laser pulses to coherently guide the energy flow along the desired paths. As a test of our quantum control capabilities we have successfully demonstrated our ability to control the reaction pathway of the chemical system stilbene. An acousto-optical modulator based pulse shaper was used at 266 nm, in a shaped pump/supercontinuum probe technique, to enhance and suppress th relative yields of the cis- to trans-stilbene isomerization. The quantum control techniques tested in the stilbene experiments are currently being used to investigate QCI of the explosive hexanitroazobenzene (HNAB).

Greenfield, Margo T [Los Alamos National Laboratory; Mcgrane, Shawn D [Los Alamos National Laboratory; Scharff, R Jason [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

2009-01-01

108

Damage Assessment Technologies for Prognostics and Proactive Management of Materials Degradation (PMMD)  

SciTech Connect

There are approximately 440 operating reactors in the global nuclear power plant (NPP) fleet with an average age greater than 20 years and design lives of 30 or 40 years. The United States is currently implementing license extensions of 20 years on many plants, and consideration is now being given to the concept of "life-beyond-60", license extension from 60 to 80 years and potentially longer. In almost all countries with NPPs, authorities are looking at some form of license renewal program. In support of NPP license renewal over the past decade, various national and international programs have been initiated. This paper discusses stressor-based prognostics and its role as part of emerging trends in Proactive Management of Materials Degradation (PMMD) applied to nuclear power plant structures, systems and components (SSC). The paper concisely explains the US Nuclear Regulatory Commission’s (NRC) program in PMMD, the basic principles of PMMD and its relationship to advanced diagnostics and prognostics. It then provides an assessment of the state of maturity for diagnostic and prognostic technologies, including NDE and related technologies for damage assessment, and the current trend to move from condition-based maintenance to on-line monitoring for advanced diagnostics and stressor-based prognostics. This development in technology requires advances in sensors; better understanding of what and how to measure within a nuclear power plant; enhanced data interrogation, communication and integration; new prediction models for damage/aging evolution; system integration for real-world deployments and quantification of uncertainties in what are inherently ill-posed problems. Stressor-based analysis is based upon understanding which stressor characteristics (e.g., pressure transients) provide a percussive indication that can be used for mapping subsequent damage due to a specific degradation mechanism. The resulting physical damage and the associated decrease in asset performance start with the application of a stressor to the component. The design engineer sets the desired operational stressor intensity level so that the degradation in the physical state of the component occurs slowly enough for the equipment to last for its required design life. In general, when the design limit of a stressor is exceeded (during operation), the component life expectancy starts to shorten. Conversely, careful control of operational parameters can enable extension of component life beyond that normally expected. For systems which were conservatively designed (such as nuclear power plants), the premise of the prognostic methodology is that a relationship can be derived that will allow a much more accurate projection of the remaining useful life. This is achieved by focusing on trending the stressor characterics rather than trending a performance metric. In this trend analysis example, the slope of the trended parameter is thought to give a measure of the degradation rate of the component performance. This is assumed to be a function of the rate of decline in the physical integrity of the equipment. Experience from measurements has shown this assumption to be true if one accounts for the nonlinearity which can occur between physical attributes and their effects on performance.

Bond, Leonard J.; Doctor, Steven R.; Griffin, Jeffrey W.; Hull, Amy B.; Malik, Shah

2009-01-16

109

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

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Nuclear material control and accounting for strategic...REGULATORY COMMISSION (CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR...Material § 74.51 Nuclear material control and accounting for...

2009-01-01

110

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

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Nuclear material control and accounting for strategic...REGULATORY COMMISSION (CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR...Material § 74.51 Nuclear material control and accounting for...

2010-01-01

111

Report of the Material Control and Material Accounting Task Force. Executive Summary.  

National Technical Information Service (NTIS)

The Material Control and Material Accounting Task Force defined the roles, objectives, and goals of material control and material accounting within the domestic Safeguards Program for licensed strategic special nuclear material (SSNM). The Task Force then...

F. L. Crane W. D. Altman W. B. Brown R. J. Dube J. W. Hockert

1978-01-01

112

Report of the Material Control and Material Accounting Task Force. Volume 1. Summary.  

National Technical Information Service (NTIS)

The Material Control and Material Accounting Task Force defined the roles, objectives, and goals of material control and material accounting within the domestic Safeguards Program for licensed strategic special nuclear material (SSNM). The Task Force then...

F. L. Crane W. D. Altman W. B. Brown R. J. Dube J. W. Hockert

1978-01-01

113

Effects of mulching materials on nitrogen mineralization, nitrogen availability and poplar growth on degraded agricultural soil  

Microsoft Academic Search

Nitrogen (N) is usually the most limiting nutrient in degraded agricultural soils and affects the growth and ecological function\\u000a of poplar (Populus spp.) plantations. We hypothesized that application of organic mulch would improve soil nitrogen availability and increase\\u000a tree growth, while the quality of mulching materials would alter the supply of essential nutrients. In this study, poplar\\u000a plantations were established

Shengzuo FangBaodong; Baodong Xie; Dong Liu; Jiujun Liu

2011-01-01

114

Proactive Management of Materials Degradation - A Review of Principles and Programs  

SciTech Connect

The U.S. Nuclear Regulatory Commission (NRC) has undertaken a program to lay the technical foundation for defining proactive actions so that future degradation of materials in light water reactors (LWRs) is limited and, thereby, does not diminish either the integrity of important LWR components or the safety of operating plants. This technical letter report was prepared by staff at Pacific Northwest National Laboratory in support of the NRC Proactive Management of Materials Degradation (PMMD) program and relies heavily on work that was completed by Dr. Joseph Muscara and documented in NUREG/CR-6923. This report concisely explains the basic principles of PMMD and its relationship to prognostics, provides a review of programs related to PMMD being conducted worldwide, and provides an assessment of the technical gaps in PMMD and prognostics that need to be addressed. This technical letter report is timely because the majority of the U.S. reactor fleet is applying for license renewal, and many plants are also applying for increases in power rating. Both of these changes could increase the likelihood of materials degradation and underline, therefore, the interest in proactive management in the future.

Bond, Leonard J.; Doctor, Steven R.; Taylor, Theodore T.

2008-08-28

115

Control of atomic layer degradation on Si substrate  

SciTech Connect

To develop 32 nm node devices, the degradation of atomic layers on the surface of Si substrates must be controlled. During the etching of a SiO{sub 2} or Si{sub 3}N{sub 4} hard mask or sidewall, the surface of Si is attended due to exposure to fluorocarbon plasma. The authors have quantitatively evaluated the relationship between the energy of incident ions and the thickness of the fluorocarbon polymer for a CH{sub 2}F{sub 2}/CF{sub 4}/Ar/O{sub 2} plasma in a dual frequency CCP system. At a fixed ion energy the thickness of the damage layer (T{sub d}) basically depended on the thickness of the fluorocarbon polymer (T{sub C-F}). When the T{sub C-F} was changed by controlling the O/CF{sub x} gas ratio, T{sub d} had a minimum thickness under the conditions at balance point: P{sub b}, under which the T{sub C-F} was nearly equal to ion penetration depth: D{sub p}. Using molecular dynamics simulation, reaction around the transition from SiO{sub 2} to Si was clarified. The damage was done to the Si before the SiO{sub 2} was completely removed, and the largest T{sub d} was observed when the SiO{sub 2} was etched off. After that, T{sub C-F} began to increase because there was no longer an outflux of O from SiO{sub 2} and the damage decreased as the unstable SiF{sub x} species in the damaged layer desorbed. Once the T{sub C-F} became thicker than the ion penetration depth, the damaged layer got buried and T{sub d} stopped changing. When the ion penetration depth was controlled to be equal to T{sub C-F} in a steady state under low ion energy conditions, the T{sub d} was reduced to less than 1 nm.

Nakamura, Y.; Tatsumi, T.; Kobayashi, S.; Kugimiya, K.; Harano, T.; Ando, A.; Kawase, T.; Hamaguchi, S.; Iseda, S. [LSI Production Division 1, Sony Semiconductor Kyushu Corp., 1883-43 Tsukuba-machi, Isahaya-shi, Nagasaki 854-0065 (Japan); Semiconductor Technology Development Division, Sony Corp., 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); LSI Production Division 1, Sony Semiconductor Kyushu Corp., 1883-43 Tsukuba-machi, Isahaya-shi, Nagasaki 854-0065 (Japan); Semiconductor Technology Development Division, Sony Corp., 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); LSI Production Division 1, Sony Semiconductor Kyushu Corp., 1883-43 Tsukuba-machi, Isahaya-shi, Nagasaki 854-0065 (Japan)

2007-07-15

116

Electron-beam treatment of poly(lactic acid) to control degradation profiles  

Microsoft Academic Search

Bioresorbable polymers such as polylactide (PLA) and polylactide-co-glycolide (PLGA) have been used successfully as biomaterials in a wide range of medical applications. However, their slow degradation rates and propensity to lose strength before mass have caused problems. A central challenge for the development of these materials is the assurance of consistent and predictable in vivo degradation. Previous work has illustrated

Marie-Louise Cairns; Glenn R. Dickson; John F. Orr; David Farrar; Klaus Hawkins; Fraser J. Buchanan

2011-01-01

117

DEGRADATION OF EMISSIONS CONTROL PERFORMANCE OF WOODSTOVES IN CRESTED BUTTE, CO  

EPA Science Inventory

The report discusses the degradation of emissions control performance of woodstoves in Crested Butte, Colorado. Four seasons of field monitoring of EPA-certified woodstoves in and around Crested Butte has demonstrated some significant failures in emissions control performance. In...

118

The nuclear materials control technology briefing book  

SciTech Connect

As national and international interests in nuclear arms control and non-proliferation of nuclear weapons, intensify, it becomes ever more important that contributors be aware of the technologies available for the measurement and control of the nuclear materials important to nuclear weapons development. This briefing book presents concise, nontechnical summaries of various special nuclear material (SNM) and tritium production monitoring technologies applicable to the control of nuclear materials and their production. Since the International Atomic Energy Agency (IAEA) operates a multinational, on-site-inspector-based safeguards program in support of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), many (but not all) of the technologies reported in this document are in routine use or under development for IAEA safeguards.

Hartwell, J.K.; Fernandez, S.J.

1992-03-01

119

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

120

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

121

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

122

Aerospace Materials Quality Control: Instructor Notes  

NSDL National Science Digital Library

This document from the Aerospace Manufacturing Education Project is intended to accompany a PowerPoint presentation on the topic of quality control of materials used in the aerospace industry. That presentation is available for download here. The presentation and notes will help students understand why quality control is important in this field. They also include details about aerospace QC teams and techniques, including non-destructive testing. These instructor notes also include links to a number of useful online references.

2012-11-14

123

Proceedings of the sixth international symposium on environmental degradation of materials in nuclear power systems - water reactors  

SciTech Connect

The operation of water reactor nuclear power plants provides a significant fraction of the world's electric power generation. At the end of 1992, approximately 360 such plants were in operation, representing a total generating capacity of 320 GWe. As these plants age, and as new designs evolve, the impact of environmental degradation of reactor materials on reliability and power plants economics is receiving increasing recognition. The Sixth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors was organized to provide a forum for exchange of the results of research and plant operating experience associated with material degradation.

Gold, R.E.; Simonen, E.P. (eds.)

1993-01-01

124

Material control for a reprocessing plant  

Microsoft Academic Search

Adequate control of special nuclear material (SNM) implies a basic knowledge of the quantities of SNM processed through or contained within a fuels processing facility with sufficient accuracy that diversion of the SNM for deleterious purposes can be detected in a timely manner. This report to the Lawrence Livermore Laboratory (LLL) describes the primary process streams containing plutonium that are

D. Rundquist; G. Bray; S. Donelson; J. Glancy; T. Gozani; L. Harris; R. McNamera; D. Pence; M. Ringham

1976-01-01

125

Quality control materials in food composition databanks  

Microsoft Academic Search

Reference materials (RMs) have emerged with the aim of improving analytical methods performance, in what regards to their validation, calibration, uncertainty, training and internal quality control, and of increasing the comparability of measurements between laboratories. Due to their unquestionable importance, but still low availability and high cost, the present work has determined the suitability of infant formula, powdered garlic, tea

I. Castanheira; C. Abrantes; M. Batista; I. Coelho; A. Sanches-Silva

2009-01-01

126

Material mix control in cement plant automation  

Microsoft Academic Search

The objective of this article is the development of a novel raw material mix proportion control algorithm for a cement plant raw mill, so as to maintain preset target mix proportion at the raw mill outlet. This algorithm utilizes one of the most basic and important tools of numerical linear algebra, the singular value decomposition (SVD), for calculation of raw

A. K. Swain

1995-01-01

127

The relation of microdamage to fracture and material property degradation in human cortical bone tissue  

NASA Astrophysics Data System (ADS)

This dissertation investigates the relation of microdamage to fracture and material property degradation of human cortical bone tissue. Fracture resistance and fatigue crack growth of microcracks were examined experimentally and material property degradation was examined through theoretical modeling. To investigate the contribution of microdamage to static fracture resistance, fracture toughness tests were conducted in the transverse and longitudinal directions to the osteonal orientation of normal bone tissue. Damage accumulation was monitored by acoustic emission during testing and was spatially observed by histological observation following testing. The results suggested that the propagation of the main crack involved weakening of the tissue by diffuse damage at the fracture plane and by formation of linear microcracks away from the fracture plane for the transverse specimens. For the longitudinal specimens, growth of the main crack occurred in the form of separations at lamellar interfaces. Acoustic emission results supported the histological observations. To investigate the contribution of ultrastructure to static fracture resistance, fracture toughness tests were conducted after altering the collagen phase of the bone tissue by gamma radiation. A significant decrease in the fracture toughness, Work-to-Fracture and the amount damage was observed due to irradiation in both crack growth directions. For cortical bone irradiated at 27.5kGy, fracture toughness is reduced due to the inhibition of damage formation at and near the crack tip. Microcrack fatigue crack growth and arrest were investigated through observations of surface cracks during cyclic loading. At the applied cyclic stresses, the microcracks propagated and arrested in less than 10,000 cycles. In addition, the microcracks were observed not to grow beyond a length of 150mum and a DeltaK of 0.5MNm-3/2, supporting a microstructural barrier concept. Finally, the contribution of linear microcracks to material property degradation was examined by developing a theoretical micromechanical damage model. The model was compared to experimentally induced damage in bone tissue. The percent contribution of linear microcracks to the total degradation was predicted to be less than 5%, indicating that diffuse damage or an unidentified form of damage is primarily responsible for material property degradation in human cortical bone tissue.

Akkus, Ozan

128

7 CFR 3201.68 - Erosion control materials.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Erosion control materials. 3201.68 Section 3201...Items § 3201.68 Erosion control materials. (a) Definition. Woven...qualifying biobased erosion control materials. By that date, Federal...

2013-01-01

129

Stability of CIGS solar cells and component materials evaluated by a step-stress accelerated degradation test method  

NASA Astrophysics Data System (ADS)

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 15°C and then a 15% relative humidity (RH) increment step, beginning from 40°C/40%RH (T/RH = 40/40) to 85°C/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

130

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

131

Evaluation of Ultrasonic and Thermal Nondestructive Evaluation for the Characterization of Aging Degradation in Braided Composite Materials.  

National Technical Information Service (NTIS)

This paper examines the ability of traditional nondestructive evaluation (NDE) techniques to measure the degradation of braided polymer composite materials subjected to thermal-humidity cycling to simulate aging. A series of braided composite coupons were...

R. E. Martin

2010-01-01

132

Evaluation of the Resistance of a Chlorinated Polyethylene Protective Garment Material to Permeation and Degradation by Liquid Chemicals.  

National Technical Information Service (NTIS)

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 Meth...

J. Ludington J. Meade W. Ellis

1985-01-01

133

Engineering hyaluronic acid hydrogel degradation to control cellular interactions and adult stem cell fate in 3D  

NASA Astrophysics Data System (ADS)

The design and implementation of extracellular matrix (ECM)-mimetic hydrogels for tissue engineering (TE) applications requires an intensive understanding of cell-material interactions, including matrix remodeling and stem cell differentiation. However, the influence of microenvironmental cues, e.g., matrix biodegradability, on cell behavior in vitro has not been well studied in the case of direct cell encapsulation within 3-dimensional (3D) hydrogels. To address these issues, a facile sequential crosslinking technique was developed that provides spatial and temporal control of 3D hydrogel degradability to investigate the importance of material design on cell behavior. Specifically, hydrogels were synthesized from hyaluronic acid (HA) macromers in a sequential process: (1) a primary Michael-type addition crosslinking using cell adhesive and matrix metalloprotease (MMP)-degradable oligopeptides to consume a portion of total reactive groups and resulting in "-UV" hydrogels permissive to cell-mediated degradation, followed by (2) a secondary, light initiated free-radical crosslinking to consume remaining reactive groups and "switch" the network to a non-degradable structure ("+UV") via the addition of non-degradable kinetic chains. Using this approach, we demonstrated control of encapsulated hMSC spreading by varying the crosslink type (i.e., the relative hydrogel biodegradability), including with spatial control. Upon incubation with bipotential soluble differentiation factors, these same degradation-mediated spreading cues resulted in an hMSC differentiation fate switch within -UV versus +UV environments. Follow-up studies demonstrated that degradation-mediated traction generation, rather than matrix mechanics or cell morphology, is the critical biophysical signal determining hMSC fate. Sequentially crosslinked HA hydrogels were also studied for the capacity to support remodeling by in vivo and ex vivo tissues, including with spatial control, toward tissue engineering (e.g., neovascularization) applications. In total, the work presented here highlights sequential crosslinking as a versatile platform technology affording processing capabilities to better mimic dynamic features of native microenvironments, including spatial patterning and temporal alteration of hydrogel degradability, toward both basic studies of cell behavior and TE applications.

Khetan, Sudhir

134

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

135

Photocatalytic degradation of textile dye X-3B using polyoxometalate–TiO 2 hybrid materials  

Microsoft Academic Search

Titanium dioxide functionalized with Keggin type polyoxometalate (POMs) [Xn+W12O40](8?n)? (XW12; Xn+=P5+, Si4+, Ge4+) were prepared by sol–gel method. The Keggin structure and dispersion state of POMs were monitored by FT-IR and XRD. The composites showed higher photocatalytic activity than pure TiO2, pure POMs or mechanical mixture of TiO2 and POMs for X-3B degradation. Among the three POMs–TiO2 hybrid materials, the

Hongxiao Jin; Qingyin Wu; Wenqin Pang

2007-01-01

136

A New Immune PID Controller in Material-Level Control  

Microsoft Academic Search

The material-level control of preheating cylinder in the thermofiner of the hot-grinding system is highly nonlinear, and also has a pure delay. Our paper proposes a promising fusion of immune algorithm and PID algorithm to deal with this challenging problem. The MATLAB-based simulations demonstrate that the proposed hybrid controller has the remarkable properties of quick response, good robustness, and satisfactory

Wei Wang; X. Z. Gao; Changhong Wang

2007-01-01

137

Towards coherent control of energetic material initiation  

NASA Astrophysics Data System (ADS)

Direct optical initiation (DOI) of energetic materials using coherent control of localized energy deposition requires understanding how the deposited energy produces a critical size hot spot, which allows propagation of the reaction and thereby initiation. The hot spot characteristics needed for growth to initiation can be studied using thin films of energetic materials. Achieving direct quantum controlled initiation (QCI) in thin film condensed phase systems requires optimally shaped ultrafast laser pulses to coherently guide the energy flow along the desired paths. As a test of our quantum control capabilities we have successfully demonstrated our ability to control the reaction pathway of the chemical system stilbene. An acousto-optical modulator based pulse shaper was used at 266 nm, in a shaped pump / supercontinuum probe technique, to enhance and suppress the relative yields of the cis- to trans-stilbene isomerization. The quantum control techniques tested in the stilbene experiments are currently being used to investigate QCI of thin films and solutions of several different explosives.

Greenfield, Margo; McGrane, Shawn; Moore, David

2009-06-01

138

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; Elwood Jr, Robert H [ORNL; Roche, Charles T [ORNL

2011-01-01

139

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

Microsoft Academic Search

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 multilayer insulation (MLI) blanket that was apparent during the second servicing mission (SM2), the decision was made to replace

Jacqueline A Townsend; Patricia A Hansen; Mark W McClendon; Kim K de Groh; Bruce A Banks

1999-01-01

140

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

141

Cometabolic Degradation of Trichloroethene by Rhodococcus sp. Strain L4 Immobilized on Plant Materials Rich in Essential Oils? †  

PubMed Central

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 ?M 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.

Suttinun, Oramas; Muller, Rudolf; Luepromchai, Ekawan

2010-01-01

142

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

2010-05-14

143

Chemical degradation in organic light-emitting devices: mechanisms and implications for the design of new materials.  

PubMed

Degradation of the materials in organic light-emitting devices (OLEDs) is the major impediment for the development of economically feasible, highly efficient and durable devices for commercial applications. Even though this chemical degradation is complex and the least understood of the different degradation modes in OLEDs, scientists were successful in providing insight into some of the responsible processes. In this progress report we will review recent advances in the elucidation of chemical degradation mechanisms: First possible reasons for defect formation and the most common and important methods to investigate those processes are covered before discussing the reactions and their products for the different types of materials present in a device. We summarize commonalities in the occurring mechanisms, and identify structural features and moieties that can be detrimental to operational stability. Some of the resulting implications on the development of new materials are presented and backed by concrete examples from literature. PMID:23450816

Schmidbauer, Susanna; Hohenleutner, Andreas; König, Burkhard

2013-03-01

144

Controlled low strength materials (CLSM), reported by ACI Committee 229.  

National Technical Information Service (NTIS)

Controlled low-strength material (CLSM) is a self-compacted, cementitious material used primarily as a backfill in lieu of compacted fill. Many terms are currently used to describe this material including flowable fill, unshrinkable fill, controlled densi...

N. Rajendran

1997-01-01

145

Computerized materials protection, control, and accountability  

SciTech Connect

The proliferation of nuclear weapons, along with the technical knowledge and materials needed to make these weapons, is an enduring problem of international urgency. Current international nuclear nonproliferation efforts are aimed at deterring, detecting, and responding to proliferation of weapons of mass destruction. These safeguards efforts are being implemented by applying preeminent science and technology to the management and control of nuclear materials. By strengthening systems of nuclear material protection, control, and accountability (MPC and A), one can reduce the threat of nuclear weapons proliferation. Two major programs of international cooperation are now underway to achieve this goal. The first is between the US Department of Energy (DOE) and the Institutes of the Russian Federation (Laboratory-to-Laboratory Program), and the second is between the US Government and Governments of the former Soviet Republics (Government-to-Government Program). As part of these programs, the DOE is working with facilities to assist them in implementing computerized MPC and A systems. This work is a collaboration between computer scientists and safeguards experts in both the US and the new Republics. The US is making available technology and expertise to enable Russian experts to build on computerized MPC and A software developed in the US. This paper describes the joint efforts of these international teams to develop sophisticated computerized MPC and A systems using modern computer hardware and software technology. These systems are being customized to meet the site-specific needs of each facility.

Whiteson, R.; Seitz, S.; Landry, R.P.; Hadden, M.L.; Painter, J.A.

1997-05-01

146

Control of Swe1p degradation by the morphogenesis checkpoint.  

PubMed Central

In the budding yeast Saccharomyces cerevisiae, a cell cycle checkpoint coordinates mitosis with bud formation. Perturbations that transiently depolarize the actin cytoskeleton cause delays in bud formation, and a 'morphogenesis checkpoint' detects the actin perturbation and imposes a G2 delay through inhibition of the cyclin-dependent kinase, Cdc28p. The tyrosine kinase Swe1p, homologous to wee1 in fission yeast, is required for the checkpoint-mediated G2 delay. In this report, we show that Swe1p stability is regulated both during the normal cell cycle and in response to the checkpoint. Swe1p is stable during G1 and accumulates to a peak at the end of S phase or in early G2, when it becomes unstable and is degraded rapidly. Destabilization of Swe1p in G2 and M phase depends on the activity of Cdc28p in complexes with B-type cyclins. Several different perturbations of actin organization all prevent Swe1p degradation, leading to the persistence or further accumulation of Swe1p, and cell cycle delay in G2.

Sia, R A; Bardes, E S; Lew, D J

1998-01-01

147

Lost circulation control materials. Progress report  

SciTech Connect

Work in FY 94 continued to investigate the use of calcium phosphate cements as lost circulation control materials for geothermal wells. The calcium phosphate cements were produced by reacting calcium aluminate cement with sodium phosphate compounds. Pumpable formulations with thickening times up to two hours at temperatures between 25 to 90{degrees}C were developed and characterized. The materials showed rapid set behaviour, early strength development, low permeability and acceptable durability in hydrothermal environments. Strengths up to 4 MPa were achieved four hours after mixing and water permeabilities were of the order of 10{sup -9} to 10{sup -7} cm/s at 24 hours. Partial replacement of calcium aluminate cement with ground granulated blast furnace slag was found to reduce the amount of borax retarder required to maintain pumpability at elevated temperatures and pressures.

Allan, M.L.; Kukacka, L.E.

1994-01-01

148

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

Code of Federal Regulations, 2013 CFR

...10 Energy 2 2013-01-01 2013-01-01 false Nuclear material control and accounting for strategic special nuclear material. 74.51 Section 74.51 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) MATERIAL CONTROL...

2013-01-01

149

Report of the Material Control and Material Accounting Task Force. Volume 3. Blueprint for the Future.  

National Technical Information Service (NTIS)

Contents: Proposed regulatory upgrades and supporting programs; Special issues-(Action criteria for inventory differences, Material balance area accounting, The analysis of inventory differences, Rapid material control, Collusion and material control and ...

F. L. Crane W. D. Altman W. B. Brown D. J. Dube J. W. Hockert

1978-01-01

150

10 CFR 835.1101 - Control of material and equipment.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Control of material and equipment. 835.1101 Section 835...RADIATION PROTECTION Radioactive Contamination Control § 835.1101 Control of material and equipment. (a) Except as...

2013-01-01

151

Bibliographic control of nonprint educational material.  

PubMed

AVLINE is an on-line data base maintained by the National Library of Medicine containing references to over 5,000 nationally available nonprint materials. Each title is screened for technical quality, processed according to NLM's categorization, and undergoes descriptive and subject cataloging. In addition to the bibliographic control, an assessment is made of educational potential and content validity by the peer appraisal process of the Association of American Medical Colleges (AAMC). AVLINE is available through the computer network that supports the MEDLINE system. The data base offers the use of a wide range of sophisticated retrieval possibilities. PMID:80405

Tonkery, D; McIlvane, M E

1978-07-01

152

Isolation and Control of Membrane Filter Degrading Microorganisms.  

National Technical Information Service (NTIS)

Reverse osmosis filtration is one of the most widely used methods of desalinization and cellulose acetate is the most common membrane material. The Roswell Test Facility (New Mexico) reverse osmosis testing program was plagued with premature failure of ce...

W. C. Lindemann

1981-01-01

153

The Chemistry of Corona Degradation of Organic Insulating Materials in High-Voltage Fields and under Mechanical Strain  

Microsoft Academic Search

Organic materials used as high-voltage electrical insulation are altered chemically and physically by corona discharges. The basic behavior of polyolefin and fluorocarbon resins were investigated under conditions of high electrical stress. The presence of corona subjects a material to ozone, acid, ultraviolet light, and bombardment by electrons and ions. Degradation under these conditions is usually confined to the surface rather

EUGENE J. McMAHON

1968-01-01

154

Theoretical investigation on degradation behaviors of spectral properties of thermal control coatings induced by charged particles  

NASA Astrophysics Data System (ADS)

The degradation of spectral properties of thermal control coatings on spacecrafts is investigated in this paper. By studying their physical components and geometry structure, the factors which determine the spectral properties of the coatings are founded. A theoretical model for calculating the spectral absorptance of coatings is proposed based on the Mie's theory and Stratified Media theory. Mathematical expressions are introduced for accounting for the effect of the complicated environment. Based on these work, a predicting model for the degradation of spectral absorptance properties of the coatings is established. To validate this model, the predicted degradation performance of spectral properties of zinc oxide based coatings under electrons and protons exposure are compared with the experimental data. A good agreement is found at the wavelength between 250 nm and 2500 nm. Finally, a useful approach for predicting the degradation behaviors of thermal control coatings on spacecrafts in orbit is established.

Han, Yuge; Ma, Wei; Xuan, Yimin

2013-10-01

155

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 reviews the use of materials control techniques to deter and detect insider malevolence.

Waddoups, I.G.

1989-11-01

156

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

157

Photocatalytic degradation of textile dye X-3B using polyoxometalate-TiO2 hybrid materials.  

PubMed

Titanium dioxide functionalized with Keggin type polyoxometalate (POMs) [X(n+)W(12)O(40)]((8-n)-) (XW(12); X(n+)=P(5+), Si(4+), Ge(4+)) were prepared by sol-gel method. The Keggin structure and dispersion state of POMs were monitored by FT-IR and XRD. The composites showed higher photocatalytic activity than pure TiO(2), pure POMs or mechanical mixture of TiO(2) and POMs for X-3B degradation. Among the three POMs-TiO(2) hybrid materials, the reactivity was: PW(12)>SiW(12)>GeW(12). With different loading weights for the same POMs, the reactivity followed the order: 30wt.%>15wt.%>45wt.%. PMID:17045740

Jin, Hongxiao; Wu, Qingyin; Pang, Wenqin

2006-07-01

158

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

159

Environmental degradation of materials during wet storage of spent nuclear fuels  

NASA Astrophysics Data System (ADS)

Wet storage is the predominant mode of storage of spent nuclear fuels. Due to legislation and other constraints, many countries do not reprocess spent fuels and have to store these for extended periods in spent fuel storage pools (SFSPs). Although the water chemistry of the pool is benign, certain factors such as stagnancy of water, crevices, and galvanic contacts between various materials of the fuel clad and the lining of the pools can result in unexpected localized corrosion. In this study, the susceptibility to localized corrosion of aluminum-1S (Al-1S), Zircaloy-2, and type 304 stainless steel (SS) has been assessed using accelerated tests with crevice bent beam (CBB) assemblies. The pool water constituents have been analyzed and electrochemical potentials (ECPs) measured in water samples drawn from different locations of the pool. The ECP has also been measured in situ, in the pools. It has been demonstrated that under conditions of crevice and galvanic contact, aluminum clad fuels from research reactors are prone to localized corrosion even in the benign environments of a SFSP. The ECP experiments indicate the importance of surface condition of the material and irradiation on degradation of various materials due to corrosion.

Kain, Vivekanand; de, P. K.; Agarwal, K.; Seetharamaih, P.

2000-06-01

160

Minimizing gain degradation in lateral PNP bipolar junction transistors using gate control  

SciTech Connect

Gain degradation in lateral PNP bipolar junction transistors is minimized by controlling the potential of a gate terminal deposited above the active base region. Gate biases that deplete the base during radiation exposure establish electric fields in the base oxide that limit the generation of oxide defects. Conversely, gate biases that accumulate the base during device operation suppress gain degradation by decreasing the probability of carrier recombination with interface states. The results presented in this paper suggest that, for gate controlled LPNP transistors designed for operation in radiation environments, a dynamic control of the gate potential improves the transistor's radiation hardness and extend its operating life.

Barnaby, H.J.; Cirba, C.; Schrimpf, R.D.; Kosier, S.; Fouillat, P.; Montagner, X.

1999-12-01

161

Detection and mitigating rod drive control system degradation in Westinghouse PWRs  

SciTech Connect

A study of the effects of aging on the Westinghouse Control Rod Drive (CRD) System was performed as part of the US NRC's Nuclear Plant aging Research (NPAR) Program. For the study, the CRD system boundary includes the power and logic cabinets associated with the manual control rod movement, and the control rod mechanism itself. The aging-related degradation of the interconnecting cables and connectors and the rod position indicating system also were considered. This paper presents the results of that study pertaining to the electrical and instrumentation portions of the CRD system including ways to detect and mitigate system degradation.

Gunther, W.; Sullivan, K.

1990-01-01

162

Control of DCG and nonsilver holographic materials  

NASA Astrophysics Data System (ADS)

We review the properties and relative usefulness of three nonsilver volume holographic recording materials that are available today. Dichromated gelatin (DCG) receives the most attention followed by Dupont Omnidex products and a light treatment of polyvinyl carbazole (PVK). Enhancement and control of color, bandwidth and diffraction efficiency of volume reflection holograms recorded in DCG, and photopolymers are discussed. Methods of increasing the bandwidth while shifting the center frequency toward the red are given for photopolymers. Red pseudo color is covered thoroughly so that the practitioner has all the elementary tools to make full color and broadband DCG holograms from scratch. The entire DCG technology is disclosed as it relates to production of high quality display holograms that span the spectrum and may be narrowband and very deep or shallow and broadband.

Rallison, Richard D.

1992-01-01

163

Posttranslational Quality Control: Folding, Refolding, and Degrading Proteins  

NSDL National Science Digital Library

Polypeptides emerging from the ribosome must fold into stable three-dimensional structures and maintain that structure throughout their functional lifetimes. Maintaining quality control over protein structure and function depends on molecular chaperones and proteases, both of which can recognize hydrophobic regions exposed on unfolded polypeptides. Molecular chaperones promote proper protein folding and prevent aggregation, and energy-dependent proteases eliminate irreversibly damaged proteins. The kinetics of partitioning between chaperones and proteases determines whether a protein will be destroyed before it folds properly. When both quality control options fail, damaged proteins accumulate as aggregates, a process associated with amyloid diseases.

Sue Wickner (National Cancer Institute;Laboratory of Molecular Biology); Michael Maurizi (National Cancer Institute;Laboratory of Cell Biology); Susan Gottesman (National Cancer Institute;Laboratory of Molecular Biology)

1999-12-03

164

Exposed hydrophobicity is a key determinant of nuclear quality control degradation  

PubMed Central

Protein quality control (PQC) degradation protects the cell by preventing the toxic accumulation of misfolded proteins. In eukaryotes, PQC degradation is primarily achieved by ubiquitin ligases that attach ubiquitin to misfolded proteins for proteasome degradation. To function effectively, PQC ubiquitin ligases must distinguish misfolded proteins from their normal counterparts by recognizing an attribute of structural abnormality commonly shared among misfolded proteins. However, the nature of the structurally abnormal feature recognized by most PQC ubiquitin ligases is unknown. Here we demonstrate that the yeast nuclear PQC ubiquitin ligase San1 recognizes exposed hydrophobicity in its substrates. San1 recognition is triggered by exposure of as few as five contiguous hydrophobic residues, which defines the minimum window of hydrophobicity required for San1 targeting. We also find that the exposed hydrophobicity recognized by San1 can cause aggregation and cellular toxicity, underscoring the fundamental protective role for San1-mediated PQC degradation of misfolded nuclear proteins.

Fredrickson, Eric K.; Rosenbaum, Joel C.; Locke, Melissa N.; Milac, Thomas I.; Gardner, Richard G.

2011-01-01

165

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

2013-08-05

166

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

PubMed

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

2013-05-14

167

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

168

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

169

Spider silk aging: initial improvement in a high performance material followed by slow degradation.  

PubMed

Spider silk possesses a unique combination of high tensile strength and elasticity resulting in extraordinarily tough fibers, compared with the best synthetic materials. However, the potential application of spider silk and biomimetic fibers depends upon retention of their high performance under a variety of conditions. Here, we report on changes in the mechanical properties of dragline and capture silk fibers from several spider species over periods up to 4 years of benign aging. We find an improvement in mechanical performance of silk fibers during the first year of aging. Fibers rapidly decrease in diameter, suggesting an increase in structural alignment and organization of molecules. One-year old silk also is stiffer and has higher stress at yield than fresh silk, whereas breaking force, elasticity, and toughness either improve or are unaffected by early aging. However, 4-year old silk shows signs of degradation as the breaking load, elasticity, and toughness are all lower than in fresh silk. Aging, however, does not reduce the tensile strength of silk. These data suggest initially rapid reorganization and tighter packaging of molecules within the fiber, followed by longer-term decomposition. We hypothesize that possibly the breakdown of amino acids via emission of ammonia gas, as is seen in long-term aging of museum silkworm fabrics, may contribute. Degradation of spider silk under benign conditions may be a concern for efforts to construct and utilize biomimetic silk analogs. However, our findings suggest an initial improvement in mechanical performance and that even old spider silk still retains impressive mechanical performance. PMID:18626974

Agnarsson, Ingi; Boutry, Cecilia; Blackledge, Todd A

2008-10-01

170

Effect of enzymatic degradation on the mechanical properties of biological scaffold materials  

PubMed Central

Background Biological scaffolds must support a complex balance of resisting enzymatic degradation while promoting tissue remodeling. Thus, the purpose of this study was to evaluate the effects of in vitro enzymatic exposure on the mechanical properties of biological scaffolds. It was hypothesized that exposure to an enzyme solution would result in decreased tensile strength and that crosslinked scaffolds would resist enzymatic degradation more effectively than noncrosslinked scaffolds. Methods Nine scaffolds were evaluated (four porcine dermis: Permacol™, CollaMend™, Strattice™, XenMatrix™; two human dermis: AlloMax™, FlexHD®; two bovine pericardium: Veritas®, PeriGuard®; and one porcine small intestine submucosa: Surgisis™). Ten specimens (n = 10) were hydrated in saline at 37 °C and subjected to uniaxial testing to establish baseline properties. 50 specimens (n = 50) were incubated in collagenase solution at 37 °C for 2, 6, 12, 24, or 30 h (n = 10 each group) followed by uniaxial tensile testing. Results Tensile strength was significantly reduced after 30 h for CollaMend™, AlloMax™, Veritas®, Strattice™, XenMatrix™, Permacol™, and FlexHD® (p < 0.01), while PeriGuard® demonstrated a slight increase in tensile strength (p = 0.0188). Crosslinked bovine pericardium (PeriGuard®) maintained greater tensile strength than noncrosslinked bovine pericardium (Veritas®) throughout all exposure periods (p < 0.0001). Similarly, crosslinked porcine dermis (Permacol™) maintained greater tensile strength than non-crosslinked porcine dermis (Strattice™ and XenMatrix™) throughout all exposure periods (p < 0.0001). Conclusions Materials that deteriorate rapidly after in vitro enzymatic exposure may also deteriorate rapidly in vivo, particularly when exposed to a wound environment with elevated levels of matrix metalloproteinases. Permacol™, CollaMend™, Strattice™, FlexHD®, and Peri-Guard® survived the longest incubation period (30 h) and withstood mechanical testing. XenMatrix™, AlloMax™, Veritas®, and Surgisis™ degraded more quickly and did not survive the longer exposure periods. Scaffolds that maintain strength characteristics after in vitro collagenase exposure may be advantageous for long-term hernia repair scenarios where elevated enzyme levels are expected.

Annor, Afua H.; Tang, Michael E.; Pui, Chi Lun; Ebersole, Gregory C.; Frisella, Margaret M.; Matthews, Brent D.

2013-01-01

171

A new alkali-activated steel slag-based cementitious material for photocatalytic degradation of organic pollutant from waste water.  

PubMed

A new type of Ni,Ca-cementitious material was firstly synthesized via a two-step reaction of alkali-activated steel slag polymerization and ion exchange. The XRF results showed that almost all the Na(+) ions in the matrix of Na,Ca-cementitious material were replaced by Ni(2+) ions at room temperature. The new hydrated products of metahalloysite (Si(2)Al(2)O(5)(OH)(4)) and calcium silicate hydrate (CSH) were formed in the Na,Ca-cementitious material. The diffuse reflectance UV-vis near infrared ray spectrum was blue-shifted due to the strong interaction between Ni(2+) and negative charge of [AlO(4)](5-) tetrahedron in the framework of cementitious material. The Ni,Ca-cementitious material was used as a catalyst for the photocatalytic degradation of methylene blue dye and showed a degradation rate of 94.39% under UV irradiation. The high photocatalytic degradation activity was suggested to be the synergistic effect of the cementitious matrix, Ni(2+) ions and the iron oxides of wustite (FeO) and calcium iron oxide (Ca(2)Fe(2)O(5)) from the steel slag. A probable mechanism of photocatalytic oxidative degradation was proposed. PMID:22284172

Zhang, Yao Jun; Liu, Li Cai; Xu, Yong; Wang, Ya Chao; Xu, De Long

2012-01-10

172

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

SciTech Connect

Three copper-based alloys --- CDA 102 (OFHC copper), CDA 613 (aluminum bronze), and CDA 715 (Cu-30Ni) --- are being considered as possible materials for the fabrication of high-level radioactive-waste disposal containers. Waste will include fuel assemblies from reactors as well as borosilicate glass forms, and will be sent to the prospective repository at Yucca Mountain, Nevada, for emplacement. The three copper-based alloys discussed here are being considered in addition to the iron- to nickel-based austenitic materials discussed in Volume 3. The decay of radionuclides will result in substantial heat generation and in fluxes of gamma radiation. In this environment, container materials may degrade by atmospheric oxidation, uniform aqueous phase corrosion, pitting, crevice corrosion, transgranular stress corrosion cracking (TGSCC) in tarnishing environments, or intergranular stress corrosion cracking (IGSCC) in nontarnishing environments. This report is a critical survey of available data on the stress corrosion cracking (SCC) of the three copper-based alloys. The requisite conditions for TGSCC and IGSCC include combinations of stress, oxygen, ammonia or nitrite, and water. Note that nitrite is generated by gamma radiolysis of moisture films in air but that ammonia is not. TGSCC has been observed in CDA 102 and CDA 613 exposed to moist ammonia-containing environments whereas SCC has not been documented for CDA 715 under similar conditions. SCC is also promoted in copper by nitrite ions. Furthermore, phosphorus-deoxidized copper is unusually susceptible to embrittlement in such environments. The presence of tin in CDA 613 prevents IGSCC. It is believed that tin segregates to grain boundaries, where it oxidizes very slowly, thereby inhibiting the oxidation of aluminum. 117 refs., 27 figs., 9 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))

1988-05-01

173

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

2011-01-01

174

Proceedings of the fifth international symposium on environmental degradation of materials in nuclear power systems - water reactors  

SciTech Connect

The Fifth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors was held August 25-29, 1991 in Monterey, California. More than 250 scientists and engineers from 17 countries participated in the symposium, which attracted materials scientists from national labs and universities, corrosion engineers from manufacturing/service industries, and nuclear plant engineers from utilities. Organized according to component and degradation method, the breakout sessions included: (1) Water chemistry/monitoring; (2) Zircaloy; (3) Austenitic Degradation 1 & 2; (4) Steam Generator Primary Side 1 & 2; (5) Steam Generator Secondary Side 1 & 2; (6) Irradiation Assisted Stress Corrosion Cracking 1 & 2; (7) Pressure Vessel Irradiation; (8) High Strength Alloys/Hard Surface/Aging; (9) Erosion Corrosion/Service Water; and (10) Low alloy steels/EAC.

NONE

1992-12-31

175

Controlled degradation of hydrogels using multi-functional cross-linking molecules.  

PubMed

Hydrogels, chemically cross-linked or physically entangled, have found a number of applications as novel delivery vehicles of drugs and cells. However, the narrow ranges of degradation rates and mechanical strength currently available from many hydrogels limits their applications. We have hypothesized that utilization of multi-functional cross-linking molecules to form hydrogels could provide a wider range and tighter control over the degradation rates and mechanical stiffness of gels than bi-functional cross-linking molecules. To address the possibility, we isolated alpha-L-guluronate residues of sodium alginate, and oxidized them to prepare poly(aldehyde guluronate) (PAG). Hydrogels were formed with either poly(acrylamide-co-hydrazide) (PAH) as a multi-functional cross-linking molecule or adipic acid dihydrazide (AAD) as a bi-functional cross-linking molecule. The initial properties and degradation behavior of both PAG gel types were monitored. PAG/PAH hydrogels showed higher mechanical stiffness before degradation and degraded more slowly than PAG/AAD gels, at the same concentration of cross-linking functional groups. The enhanced mechanical stiffness and prolonged degradation behavior could be attributed to the multiple attachment points of PAH in the gel at the same concentration of functional groups. This approach to regulating gel properties with multifunctional cross-linking molecules could be broadly used in hydrogels. PMID:14751730

Lee, Kuen Yong; Bouhadir, Kamal H; Mooney, David J

2004-06-01

176

PAH degradation and redox control in an electrode enhanced sediment cap.  

PubMed

Capping is typically used to control contaminant release from the underlying sediments. However, the presence of conventional sediment caps will often eliminate or slow natural degradation that might otherwise occur at the surface sediment. The objective of this study was to explore the potential of a novel reactive capping, an electrode enhanced cap for the remediation of PAH contaminated sediment. The study on electrode enhanced biodegradation of PAH in slurries showed that naphthalene concentration decreased from ~1000 ?g/L to ~50 ?g/L, and phenanthrene decreased from ~150 ?g/L to ~30 ?g/L in ElectroBioReactor within 4 days, and the copy numbers of PAH degrading genes increased by almost 2 orders of magnitude. In a cap microcosm, two carbon electrodes were emplaced within a sediment cap with an applied potential of 2 V. The anode was placed at the sediment-cap interface encouraging oxidizing conditions. Oxidation and Reduction Potential (ORP) profiles showed redox potential approximately 60-100 mV higher at the sediment-cap interface with the application of voltage than in controls. Vertical profiles of phenanthrene porewater concentration were obtained by PDMS-coated fiber, and results showed that phenanthrene at the depth of 0-0.5 cm below the anode was degraded to ~70% of the initial concentration within 10 weeks. PAH degrading genes showed an increase of approximately 1 order of magnitude at the same depth. The no power controls showed no degradation of PAH. These findings suggest that electrode enhanced capping can be used to control redox potential, provide microbial electron acceptor, and stimulate PAH degradation. PMID:23329859

Yan, Fei; Reible, Danny D

2012-03-14

177

PAH degradation and redox control in an electrode enhanced sediment cap  

PubMed Central

Capping is typically used to control contaminant release from the underlying sediments. However, the presence of conventional sediment caps will often eliminate or slow natural degradation that might otherwise occur at the surface sediment. The objective of this study was to explore the potential of a novel reactive capping, an electrode enhanced cap for the remediation of PAH contaminated sediment. The study on electrode enhanced biodegradation of PAH in slurries showed that naphthalene concentration decreased from ~1000 ?g/L to ~50 ?g/L, and phenanthrene decreased from ~150 ?g/L to ~30 ?g/L in ElectroBioReactor within 4 days, and the copy numbers of PAH degrading genes increased by almost 2 orders of magnitude. In a cap microcosm, two carbon electrodes were emplaced within a sediment cap with an applied potential of 2 V. The anode was placed at the sediment-cap interface encouraging oxidizing conditions. Oxidation and Reduction Potential (ORP) profiles showed redox potential approximately 60-100 mV higher at the sediment-cap interface with the application of voltage than in controls. Vertical profiles of phenanthrene porewater concentration were obtained by PDMS-coated fiber, and results showed that phenanthrene at the depth of 0-0.5 cm below the anode was degraded to ~70% of the initial concentration within 10 weeks. PAH degrading genes showed an increase of approximately 1 order of magnitude at the same depth. The no power controls showed no degradation of PAH. These findings suggest that electrode enhanced capping can be used to control redox potential, provide microbial electron acceptor, and stimulate PAH degradation.

Yan, Fei; Reible, Danny D.

2012-01-01

178

Controlling elastic waves with isotropic materials  

NASA Astrophysics Data System (ADS)

Design of functional devices with isotropic materials has significant advantages, as regards easy fabrication and broadband application. In this letter, we present a method to derive isotropic transformation material parameters for elastodynamics under local conformal transformation. The transformed material parameters are then applied to design a beam bender, a four-beam antenna and an approximate carpet cloak for elastic wave with isotropic materials, validated by the numerical simulations.

Chang, Zheng; Hu, Jin; Hu, Gengkai; Tao, Ran; Wang, Yue

2011-03-01

179

Proceedings of the sixth international symposium on environmental degradation of materials in nuclear power systems - water reactors  

Microsoft Academic Search

The operation of water reactor nuclear power plants provides a significant fraction of the world's electric power generation. At the end of 1992, approximately 360 such plants were in operation, representing a total generating capacity of 320 GWe. As these plants age, and as new designs evolve, the impact of environmental degradation of reactor materials on reliability and power plants

R. E. Gold; E. P. Simonen

1993-01-01

180

Prediction of thermal degradation of thermoprotective materials on the basis of their composition and properties of components  

Microsoft Academic Search

Thermal decomposition of thermoprotective materials based on phenolformaldehyde resin and carbon cloth with different contents of components is studied. Physical and mathematical models for the process are proposed. It is shown that the mass loss in carbon fiber reinforced plastics is determined by thermal degradation of the components and can be described by a generic kinetic scheme with a given

V. I. Zinchenko; V. V. Nesmelov; V. D. Gol’din

2005-01-01

181

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

182

Multiple phosphorylation events control mitotic degradation of the muscle transcription factor Myf5  

PubMed Central

Background The two myogenic regulatory factors Myf5 and MyoD are basic helix-loop-helix muscle transcription factors undergoing differential cell cycle dependent proteolysis in proliferating myoblasts. This regulated degradation results in the striking expression of these two factors at distinct phases of the cell cycle, and suggests that their precise and alternated disappearance is an important feature of myoblasts, maybe connected to the maintenance of the proliferative status and/or commitment to the myogenic lineage of these cells. One way to understand the biological function(s) of the cyclic expression of these proteins is to specifically alter their degradation, and to analyze the effects of their stabilization on cells. To this aim, we undertook the biochemical analysis of the mechanisms governing Myf5 mitotic degradation, using heterologous systems. Results We show here that mitotic degradation of Myf5 is conserved in non-myogenic cells, and is thus strictly under the control of the cell cycle apparatus. Using Xenopus egg extracts as an in vitro system to dissect the main steps of Myf5 mitotic proteolysis, we show that (1) Myf5 stability is regulated by a complex interplay of phosphorylation/dephosphorylation, probably involving various kinases and phosphatases, (2) Myf5 is ubiquitylated in mitotic extracts, and this is a prerequisite to its degradation by the proteasome and (3) at least in the Xenopus system, the E3 responsible for its mitotic degradation is not the APC/C (the major E3 during mitosis). Conclusion Altogether, our data strongly suggest that the mitotic degradation of Myf5 by the ubiquitin-proteasome system is precisely controlled by multiple phosphorylation of the protein, and that the APC/C is not involved in this process.

Doucet, Christine; Gutierrez, Gustavo J; Lindon, Catherine; Lorca, Thierry; Lledo, Gwendaline; Pinset, Christian; Coux, Olivier

2005-01-01

183

Regulation of Silk Material Structure by Temperature-Controlled Water Vapor Annealing  

PubMed Central

We present a simple and effective method to obtain refined control of the molecular structure of silk biomaterials through physical temperature-controlled water vapor annealing (TCWVA). The silk materials can be prepared with control of crystallinity, from a low content using conditions at 4°C (alpha-helix dominated silk I structure), to highest content of ~60% crystallinity at 100°C (beta-sheet dominated silk II structure). This new physical approach covers the range of structures previously reported to govern crystallization during the fabrication of silk materials, yet offers a simpler, green chemistry, approach with tight control of reproducibility. The transition kinetics, thermal, mechanical, and biodegradation properties of the silk films prepared at different temperatures were investigated and compared by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), uniaxial tensile studies, and enzymatic degradation studies. The results revealed that this new physical processing method accurately controls structure, in turn providing control of mechanical properties, thermal stability, enzyme degradation rate, and human mesenchymal stem cell interactions. The mechanistic basis for the control is through the temperature controlled regulation of water vapor, to control crystallization. Control of silk structure via TCWVA represents a significant improvement in the fabrication of silk-based biomaterials, where control of structure-property relationships is key to regulating material properties. This new approach to control crystallization also provides an entirely new green approach, avoiding common methods which use organic solvents (methanol, ethanol) or organic acids. The method described here for silk proteins would also be universal for many other structural proteins (and likely other biopolymers), where water controls chain interactions related to material properties.

Hu, Xiao; Shmelev, Karen; Sun, Lin; Gil, Eun-Seok; Park, Sang-Hyug; Cebe, Peggy; Kaplan, David L.

2011-01-01

184

Some Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository Study (The Yucca Mountain Project)  

SciTech Connect

The safe disposal of radioactive waste requires that the waste be isolated from the environment until radioactive decay has reduced its toxicity to innocuous levels for plants, animals, and humans. All of the countries currently studying the options for disposing of high-level nuclear waste (HLW) have selected deep geologic formations to be the primary barrier for accomplishing this isolation. In U.S.A., the Nuclear Waste Policy Act of 1982 (as amended in 1987) designated Yucca Mountain in Nevada as the potential site to be characterized for high-level nuclear waste (HLW) disposal. Long-term containment of waste and subsequent slow release of radionuclides into the geosphere will rely on a system of natural and engineered barriers including a robust waste containment design. The waste package design consists of a highly corrosion resistant Ni-based Alloy 22 cylindrical barrier surrounding a Type 316 stainless steel inner structural vessel. The waste package is covered by a mailbox-shaped drip shield composed primarily of Ti Grade 7 with Ti Grade 24 structural support members. The U.S. Yucca Mountain Project has been studying and modeling the degradation issues of the relevant materials for some 20 years. This paper reviews the state-of-the-art understanding of the degradation processes based on the past 20 years studies on Yucca Mountain Project (YMP) materials degradation issues with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the 10,000 years regulatory period. This paper provides an overview of the current understanding of the likely degradation behavior of the waste package and drip shield in the repository after the permanent closure of the facility. The degradation scenario discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking of Alloy 22 and titanium alloys. The effects of microbial activity and radiation on degradation of Alloy 22 and titanium alloys are also discussed. Further, for titanium alloys, the effects of fluorides, bromides, calcium ions, and galvanic coupling to less noble metals are further considered. It is concluded that, as far as materials degradation is concerned, the materials and design adopted in the U.S. Yucca Mountain Project will provide sufficient safety margins within the 10,000-years regulatory period.

F. Hua; P. Pasupathi; N. Brown; K. Mon

2005-09-19

185

The Effect of Antioxidants on Suppression of Thermal Degradation of Insulation Material  

NASA Astrophysics Data System (ADS)

Thermal degradation of EPDM and the effect of antioxidants on the degradation of EPDM was investigated. Using FT-IR (Fourier transform infrared spectrophotometer) micrometer the degree of degradation was analyzed. A new evaluation method of mapping measurement was introduced and showed to be very useful. Among oxidants studied, the phenolic antioxidant 4,4'-tiobis(3-methyl-6-tert.-Butyl phenol was confirmed to be useful. A synergetic effects between phenolic antioxidant 2,2'-methylene- bis (4-methyl-6-tert.buthylphenol) and sulfur type antioxidant, dilauryl thiodipropionate, was also confirmed. The temperature dependence of thermal degradation of EPDM was also analyzed.

Sagae, Masahiro; Sekii, Yasuo; Yoshino, Hiroto; Miyake, Koujirou

186

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

187

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

188

Ag2S nanoparticle encapsulated in mesoporous material nanoparticles and its application for photocatalytic degradation of dye in aqueous solution  

NASA Astrophysics Data System (ADS)

Semiconductor loaded mesoporous materials in general possess greater photocatalytic activity than pure semiconductors. Hence, with an attempt to achieve higher photocatalytic activity, Ag2S/MCM-41 photocatalysts were prepared by ion exchange method and used for the photocatalytic degradation of methylene blue. The materials were characterized by different analytical techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and BET (Brunauer-Emmert-Teller) experiments. The effect of Ag2S, MCM-41 support and different wt% of Ag2S over the support on the photocatalytic degradation and influence of parameters such as Ag2S loading, catalyst a mount, pH and initial concentration of dye on degradation are evaluated. The degradation reaction follows pseudo-first order kinetics. It was seen that 0.6 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. The degradation efficiency was decreased in dye concentration above 3.2 ppm for dye.

Pourahmad, A.

2012-08-01

189

Control of translation and mRNA degradation by miRNAs and siRNAs  

Microsoft Academic Search

The control of translation and mRNA degradation is an important part of the regulation of gene expression. It is now clear that small RNA molecules are common and effective modulators of gene expression in many eukary- otic cells. These small RNAs that control gene expres- sion can be either endogenous or exogenous micro RNAs (miRNAs) and short interfering RNAs (siRNAs)

Marco Antonio Valencia-Sanchez; Jidong Liu; Gregory J. Hannon; Roy Parker

2009-01-01

190

On Social and Material Aspects of Technological Control.  

ERIC Educational Resources Information Center

Suggests that Hugh Lacey's example of a clear-cut distinction between material and social constraints or possibilities in the Green Revolution is misleading. Proposes a material analysis of the control situation placed within the material framework of the social structure within which the control system is employed. (Author/WRM)

Herfel, William E.

1999-01-01

191

On Social and Material Aspects of Technological Control.  

ERIC Educational Resources Information Center

|Suggests that Hugh Lacey's example of a clear-cut distinction between material and social constraints or possibilities in the Green Revolution is misleading. Proposes a material analysis of the control situation placed within the material framework of the social structure within which the control system is employed. (Author/WRM)|

Herfel, William E.

1999-01-01

192

Evaluation on surface degradation of polymer insulating materials using GC\\/MS  

Microsoft Academic Search

The present contribution describes an analytical technique which can be used to investigate degradation phenomena of silicones and provide a quantitative evaluation of surface degradation. The technique employed in the present investigation is based on the use of gas chromatography\\/mass spectrometer (GC\\/MS) methods

H. Homma; T. Kuroyagi; K. Izumi; C. L. Mirley; J. Ronzello; S. A. Boggs

1995-01-01

193

Development and evaluation of modified whetlerite, an adsorbent material for in situ degradation of sulphur mustard  

Microsoft Academic Search

Whetlerite carbon, which is in use in nuclear, biological and chemical filtration systems can degrade highly volatile chemical warfare gases such as phosgene, cyanogen chloride, hydrogen cyanide, etc. Degradation of vesicants such as sulphur mustard (HD) over whetlerite has not been extensively studied, except that the probability of some hydrolysis has been reported. In order to investigate the latter and

Abha Sharma; Amit Saxena; Beer Singh; Malladi Venkata Satya Suryanarayana; Kumaran Ganeshan; Krishnamurthy Sekhar; K. K. Dwivedi

2006-01-01

194

On the degraded effectiveness of diffusion synthetic acceleration for multidimensional sn calculations in the presence of material discontinuities  

SciTech Connect

We investigate the degradation in performance of diffusion synthetic acceleration (DSA) methods in problems with discontinuities in material properties. A loss in the effectiveness of DSA schemes has been Observed before with other discretizations in two dimensions under certain conditions. We present more evidence in support of the conjecture that DSA effectiveness can degrade in multidimensional problems with discontinuities in total cross section, regardless of the particular physical configuration or spatial discretization. Through Fourier analysis and numerical experiments, we identify a set of representative problems for which established DSA schemes are ineffective, focusing on highly diffusive problems for which DSA is most needed. We consider a lumped, linear discontinuous spatial discretization of the S N transport equation on three-dimensional, unstructured tetrahedral meshes and look ata fully consistent and a 'partially consistent' DSA method for this discretization. We find that the effectiveness of both methods can be significantly degraded in the presence of material discontinuities. A Fourier analysis in the limit of decreasing cell optical thickness is shown that supports the view that the degraded effectiveness of a fully consistent DSA scheme simply reflects the failure of the spatially continuous DSA method in problems where material discontinuities are present. Key Words: diffusion synthetic acceleration, discrete ordinates, deterministic transport methods, unstructured meshes

Warsa, J. S. (James S.); Wareing, T. A. (Todd A.); Morel, J. E.

2002-01-01

195

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.

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

196

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

PubMed

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

2011-12-06

197

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

198

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

199

Comparison of tele-operation and supervisory control for navigation and driving with degraded communications  

NASA Astrophysics Data System (ADS)

Teleoperation is the currently accepted method of control of military unmanned ground vehicles (UGVs) in the field. Degraded communications affects the operator's tasks of driving, navigating and maintaining UGV situation awareness. A potential approach to address this challenge is to provide the UGV with local autonomy to generate driving commands (translation and rotation rates). This paper describes an experiment and preliminary results comparing "point-and-go" supervisory control in which the operator designates a goal point on the 2D driving display to teleoperation as a function of communications degradation and terrain roughness. Three methods of visual supervisory control were tested (visual dead reckoning and two visual sevoing methods) and compared to teleoperation.

Witus, Gary; Ellis, R. Darin; Karlsen, Robert; Hunt, Shawn

2010-04-01

200

Syntrophic degradation of proteinaceous materials by the thermophilic strains Coprothermobacter proteolyticus and Methanothermobacter thermautotrophicus.  

PubMed

Protein is a major component of organic solid wastes, and therefore, it is necessary to further elucidate thermophilic protein degradation process. The effects of hydrogenotrophic methanogens on protein degradation were investigated using the proteolytic bacterial strain CT-1 that was isolated from a methanogenic thermophilic (55°C) packed-bed reactor degrading artificial garbage slurry. Strain CT-1 was closely related to Coprothermobacter proteolyticus, which is frequently found in methanogenic reactors degrading organic solid wastes. Strain CT-1 was cultivated in the absence or presence of Methanothermobacter thermautotrophicus by using 3 kinds of proteinaceous substrates. Degradation rates of casein, gelatin, and bovine serum albumin were higher in co-cultures than in monocultures. Strain CT-1 showed faster growth in co-cultures than in monocultures. M. thermautotrophicus comprised 5.5-6.0% of the total cells in co-culture. Increased production of ammonia and acetate was observed in co-cultures than in monocultures, suggesting that addition of M. thermautotrophicus increases the products of protein degradation. Hydrogen produced in the monocultures was converted to methane in co-cultures. These results suggest that thermophilic proteolytic bacteria find it favorable to syntrophically degrade protein in a methanogenic environment, and that it is important to retain hydrogen-scavenging methanogens within the reactor. PMID:21802987

Sasaki, Kengo; Morita, Masahiko; Sasaki, Daisuke; Nagaoka, Jun; Matsumoto, Norio; Ohmura, Naoya; Shinozaki, Hiraku

2011-07-29

201

Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants  

SciTech Connect

When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of aging of structures and components in NPPs. Three specific areas that are included in the KAERI research project, related to seismic probabilistic risk assessment (PRA), are probabilistic seismic hazard analysis, seismic fragility analysis including the effects of aging, and a plant seismic risk analysis. To support the development of seismic capability evaluation technology for degraded structures and components, KAERI entered into a collaboration agreement with Brookhaven National Laboratory (BNL) in 2007. The collaborative research effort is intended to continue over a five year period with the goal of developing seismic fragility analysis methods that consider the potential effects of age-related degradation of SSCs, and using these results as input to seismic PRAs. In the Year 1 scope of work BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. This information is presented in the Annual Report for the Year 1 Task, identified as BNL Report-81741-2008 and also designated as KAERI/RR-2931/2008. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, the report provides a description of U.S. current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. This report describes the research effort performed by BNL for the Year 2 scope of work. This research focused on methods that could be used to represent the long-term behavior of materials used at NPPs. To achieve this BNL reviewed time-dependent models which can approximate the degradation effects of the key materials used in the construction of structures and passive components determined to be of interest in the Year 1 effort. The intent was to review the degradation models that would cover the most common time-dependent changes in material properties for concrete and steel components.

Nie,J.; Braverman, J.; Hofmayer, C.; Kim, M. K.; Choi, I-K.

2009-04-27

202

Control and Computation in Smart Material Structures.  

National Technical Information Service (NTIS)

The research carried out dealt with mathematical modeling, computation, and model validation in smart material structures. In particular a focused study of laminated curved beam with embedded piezoceramic patches was conducted. There has been widespread i...

N. G. Medhin

1998-01-01

203

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

204

Imprinted sol-gel materials for monitoring degradation products in automotive oils by shear transverse wave.  

PubMed

Titania sol-gel layers imprinted with capric acid have been used as synthetic receptors for highly sensitive detection of oxidized products resulting from degradation of automotive engine oil. These layers have been applied as sensitive coating material on shear transverse wave (STW) resonators of frequencies ranging from 100 MHz to 430 MHz. A relatively small size of STW resonators, i.e. about 2 mm for 430 MHz makes these devices extremely useful while considering the concept of miniaturization. It has been proved experimentally that by increasing fundamental resonance frequency of these devices, a very high sensor response i.e. 22 kHz up to 460 kHz can be generated. The geometry of long chain capric acid fits best as recognition element in the synthesis of imprinted TiO(2) network. The thin titania layers coated on transducer surface provide excellent diffusion pathways to oxidized products of waste engine oil for selective and reversible re-inclusion i.e. recovery time of 30 min. Viscosity effects of oxidized engine oil can be minimized by shear waves which do not dissipate considerable amount of energy that ensure smooth liquid phase operation. Different oxidized products i.e. carbonic acids and esters can be characterized in lubricant via infra-red (IR) spectroscopy. The increasing IR absorbance of different waste oil samples is a clear indication of increasing concentration of carbonyl group. The IR absorbance of carbonyl groups is directly correlated to the age of respective waste engine oil samples and a quantitative relationship between sensor responses from STWs and IR absorbance was also developed. PMID:20708116

Mujahid, Adnan; Afzal, Adeel; Glanzing, Gerd; Leidl, Anton; Lieberzeit, Peter A; Dickert, Franz L

2010-07-15

205

Microbial kinetic model for the degradation of poorly soluble organic materials.  

PubMed

A novel mechanistic model is presented that describes the aerobic biodegradation kinetics of soybean biodiesel and petroleum diesel in batch experiments. The model was built on the assumptions that biodegradation takes place in the aqueous phase according to Monod kinetics, and that the substrate dissolution kinetics at the oil/water interface is intrinsically fast compared to biodegradation kinetics. Further, due to the very low aqueous solubility of these compounds, the change in the substrate aqueous-phase concentration over time was assumed to approaches zero, and that substrate aqueous concentration remains close to the saturation level while the non-aqueous phase liquid (NAPL) is still significant. No former knowledge of the saturation substrate concentration (S(sat)) and the Monod half-saturation constant (K(s)) was required, as the term S(sat)/(K(s) + S(sat)) in the Monod equation remained constant during this phase. The n-alkanes C10-C24 of petroleum diesel were all utilized at a relatively constant actual specific utilization rate of 0.01-0.02 mg-alkane/mg-biomass-hr, while the fatty acid methyl esters (FAMEs) of biodiesel were utilized at actual specific rates significantly higher with increasing carbon chain length and lower with increasing number of double bonds. The results were found to be in agreement with kinetic, genetic, and metabolic evidence reported in the literature pertaining to microbial decay rates, uptake mechanisms, and the metabolic pathway by which these compounds are assimilated into microorganisms. The presented model can be applied, without major modifications, to estimate meaningful kinetic parameters from batch experiments, as well as near source zone field application. We suggest the estimated actual microbial specific utilization rate (kC) of such materials to be a better measure of the degradation rate when compared to the maximum specific utilization rate (k), which might be orders of magnitude higher than kC and might never be observed in reality. PMID:23340014

Yassine, Mohamad H; Suidan, Makram T; Venosa, Albert D

2012-12-19

206

Bioactive materials to control cell cycle  

Microsoft Academic Search

Many of the present generation biomaterials are still based upon the early concept that implantable materials should be bioinert\\u000a and therefore designed to evoke minimal tissue response, if none. However, a growing body of clinical data demonstrates that\\u000a the long survivability of these materials is hampered by high rates of failure, which is primarily attributed to interfacial\\u000a instability. It has

L. L. Hench; J. M. Polak; I. D. Xynos; L. D. K. Buttery

2000-01-01

207

Assessing the biocompatibility of degradable metallic materials: state-of-the-art and focus on the potential of genetic regulation.  

PubMed

For decades, the design, development and use of metallic biomaterials has focused on the corrosion resistance of these materials once implanted in the human body. Recently, degradable metallic biomaterials (DMMs) have been proposed for some specific applications, including paediatric, orthopaedic and cardiovascular applications. DMMs are expected to disappear via corrosion after providing structural support for a certain period of time depending on the application site. Over the past decades, a wide-ranging and comprehensive set of in vitro, in vivo and for some cases also ex vivo tests have been proposed and exhaustively investigated for conventional corrosion-resistant metallic biomaterials. Standardization and regulatory bodies in the United States, Japan and Europe have therefore developed tests to license corrosion-resistant metals for use as "biomaterials". This is not the case for DMMs. Once implanted, this new class of biomaterials is expected to support the healing process of a diseased tissue or organ while degrading at a potentially adjustable degradation rate. The tests developed for corrosion-resistant metals cannot simply be transposed to DMMs. These tests can in some cases be adapted, but the expected unique properties of DMMs should also inspire and lead to the design and the development of new specific tests. The current challenge is how to assess the tolerance of surrounding tissues and organs to the presence of degradation products. This work precisely focuses on this topic. The tests usually used to assess the biocompatibility of conventional corrosion-resistant metals are briefly reviewed. Then, genetic regulation is proposed as an original and novel approach to assess the biocompatibility of DMMs. This method appears to predict cell behaviour in the presence of degradation products that are closely related to DNA damage. Various genes have been related to the toxicity and inflammatory responses, indicating their role as biomarkers to assess the toxicity of degradation products. Finally, some gene families that have the potential to be applied as biomarkers of degradation product toxicity are summarized. PMID:20176149

Purnama, Agung; Hermawan, Hendra; Couet, Jacques; Mantovani, Diego

2010-02-20

208

Control of Cholesterol Synthesis through Regulated ER-Associated Degradation of HMG CoA Reductase  

PubMed Central

Multiple mechanisms for feedback control of cholesterol synthesis converge on the rate-limiting enzyme in the pathway, 3-hydroxy-3-methylglutaryl coenzyme A reductase. This complex feedback regulatory system is mediated by sterol and nonsterol metabolites of mevalonate, the immediate product of reductase activity. One mechanism for feedback control of reductase involves rapid degradation of the enzyme from membranes of the endoplasmic reticulum (ER). This degradation results from the accumulation of sterols in ER membranes, which triggers binding of reductase to ER membrane proteins called Insig-1 and Insig-2. Insig binding leads to the recruitment of a membrane-associated ubiquitin ligase called gp78 that initiates ubiquitination of reductase. Ubiquitinated reductase then becomes extracted from ER membranes and is delivered to cytosolic 26S proteasomes through an unknown mechanism that is mediated by the gp78-associated ATPase Valosin-containing protein/p97 and appears to be augmented by nonsterol isoprenoids. Here, we will highlight several advances that have led to the current view of mechanisms for sterol-accelerated, ER-associated degradation of reductase. In addition, we will discuss potential mechanisms for other aspects of the pathway such as selection of reductase for gp78-mediated ubiquitination, extraction of the ubiquitinated enzyme from ER membranes, and the contribution of Insig-mediated degradation to overall regulation of reductase in whole animals.

Jo, Youngah; DeBose-Boyd, Russell A.

2010-01-01

209

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.

'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

210

Defective in mitotic arrest 1 (Dma1) ubiquitin ligase controls G1 cyclin degradation.  

PubMed

Progression through the G(1) 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 G(1) cyclin degradation. Here, we report the design of a genetic screening that uncovered Dma1 as another E3 ligase that targets G(1) 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 G(1) cyclin degradation that we report here could help elucidate the specific roles of the redundant CDK-cyclin complexes in G(1). PMID:23264631

Hernández-Ortega, Sara; Bru, Samuel; Ricco, Natalia; Ramírez, Sara; Casals, Núria; Jiménez, Javier; Isasa, Marta; Crosas, Bernat; Clotet, Josep

2012-12-21

211

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

212

Feasibility study of polyhydroxyalkanote production for materials recycling using naturally occurring pollutant degraders  

Microsoft Academic Search

For eco-friendly recycling and reuses of biomaterials with sustainability, this feasibility study tended to use indigenous pollutant degrading bacteria for the production of biodegradable polymers – polyhydroxyalkanotes (PHAs) during wastewater treatment. First, feasible PHA-producing strains were qualitatively screened among pollutant-degrading microbes via Sudan black B staining (SB staining). Next, according to batch cultures using lauric acid as sole carbon source,

Bor-Yann Chen; Tz-Jau Shiau; Yu-Hong Wei; Wen-Ming Chen; Bing-Hua Yu; Chia-Yi Yen; Chung-Chuan Hsueh

213

A LOV2 domain-based optogenetic tool to control protein degradation and cellular function.  

PubMed

Light perception is indispensable for plants to respond adequately to external cues and is linked to proteolysis of key transcriptional regulators. To provide synthetic light control of protein stability, we developed a generic photosensitive degron (psd) module combining the light-reactive LOV2 domain of Arabidopsis thaliana phot1 with the murine ornithine decarboxylase-like degradation sequence cODC1. Functionality of the psd module was demonstrated in the model organism Saccharomyces cerevisiae. Generation of conditional mutants, light regulation of cyclin-dependent kinase activity, light-based patterning of cell growth, and yeast photography exemplified its versatility. In silico modeling of psd module behavior increased understanding of its characteristics. This engineered degron module transfers the principle of light-regulated degradation to nonplant organisms. It will be highly beneficial to control protein levels in biotechnological or biomedical applications and offers the potential to render a plethora of biological processes light-switchable. PMID:23601651

Renicke, Christian; Schuster, Daniel; Usherenko, Svetlana; Essen, Lars-Oliver; Taxis, Christof

2013-04-18

214

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

PubMed Central

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.

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

2011-01-01

215

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

216

APC/CCdc20 controls the ubiquitin-mediated degradation of p21 in prometaphase  

PubMed Central

During the G1/S transition, p21 proteolysis is mediated by Skp2; however, p21 re-accumulates in G2 and is degraded again in prometaphase. How p21 degradation is controlled in mitosis remains unexplored. We found that Cdc20 (an activator of the ubiquitin ligase APC/C) binds p21 in cultured cells and identified a D-box motif in p21 necessary for APC/CCdc20-mediated ubiquitylation of p21. Overexpression of Cdc20 or Skp2 destabilized wild type p21; however, only Skp2, but not Cdc20, was able to destabilize a p21(D-box) mutant. Silencing of Cdc20 induced an accumulation of p21, increased the fraction of p21 bound to Cdk1, and inhibited Cdk1 activity in p21+/+ prometaphase cells but not in p21?/ ? cells. Thus, in contrast to anaphase, during which Cdc20 induces Cdk1 inactivation by directing the proteolysis of cyclins, in prometaphase Cdc20 positively regulates Cdk1 by mediating the degradation of p21. We propose that the APC/CCdc20-mediated degradation of p21 contributes to the full activation of Cdk1 necessary for mitotic events and prevents mitotic slippage during spindle checkpoint activation.

Amador, Virginia; Ge, Sheng; Santamaria, Patricia G.; Guardavaccaro, Daniele; Pagano, Michele

2007-01-01

217

APC/C(Cdc20) controls the ubiquitin-mediated degradation of p21 in prometaphase.  

PubMed

During the G1/S transition, p21 proteolysis is mediated by Skp2; however, p21 reaccumulates in G2 and is degraded again in prometaphase. How p21 degradation is controlled in mitosis remains unexplored. We found that Cdc20 (an activator of the ubiquitin ligase APC/C) binds p21 in cultured cells and identified a D box motif in p21 necessary for APC/C(Cdc20)-mediated ubiquitylation of p21. Overexpression of Cdc20 or Skp2 destabilized wild-type p21; however, only Skp2, but not Cdc20, was able to destabilize a p21(D box) mutant. Silencing of Cdc20 induced an accumulation of p21, increased the fraction of p21 bound to Cdk1, and inhibited Cdk1 activity in p21(+/+) prometaphase cells, but not in p21(-/-) cells. Thus, in prometaphase Cdc20 positively regulates Cdk1 by mediating the degradation of p21. We propose that the APC/C(Cdc20)-mediated degradation of p21 contributes to the full activation of Cdk1 necessary for mitotic events and prevents mitotic slippage during spindle checkpoint activation. PMID:17679094

Amador, Virginia; Ge, Sheng; Santamaría, Patricia G; Guardavaccaro, Daniele; Pagano, Michele

2007-08-01

218

10 CFR 71.117 - Identification and control of materials, parts, and components.  

Code of Federal Regulations, 2013 CFR

...false Identification and control of materials, parts, and components...117 Identification and control of materials, parts, and components...for the identification and control of materials, parts, and...

2013-01-01

219

10 CFR 72.156 - Identification and control of materials, parts, and components.  

Code of Federal Regulations, 2013 CFR

...false Identification and control of materials, parts, and components...156 Identification and control of materials, parts, and components...for the identification and control of materials, parts, and...

2013-01-01

220

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

221

Conduction-Cooled Superconducting Magnet for Material Control Application  

Microsoft Academic Search

The conduction-cooled superconducting magnet with operating current of 180 A is designed, fabricated, and tested for material control application. The superconducting magnet has the effective standard warm bore of 52 mm and the maximum central field of 3 Tesla. Since magnetic field gradient should be larger at the end rather than at the center of the magnet for material control,

Yeon Suk Choi; Dong Lak Kim; Byoung Seob Lee; Hyung Suk Yang; Thomas A. Painter

2009-01-01

222

Design of a smart material actuator for rotor control  

NASA Astrophysics Data System (ADS)

The results of a study to conceptually define an on-blade smart material actuator for primary and active control on a servoflap rotor are presented. Actuator design drivers, goals, and requirements are defined. For a previously developed hybrid actuator concept, the design of the cyclic and active (high speed) control actuator and feasibility of the collective (low speed) actuator and stroke multiplier are investigated. Sizing of actuator components based on AH-64 servoflap requirements shows that collective control using shape memory alloys is well within the capability of the material. Cyclic and active control using magnetostrictive material, leads to a reduced maneuver envelope due to weight and volume constraints. The promise of smart materials can be realized incrementally as the materials and actuator design approaches mature. Future improvements in smart material performance and actuator technology, and additional rotor system design changes to reduced load and motion requirements should provide the full AH-64 maneuver envelope.

Straub, Friedrich K.; Merkley, Donald J.

1995-05-01

223

Design of a smart material actuator for rotor control  

NASA Astrophysics Data System (ADS)

The results of a study to conceptually define an on-blade smart material actuator for primary and active control on a servoflap rotor are presented. Actuator design drivers, goals, and requirements are defined. For a previously developed hybrid actuator concept, the design of the cyclic and active (high speed) control actuator and feasibility of the collective (low speed) actuator and stroke multiplier are investigated. Sizing of actuator components based on AH-64 servoflap requirements shows that collective control using shape memory alloys is well within the capability of the material. Cyclic and active control using magnetostrictive material, leads to a reduced maneuver envelope due to weight and volume constraints. The promise of smart materials can be realized incrementally as the materials and actuator design approaches mature. Future improvements in smart material performance and actuator technology, and additional rotor system design changes to reduce load and motion requirements should provide the full AH-64 maneuver envelope.

Straub, Friedrich K.; Merkley, Donald J.

1997-06-01

224

Macroporous hydrogels based on 2-hydroxyethyl methacrylate. Part 5: Hydrolytically degradable materials  

Microsoft Academic Search

Macroporous hydrogels based on 2-hydroxyethyl methacrylate, 2-ethoxyethyl methacrylate and N-(2-hydroxypropyl)methacrylamide, methacrylic acid and [2-(methacryloyloxy)ethyl]trimethylammonium chloride crosslinked with\\u000a N,O-dimethacryloylhydroxylamine were prepared. Hydrogels were degraded in a buffer of pH 7.4. Completely water-soluble polymers\\u000a were obtained over time periods ranging from 2 to 40 days. The process of degradation was followed gravimetrically and by\\u000a optical and electron microscopy. In vivo biological tests

Martin P?ádný; Ji?í Michálek; Petr Lesný; Aleš Hej?l; Ji?í Vacík; Miroslav Šlouf; Eva Syková

2006-01-01

225

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

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Nuclear material control and accounting for special nuclear...REGULATORY COMMISSION (CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR...Significance § 74.31 Nuclear material control and accounting for special...

2009-01-01

226

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

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Nuclear material control and accounting for special nuclear...REGULATORY COMMISSION (CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR...Significance § 74.41 Nuclear material control and accounting for special...

2009-01-01

227

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

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Nuclear material control and accounting for special nuclear...REGULATORY COMMISSION (CONTINUED) MATERIAL CONTROL AND ACCOUNTING OF SPECIAL NUCLEAR...Significance § 74.31 Nuclear material control and accounting for special...

2010-01-01

228

Optimal interface between principal deterrent systems and material accounting. [Accounting, physical security and material control systems  

Microsoft Academic Search

The purpose of this study is to find an optimal blend between three safeguards systems for special nuclear material (SNM), the material accounting system and the physical security and material control systems. The latter two are denoted as principal deterrent systems. The optimization methodology employed is a two-stage decision algorithm, first an explicit maximization of expected diverter benefits and subsequently

P. J. Deiermann; J. H. Opelka

1983-01-01

229

The incorporation of space charge degradation in the life model for electrical insulating materials  

Microsoft Academic Search

The time function of the Eyring reaction rate theory of insulation life is modified to demonstrate a physical origin for temperature threshold. Various mechanisms by which trapped charges may be involved in degrading the polymer are examined, and incorporated into the life model through an alteration to the free energies of the reacting system. The corresponding life functions are shown

L. Dissado; G. Mazzanti; G. C. Montanari

1995-01-01

230

Control of xanthan-degrading organisms in the Loudon pilot: approach, methodology, and results  

SciTech Connect

An investigation of loss of mobility control in Exxon's Loudon micellar/polymer pilot test has confirmed that loss was caused by microbial degradation of the xanthan biopolymer used to viscosify the microemulsion and polymer drive banks. This study describes techniques which were used to sample and culture bacteria from the Loudon pilot and demonstrate that these mixed cultures are able to degrade xanthan rapidly under reservoir conditions. Laboratory studies show that, under anaerobic conditions, bacteria cultured from the Loudon pilot can cause over 90% loss of xanthan viscosity in micellar/polymer fluids within 7 days. An extensive laboratory screening program was conducted to identify biocides that are effective against the offending organisms. Complete kill of the organisms, biocide compatibility (with biopolymer, formation rock, field brines, and microemulsion), cost effectiveness, and chemical stability were key parameters. Of the biocides tested, formaldehyde was found to be the most consistently effective.

Bragg, J.R.; Maruca, S.D.; Gale, W.W.; Gall, L.S.; Wernau, W.C.

1983-01-01

231

Inoculation of Pichia kudriavzevii RB1 degrades the organic acids present in raw compost material and accelerates composting.  

PubMed

In this study, the yeast strain Pichia kudriavzevii RB1 was used as an inoculum to accelerate organic matter degradation of rabbit food with added organic acids, which was used as a model food waste for composting. The RB1 strain rapidly degraded the organic acids present in the raw compost material, leading to an increase in pH beyond the neutral level, within 2days. Both mesophilic and thermophilic bacteria proliferated faster in the compost with RB1 inoculation than in that without inoculation. Although the yeast died with the increase in compost temperature, it affected the early stages of composting prior to the thermophilic stage and accelerated the composting process by 2days by eliminating the initial lag phase seen in the growth of other microorganisms. Moreover, populations of Bacillus thermoamylovorans, Bacillus foraminis, and Bacillus coagulans became dominant during the thermophilic stages of both composting with and without RB1 inoculation. PMID:23886646

Nakasaki, Kiyohiko; Araya, Shogo; Mimoto, Hiroshi

2013-07-08

232

Thermal degradation of collagen-based materials that are supports of cultural and historical objects  

Microsoft Academic Search

The thermal analysis methods (TG, DTG and DTA) were used for the investigation of the thermal degradation of some recent manufactured\\u000a tanned leathers, leathers that are supports of cultural or historical objects (leather from book covers (XVII-XIX centuries);\\u000a leather from an Austrian belt (Franz Joseph period), Cordoba leather (XVII century), lining leathers), recent and patrimonial\\u000a parchments and recent extracted collagen

P. Budrugeac; L. Miu; V. Bocu; F. J. Wortman; C. Popescu

2003-01-01

233

Local morphological and dimensional changes of enzyme-degraded cellulose materials measured by atomic force microscopy  

Microsoft Academic Search

A study of the degradation effects of enzyme treatment on the dimensional changes of cellulose aggregate fibrils (CAFs) with\\u000a dimensions of ?100,000 × 3,000 × 300 nm from fully bleached kraft fiber was performed. CAFs were incubated with cellulase\\u000a for up to 32 h. The insoluble CAFs fragments remaining after enzymatic hydrolysis were then subjected to variable relative\\u000a humidity (RH). Each sample was imaged by an

Jung Myoung Lee; John A. Heitmann; Joel J. Pawlak

2007-01-01

234

Influence of surface printing materials on the degradability of biodegradable plastic films in soil  

Microsoft Academic Search

Effect of surface printing on the biodegradability of plastic films was studied. Biodegradable films (polybutylene-succinate (PBS)) printed with four kinds of gravure inks were placed in soil for 1 year. The inks consisted of carbon black-pigment with four kinds of resins: poly-(?-caprolactone) (PCL), nitrocellulose-polyamide blended resin (NT), polyvinyl chloride-vinyl acetate copolymer (V), and nitrocellulose (NC). Degradation of film specimens printed

Akira Hoshino; Shinzou Kanao; Kenji Fukushima; Shigeichi Sakai; Makoto Kimura

2003-01-01

235

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

Microsoft Academic Search

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

1993-01-01

236

Direct product quality control for energy efficient climate controlled transport of agro-material  

Microsoft Academic Search

A (model-based) Product Quality Controller is presented for climate controlled operations involving agro-material, such as storage and transport. This controller belongs to the class of Model Predictive Controllers and fits in a previously developed hierarchical control structure. The new Product Quality Controller rejects disturbances and tracks the product quality by means of the product responses respiration and fermentation. To achieve

G. J. C. Verdijck; H. A. Preisig; G. van Straten

2005-01-01

237

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.

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

2013-01-01

238

A tuneable switch for controlling environmental degradation of bioplastics: addition of isothiazolinone to polyhydroxyalkanoates.  

PubMed

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

2013-10-11

239

Smart-Material Actuated Missile Flight Control Surfaces Feasibility Study.  

National Technical Information Service (NTIS)

The use of smart materials for rotorcraft control surface actuation at laboratory scale has performed large strides forward and the scale up of these results from laboratory into prototype demonstrations is imminent and could happen in the near future. Ho...

V. Giurgiutiu R. Pomirleanu

2000-01-01

240

Materials for Adaptive Structural Acoustic Control. Volume 5.  

National Technical Information Service (NTIS)

This report documents work carried forward over the fourth year of a five year ONR sponsored University Research initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' The program has continued to underpin the development of new e...

L. E. Cross

1996-01-01

241

Materials for Adaptive Structural Acoustic Control. Volume 4.  

National Technical Information Service (NTIS)

This report documents work carried forward over the fourth year of a five year ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' The program has continued to underpin the development of new e...

L. E. Cross

1996-01-01

242

Materials for Adaptive Structural Acoustic Control. Volume 6.  

National Technical Information Service (NTIS)

This report documents work carried forward over the fourth year of a five year ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' The program has continued to underpin the development of new e...

L. E. Cross

1996-01-01

243

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

244

21 CFR 862.3280 - Clinical toxicology control material.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Clinical toxicology control material. 862.3280 Section 862...MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Toxicology Test Systems § 862.3280 Clinical...

2010-04-01

245

21 CFR 862.3280 - Clinical toxicology control material.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Clinical toxicology control material. 862.3280 Section 862...MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Toxicology Test Systems § 862.3280 Clinical...

2009-04-01

246

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

National Technical Information Service (NTIS)

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 techniqu...

W. M. Bullis

1972-01-01

247

Spoken commands control robot that handles radioactive materials.  

National Technical Information Service (NTIS)

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, ...

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

1989-01-01

248

Human performance: An essential element in materials control and accountability.  

National Technical Information Service (NTIS)

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 fa...

S. B. Haber J. Allentuck

1996-01-01

249

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

National Technical Information Service (NTIS)

The report describes NBS activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices. Significant accomplishments during this reporting period include design of a plan to provide standard ...

W. M. Bullis

1973-01-01

250

Material flow control and scheduling in a disassembly environment  

Microsoft Academic Search

This paper presents a technique to control the material flow in a disassembly environment using the Flexible Kanban System (FKS). The implementation and effectiveness of the FKS is demonstrated using a case example.

Elif Kizilkaya; Surendra M. Gupta

1998-01-01

251

Testbed for Advanced Materials Control and Accounting Concepts.  

National Technical Information Service (NTIS)

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/ w...

R. M. Tisinger

1988-01-01

252

Soft magnetic properties of nano-structure-controlled magnetic materials  

Microsoft Academic Search

The soft magnetic properties of nano-structure-controlled NANOCON magnetic materials have been studied. The NANOCON materials consist of Fe-based soft magnetic metal particles which are separated from each other by insulation layers of metal oxides on the order of 10 nm thick. The permeability of NANOCON materials was constant up to 10 MHz due to the small isolated particles size compared

Y. Sugaya; O. Inoue; K. Kugimiya

1994-01-01

253

An automated model for materials management and control  

Microsoft Academic Search

Current, manual, materials management and control procedures are unsatisfactory: they are labour intensive, inaccurate and error prone. The result is waste and surplus of materials, delays, decrease in productivity and lack of up?to?date, real?time information regarding the status of purchase orders (PO), the levels of inventory, the actual vs. planned usage of materials, and others. The purpose of the present

R. Navon; O. Berkovich

2006-01-01

254

Intelligent sensorless control of a smart-material actuator  

Microsoft Academic Search

In this paper, intelligent sensorless control of a smart-material actuator is presented. The smart material that we used to develop a novel type of linear actuator is Terfenol-D. The peristaltic motion in the actuator is generated by inducing a traveling magnetic field inside the Terfenol-D element. The sensorless control of the actuator is based on an observation illustrating a direct

Ali Sadighi; Won-jong Kim

2010-01-01

255

Adaptive identification and control of hysteresis in smart materials  

Microsoft Academic Search

Hysteresis hinders the effective use of smart materials in sensors and actuators. This paper addresses recursive identification and adaptive inverse control of hysteresis in smart material actuators, where hysteresis is modeled by a Preisach operator with a piecewise uniform density function. Two classes of identification schemes are proposed and compared, one based on the hysteresis output, the other based on

Xiaobo Tan; John S. Baras

2005-01-01

256

Systems Analysis for Materials Control and Accountancy Technology.  

National Technical Information Service (NTIS)

The objective of this study is to upgrade Materials Control and Accountancy (MC and A) technology over the flows of special nuclear materials throughout the DOE complex of fuel cycles. The program focus is to develop a ''Management Tool'' for decision sup...

T. A. Daly R. G. Bucher A. B. Rothman I. Charak P. J. Persiani

1987-01-01

257

Systems analysis for materials control and accountancy technology  

Microsoft Academic Search

The objective of this study is to upgrade Materials Control and Accountancy (MC and A) technology over the flows of special nuclear materials throughout the DOE complex of fuel cycles. The program focus is to develop a ''Management Tool'' for decision support in evaluating MC and A upgrades, and in validating the MC and A aspects of the Master Safeguards

T. A. Daly; R. G. Bucher; A. B. Rothman; I. Charak; P. J. Persiani

1987-01-01

258

Assessing the correlation between anaerobic toluene degradation activity and bssA concentrations in hydrocarbon-contaminated aquifer material.  

PubMed

The assessment of biodegradation activity in contaminated aquifers is critical to demonstrate the performance of bioremediation and natural attenuation and to parameterize models of contaminant plume dynamics. Real time quantitative PCR (qPCR) was used to target the catabolic bssA gene (coding for benzylsuccinate synthase) and a 16S rDNA phylogenetic gene (for total Bacteria) as potential biomarkers to infer on anaerobic toluene degradation rates. A significant correlation (P = 0.0003) was found over a wide range of initial toluene concentrations (1-100 mg/l) between toluene degradation rates and bssA concentrations in anaerobic microcosms prepared with aquifer material from a hydrocarbon contaminated site. In contrast, the correlation between toluene degradation activity and total Bacteria concentrations was not significant (P = 0.1125). This suggests that qPCR targeting of functional genes might offer a simple approach to estimate in situ biodegradation activity, which would enhance site investigation and modeling of natural attenuation at hydrocarbon-contaminated sites. PMID:20204467

Kazy, Sufia K; Monier, Amy L; Alvarez, Pedro J J

2010-03-04

259

Rapid-Setting Controlled Low-Strength Material for Routine and Emergency Rehabilitation of Transportation Materials.  

National Technical Information Service (NTIS)

An experimental investigation of rapid setting controlled low-strength materials (CLSM) mixtures is described in this research report. The setting and hardening times of CLSM batched with concrete accelerators (chloride and non-chloride) were evaluated us...

C. E. Pierce S. Ihekweazu

2004-01-01

260

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

National Technical Information Service (NTIS)

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 Interna...

E. Sechkar G. Tollis J. Dever R. Messer S. Miller

2002-01-01

261

The Hypoxia-controlled FBXL14 Ubiquitin Ligase Targets SNAIL1 for Proteasome Degradation*  

PubMed Central

The transcription factor SNAIL1 is a master regulator of epithelial to mesenchymal transition. SNAIL1 is a very unstable protein, and its levels are regulated by the E3 ubiquitin ligase ?-TrCP1 that interacts with SNAIL1 upon its phosphorylation by GSK-3?. Here we show that SNAIL1 polyubiquitylation and degradation may occur in conditions precluding SNAIL1 phosphorylation by GSK-3?, suggesting that additional E3 ligases participate in the control of SNAIL1 protein stability. In particular, we demonstrate that the F-box E3 ubiquitin ligase FBXl14 interacts with SNAIL1 and promotes its ubiquitylation and proteasome degradation independently of phosphorylation by GSK-3?. In vivo, inhibition of FBXl14 using short hairpin RNA stabilizes both ectopically expressed and endogenous SNAIL1. Moreover, the expression of FBXl14 is potently down-regulated during hypoxia, a condition that increases the levels of SNAIL1 protein but not SNAIL1 mRNA. FBXL14 mRNA is decreased in tumors with a high expression of two proteins up-regulated in hypoxia, carbonic anhydrase 9 and TWIST1. In addition, Twist1 small interfering RNA prevents hypoxia-induced Fbxl14 down-regulation and SNAIL1 stabilization in NMuMG cells. Altogether, these results demonstrate the existence of an alternative mechanism controlling SNAIL1 protein levels relevant for the induction of SNAIL1 during hypoxia.

Vinas-Castells, Rosa; Beltran, Manuel; Valls, Gabriela; Gomez, Irene; Garcia, Jose Miguel; Montserrat-Sentis, Barbara; Baulida, Josep; Bonilla, Felix; de Herreros, Antonio Garcia; Diaz, Victor M.

2010-01-01

262

The anaerobic degradability of thermoplastic starch: polyvinyl alcohol blends: potential biodegradable food packaging materials.  

PubMed

A systematic study on the anaerobic degradability of a series of starch:polyvinyl alcohol (TPS:PVOH) blends was performed to determine their fate upon disposal in either anaerobic digesters or bioreactor landfills. The aims of the study were to measure the rate and extent of solubilisation of the plastics. The extent of substrate solubilisation on a COD basis reached 60% for a 90:10 (w/w) blend of TPS:PVOH, 40% for 75:25, 30% for 50:50 and 15% for PVOH only. The rate of substrate solubilisation was most rapid for the 90:10 blend (0.041 h(-1)) and decreased with the amount of starch in the blend in the following order 0.034 h(-1)(75:25); 0.023 h(-1)(50:50). The total solids that remained after 900 h were 10 wt.% (90:10); 23 wt.% (75:25); 55 wt.% (50:50); 90 wt.% (0:100). Starch containing substrates produced a higher concentration of volatile fatty acids (VFAs) and biogas, compared to the 0:100 substrate. The major outcome was that PVOH inhibited the degradation of the starch from the blend. PMID:18990564

Russo, Melissa A L; O'Sullivan, Cathryn; Rounsefell, Beth; Halley, Peter J; Truss, Rowan; Clarke, William P

2008-11-05

263

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...

264

Design of a smart material actuator for rotor control  

Microsoft Academic Search

The results of a study to conceptually define an on-blade smart material actuator for primary and active control on a servoflap rotor are presented. Actuator design drivers, goals, and requirements are defined. For a previously developed hybrid actuator concept, the design of the cyclic and active (high speed) control actuator and feasibility of the collective (low speed) actuator and stroke

Friedrich K. Straub; Donald J. Merkley

1995-01-01

265

Design of a smart material actuator for rotor control  

Microsoft Academic Search

The results of a study to conceptually define an on-blade smart material actuator for primary and active control on a servoflap rotor are presented. Actuator design drivers, goals, and requirements are defined. For a previously developed hybrid actuator concept, the design of the cyclic and active (high speed) control actuator and feasibility of the collective (low speed) actuator and stroke

Friedrich K. Straub; Donald J. Merkley

1997-01-01

266

Bibliographic Control of Large Quantities of Research Material  

Microsoft Academic Search

Although the term bibliographic control usually refers to methods libraries employ to manage their holdings, it is also applicable to the management of large quantities of research material. Effective bibliographic control is a particular problem for the individual researcher involved in the construction of a bibliography ranging from several hundred to several thousand items. This article describes bibliographic methods for

Martha M. Evans

1983-01-01

267

Evaluating the contributions of material control to insider protection  

SciTech Connect

Facilities handling nuclear material must be adequately protected against a spectrum of threats including insiders, outsiders, and collusion among insider and outsider adversaries. To counter these threats, facilities implement an integrated system of physical protection (PP), material control (MC), and material accountability (MA). (Personnel Security Assurance Programs are also used to help deter and detect potential insider adversaries.) Naturally, the contribution of each of these systems to protection against the different threats varies. Material control plays an important role in protecting against the insider threat and in assuring that material is where it should be. Evaluating its contributions, however, to the overall protection is challenging. This paper focuses on one of the modules of the ASSESS code --- a state-of-the-art safeguards evaluation tool developed jointly with Sandia National Laboratories --- and discusses its use for assessing the contributions of MC to an overall insider protection program and for evaluating the safeguards benefits of new MC technologies. 2 refs.

Al-Ayat, R.A. (Lawrence Livermore National Lab., CA (USA))

1989-06-29

268

Role of superoxide anion in contaminant degradation by hydrogen peroxide in the presence of sandy aquifer material  

SciTech Connect

The decomposition of hydrogen peroxide (H{sub 2}O{sub 2}) in the presence of metal oxides has frequently been described by a modified Haber-Weiss mechanism, which involves a redox reaction where H{sub 2}O, can accept an electron from a metal surface site (Eq. 1) or donate an electron to a surface site (Eq.2), S + H{sub 2}O{sub 2} {r_arrow}S{sup +} + OH{sup -} + {lg_bullet}OH S{sup +} + H{sub 2}O{sub 2} {r_arrow} S + H{sup +} + {lg_bullet}HO{sub 2} where [S] represents a reduced surface site and [S+] represents an oxidized surface site respectively. These reactions involve the formation of hydroxyl radical (OH{lg_bullet}) and perhydroxyl radical ({lg_bullet}HO{sub 2}). in addition, superoxide anion (O{sub 2}{sup -}) is present because it is in equilibrium with {lg_bullet}HO according to: {lg_bullet}HO{sub 2}{longleftrightarrow} H{sup +} + O{sub 2}- pKa=4.8. The hydroxyl radical is a non-specific powerful oxidant, capable of reacting with a number of organic compounds at near diffusion-limited reaction rates. Consequently, several researchers have studied surface catalyzed H{sub 2}O{sub 2} decomposition for the purpose of organic contaminant degradation. For example, trichloroethylene and pentachlorophenol were effectively degraded in column experiments with H{sub 2}O{sub 2} and a coarse sand. The purpose of this study was to examine the role of superoxide anion in the degradation of contaminants in materials similar to aquifer materials.

Miller, C.M. [Univ. of Akron, OH (United States); Valentine, R.L. [Univ. of Iowa, Iowa City, IA (United States)

1996-12-31

269

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

270

Probabilistic material strength degradation model for Inconel 718 components subjected to high temperature, mechanical fatigue, creep and thermal fatigue effects  

NASA Astrophysics Data System (ADS)

This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

Bast, Callie Corinne Scheidt

1994-03-01

271

Saltstone Disposal Facility Closure Cap Configuration and Degradation Base Case: Institutional Control to Pine Forest Scenario  

SciTech Connect

The Performance Assessment (PA) for the Saltstone Disposal Facility (SDF) is currently under revision. As part of the PA revision and as documented herein, the closure cap configuration has been reevaluated and closure cap degradation mechanisms and their impact upon infiltration through the closure cap have been evaluated for the institutional control to pine forest, land use scenario. This land use scenario is considered the base case land use scenario. This scenario assumes a 100-year institutional control period following final SDF closure during which the closure cap is maintained. At the end of institutional control, it is assumed that a pine forest succeeds the cap's original bamboo cover. Infiltration through the upper hydraulic barrier layer of the closure cap as determined by this evaluation will be utilized as the infiltration input to subsequent PORFLOW vadose zone contaminant transport modeling, which will also be performed as part of the PA revision. The impacts of pine forest succession, erosion, and colloidal clay migration as degradation mechanisms on the hydraulic properties of the closure cap layers over time have been estimated and the resulting infiltration through the closure cap has been evaluated. The primary changes caused by the degradation mechanisms that result in increased infiltration are the formation of holes in the upper GCL by pine forest succession and the reduction in the saturated hydraulic conductivity of the drainage layers due to colloidal clay migration into the layers. Erosion can also result in significant increases in infiltration if it causes the removal of soil layers, which provide water storage for the promotion of evapotranspiration. For this scenario, infiltration through the upper GCL was estimated at approximately 0.29 inches/year under initial intact conditions, it increased to approximately 11.6 inches/year at year 1000 in nearly a linear fashion, and it approached an asymptote of around 14.1 inches/year at year 1800 and thereafter. At year 1800, it was estimated that holes covered approximately 0.3 percent of the GCL due to root penetration, and that this resulted in an infiltration near that of typical background infiltration (i.e. as though the GCL were not there at all). This demonstrated that a very small area of holes essentially controlled the hydraulic performance of the GCL.

Phifer, M.A.

2004-03-19

272

MICROBIAL DEGRADATION OF SELECTED HAZARDOUS MATERIALS: PENTACHLOROPHENOL, HEXACHLOROCYCLOPENTADIENE, AND METHYL PARATHION  

EPA Science Inventory

This program evaluated the use of selected pure culture microrganisms for potential in biodegrading the hazardous materials pentachlorophenol (PCP), hexachlorocyclopentadiene (HCCP), and methyl parathion (MP). Each chemical was separately challenged by each of 24 organisms in aqu...

273

Requirement for alanine in the amino acid control of deprivation-induced protein degradation in liver.  

PubMed Central

Protein degradation in liver is actively controlled by a small group of inhibitory amino acids--leucine, tyrosine (or phenylalanine), glutamine, proline, histidine, tryptophan, and methionine. Other evidence, however, suggests that one or more of the remaining 12 noninhibitory amino acids is also required for suppression of proteolysis at normal concentrations. This question was investigated in livers of fed rats perfused in the single-pass mode. The deletion of alanine at normal (1x), but not at 4x or 10x normal, plasma amino acid concentrations evoked a near-maximal acceleration of protein degradation. No other noninhibitory amino acid was effective. Because alanine alone was not directly inhibitory and its omission was not associated with a decrease in inhibitory amino acid pools, alanine was presumed to act as a coregulator in the expression of inhibitory activity. When tested alone, the inhibitory group was as effective as the complete mixture at 0.5x and 4x levels, but it lost its suppressive ability within a narrow zone of concentration centered slightly above 1x. The addition of 1x (0.48 mM) alanine completely restored the inhibition. Pyruvate and lactate could be effectively substituted, but only at concentrations 10-20 times greater than that of alanine. These, together with earlier findings, indicate the existence of a regulatory complex that recognizes specific amino acids and transmits positive and negative signals to proteolytic sites. The results also suggest that alanine can provide an important regulatory link between energy demands and protein degradation.

Poso, A R; Mortimore, G E

1984-01-01

274

Ascorbic acid degradation kinetics in mushrooms in a high-temperature short-time process controlled by a thermoresistometer  

Microsoft Academic Search

The degradation of ascorbic acid was studied in mushrooms heated at temperatures between 110 and 140°C, high-temperature short-time conditions, in a five-channel computer-controlled thermoresistometer. The kinetics parameters were calculated on the assumption that there are 2 degradation mechanisms, one aerobic (during the first few seconds of the process) and the other anaerobic. The 2 stages followed first-order reaction kinetics, with

R Blasco; M. J Esteve; A Fr??gola; M Rodrigo

2004-01-01

275

Molecular chaperones and substrate ubiquitination control the efficiency of endoplasmic reticulum-associated degradation  

PubMed Central

The endoplasmic reticulum (ER) must contend with a large protein flux, which is especially notable in cells dedicated to secreting hormone-regulated gene products. Because of the complexity of the protein folding pathway and the potential for genetic or stochastic errors, a significant percentage of these nascent secreted proteins fail to acquire their native conformations. If these species cannot be cleared from the ER, they may aggregate, which leads to cell death. To lessen the effects of potentially toxic polypeptides, aberrant ER proteins are destroyed via a process known as ER-associated degradation (ERAD). ERAD substrates are selected by molecular chaperones and chaperone-like proteins, and prior to degradation most substrates are ubiquitin-modified. Together with the unfolded protein response, the ERAD pathway is a critical component of the protein quality control machinery in the ER. Although emerging data continue to link ERAD with human diseases, most of our knowledge of this pathway arose from studies using a model eukaryote, the yeast Saccharomyces cerevisiae. In this review, we will summarize the discoveries that led to our current understanding of this pathway, focusing primarily on experiments in yeast. We will also indicate links between ERAD and disease and emphasize future research avenues.

Goeckeler, J. L.; Brodsky, J. L.

2011-01-01

276

?TrCP controls GH receptor degradation via two different motifs.  

PubMed

The physiological roles of GH are broad and include metabolism regulation and promotion of somatic growth. Therefore, the responsiveness of cells to GH must be tightly regulated. This is mainly achieved by a complex and well-controlled mechanism of GH receptor (GHR) endocytosis. GHR endocytosis occurs independently of GH and requires the ubiquitin ligase, SCF (?TrCP) that is recruited to the ubiquitin-dependent endocytosis (UbE) motif in the cytoplasmic tail of the GHR. In this study we report that, in addition to the UbE motif, a downstream degron, DSGRTS, binds to ?TrCP. The WD40 residues on ?TrCP involved in the interaction with this sequence are identical to the ones necessary for binding the classical motif, DSGxxS, in inhibitor of NF?B signalling, and ?-catenin. Previously, we showed that this motif is not involved in GH-induced endocytosis. We show here that the DSGRTS sequence significantly contributes to GHR endocytosis/degradation in basal conditions, whereas the UbE motif is involved both in basal and GH-induced conditions. These findings explain the high rate of GHR degradation under basal conditions, which is important for regulating the responsiveness of cells to GH. PMID:22034227

da Silva Almeida, Ana C; Strous, Ger J; van Rossum, Agnes G S H

2011-10-27

277

CAF-I-dependent control of degradation of the discontinuous strands during mismatch repair.  

PubMed

DNA mismatch repair (MMR) is a multifunctional process that promotes genetic stability and suppresses carcinogenesis. Correction of DNA replication errors is its major function. Despite the importance of MMR, its functioning in eukaryotes is not well understood. Here we report that human mismatch correction reactions in cell-free extracts occur during concomitant nick-dependent nucleosome assembly shaped by the replication histone chaperone CAF-I. Concomitant nucleosome assembly protects the discontinuous mismatch-containing strands from excessive degradation by MMR machinery. Such protection is also demonstrated in a defined purified system that supports both mismatch correction and CAF-I-dependent histone H3-H4 deposition reactions. In addition, we find that the mismatch recognition factor MutS? suppresses CAF-I-dependent histone H3-H4 deposition in a mismatch-dependent manner. We suggest that there is active crosstalk between MMR and replication-dependent nucleosome assembly during the correction of DNA replication errors and, as a result, the nascent mismatch-containing strands are degraded in a controlled manner. PMID:21282622

Kadyrova, Lyudmila Y; Blanko, Elena Rodriges; Kadyrov, Farid A

2011-01-31

278

CAF-I-dependent control of degradation of the discontinuous strands during mismatch repair  

PubMed Central

DNA mismatch repair (MMR) is a multifunctional process that promotes genetic stability and suppresses carcinogenesis. Correction of DNA replication errors is its major function. Despite the importance of MMR, its functioning in eukaryotes is not well understood. Here we report that human mismatch correction reactions in cell-free extracts occur during concomitant nick-dependent nucleosome assembly shaped by the replication histone chaperone CAF-I. Concomitant nucleosome assembly protects the discontinuous mismatch-containing strands from excessive degradation by MMR machinery. Such protection is also demonstrated in a defined purified system that supports both mismatch correction and CAF-I-dependent histone H3–H4 deposition reactions. In addition, we find that the mismatch recognition factor MutS? suppresses CAF-I-dependent histone H3–H4 deposition in a mismatch-dependent manner. We suggest that there is active crosstalk between MMR and replication-dependent nucleosome assembly during the correction of DNA replication errors and, as a result, the nascent mismatch-containing strands are degraded in a controlled manner.

Kadyrova, Lyudmila Y.; Blanko, Elena Rodriges; Kadyrov, Farid A.

2011-01-01

279

Control of xanthan-degrading organisms in the Loudon pilot: Approach, methodology, and results  

SciTech Connect

An investigation of loss of mobility control in Exxon's Loudon micellar/polymer pilot test has confirmed that loss was caused by microbial degradation of the xanthan biopolymer used to viscosify the microemulsion and polymer drive banks. This paper describes techniques which were used to sample and culture bacteria from the Loudon pilot and demonstrate that these mixed cultures are able to degrade xanthan rapidly under reservoir conditions. Laboratory studies show that, under anaerobic conditions, bacteria cultured from the Loudon pilot can cause over 90% loss of xanthan viscosity in micellar/polymer fluids within seven days. To remedy this problem, an extensive laboratory screening program was conducted to identify biocides that are effective against the offending organisms. Complete kill of the organisms under repeated laboratory challenge tests was the chief screening criterion. Biocide compatibility (with biopolymer, formation rock, field brines, and microemulsion), cost effectiveness, and chemical stability were also judged key parameters for effectiveness in field applications. Of the biocides tested against the Loudon organisms, formaldehyde was found to be the most consistently effective, providing complete kill and persistence at levels of 500 to 2000 ppm. Formaldehyde was shown to reduce bacteria below detectable levels in the formation and permit propagation of xanthan in a follow-up test conducted within the highly contaminated pilot zone. Therefore, formaldehyde should be an effective biocide for future floods at Loudon.

Bragg, J.R.; Beck, D.; Gale, W.W.; Gall, L.S.; Goldman, I.M.; Laskin, A.I.; Maruca, S.D.; Naslund, L.A.; Wernau, W.C.

1983-10-01

280

Hydrogen peroxide generation and photocatalytic degradation of estrone by microstructural controlled ZnO nanorod arrays  

NASA Astrophysics Data System (ADS)

The strong oxidant, hydrogen peroxide (H2O2), generated by ZnO nanorod arrays under UV light irradiation was monitored by fluorescence analysis. The ZnO nanorod arrays were synthesized via a low temperature hydrothermal method and their dimensions, i.e., diameter and height, can be controlled by adjusting the concentration of zinc nitrate (Zn(NO3)2·6H2O) and hexamethylenetetramine (HMT). The morphology, nanostructure, surface roughness and optical property were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmittance spectra, respectively. The ZnO nanorod arrays were applied in the degradation of estrone, which is an emerging steroid estrogen contaminant. The results revealed that the ZnO nanorod array produced from 25 mM Zn2+ and HMT had the highest aspect ratio, the largest surface roughness and the lowest band gap energy, which was beneficial to the efficiency of UV light utilization, photocatalytic degradation of estrone and H2O2 generation.

Liu, Yangsi; Han, Jie; Qiu, Wei; Gao, Wei

2012-12-01

281

Systems analysis for materials control and accountancy technology  

Microsoft Academic Search

The objective is to upgrade Materials Control and Accountancy (MCandA) technology over the flows of special nuclear materials throughout the DOE complex of fuel cycles. The program focus is to develop a ''Management Tool'' for decision support in evaluating MCandA upgrades, and invalidating the MCandA aspects of the Master Safeguards and Security Agreements (MSSA) effectiveness. The approach is the computerization

T. A. Daly; R. G. Bucher; A. B. Rothman; I. Charak; P. J. Persiani

1987-01-01

282

Controllable optical black hole in left-handed materials.  

PubMed

Halting and storing light by infinitely decelerating its speed, in the absence of any form of external control, is extremely di+/-cult to imagine. Here we present a theoretical prediction of a controllable optical black hole composed of a planar left-handed material slab. We reveal a criterion that the effective round-trip propagation length in one zigzag path is zero, which brings light to a complete standstill. Both theory and ab initio simulation demonstrate that this optical black hole has degrees flexible controllability for the speed of light. Surprisingly, the ab initio simulations reveal that our scheme has degrees flexible controllability for swallowing, holding, and releasing light. PMID:20174039

Bai, Qiang; Chen, Jing; Shen, Nian-Hai; Cheng, Chen; Wang, Hui-Tian

2010-02-01

283

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

284

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

285

Systematic control of experimental inconsistency in combinatorial materials science.  

PubMed

We developed a method to systematically control experimental inconsistency, which is one of the most troublesome and difficult problems in high-throughput combinatorial experiments. The topic of experimental inconsistency is never addressed, even though all scientists in the field of combinatorial materials science face this very serious problem. Experimental inconsistency and material property were selected as dual objective functions that were simultaneously optimized. Specifically, in an attempt to search for promising phosphors with high reproducibility, photoluminescence (PL) intensity was maximized, and experimental inconsistency was minimized by employing a multiobjective evolutionary optimization-assisted combinatorial materials search (MOEO combinatorial material search) strategy. A tetravalent manganese-doped alkali earth germanium/titanium oxide system was used as a model system to be screened using MOEO combinatorial materials search. As a result of MOEO reiteration, we identified a halide-detached deep red phosphor with improved PL intensity and reliable reproducibility. PMID:19061418

Sharma, Asish Kumar; Kulshreshtha, Chandramouli; Sohn, Keemin; Sohn, Kee-Sun

286

Chemical Degradation in Thermally Treated Ferrite/Superconductor Multiphase Materials: Modeling Parameters  

NASA Astrophysics Data System (ADS)

Solid state chemical evolutions are studied in the case of superconductor/ferrite composites as a function of time and temperature. Pellets have been fabricated from ferrite NiFe2O4 and superconducting cuprate Bi1.6Pb0.4Sr2Ca2Cu3O10+X (noted as Bi-2223). Two types of experimental approaches are presented: high-temperature electrical complex impedance spectroscopy, and EDAX analyses performed from scanning electron microscopy. From the in situ electrical analyses, two steps in the solid state chemical evolutions have been evidenced for the first time. They can be associated with two types of solid state reactions: (i) direct reactions between the ferrite phase and the superconducting matrix and (ii) a self-degradation of the superconducting phase probably associated with a homogenization of elements. The electrical analyses are modeled using two types of kinetics parameters. From the EDAX analyses, the local distribution of each element is determined. The concentration profiles found for the various elements (Ni, Fe, Bi, Sr, Ca, Cu) are interpreted in terms of a virtual diffusion law involving virtual D* coefficients. These coefficients are found to be of about 10-11 (cm2/s) in the range 800-830°C.

Kopia-Zastawa, Agnes; Suliga, I.; Siwek, A.; Kusinski, J.; Villain, S.; Fremy, M. A.; Pischedda, M. H.; Gavarri, J. R.

2001-09-01

287

Degradation of space exposed surfaces by hypervelocity dust bombardment, and refractory materials for space  

Microsoft Academic Search

Dust particles with diameters below 100?m represent an important part of the space environment. Objects like satellites or spacecrafts, are constantly bombarded with particles of cosmic velocities of 10km\\/s and more. These hypervelocity impacts lead to evaporation of a large fraction of these particles and to the formation of craters on the material surfaces which exhibit diameters which are up

H. M. Ortner; F. J. Stadermann

2009-01-01

288

Degradation and Stabilization of Low-density Polyethylene Films used as Greenhouse Covering Materials  

Microsoft Academic Search

A large quantity of plastics is used annually world-wide in the agricultural sector, of which a significant amount is intended for protected cultivation, in greenhouses and low tunnels. For this specific application, thin films of low-density polyethylene is the most widespread material used. As expected, due to the harsh conditions met during their use, from ultraviolet irradiation, heat, agrochemicals, as

P. A. Dilara; D. Briassoulis

2000-01-01

289

Degradation of recycled PET fibers in Portland cement-based materials  

Microsoft Academic Search

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

D. A.. Silva; A. M. Betioli; P. J. P. Gleize; H. R. Roman; L. A. Gómez; J. L. D. Ribeiro

2005-01-01

290

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

291

Selective destruction of abnormal proteins by ubiquitin-mediated protein quality control degradation  

PubMed Central

Misfolded proteins are continuously produced in the cell and present an escalating detriment to cellular physiology if not managed effectively. As such, all organisms have evolved mechanisms to address misfolded proteins. One primary way eukaryotic cells handle the complication of misfolded proteins is by destroying them through the ubiquitin-proteasome system. To do this, eukaryotes possess specialized ubiquitin-protein ligases that have the capacity to recognize misfolded proteins over normally folded proteins. The strategies used by these Protein Quality Control (PQC) ligases to target the wide variety of misfolded proteins in the cell will likely be different than those used by ubiquitin-protein ligases that function in regulated degradation to target normally folded proteins. In this review, we highlight what is known about how misfolded proteins are recognized by PQC ubiquitin-protein ligases.

Fredrickson, Eric K.; Gardner, Richard G.

2012-01-01

292

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...

293

Degradation and Reuse of Radiative Thermal Protection System Materials for the Space Shuttle.  

National Technical Information Service (NTIS)

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 al...

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

1971-01-01

294

Artificial neural network predictions of degradation of nonmetallic lining materials from laboratory tests  

SciTech Connect

Such organic materials of construction as plastics (thermoplastics and thermosets) and elastomers play an increasingly important role in the containment of corrosive fluids. One major impediment to their routine use is the inability to predict their performance from laboratory tests rapidly and reliably. Artificial neural networks are computer simulations that have the potential to find the same patterns that corrosion practitioners recognize to relate experimental test results to lifetime predictions. This potential was used to construct an artificial neural network to recognize the pattern between results from a sequential immersion test for organic nonmetallic lining materials and their ability to function as linings in actual applications. The network was shown to predict field performance. The network was incorporated within an expert system to simplify data input and output, to allow for simple consistency checks between sample appearance and network output, and to make the final prediction.

Silverman, D.C. (Monsanto Co., St. Louis, MO (United States))

1994-06-01

295

Dysprosium titanate as an absorber material for control rods  

Microsoft Academic Search

Disprosium titanate is an attractive control rod material for the thermal neutron reactors. Its main advantages are: insignificant swelling, no out-gassing under neutron irradiation, rather high neutron efficiency, a high melting point (?1870°C), non-interaction with the cladding at temperatures above 1000°C, simple fabrication and easily reprocessed non-radioactive waste. It can be used in control rods as pellets and powder. The

V. D. Risovany; E. E. Varlashova; D. N. Suslov

2000-01-01

296

Migration of volatile degradation products into ozonated water from plastic packaging materials.  

PubMed

Migration of volatile degradation products from poly(ethylene terephthalate) (PET) and high-density polyethylene (HDPE) bottles, polypropylene (PP) caps and ethyl vinyl acetate (EVA) liners into ozonated water was measured. Polymer strips were immersed in deionized and distilled water with ozone concentrations of 0.5, 2.5 and/or 5 mg kg(-1) inside 35-ml vials, which were clamp-sealed and stored at 40 degrees C for 10 days. A purge-and-trap unit was developed to extract volatile products from the ozonated water in vials. The extractables were trapped in an adsorbent tube and analysed using a GC-MS coupled with an automated thermal desorber (ATD). Mass spectra were interpreted by comparison with a NIST mass spectral library, and an internal standard method was used to quantify the extractables of interest. Several volatile compounds found in ozonated water that had been in contact with PP, EVA and HDPE polymers included butanal, pentanal, hexanal, heptanal, octanal, nonanal, 2,2-dimethyl propanal, 3-hexanone, 2-hexanone and heptanone. These compounds could cause off-taste and off-odour with a low organoleptic threshold. In general, the concentrations of these volatile compounds increased with an increased exposure to ozone. The highest concentration found was 14.1 +/- 0.6 microg kg(-1) for hexanal with a 5 mg kg(-1) ozone treatment of PP caps. Even at a treatment level of 5 mg kg(-1) ozone, which is greater than 10 times the current regulatory limits for bottled water, the extractables migrating from those polymers were within the levels permitted by the FDA. For the PET sample, no significant peaks were observed before or after ozonation. These results imply that PP caps containing EVA liners may be major sources of off-odour and taste in ozonated bottled water. PMID:14594682

Song, Y S; Al-Taher, F; Sadler, G

2003-10-01

297

Degradation behaviour of polymeric materials found in auto Shredder residue wastes  

Microsoft Academic Search

The thermogravimetry of a series of 50\\/50 mixtures of polypropylene, acrylonitrile\\/butadiene\\/styrene, polyvinyl chloride and\\u000a polyurethane polymers have been studied as representative of the major polymeric materials found in automobile shredder residues.\\u000a The weight loss behaviour of these polymeric mixes have been compared with the results calculated from the individual polymeric\\u000a components. This comparison of the thermogravimetry curves and the calculated

M. Day; J. D. Cooney; C. Klein

1993-01-01

298

SBE type cobalt aluminophosphate nanoporous materials: Degradation of the structure-directing agent  

Microsoft Academic Search

The extent of detemplation of cobalt containing aluminophosphates (SBE; Co\\/Al=1) was investigated. SBE powder crystals were obtained for the first time by extending the aging stage during synthesis. While X-ray powder diffraction data confirmed the presence of a rich Co-SBE phase, scanning electron microscopy images indicated that the crystal morphology was no longer a truncated hexahedron. Instead, the material displayed

Daphne S. Belén-Cordero; Sandra Méndez-González; Arturo J. Hernández-Maldonado

2008-01-01

299

Accelerated-aging tests for predicting radiation degradation of organic materials  

Microsoft Academic Search

Long-term aging of organic materials in reactor containment buildings has become a major issue within the nuclear community. In this article, the status of radiation-aging qualification test requirements in several countries is reviewed, and problems with the current aging methodologies are described. These problems include dose-rate and synergistic effects and environmental synergisms, which have been found for many different polymeric

R. L. Clough; K. T. Gillen; J. L. Campan; G. Gaussens; H. Schoenbacher; T. Seguchi; H. Wilski; S. Machi

1984-01-01

300

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

Microsoft Academic Search

Three copper-based alloys --- CDA 102 (OFHC copper), CDA 613 (aluminum bronze), and CDA 715 (Cu-30Ni) --- are being considered as possible materials for the fabrication of high-level radioactive-waste disposal containers. Waste will include fuel assemblies from reactors as well as borosilicate glass forms, and will be sent to the prospective repository at Yucca Mountain, Nevada, for emplacement. The three

J. C. Farmer; R. A. Van Konynenburg; R. D. McCright; G. E. Gdowski

1988-01-01

301

Time-dependent degradation of titanium osteoconductivity: An implication of biological aging of implant materials  

Microsoft Academic Search

The shelf life of implantable materials has rarely been addressed. We determined whether osteoconductivity of titanium is stable over time. Rat bone marrow-derived osteoblasts were cultured on new titanium disks (immediately after acid-etching), 3-day-old (stored after acid-etching for 3 days in dark ambient conditions), 2-week-old, and 4-week-old disks. Protein adsorption capacity, and osteoblast migration, attachment, spread, proliferation and mineralization decreased

Wael Att; Norio Hori; Masato Takeuchi; Jianyong Ouyang; Yang Yang; Masakazu Anpo; Takahiro Ogawa

2009-01-01

302

Strength properties of fly ash based controlled low strength materials.  

PubMed

Controlled low strength material (CLSM) is a flowable mixture that can be used as a backfill material in place of compacted soils. Flowable fill requires no tamping or compaction to achieve its strength and typically has a load carrying capacity much higher than compacted soils, but it can still be excavated easily. The selection of CLSM type should be based on technical and economical considerations for specific applications. In this study, a mixture of high volume fly ash (FA), crushed limestone powder (filler) and a low percentage of pozzolana cement have been tried in different compositions. The amount of pozzolana cement was kept constant for all mixes as, 5% of fly ash weight. The amount of mixing water was chosen in order to provide optimum pumpability by determining the spreading ratio of CLSM mixtures using flow table method. The shear strength of the material is a measure of the materials ability to support imposed stresses on the material. The shear strength properties of CLSM mixtures have been investigated by a series of laboratory tests. The direct shear test procedure was applied for determining the strength parameters Phi (angle of shearing resistance) and C(h) (cohesion intercept) of the material. The test results indicated that CLSM mixtures have superior shear strength properties compared to compacted soils. Shear strength, cohesion intercept and angle of shearing resistance values of CLSM mixtures exceeded conventional soil materials' similar properties at 7 days. These parameters proved that CLSM mixtures are suitable materials for backfill applications. PMID:17331642

Türkel, S

2007-02-03

303

Ion-irradiation enhancement of materials degradation in Fe-Cr single crystals detected by magnetic technique  

NASA Astrophysics Data System (ADS)

Single crystalline Fe-20%Cr film was prepared using a molecular beam epitaxy technique, and 2.4 MeV Cu2+ ion-irradiation was subsequently carried out at room temperature and at 748 K. Magnetic hysteresis measurement and magnetic domain observation showed that room-temperature irradiation did not have a large effect on the magnetic properties of Fe-20%Cr films. However, irradiation at 748 K caused a significant magnetic hardening and a drastic change in domain structures. It is assumed that the domain characteristics reflect the formation of chromium-rich precipitates due to the phase separation accelerated by irradiation. This study demonstrates the feasibility of nondestructive magnetic techniques for evaluating the materials degradation of Fe-Cr alloys under the irradiation environment.

Kamada, Yasuhiro; Watanabe, Hideo; Mitani, Seiji; Mohapatra, Jitendra Narayana; Kikuchi, Hiroaki; Kobayashi, Satoru; Mizuguchi, Masaki; Takanashi, Koki

2013-11-01

304

Enhancement of the diesel oil degradation ability of a marine bacterial strain by immobilization on a novel compound carrier material.  

PubMed

A novel floatable and biodegradable carrier material was made by coating puffed foxtail millet (PFM) with a calcium alginate (CA)-chitosan compound membrane. A diesel oil-degrading marine bacterial strain, Acinetobacter sp. F9, was immobilized on the carrier material. The number of viable F9 cells immobilized on the carrier material reached approximately 5×10(9) CFU/g. This formulation could be stored at -20°C and 4°C for 10 weeks without a significant decrease in the number of viable immobilized cells. SEM results showed that the coating membrane was porous and that F9 cells were immobilized on the walls of the pores. The immobilized F9 cells were able to remove more than 90% of the diesel oil by the second day, while free F9 cells did not remove 90% of the diesel oil until the seventh day. GC-MS analysis indicated that the immobilized F9 cells could remove diesel oil more completely than free cells. The immobilization of the F9 cells enhanced their ability to biodegrade diesel oil. PMID:23231916

Hou, Dengyong; Shen, Xianrong; Luo, Qun; He, Ying; Wang, Qingrong; Liu, Qiong

2012-12-08

305

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

SciTech Connect

An atomic oxygen exposure facility has been 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 material for use in low earth orbit. The studies that are being undertaken using the facility will provide (1) absolute reaction cross sections for use in engineering design problems, (2) formulations of reaction mechanisms for use in selection of suitable existing materials and design of new more resistant ones, and (3) 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 (1) a cw laser sustained discharge source of O-atoms having a variable energy up to 5 eV and an intensity of between 10/sup 15/-10/sup 17/ O-atoms s/sup -1/ cm/sup -2/, (2) an atomic beam formation and diagnostics system consisting of various stages of differential pumping, mass spectrometer detector and time-of-flight analysis, (3) a spinning rotor viscometer for absolute O-atom flux measurements, and (4) provision for using the system for calibration of flight instruments. 15 refs., 10 figs.

Cross, J.B.; Spangler, L.H.; Hoffbauer, M.A.; Archuleta, F.A.

1986-01-01

306

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

307

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

308

MEASUREMENT TECHNIQUES FOR INORGANIC TRACE MATERIALS IN CONTROL SYSTEM STREAMS  

EPA Science Inventory

The report gives results of a study showing that inorganic materials in control process streams at trace levels can be determined using modified, commercially available sampling equipment and atomic absorption analysis procedures; however, special care must be taken to attain hig...

309

Temperature controlled material irradiation in the advanced test reactor  

Microsoft Academic Search

The United States Department of Energy (US DOE) has initiated the development of an Irradiation Test Vehicle (ITV) for fusion materials irradiation at the Advanced Test Reactor (ATR) in Idaho Falls, Idaho, USA. The ITV is capable of providing neutron spectral tailoring and individual temperature control for up to 15 experiment capsules simultaneously. The test vehicle consists of three In-Pile

F. W Ingram; A. J Palmer; D. J Stites

1998-01-01

310

Development of Soil-Based Controlled Low-Strength Materials.  

National Technical Information Service (NTIS)

This study reports research on the use of soil-based controlled low-strength material (CLSM) as an economical approach to conventional backfilling at new navigation lock chambers and other large construction activities. The case study was a proposed lock ...

B. H. Green

1999-01-01

311

Application of smart materials to helicopter rotor active control  

Microsoft Academic Search

Helicopter design is limited by the compromise inherent in meeting hover and forward flight requirements, and the unsteady environment encountered in forward flight. Active control of helicopter rotors using smart material, in-blade actuation can overcome these barriers and provide substantial reductions in noise and vibrations and improved performance. The present study covers the blade\\/actuator integration and actuator development for a

Friedrich K. Straub; Mark A. Ealey; Lawrence M. Schetky

1997-01-01

312

Active smart material control system for buffet alleviation  

Microsoft Academic Search

Vertical tail buffeting is a serious multidisciplinary problem that limits the performance and maneuverability of twin-tail fighter aircraft. The buffet problem occurs at high angles of attack when the vortical flow breaks down ahead of the vertical tails resulting in unsteady and unbalanced loads on the tails leading to their premature fatigue failure. An active smart material control system, using

Essam F. Sheta; Robert W. Moses; Lawrence J. Huttsell

2006-01-01

313

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

314

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

315

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

316

Quasi-electrostatic converters in materials' quality control  

Microsoft Academic Search

The action of electrostatic converters is based on well known in physics phenomenon of electrostatic induction. A construction of converters may be various depending on properties of materials (structures) under investigation and on control or measurement objectives. Schematic diagrams of vibrating probe converter and capacity converter with linear varying voltage pulse source are presented in the paper and the main

S. Sakalauskas; R. Pûras; Z. Vaitonis

317

A testbed for advanced materials control and accounting concepts  

Microsoft Academic Search

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

Tisinger

1988-01-01

318

System analysis for material control and accountancy technology  

SciTech Connect

The systems analysis for material control and accountancy technology (SAMCAT) program involves a working group structured to ensure that direct operating measurements, accountancy experience, and knowledge of the processes and flows of nuclear material in the total US Department of Energy (DOE) complex of production fuel cycles would be the major bases for developing and implementing a plan of action. This working group consists of facility operators, DOE Office of Safeguards Security headquarters and field offices, and government laboratories. The program focus is to develop a system for decision support in validating the material control and accountancy (MC A) aspects of the masters safeguards and security agreements effectiveness and in evaluating proposed MC A upgrades. This paper is a status report on the current capabilities of the system.

Persiani, P.J.; Daly, T.A.; Bucher, R.G.; Rothman, A.B.; Cha, B.C.; Trevorrow, L.E.; Seefeldt, W.B. (Argonne National Lab., IL (USA))

1987-01-01

319

21 CFR 866.5910 - Quality control material for cystic fibrosis nucleic acid assays.  

Code of Federal Regulations, 2010 CFR

... Quality control material for cystic fibrosis nucleic acid assays. 866... Quality control material for cystic fibrosis nucleic acid assays. (a...Quality control material for cystic fibrosis nucleic acid assays. A...

2010-04-01

320

21 CFR 866.5910 - Quality control material for cystic fibrosis nucleic acid assays.  

Code of Federal Regulations, 2010 CFR

... Quality control material for cystic fibrosis nucleic acid assays. 866... Quality control material for cystic fibrosis nucleic acid assays. (a...Quality control material for cystic fibrosis nucleic acid assays. A...

2009-04-01

321

21 CFR 866.5910 - Quality control material for cystic fibrosis nucleic acid assays.  

Code of Federal Regulations, 2013 CFR

... Quality control material for cystic fibrosis nucleic acid assays. 866... Quality control material for cystic fibrosis nucleic acid assays. (a...Quality control material for cystic fibrosis nucleic acid assays. A...

2013-04-01

322

10 CFR 72.154 - Control of purchased material, equipment, and services.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Control of purchased material, equipment, and...Assurance § 72.154 Control of purchased material, equipment, and...by the purchased material and equipment...effectiveness of the control of quality by...

2013-01-01

323

Systems analysis for materials control and accountancy technology  

SciTech Connect

The objective is to upgrade Materials Control and Accountancy (MCandA) technology over the flows of special nuclear materials throughout the DOE complex of fuel cycles. The program focus is to develop a ''Management Tool'' for decision support in evaluating MCandA upgrades, and invalidating the MCandA aspects of the Master Safeguards and Security Agreements (MSSA) effectiveness. The approach is the computerization of the nuclear materials flow charts, identification of key measurement locations in the production and product fuel cycle, and construct data information processing at each measurement location. The program is to provide the Office of Safeguards and Security (OSS) with a timely management decision support system in planning MCandA safeguards technology upgrades over the nuclear materials production and product cycles.

Daly, T.A.; Bucher, R.G.; Rothman, A.B.; Charak, I.; Persiani, P.J.

1987-07-01

324

Systems analysis for materials control and accountancy technology  

SciTech Connect

The objective of this study is to upgrade Materials Control and Accountancy (MC and A) technology over the flows of special nuclear materials throughout the DOE complex of fuel cycles. The program focus is to develop a ''Management Tool'' for decision support in evaluating MC and A upgrades, and in validating the MC and A aspects of the Master Safeguards and Security Agreements (MSSA) effectiveness. The approach is the computerization of the nuclear materials flow charts, identification of key measurement locations in the production and product fuel cycle, and construct data information processing at each measurement location. The program is to provide the Office of Safeguards and Security (OSS) with a timely management decision support system in planning MC and A safeguards technology upgrades over the nuclear materials production and product cycles.

Daly, T.A.; Bucher, R.G.; Rothman, A.B.; Charak, I.; Persiani, P.J.

1987-01-01

325

Materials for adaptive structural acoustic control, volume 1  

NASA Astrophysics Data System (ADS)

This report documents work carried out in the Materials Research Laboratory of the Pennsylvania State University over the first year of a new ONR sponsored University Research Initiative (URI) entitled Materials for Adaptive Structural Acoustic Control. For this report the activities have been grouped under the following topic headings: (1) General Summary Papers; (2) Materials Studies; (3) Composite Sensors; (4) Actuator Studies; (5) Integration Issues; (6) Processing Studies; and (7) Thin Film Ferroelectrics. In material studies important advances have been made in the understanding of the evaluation of relaxor behavior in the PLZT's and of the order disorder behavior in lead scandium tantalate:lead titanate solid solutions and of the Morphotropic Phase Boundary in this system.

Cross, L. E.

1993-04-01

326

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

327

An application of neural networks to process and materials control  

SciTech Connect

Process control consists of two basic elements: a model of the process and knowledge of the desired control algorithm. In some cases the level of the control algorithm is merely supervisory, as in an alarm-reporting or anomaly-detection system. If the model of the process is known, then a set of equations may often be solved explicitly to provide the control algorithm. Otherwise, the model has to be discovered through empirical studies. Neural networks have properties that make them useful in this application. They can learn (make internal models from experience or observations). The problem of anomaly detection in materials control systems fits well into this general control framework. To successfully model a process with a neutral network, a good set of observables must be chosen. These observables must in some sense adequately span the space of representable events, so that a signature metric can be built for normal operation. In this way, a non-normal event, one that does not fit within the signature, can be detected. In this paper, we discuss the issues involved in applying a neural network model to anomaly detection in materials control systems. These issues include data selection and representation, network architecture, prediction of events, the use of simulated data, and software tools. 10 refs., 4 figs., 1 tab.

Howell, J.A.; Whiteson, R.

1991-01-01

328

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

329

SCF(KMD) controls cytokinin signaling by regulating the degradation of type-B response regulators.  

PubMed

Cytokinins are plant hormones that play critical roles in growth and development. In Arabidopsis, the transcriptional response to cytokinin is regulated by action of type-B Arabidopsis response regulators (ARRs). Although central elements in the cytokinin signal transduction pathway have been identified, mechanisms controlling output remain to be elucidated. Here we demonstrate that a family of F-box proteins, called the kiss me deadly (KMD) family, targets type-B ARR proteins for degradation. KMD proteins form an S-phase kinase-associated PROTEIN1 (SKP1)/Cullin/F-box protein (SCF) E3 ubiquitin ligase complex and directly interact with type-B ARR proteins. Loss-of-function KMD mutants stabilize type-B ARRs and exhibit an enhanced cytokinin response. In contrast, plants with elevated KMD expression destabilize type-B ARR proteins leading to cytokinin insensitivity. Our results support a model in which an SCF(KMD) complex negatively regulates cytokinin responses by controlling levels of a key family of transcription factors. PMID:23720308

Kim, Hyo Jung; Chiang, Yi-Hsuan; Kieber, Joseph J; Schaller, G Eric

2013-05-29

330

Engineering and Design: Controlled Low Strength Material With Coal- Combustion Ash and Other Recycled Materials.  

National Technical Information Service (NTIS)

This letter provides information and guidance for design and construction of controlled low strength material (CLSM). CLSM has many applications but has been primarily used as a flowable, self-compacting fill in place of a compacted fill. An example speci...

D. A. Beranek

1996-01-01

331

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

332

Materials for adaptive structural acoustic control, volume 2  

NASA Astrophysics Data System (ADS)

This report documents work carried out in the Materials Research Laboratory of the Pennsylvania State University over the first year of a new ONR sponsored University Research Initiative (URI) entitled Materials for Adaptive Structural Acoustic Control. For this report the activities have been grouped under the following topic headings: (1) General Summary Papers; (2) Materials Studies; (3) Composite Sensors; (4) Actuator Studies; (5) Integration Issues; (6) Processing Studies; (7) Thin Film Ferroelectrics. In material studies important advances have been made in the understanding of the evaluation of relaxor behavior in the PLZT's and of the order disorder behavior in lead scandium tantalate:lead titanate solid solutions and of the Morphotropic Phase Boundary in this system. For both composite sensors and actuators we have continued to explore and exploit the remarkable versatility of the flextensional moonie type structure. Finite element (FEA) calculations have given a clear picture of the lower order resonant modes and permitted the evaluation of various end cap metals, cap geometries and load conditions. In actuator studies multilayer structures have been combined with flextensional moonie endcaps to yield high displacement (50 micrometers) compact structures. Electrically controlled shape memory has been demonstrated in lead zirconate stannate titanate compositions, and used for controlling a simple latching relay.

Cross, L. E.

1993-04-01

333

Materials for adaptive structural acoustic control, volume 3  

NASA Astrophysics Data System (ADS)

This report documents work carried out in the Materials Research Laboratory of the Pennsylvania State University over the first year of a new ONR sponsored University Research Initiative (URI) entitled Materials for Adaptive Structural Acoustic Control. For this report the activities have been grouped under the following topic headings: (1) General Summary Papers; (2) Materials Studies; (3) Composite Sensors; (4) Actuator Studies; (5) Integration Issues; (6) Processing Studies; and (7) Thin Film Ferroelectrics. In material studies important advances have been made in the understanding of the evaluation of relaxor behavior in the PLZT's and of the order-disorder behavior in lead scandium tantalate:lead titanate solid solutions and of the Morphotropic Phase Boundary in this system. For both composite sensors and actuators, we have continued to explore and exploit the remarkable versatility of the flextensional moonie type structure. Finite element (FEA) calculations have given a clear picture of the lower order resonant modes and permitted the evaluation of various end cap metals, cap geometries, and load conditions. In actuator studies multilayer structures have been combined with flextensional moonie endcaps to yield high displacement (50 micrometers) compact structures. Electrically controlled shape memory has been demonstrated in lead zirconate stannate titanate compositions, and used for controlling a simple latching relay.

Cross, L. E.

1993-04-01

334

Anomaly and error detection in computerized materials control & accountability databases  

SciTech Connect

Unites States Department of Energy sites use computerized material control and accountability (MC&A) systems to manage the large amounts of data necessary to control and account for their nuclear materials. Theft or diversion of materials from these sites would likely result in anomalies in the data, and erroneous information greatly reduces the value of the information to its users. Therefore, it is essential that MC&A data be periodically assessed for anomalies or errors. At Los Alamos National Laboratory, we have been developing expert systems to provide efficient, cost-effective, automated error and anomaly detection. Automated anomaly detection can provide assurance of the integrity of data, reduce inventory frequency, enhance assurance of physical inventory, detect errors in databases, and gain a better perspective on overall facility operations. The Automated MC&A Database Assessment Project is aimed at improving anomaly and error detection in MC&A databases and increasing confidence in the data. We are working with data from the Los Alamos Plutonium Facility and the Material Accountability and Safeguards System, the Facility`s near-real-time computerized nuclear material accountability and safeguards system. This paper describes progress in customizing the expert systems to the needs of the users of the data and reports on our results.

Whiteson, R.; Hoffbauer, B.; Yarbro, T.F. [and others

1997-09-01

335

Agricultural biological reference materials for analytical quality control  

SciTech Connect

Cooperative work is under way at Agriculture Canada, US Department of Agriculture, and US National Bureau of Standards in an attempt to fill some of the gaps in the world repertoire of reference materials and to provide much needed control materials for laboratories' day to day operations. This undertaking involves the preparation and characterization of a number of agricultural and food materials for data quality control for inorganic constituents. Parameters considered in the development of these materials were material selection based on importance in commerce and analysis; techniques of preparation, processing, and packaging; physical and chemical characterization; homogeneity testing and quantitation (certification). A large number of agricultural/food products have been selected to represent a wide range of not only levels of sought-for constituents (elements) but also a wide range of matrix components such as protein, carbohydrate, dietary fiber, fat, and ash. Elements whose concentrations are being certified cover some two dozen major, minor, and trace elements of nutritional, toxicological, and environmental significance.

Ihnat, M.

1986-01-01

336

Evaluating the contributions of material control to insider protection  

SciTech Connect

Facilities handling nuclear material must be adequately protected against a spectrum of threats including insiders, outsiders, and collusion among insider and outsider adversaries. To counter these threats, facilities implement an integrated system of physical protection (PP), material control (MC), and material accountability (MA). (Personnel security assurance programs are also used to help deter and detect potential insider adversaries.) Naturally, the contribution of each of these systems to protection against the different threats varies. Material control plays an important role in protecting against the insider threat and in assuring that material is where it should be. Evaluating its contributions however, to the overall protection is challenging. This paper addresses these challenges, describes approaches we have developed to help assess the adequacy of protection, and demonstrates their use in evaluating the contribution of alternative configurations of MC systems. This paper focuses on one of the modules of the ASSESS code- a state-of-the-art safeguards evaluation tool developed jointly with Sandia National Laboratories-and discusses its use for assessing the contributions of MC to an overall insider protection program and for evaluating the safeguards benefits of new MC technologies.

Al-Ayat, R.A. (Lawrence Livermore National Lab., CA (USA))

1989-11-01

337

Maximising municipal solid waste - Legume trimming residue mixture degradation in composting by control parameters optimization.  

PubMed

Composting is one of the most successful biological processes for the treatment of the residues enriched in putrescible materials. The optimization of parameters which have an influence on the stability of the products is necessary in order to maximize recycling and recovery of waste components. The influence of the composting process parameters (aeration, moisture, C/N ratio, and time) on the stability parameters (organic matter, N-losses, chemical oxygen demand, nitrate, biodegradability coefficient) of the compost was studied. The composting experiment was carried out using Municipal Solid Waste (MSW) and Legume Trimming Residues (LTR) in 200 L isolated acrylic barrels following a Box-Behnken central composite experimental design. Second-order polynomial models were found for each of the studied compost stability parameter, which accurately described the relationship between the parameters. The differences among the experimental values and those estimated by using the equations never exceeded 10% of the former. Results of the modelling showed that excluding the time, the C/N ratio is the strongest variable influencing almost all the stability parameters studied in this case, with the exception of N-losses which is strongly dependent on moisture. Moreover, an optimized ratio MSW/LTR of 1/1 (w/w), moisture content in the range of 40-55% and moderate to low aeration rate (0.05-0.175 Lair kg(-)(1) min(-1)) is recommended to maximise degradation and to obtain a stable product during co-composting of MSW and LTR. PMID:23764508

Cabeza, I O; López, R; Ruiz-Montoya, M; Díaz, M J

2013-06-10

338

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

339

Effects of gate material on Fowler-Nordheim stress induced thin silicon dioxide degradation under negative gate bias  

NASA Astrophysics Data System (ADS)

An exhaustive theoretical investigation on the role of gate material as well as commonly used metal deposition processes [viz., electron beam (e-beam) evaporation and thermal evaporation] on high-field stress-induced dielectric breakdown and/or degradation of identically thick (8-10 nm) thermally grown silicon dioxide (SiO2) films used in memory devices has been reported. Gate materials studied here are n+-polycrystalline silicon (polySi) and aluminum (Al) with n-channel metal-oxide-semiconductor field effect transistor structures. Results will be shown here during constant current and constant field Fowler-Nordheim (FN) tunnel injection from the gate into SiO2. Our theoretical results establish that Al-gated structures exhibit poorer dielectric integrity compared to polySi-gated structures under both types of FN stressing technique. Furthermore, compared to thermally deposited Al-gated samples, e-beam evaporated Al-gated samples show slightly higher gate oxide deterioration in either mode of FN stressing studied here.

Samanta, Piyas; Chan, Mansun

2004-08-01

340

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

341

Erosion kinetics of hydrolytically degradable polymers.  

PubMed Central

Degradable polymers are beginning to play an increasing role as materials for environmental and medical applications. Understanding factors that control erosion, such as bond cleavage and the dissolution and diffusion of degradation products, will be critical to the future development of these materials. Erosion kinetics, photomicroscopy, and infrared spectroscopy were used to understand the erosion mechanism of two families of degradable polymers, polyanhydrides and polyesters. Polyanhydrides exhibit behavior more characteristic of surface erosion, whereas the polyesters exhibit bulk erosion patterns. Control of erosion times from a few days to several years can be achieved by a judicious choice of monomer units and bond selection. Images

Tamada, J A; Langer, R

1993-01-01

342

A new multiplex-PCR comprising autosomal and y-specific STRs and mitochondrial DNA to analyze highly degraded material.  

PubMed

The analysis of short tandem repeats is one of the most powerful tools in forensic genetics. Forensic practice sometimes requires the individualization of samples that may contain only highly degraded nuclear DNA, mitochondrial DNA or PCR inhibitors that hamper DNA amplification. We designed a new multiplex PCR with reduced size amplicons (<200 bp), providing a double sex determination (amelogenin plus two Y-STRs), the detection of two autosomal markers and the amplification of mitochondrial specific fragments from the hypervariable region I (HVI). Additionally, a quality sensor was developed to check for the presence of any PCR inhibitors. The new multiplex PCR shows a reproducible detection threshold down to 25 pg and gives signals even out of highly degraded materials. All signals are reproducible and reliable as it could be shown in comparison to results from commercially available STR multiplex-PCRs. In no case DNA fragments were detectable using any other assay when the quality sensor was not detectable. There was a good correlation between detection of mitochondrial specific fragments in the multiplex-PCR and success of subsequent sequencing of HVI region. The same could be shown for STR analysis: Most samples successfully analyzed in our PCR yielded at least a partial STR profile using a commercial STR kit. We present an assay that allows an easy, reliable, and cost efficient evaluation of DNA sample quality combined with a first rough sample individualization and sex determination suitable for forensic purposes. This assay may help the forensic lab personnel to decide on further sample processing. PMID:19215878

von Wurmb-Schwark, Nicole; Preusse-Prange, Andrea; Heinrich, Anke; Simeoni, Eva; Bosch, Thomas; Schwark, Thorsten

2009-01-07

343

ENHANCED DEGRADATION OF ATRAZINE UNDER FIELD CONDITIONS CORRELATES WITH A LOSS OF WEED CONTROL IN THE GLASSHOUSE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Enhanced degradation of atrazine has been reported in the literature indicating the potential for reduced residual weed control with this herbicide. Experiments were conducted to determine the field dissipation of atrazine in three cropping systems: continuous Zea mays L. (CC) receiving atrazine a...

344

Computer Simulation of Scaffold Degradation  

NASA Astrophysics Data System (ADS)

Scaffolds are porous biocompatible materials with suitable microarchitectures that are designed to allow for cell adhesion, growth and proliferation. They are used in combination with cells in regenerative medicine to promote tissue regeneration by means of a controlled deposition of natural extracellular matrix by the hosted cells therein. This healing process is in many cases accompanied by scaffold degradation up to its total disappearance when the scaffold is made of a biodegradable material. This work presents a computational model that simulates the degradation of scaffolds. The model works with three-dimensional microstructures, which have been previously discretised into small cubic homogeneous elements, called voxels. The model simulates the evolution of the degradation of the scaffold using a Monte Carlo algorithm, which takes into account the curvature of the surface of the fibres. The simulation results obtained in this study are in good agreement with empirical degradation measurements performed by mass loss on scaffolds after exposure to an etching alkaline solution.

Erkizia, G.; Rainer, A.; De Juan-Pardo, E. M.; Aldazabal, J.

2010-11-01

345

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

346

Use of Degradation Tags To Control Protein Levels in the Cyanobacterium Synechocystis sp. Strain PCC 6803  

PubMed Central

We generated a collection of ssrA-based C-terminal protein degradation tags with different degradation strengths. The steady-state fluorescence levels of different enhanced yellow fluorescent protein (eYFP) tag variants in a Synechocystis sp. indicated a tunable range from 1% to 50% of untagged eYFP.

Landry, Brian P.; Stockel, Jana

2013-01-01

347

Methods of Verification, Accountability and Control of Special Nuclear Material  

SciTech Connect

This session demonstrates nondestructive assay (NDA) measurement, surveillance and analysis technology required to protect, control and account (MPC and A) for special nuclear materials (SNM) in sealed containers. These measurements, observations and analyses comprise state-of-the art, strengthened, SNM safeguards systems. Staff member specialists, actively involved in research, development, training and implementation worldwide, will present six NDA verification systems and two software tools for integration and analysis of facility MPC and A data.

Stewart, J.E.

1999-05-03

348

Agent-Oriented Material Flow Control System Based on DCOM  

Microsoft Academic Search

This paper reports on the design and realization of an agent-oriented control system dedicated for material flow systems. The implementation is based on DCOM (Distributed Component Object Model). Regarding the increasing availability, performance and acceptance of distributed object-oriented systems as well as the growing number of agent-oriented software it is natural to adapt and use the capabilities of both object-oriented

Ronald Schoop; Ralf Neubert

2000-01-01

349

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; Elwood Jr, Robert H [ORNL

2011-01-01

350

A Degradable, Thermo-sensitive Poly(N-isopropyl acrylamide)-Based Scaffold with Controlled Porosity for Tissue Engineering Applications  

PubMed Central

We have developed a thermoresponsive poly(N-isopropyl acrylamide)-based scaffold with degradability and controlled porosity. Biodegradable poly(N-isopropyl acrylamide) hydrogels were synthesized by photo-copolymerization of N-isopropylacrylamide with 2-methylene-1,3-dioxepane and polycaprolactone dimethacrylate. The hydrogels’ phase transition temperature, swelling and viscoelastic properties, as well as hydrolytic degradability at 25 and 37°C, were explored. A sphere-templating technique was applied to fabricate hydrogel scaffolds with controllable pore size and a highly interconnected porous structure. The scaffold pore diameter change as a function of temperature was evaluated and, as expected, pores decreased in diameter when the temperature was raised to 37°C. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test results suggested neither the scaffolds nor their degradation products were cytotoxic to NIH3T3 cells. Scaffolds with 55±5 ?m pore diameter were loaded with NIH3T3 cells and then were warmed to 37°C entrapping cells in pores approximately 39 ?m in diameter, a size range we have found to be optimal for angiogenesis and biointegration. Cells showed uniform infiltration and an elongated morphology after 7 days of culture. Due to the controlled monodisperse pore diameter, highly interconnected architecture, fully degradable chemistry and thermoresponsive properties, the polyNIPAM-based scaffolds developed here are attractive for applications in tissue engineering.

Galperin, Anna; Long, Thomas J.; Ratner, Buddy D.

2010-01-01

351

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

352

A modelling and control structure for product quality control in climate-controlled processing of agro-material  

Microsoft Academic Search

In this paper a modelling and control structure for product quality control is presented for a class of operations that processes agro-material. This class can be characterised as climate-controlled operations, such as storage, transport and drying. The basic model consists of three parts. These are the quality and behaviour of the product, and its direct and indirect environment. This decomposition

G. J. C. Verdijck; G. van Straten

2002-01-01

353

Control and accountancy of nuclear materials in a uranium enrichment plant  

SciTech Connect

A nuclear material control and accountancy system has been developed by Goodyear Atomic Corporation to meet safeguards and security requirements. It comprises three major elements: physical security, nuclear material control, and nuclear material accounting. This safeguards system is called Dynamic Material Control and Accountancy System (DYMCAS). The system approaches real-time computer control on a transaction-by-transaction basis.

Hurt, N.H.

1985-05-21

354

Controlled synthesis of Au-loaded Fe3O4@C composite microspheres with superior SERS detection and catalytic degradation abilities for organic dyes.  

PubMed

Bifunctional Au-loaded Fe3O4@C composite microspheres were controllably synthesized by coating of Au nanoparticles (NPs) on the surface of the poly(diallyldimethylammonium chloride) (PDDA) functionalized Fe3O4@C microspheres. The amount of Au loading can be effectively tuned by altering the feeding amounts of solution Au NPs or further growth. The obtained Au-loaded Fe3O4@C composite microspheres exhibit both superior surface-enhanced Raman scattering (SERS) sensitivity and catalytic degradation activity for organic dyes. The SERS signal intensity of methylene blue (MB) distinctly enhances with the increase of Au loading, which endows increased Raman 'hot spots' and provides a significant enhancement of the Raman signal through electromagnetic (EM) field enhancements. Furthermore, the catalytic experiments of the Fe3O4@C@Au composite microspheres with the highest Au loading demonstrate that the model organic dye of MB molecules could be degraded within 10 min and the catalytic activity could be recovered without sharp activity loss in six runs, which indicates their superior catalytic degradation activity. The reason could be mainly ascribed to the synergistic effects of small size of Au NPs, the good adsorption behavior of carbon layers and the excellent dispersivity of the composite microspheres induced by the sandwiched carbon layers. The results indicate that the bifunctional Au-loaded Fe3O4@C composite microspheres could be served as promising materials in wastewater treatment. PMID:23615540

Gan, Zibao; Zhao, Aiwu; Zhang, Maofeng; Tao, Wenyu; Guo, Hongyan; Gao, Qian; Mao, Ranran; Liu, Erhu

2013-04-24

355

Legumain/asparaginyl endopeptidase controls extracellular matrix remodeling through the degradation of fibronectin in mouse renal proximal tubular cells.  

PubMed

Legumain/asparaginyl endopeptidase (EC 3.4.22.34) is a novel cysteine protease that is abundantly expressed in the late endosomes and lysosomes of renal proximal tubular cells. Recently, emerging evidence has indicated that legumain might play an important role in control of extracellular matrix turnover in various pathological conditions such as tumor growth/metastasis and progression of atherosclerosis. We initially found that purified legumain can directly degrade fibronectin, one of the main components of the extracellular matrix, in vitro. Therefore, we examined the effect of legumain on fibronectin degradation in cultured mouse renal proximal tubular cells. Fibronectin processing can be inhibited by chloroquine, an inhibitor of lysosomal degradation, and can be enhanced by the overexpression of legumain, indicating that fibronectin degradation occurs in the presence of legumain in lysosomes from renal proximal tubular cells. Furthermore, in legumain-deficient mice, unilateral ureteral obstruction (UUO)-induced renal interstitial protein accumulation of fibronectin and renal interstitial fibrosis were markedly enhanced. These findings indicate that legumain might have an important role in extracellular matrix remodeling via the degradation of fibronectin in renal proximal tubular cells. PMID:17350006

Morita, Yoshikata; Araki, Hisazumi; Sugimoto, Toshiro; Takeuchi, Keisuke; Yamane, Takuya; Maeda, Toshinaga; Yamamoto, Yoshio; Nishi, Katsuji; Asano, Masahide; Shirahama-Noda, Kanae; Nishimura, Mikio; Uzu, Takashi; Hara-Nishimura, Ikuko; Koya, Daisuke; Kashiwagi, Atsunori; Ohkubo, Iwao

2007-03-05

356

49 CFR 33.52 - Controlling the general distribution of a material in the civilian market.  

Code of Federal Regulations, 2012 CFR

...52 Controlling the general distribution of a material in the civilian...used to control the general distribution of a material in the civilian...significant dislocation of the normal distribution of such material in the...

2012-10-01

357

10 CFR 217.52 - Controlling the general distribution of a material in the civilian market.  

Code of Federal Regulations, 2013 CFR

...52 Controlling the general distribution of a material in the civilian...used to control the general distribution of a material in the civilian...significant dislocation of the normal distribution of such material in the...

2013-01-01

358

Control and Accountancy of Nuclear Materials in a Uranium Enrichment Plant.  

National Technical Information Service (NTIS)

A nuclear material control and accountancy system has been developed by Goodyear Atomic Corporation to meet safeguards and security requirements. It comprises three major elements: physical security, nuclear material control, and nuclear material accounti...

N. H. Hurt

1985-01-01

359

5 CFR 1312.26 - Control of secret and confidential material.  

Code of Federal Regulations, 2013 CFR

...used to establish accountability controls on all Secret material received or produced within OMB offices...each use and protected as classified material not subject to controls. Destruction of such materials will be as prescribed in §...

2013-01-01

360

10 CFR 71.115 - Control of purchased material, equipment, and services.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Control of purchased material, equipment, and services. ...AND TRANSPORTATION OF RADIOACTIVE MATERIAL Quality Assurance § 71.115 Control of purchased material, equipment, and...

2013-01-01

361

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

2012-03-22

362

Kinetic study of photocatalytic degradation of carbamazepine, clofibric acid, iomeprol and iopromide assisted by different TiO2 materials--determination of intermediates and reaction pathways.  

PubMed

The light-induced degradation of clofibric acid, carbamazepine, iomeprol and iopromide under simulated solar irradiation has been investigated in aqueous solutions suspended with different TiO2 materials (P25 and Hombikat UV100). Kinetic studies showed that P25 had a better photocatalytic activity for clofibric acid and carbamazepine than Hombikat UV100. For photocatalytic degradation of iomeprol Hombikat UV100 was more suitable than P25. The results can be explained by the higher adsorption capacity of Hombikat UV100 for iomeprol. The study also focuses on the identification and quantification of possible degradation products. The degradation process was monitored by determination of sum parameters and inorganic ions. In case of clofibric acid various aromatic and aliphatic degradation products have been identified and quantified. A possible multi-step degradation scheme for clofibric acid is proposed. This study proves the high potential of the photocatalytic oxidation process to transform and mineralize environmentally relevant pharmaceuticals and contrast media in water. PMID:14769415

Doll, Tusnelda E; Frimmel, Fritz H

2004-02-01

363

Use of Imaging for Nuclear Material Control and Accountability  

SciTech Connect

The recent addition of imaging to the Nuclear Materials and Identification System (NMIS) using a small portable DT neutron generator with an embedded alpha detector to time and directionally tag neutrons from the DT reaction is discussed. The generator weighs {approx}35 lbs including power supplies (5 x 10{sup 7} n/sec) and operates on 50 watts power. Thus, the source can be easily moved to a variety of locations within an operational facility with minimum impact on operations or can be used at a fixed location for example to monitor receipts. Imaging NMIS (INMIS) not only characterizes the detailed shape of a containerized object by transmission tomography but determines the presence of fissile material by measuring the emitted radiation from induced fission. Previous work has shown that this type of imaging has a variety of applications other than nuclear material control and accountability (NMC&A). These include nonproliferation applications such as verification of configuration of nuclear weapons/components shipped or received, warhead authentication behind an information barrier, and traceability of weapons components both fissile and non fissile in dismantlement and counter terrorism. This paper concentrates on the use for NMC&A. Some of the NMC&A applications discussed are: verifying inventory and receipts, making more accurate holdup measurements especially where thicknesses of materials affect gamma ray spectrometry , determining the shape of unknown configurations of fissile materials where the material type may be known but not the form, determining the oxidation of fissile metal in storage cans, fingerprinting the content of storage containers going into a storage facility, and determining unknown configurations for criticality safety.

Mullens, James Allen [ORNL; Hausladen, Paul [ORNL; Bingham, Philip R [ORNL; Archer, Daniel E [ORNL; Grogan, Brandon R [ORNL; Mihalczo, John T [ORNL

2007-01-01

364

Controlling nanoparticle formation via sizable cages of supramolecular soft materials.  

PubMed

We present a new generic strategy to fabricate nanoparticles in the "cages" within the fibrous networks of supramolecular soft materials. As the cages can be acquired by a design-and-production manner, the size of nanoparticles synthesized within the cages can be tuned accordingly. To implement this idea, both selenium and silver were chosen for the detailed investigation. It follows that the sizes of selenium and silver nanoparticles can be controlled by tuning the pore size of the fiber networks in the material. When the concentration of the gelator is high enough, monodisperse nanoparticles can be prepared. More interestingly, the morphology of the nanoparticles can be altered: silver disks can be formed when the concentrations of both the gelator and silver nitrate are sufficiently low. As the fiber network serves as a physical barrier and semisolid support for the nanoparticles, the stability in the aqueous media and the ease of application of these nanoparticles can be substantially enhanced. This robust surfactant-free approach will not only allow the controlled fabrication of nanoparticles, but also can be applied to the fabrication of composite materials for robust applications. PMID:21627079

Li, Jing-Liang; Liu, Xiang-Yang; Wang, Xun-Gai; Wang, Rong-Yao

2011-05-31

365

A new neutron absorber material for criticality control  

SciTech Connect

A new neutron absorber material based on a nickel metal matrix composite has been developed for applications such as the Transport, Aging, and Disposal (TAD) canister for the Yucca Mountain Project. This new material offers superior corrosion resistance to withstand the more demanding geochemical environments found in a 300,000 year to a million year repository. The lifetime of the TAD canister is currently limited to 10,000 years, reflecting the focus of current regulations embodied in 10 CFR 63. The use of DOE-owned nickel stocks from decommissioned enrichment facilities could reduce the cost compared to stainless steel/boron alloy. The metal matrix composite allows the inclusion of more than one neutron absorber compound, so that the exact composition may be adjusted as needed. The new neutron absorber material may also be used for supplementary criticality control of stored or transported PWR spent fuel by forming it into cylindrical pellets that can be inserted into a surrogate control rod. (authors)

Wells, Alan H. [PhD Consultant, 2846 Peachtree Walk, Duluth, GA 30096 (United States)

2007-07-01

366

Composite Materials Having Low Filler Percolation Thresholds and Methods of Controlling Filler Interconnectivity.  

National Technical Information Service (NTIS)

Composite materials are disclosed having low filler percolation thresholds for filler materials into the composite matrix material along with methods of controlling filler interconnectivity within the composite matrix material. Methods are, thus, disclose...

C. J. Capozzi R. Qu R. A. Gerhardt R. J. Samuels Z. Li

2006-01-01

367

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...

368

Degradation of CrN films at high temperature under controlled atmosphere  

Microsoft Academic Search

The degradation of CrN films was investigated over temperatures of 400-1200 °C in air, nitrogen, and forming gas (N2\\/H2=9) by analyzing changes in color and appearance, as well as microstructures. The degradation mainly included color changes and cracks occurring on the film surface. The color change resulting from low-temperature\\/short-time annealing was due to the formation of an additional Cr2N phase,

Fu-Hsing Lu; Hong-Ying Chen; Chih-Hung Hung

2003-01-01

369

Controlling the spatial distribution of ECM components in degradable PEG hydrogels for tissue engineering cartilage  

Microsoft Academic Search

In developing a scaffold to support new tissue growth, the degradation rate and mass loss profiles of the scaffold are important design parameters. In this study, hy- drogels were prepared by copolymerizing a degradable mac- romer, poly(lactic acid)-b-poly(ethylene glycol)-b-poly(lactic acid) endcapped with acrylate groups (PEG-LA-DA) with a nondegradable macromer, poly(ethylene glycol) dimethac- rylate (PEGDM). The resulting hydrogels exhibited a range

Stephanie J. Bryant; Kristi S. Anseth

370

Light control terahertz modulator based on the semiconductor material  

NASA Astrophysics Data System (ADS)

We have demonstrated a light control terahertz modulation system based on the semiconductor material, the system is composed of a commercial 850nm 10Gbps light source and a continuous THz source. The semiconductor device is the epitaxial growth Si layer on Si substrate wafer. When the 850nm light and continuous terahertz waves incident simultaneously to this semiconductor wafer, the modulated light can excite photogenerated carriers. And the carrier determines the absorption of terahertz waves, so the amplitude of output terahertz waves will be modulated. The tested modulation depth is 35%. The semiconductor material carriers lifetime determines both the modulation depth and modulation speed. So the carrier lifetime should be trade off considered. The modulation speed has been theoretical calculated and experimental tested. The carriers lifetime is tested about 2ns, and the modulation speed is calculated beyond gigabit per second.

Cui, Hailin; Jiao, Lei; Zhou, Qingli; Li, Lijuan

2013-08-01

371

[Effect of organic materials in controlling cucumber seedling diseases].  

PubMed

In this work, pot experiments with organic materials were carried out to study the alleviation of Fusarim wilt and Rhizictonia wilt of cucumber and the changes of soil microorganism. The results showed that rice straw, pig feces and wood chip could alleviate Fusarium wiltand Rhizoctonia wilt of cucumber, and the effect of rice strawwas most significant, followed by pig feces and wood chip. The amount of soil microbes was higher in organic materials treatments than in control. The total amount of actinomyces and epidhyte which can inhibit the growth of pathogen was the highest in rice straw treatment, followed by pig feces treatment. No significant change of soil microbial amount was found in wood chip treatment. PMID:15320412

Yuan, Fei; Peng, Yu; Zhang, Chunlan; Shen, Qirong

2004-05-01

372

Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation.  

PubMed

Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3. PMID:20544804

Fu, Qiang; Rahaman, Mohamed N; Fu, Hailuo; Liu, Xin

2010-10-01

373

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

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Nuclear material control and accounting for special nuclear material of moderate strategic significance. 74.41 Section 74.41 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED)...

2013-01-01

374

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

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Nuclear material control and accounting for special nuclear material of low strategic significance. 74.31 Section 74.31 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED)...

2013-01-01

375

Amoxicillin-degradation products formed under controlled environmental conditions: identification and determination in the aquatic environment.  

PubMed

Amoxicillin (AMX) is a widely used penicillin-type antibiotic whose presence in the environment has been widely investigated, despite its rapid hydrolysis to various degradation products (DPs). In this work, the formation of AMX DPs was studied in various aqueous solutions containing 100?gmL(-1) AMX. Three phosphate buffer solutions, at pH 5, pH 7 and pH 8, and a fourth buffer solution at pH 7 with the addition of the bivalent ions Mg(2+)and Ca(2) as chelating agents, were examined under controlled environmental conditions. In addition, two solutions from natural sources were examined secondary effluents and tap water. The obtained DPs were identified by their MS/MS, UV and NMR spectra (obtained from pure compounds isolated by preparative HPLC) as: AMX penicilloic acid (ADP1/2), AMX penilloic acid (ADP4/5) and phenol hydroxypyrazine (ADP6). Two additional detected DPs AMX 2',5'-diketopiperazine (ADP8/9), and AMX-S-oxide (ADP3) were reported and discussed in our previous publications. These DPs were then detected in secondary effluent and groundwater from a well located beneath agricultural fields continuously irrigated with secondary effluent. Concentrations in the secondary effluent were: ADP1/2, several micrograms per liter; ADP4/5, 0.15?gL(-1), and ADP8/9, 0.5?gL(-1). ADP6 were detected but not quantified. In the groundwater, only ADP8/9 was detected, at a concentration of 0.03?gL(-1). The detection and quantification of DPs of other investigated drugs is recommended as an integral part of any study, method or technique dealing with pharmaceutical residues in aquatic environments. PMID:23466086

Gozlan, Igal; Rotstein, Adi; Avisar, Dror

2013-03-07

376

Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants  

Microsoft Academic Search

When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of

J. Nie; J. Braverman; C. Hofmayer; M. K. Kim; I. K. Choi

2009-01-01

377

Probabilistic material strength degradation model for Inconel 718 components subjected to high temperature, high-cycle and low-cycle mechanical fatigue, creep and thermal fatigue effects  

NASA Astrophysics Data System (ADS)

The development of methodology for a probabilistic material strength degradation is described. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing predictions of high-cycle mechanical fatigue and high temperature effects with experiments are presented. Results from this limited verification study strongly supported that material degradation can be represented by randomized multifactor interaction models.

Bast, Callie C.; Boyce, Lola

1995-11-01

378

Controlled Chemistry Helium High Temperature Materials Test Loop  

SciTech Connect

A system to test aging and environmental effects in flowing helium with impurity content representative of the Next Generation Nuclear Plant (NGNP) has been designed and assembled. The system will be used to expose microstructure analysis coupons and mechanical test specimens for up to 5,000 hours in helium containing potentially oxidizing or carburizing impurities controlled to parts per million levels. Impurity levels in the flowing helium are controlled through a feedback mechanism based on gas chromatography measurements of the gas chemistry at the inlet and exit from a high temperature retort containing the test materials. Initial testing will focus on determining the nature and extent of combined aging and environmental effects on microstructure and elevated temperature mechanical properties of alloys proposed for structural applications in the NGNP, including Inconel 617 and Haynes 230.

Richard N. WRight

2005-08-01

379

Advanced Fluidic Controls for Integrated Propulsion Systems. Part 2. Materials and Fabrication Techniques for High Temperature Turbine Engine Controls.  

National Technical Information Service (NTIS)

An investigation of materials and fabrication techniques for fluidic components used in fluidic fuel control systems for advanced propulsion systems was conducted. The program consisted of: (1) materials selection, (2) materials evaluation and (3) fabrica...

K. E. Solie L. L. Sherwood R. F. Waters

1968-01-01

380

Growth and enrichment of pentachlorophenol-degrading microorganisms in the nutristat, a substrate concentration-controlled continuous culture  

SciTech Connect

The nutristat, a substrate concentration-controlled continuous culture, was used to grow pentachlorophenol (PCP)-degrading microorganisms. The PCP concentration control system consisted of on-line measurement of the PCP concentration in the culture vessel with a tangential filter and a flowthrough spectrophotometer. With PCP concentrations between 45 and 77 [mu]M, a stable situation was established in the nutristat, with an average dilution rate of 0.035 [+-] 0.003 h[sup [minus]1]. Compared with those of fed-batch cultures and chemostat cultures, the growth rates of microorganisms in the PCP nutristat were significantly higher, leading to considerable time savings in the enrichment procedure. In addition, PCP accumulation to severe inhibitory levels in the culture is prevented because the set point determines the (maximum) PCP concentration in the culture. The use of the nutristat as a tool for the growth of bacteria that degrade toxic compounds is discussed.

Rutgers, M.; Bogte, J.J.; Breure, A.M.; Van Andel, J.G. (National Institute of Public Health and Environmental Protection, Bilthoven (Netherlands))

1993-10-01

381

Modified midi- and mini-multiplex PCR systems for mitochondrial DNA control region sequence analysis in degraded samples.  

PubMed

Two multiplex polymerase chain reaction (PCR) systems (Midiplex and Miniplex) were developed for the amplification of the mitochondrial DNA (mtDNA) control region, and the efficiencies of the multiplexes for amplifying degraded DNA were validated using old skeletal remains. The Midiplex system consisted of two multiplex PCRs to amplify six overlapping amplicons ranging in length from 227 to 267 bp. The Miniplex system consisted of three multiplex PCRs to amplify 10 overlapping short amplicons ranging in length from 142 to 185 bp. Most mtDNA control region sequences of several 60-year-old and 400-500-year-old skeletal remains were successfully obtained using both PCR systems and consistent with those previously obtained by monoplex amplification. The multiplex system consisting of smaller amplicons is effective for mtDNA sequence analyses of ancient and forensic degraded samples, saving time, cost, and the amount of DNA sample consumed during analysis. PMID:23406419

Kim, Na Young; Lee, Hwan Young; Park, Sun Joo; Yang, Woo Ick; Shin, Kyoung-Jin

2013-02-13

382

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

383

Impacts of NBTI\\/PBTI on Timing Control Circuits and Degradation Tolerant Design in Nanoscale CMOS SRAM  

Microsoft Academic Search

Negative-bias temperature instability (NBTI )a nd positive-bias temperature instability (PBTI) weaken PFET and NFET over the lifetime of usage, leading to performance and reliability degradation of nanoscale CMOS SRAM. In addition, most of the state-of-the-art SRAM designs employ replica timing control circuit to mitigate the effects of leakage and process vari- ation, optimize the performance, and reduce power consumption. NBTI

Hao-I. Yang; Shyh-Chyi Yang; Wei Hwang; Ching-Te Chuang

2011-01-01

384

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

385

Model for Staebler-Wronski degradation deduced from long-term, controlled light-soaking experiments  

SciTech Connect

Long-term light-soaking experiments of amorphous silicon photovoltaic modules have now established that stabilization of the degradation occurs at levels that depend significantly on the operating conditions, as well as on the operating history of the modules. The authors suggest that stabilization occurs because of the introduction of degradation mechanisms with different time constants and annealing activation energies, depending on the exposure conditions. Stabilization will occur once a sufficient accumulation of different degradation mechanisms occurs. They find that operating module temperature during light-soaking is the most important parameter for determining stabilized performance. Next in importance is the exposure history of the device. The precise value of the light intensity seems least important in determining the stabilized efficiency, as long as its level is a significant fraction of 1-sun.

Von Roedern, B.; del Cueto, J. A.

2000-05-15

386

Autophagy plays a critical role in the degradation of active RHOA, the control of cell cytokinesis, and genomic stability.  

PubMed

Degradation of signaling proteins is one of the most powerful tumor-suppressive mechanisms by which a cell can control its own growth. Here, we identify RHOA as the molecular target by which autophagy maintains genomic stability. Specifically, inhibition of autophagosome degradation by the loss of the v-ATPase a3 (TCIRG1) subunit is sufficient to induce aneuploidy. Underlying this phenotype, active RHOA is sequestered via p62 (SQSTM1) within autolysosomes and fails to localize to the plasma membrane or to the spindle midbody. Conversely, inhibition of autophagosome formation by ATG5 shRNA dramatically increases localization of active RHOA at the midbody, followed by diffusion to the flanking zones. As a result, all of the approaches we examined that compromise autophagy (irrespective of the defect: autophagosome formation, sequestration, or degradation) drive cytokinesis failure, multinucleation, and aneuploidy, processes that directly have an impact upon cancer progression. Consistently, we report a positive correlation between autophagy defects and the higher expression of RHOA in human lung carcinoma. We therefore propose that autophagy may act, in part, as a safeguard mechanism that degrades and thereby maintains the appropriate level of active RHOA at the midbody for faithful completion of cytokinesis and genome inheritance. PMID:23704209

Belaid, Amine; Cerezo, Michaël; Chargui, Abderrahman; Corcelle-Termeau, Elisabeth; Pedeutour, Florence; Giuliano, Sandy; Ilie, Marius; Rubera, Isabelle; Tauc, Michel; Barale, Sophie; Bertolotto, Corinne; Brest, Patrick; Vouret-Craviari, Valérie; Klionsky, Daniel J; Carle, Georges F; Hofman, Paul; Mograbi, Baharia

2013-05-23

387

Biologically inspired autonomous structural materials with controlled toughening and healing  

NASA Astrophysics Data System (ADS)

The field of structural health monitoring (SHM) has made significant contributions in the field of prognosis and damage detection in the past decade. The advantageous use of this technology has not been integrated into operational structures to prevent damage from propagating or to heal injured regions under real time loading conditions. Rather, current systems relay this information to a central processor or human operator, who then determines a course of action such as altering the mission or scheduling repair maintenance. Biological systems exhibit advanced sensory and healing traits that can be applied to the design of material systems. For instance, bone is the major structural component in vertebrates; however, unlike modern structural materials, bone has many properties that make it effective for arresting the propagation of cracks and subsequent healing of the fractured area. The foremost goal for the development of future adaptive structures is to mimic biological systems, similar to bone, such that the material system can detect damage and deploy defensive traits to impede damage from propagating, thus preventing catastrophic failure while in operation. After sensing and stalling the propagation of damage, the structure must then be repaired autonomously using self healing mechanisms motivated by biological systems. Here a novel autonomous system is developed using shape memory polymers (SMPs), that employs an optical fiber network as both a damage detection sensor and a network to deliver stimulus to the damage site initiating adaptation and healing. In the presence of damage the fiber optic fractures allowing a high power laser diode to deposit a controlled level of thermal energy at the fractured sight locally reducing the modulus and blunting the crack tip, which significantly slows the crack growth rate. By applying a pre-induced strain field and utilizing the shape memory recovery effect, thermal energy can be deployed to close the crack and return the system to its original operating state. The entire system will effectively detect, self toughen, and subsequently heal damage as biological materials such as bone does.

Garcia, Michael E.; Sodano, Henry A.

2010-03-01

388

Materials control and accountability challenges associated with plutonium inventories  

SciTech Connect

There are currently many initiatives underway within the Department of Energy (DOE) to safely and securely manage large plutonium inventories arising from weapons dismantlement, changing missions and facility operations. Plutonium inventory information is increasingly accessible to the public as a result of the secretary of energy`s openness initiative. As a result, knowledge of these inventories and levels to which the department has accounted for and controlled these inventories, will be under increased scrutiny from a variety of interest groups. The quality of this accountability data and what this data means will greatly influence the public`s perception of how the US is protecting its plutonium inventories. In addition, the department`s safeguards program provides an essential basis for the application of International Atomic Energy Agency (IAEA) safeguards that, in addition to possibly other international control regimes, will be in place over a large portion of these future inventories. The capability and functionality of the department`s nuclear safeguards program will be important contributors to the success of US programs for the responsible stewardship of these vast plutonium inventories. This paper discusses some of the challenges, in terms of specific issues relating to one part of the department`s safeguards program--materials control and accountability (MC and A)--to meet the growing domestic and international requirements and expectations associated with these plutonium inventories.

Crawford, D.W. [USDOE Office of Safeguards and Security, Washington, DC (United States)

1996-07-01

389

Negative thermal expansion materials: technological key for control of thermal expansion  

Microsoft Academic Search

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over ?30 ppm K?1. Such giant NTE is opening a new

Koshi Takenaka

2012-01-01

390

Effect of Operating-Point-Control Strategy on the Annual Energy Production of Degraded Photovoltaic Arrays.  

National Technical Information Service (NTIS)

A new computer simulation of the annual operation of degraded flat-plate photovoltaic (PV) arrays is used to evaluate the need for maximum-power-point tracking in real PV systems. The simulations are based on single-glitch I-V curve shapes rather than par...

H. M. Branz

1982-01-01

391

Amino acid control of autophagic sequestration and protein degradation in isolated rat hepatocytes  

PubMed Central

Sequestration of the inert cytosolic marker [14C]sucrose by sedimentable organelles was measured in isolated rat hepatocytes made transiently permeable to sucrose by means of electropermeabilization. Lysosomal integrity, protein degradation, autophagic sequestration, and other cellular functions were not significantly impaired by the electric treatment. Hepatocytes sequestered sucrose at an initial rate of approximately 10%/h, which is threefold higher than the estimated rate of autophagic-lysosomal protein degradation. Almost one-third would appear to represent mitochondrial fluid uptake; the rest was nearly completely and specifically inhibited by 3-methyladenine (3MA) and can be regarded as autophagic sequestration. A complete amino acid mixture was somewhat less inhibitory than 3MA, and partially antagonized the effect of the latter. This paradoxical effect, taken together with the high sequestration rate, may suggest heterogeneity as well as selectivity in autophagic sequestration. There was no detectable recycling of sequestered [14C]sucrose between organelles and cytosol. Studies of individual amino acids revealed histidine as the most effective sequestration inhibitor. Leucine may have a regulatory function, as indicated by its unique additive/synergistic effect, and a combination of Leu + His was as effective as the complete amino acid mixture. Asparagine inhibited sequestration only 20%, i.e., its very strong effect on overall (long-lived) protein degradation must partially be due to post-sequestrational inhibition. The lysosomal (amine-sensitive) degradation of short-lived protein was incompletely inhibited by 3MA, indicating a contribution from nonautophagic processes like crinophagy and endocytic membrane influx. The ability of an amino acid mixture to specifically antagonize the inhibition of short-lived protein degradation by AsN + GIN (but not by 3MA) may suggest complex amino acid interactions at the level of fusion between lysosomes and other vesicles in addition to the equally complex interactions at the level of autophagic sequestration.

1984-01-01

392

Controlling the Casimir force via the electromagnetic properties of materials  

SciTech Connect

The control of the Casimir force between two parallel plates can be achieved through adjusting the frequency-dependent electromagnetic properties of materials of the two plates. We show that, for different plate separations, the main contribution to the Casimir force comes from different frequency regions: For smaller (larger) separation, it comes from the higher (lower) frequency region. When the separation of the plates increases, the Casimir force can vary from attractive to repulsive and/or vice versa, by selecting the two plates with suitable electromagnetic properties. We discuss how a restoring Casimir force, which varies from repulsive to attractive by increasing the separation, can be realized and that the stable equilibrium is formed at zero Casimir force.

Yang Yaping; Chen Hong [Department of Physics, Tongji University, Shanghai 200092 (China); Zeng Ran [Department of Physics, Tongji University, Shanghai 200092 (China); School of Telecommunication, Hangzhou Dianzi University, Hangzhou 300018 (China); Zhu Shiyao [Department of Physics, Hong Kong Baptist University (Hong Kong); Zubairy, M. Suhail [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States)

2010-02-15

393

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

394

Soybean oil-degrading bacterial cultures as a potential for control of green peach aphids (Myzus persicae).  

PubMed

Microorganisms capable of degrading crude oil were isolated and grown in soybean oil as a sole carbon source. The microbial cultures were used to control green peach aphids in vitro. Approximately 60% mortality of aphids was observed when the cultures were applied alone onto aphids. To examine the cultures as a pesticide formulation mixture, the cultures were combined with a low dose of the insecticide imidacloprid (one-fourth dose of recommended field-application rate) and applied onto aphids. The cultures enhanced significantly the insecticidal effectiveness of imidacloprid, which was higher than imidacloprid alone applied at the low dose. The isolated microorganisms exhibited high emulsifying index values and decreased surface tension values after being grown in soybean oil media. GC/MS analyses showed that microorganisms degraded soybean oil to fatty acids. The cultures were suggested to play the roles of wetting, spreading, and sticking agents to improve the effectiveness of imidacloprid. This is the first report on the control of aphids by using oil-degrading microbial cultures. PMID:18156788

Kim, Seul Ki; Kim, Seo Ri; Choi, Min Seok; Park, Chang Eon; Kim, Young Cheol; Kim, Kil Yong; Whang, Kyung Sook; Oh, Kyung-Taek; Kim, In Seon

2007-10-01

395

[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

396

Understanding and control of optical performance from ceramic materials  

SciTech Connect

This report summarizes a two-year Laboratory-Directed Research and Development (LDRD) program to gain understanding and control of the important parameters which govern the optical performance of rare-earth (RE) doped ceramics. This LDRD developed the capability to determine stable atomic arrangements in RE doped alumina using local density functional theory, and to model the luminescence from RE-doped alumina using molecular dynamic simulations combined with crystal-field calculations. Local structural features for different phases of alumina were examined experimentally by comparing their photoluminescence spectra and the atomic arrangement of the amorphous phase was determined to be similar to that of the gamma phase. The luminescence lifetimes were correlated to these differences in the local structure. The design of both high and low-phonon energy host materials was demonstrated through the growth of Er-doped aluminum oxide and lanthanum oxide. Multicomponent structures of rare-earth doped telluride glass in an alumina and silica matrix were also prepared. Finally, the optical performance of Er-doped alumina was determined as a function of hydrogen content in the host matrix. This LDRD is the groundwork for future experimentation to understand the effects of ionizing radiation on the optical properties of RE-doped ceramic materials used in space and other radiation environments.

Barbour, J.C.; Knapp, J.A.; Potter, B.G.; Jennison, D.R.; Verdozzi, C.A.; Follstaedt, D.M. [Sandia National Labs., Albuquerque, NM (United States); Bendale, R.D.; Simmons, J.H. [Univ. of Florida, Gainesville, FL (United States). Materials Science and Engineering Dept.

1998-06-01

397

Controllable biomimetic adhesion using embedded phase change material  

NASA Astrophysics Data System (ADS)

In many cases, such as in the instance of climbing robots or temporary adhesives, there is the need to be able to dynamically control the level of adhesion a biomimetic dry adhesive can provide. In this study, the effect of changing the backing layer stiffness of a dry adhesive is examined. Embedding a phase change material within the backing of a synthetic dry adhesive sheet allows the stiffness to be tailored at different points of a preload and adhesion cycle. Larger contact areas and more equal load sharing between adhesive fibres can be achieved by increasing the backing layer stiffness after initial deformation when the adhesive backing is loaded in its softened state. Adhesion behaviour is examined when the backing layer is maintained in solid and softened phases during complete load cycles and for load cycles under the condition of contact with the softened phase backing followed by pull-off during the solid phase. Absolute adhesion force is increased for trials in which a soft backing layer hardens prior to pull-off. This effect is due to the increased contact area made between the rounded probe and the softened material during preloading and the more equal load sharing condition during pull-off when the backing layer becomes stiff again.

Krahn, J.; Sameoto, D.; Menon, C.

2011-01-01

398

Device for controlling the pouring of molten materials  

DOEpatents

A device for controlling the pouring of a molten material from a crucible or other container. The device (10) includes an annular retainer ring (12) for mounting in the drain opening in the bottom of a conventional crucible (16), the retainer ring defining a opening (14) therethrough. The device (10) also includes a plug member (22) having an annular forward end portion (24) for force-fit reception in the opening (14) of the retainer ring (12) to selectively seal the opening (14) and for being selectively forced through the opening (14). The plug member (22) has a rear end portion (26) for being positioned within the crucible (16), the rear end portion (26) including stop means for prohibiting the rear end portion from passing through the opening (14) in the retainer ring (12) when the forward end portion (24) is selectively forced through the opening. The plug member (22) defines at least one, and preferably a plurality of flutes (32), each extending from a point rearward the annular forward end portion (24) of the plug member (22), and forward the stop means, to a point rearward of the stop means. The flutes (32) permit fluid communication between the interior and exterior of the crucible (16) when the forward end portion (24) of the plug member (22) is forced through the opening (14) in the retaining ring (12) such that the molten material is allowed to flow from the crucible (16).

Moore, Alan F. (Knoxville, TN); Duncan, Alfred L. (Clinton, TN)

1994-01-01

399

Device for controlling the pouring of molten materials  

DOEpatents

A device is described for controlling the pouring of a molten material from a crucible or other container. The device includes an annular retainer ring for mounting in the drain opening in the bottom of a conventional crucible, the retainer ring defining a opening there through. The device also includes a plug member having an annular forward end portion for force-fit reception in the opening of the retainer ring to selectively seal the opening and for being selectively forced through the opening. The plug member has a rear end portion for being positioned within the crucible, the rear end portion including stop means for prohibiting the rear end portion from passing through the opening in the retainer ring when the forward end portion is selectively forced through the opening. The plug member defines at least one, and preferably a plurality of flutes, each extending from a point rearward the annular forward end portion of the plug member, and forward the stop means, to a point rearward of the stop means. The flutes permit fluid communication between the interior and exterior of the crucible when the forward end portion of the plug member is forced through the opening in the retaining ring such that the molten material is allowed to flow from the crucible. 5 figures.

Moore, A.F.; Duncan, A.L.

1994-02-15

400

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

401

Disorder targets misorder in nuclear quality control degradation: a disordered ubiquitin ligase directly recognizes its misfolded substrates  

PubMed Central

Summary Protein quality control (PQC) degradation systems protect the cell from the toxic accumulation of misfolded proteins. Because any protein can become misfolded, these systems must be able to distinguish abnormal proteins from normal ones, yet be capable of recognizing the wide variety of distinctly shaped misfolded proteins they are likely to encounter. How individual PQC degradation systems accomplish this remains an open question. Here we show that the yeast nuclear PQC ubiquitin ligase San1 directly recognizes its misfolded substrates via intrinsically disordered N- and C-terminal domains. These disordered domains are punctuated with small segments of order and high sequence conservation that serve as substrate-recognition sites San1 uses to target its different substrates. We propose that these substrate-recognition sites, interspersed among flexible, disordered regions, provide San1 an inherent plasticity that allows it to bind its many, differently shaped misfolded substrates.

Rosenbaum, Joel C.; Fredrickson, Eric K.; Oeser, Michelle L.; Garrett-Engele, Carrie M.; Locke, Melissa N.; Richardson, Lauren A.; Nelson, Zara W.; Hetrick, Elizabeth D.; Milac, Thomas I.; Gottschling, Daniel E.; Gardner, Richard G.

2011-01-01

402

Safeguards Material Control and Accounting Program: Quarterly Report July-September 1979.  

National Technical Information Service (NTIS)

Activity for the quarter July-September 1979 in the Material Control Safeguards Evaluation Program, is summarized. Progress was made in developing a computer-based methodology for identifying vulnerabilities in Material Control and Accounting (MCA) system...

D. R. Dunn

1980-01-01

403

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

National Technical Information Service (NTIS)

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 SS...

V. P. Martyanov L. Kasumova R. A. Babcock C. Heinberg

2003-01-01

404

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

PubMed

Mg-4wt.% Zn-0.5wt.% 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 7days of immersion but exhibited accelerated degradation after 14 and 21days, 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 21days. 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 3days 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

2013-07-12

405

Prescriptive concepts for advanced nuclear materials control and accountability systems  

SciTech Connect

Networking- and distributed-processing hardware and software have the potential of greatly enhancing nuclear materials control and accountability (MC and A) systems, from both safeguards and process operations perspectives, while allowing timely integrated safeguards activities and enhanced computer security at reasonable cost. A hierarchical distributed system is proposed consisting of groups of terminal and instruments in plant production and support areas connected to microprocessors that are connected to either larger microprocessors or minicomputers. These micros and/or minis are connected to a main machine, which might be either a mainframe or a super minicomputer. Data acquisition, preliminary input data validation, and transaction processing occur at the lowest level. Transaction buffering, resource sharing, and selected data processing occur at the intermediate level. The host computer maintains overall control of the data base and provides routine safeguards and security reporting and special safeguards analyses. The research described outlines the distribution of MC and A system requirements in the hierarchical system and distributed processing applied to MC and A. Implications of integrated safeguards and computer security concepts for the distributed system design are discussed. 10 refs., 4 figs.

Whitty, W.J.; Strittmatter, R.B.; Ford, W.; Tisinger, R.M.; Meyer, T.H.

1987-06-01

406

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

407

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.

2013-01-01

408

ReflectoActive{trademark} Seals for Materials Control and Accountability  

SciTech Connect

The ReflectoActive{trademark} Seals system, a continuously monitored fiber optic, active seal technology, provides real-time tamper indication for large arrays of storage containers. The system includes a PC running the RFAS software, an Immediate Detection Unit (IDU), an Optical Time Domain Reflectometer (OTDR), links of fiber optic cable, and the methods and devices used to attach the fiber optic cable to the containers. When a breach on any of the attached fiber optic cable loops occurs, the IDU immediately signals the connected computer to control the operations of an OTDR to seek the breach location. The ReflectoActive{trademark} Seals System can be adapted for various types of container closure designs and implemented in almost any container configuration. This automatic protection of valued assets can significantly decrease the time and money required for surveillance. The RFAS software is the multi-threaded, client-server application that monitors and controls the components of the system. The software administers the security measures such as a two-person rule as well as continuous event logging. Additionally the software's architecture provides a secure method by which local or remote clients monitor the system and perform administrative tasks. These features provide the user with a robust system to meet today's material control and accountability needs. A brief overview of the hardware, and different hardware configurations will be given. The architecture of the system software, and its benefits will then be discussed. Finally, the features to be implemented in future versions of the system will be presented.

Richardson, G.D.; Younkin, J.R.; Bell, Z.W.

2002-01-01

409

CONTROL OF PIERCE'S DISEASE THROUGH DEGRADATION OF XANTHAN GUM Project Leader  

Microsoft Academic Search

Acinetobacter johnsonii GX123, a Xylella gum-degrading endophyte was co-inoculated with Xylella fastidiosa strain Texas in oleander plants to determine its efficacy as a biocontrol agent in preliminary experiments. Symptoms appeared in both plants inoculated with X. fastidiosa alone and plants co-inoculated with the endophyte. However, symptoms were more severe and appeared earlier in plants inoculated with X. fastidiosa than in

Donald A. Cooksey; Neal L. Schiller; Rosina Bianco; Seung-Don Lee; Korsi Dumenyo

410

Multiple phosphorylation events control mitotic degradation of the muscle transcription factor Myf5  

Microsoft Academic Search

BACKGROUND: The two myogenic regulatory factors Myf5 and MyoD are basic helix-loop-helix muscle transcription factors undergoing differential cell cycle dependent proteolysis in proliferating myoblasts. This regulated degradation results in the striking expression of these two factors at distinct phases of the cell cycle, and suggests that their precise and alternated disappearance is an important feature of myoblasts, maybe connected to

Christine Doucet; Gustavo J Gutierrez; Catherine Lindon; Thierry Lorca; Gwendaline Lledo; Christian Pinset; Olivier Coux

2005-01-01

411

The antioxidant effect in controlling thermal degradation of a low density polyethylene blown film  

Microsoft Academic Search

It is well known that antioxidants are widely used to prevent thermal degradation of high density and linear low density polyethylene. Antioxidants are not always present in low density polyethylene and only small amounts are usually added to these resins. In this work the effect of an antioxidant system on a low density resin having MFI (190 °C\\/2.16 kg)=2 g\\/10?

P Mariani; G Carianni; F. P La Mantia

2004-01-01

412

Ydj1 Protects Nascent Protein Kinases from Degradation and Controls the Rate of Their Maturation  

Microsoft Academic Search

Received 3 April 2007\\/Accepted 15 April 2008 Ydj1 is a Saccharomyces cerevisiae Hsp40 molecular chaperone that functions with Hsp70 to promote polypeptide folding. We identified Ydj1 as being important for maintaining steady-state levels of protein kinases after screening several chaperones and cochaperones in gene deletion mutant strains. Pulse-chase analyses revealed that a portion of Tpk2 kinase was degraded shortly after

Atin K. Mandal; Nadinath B. Nillegoda; Jennifer A. Chen; Avrom J. Caplan

2008-01-01

413

A signalling pathway controlling c-Myc degradation that impacts oncogenic transformation of human cells  

Microsoft Academic Search

The stability of c-Myc is regulated by multiple Ras effector pathways. Phosphorylation at Ser 62 stabilizes c-Myc, whereas subsequent phosphorylation at Thr 58 is required for its degradation. Here we show that Ser 62 is dephosphorylated by protein phosphatase 2A (PP2A) before ubiquitination of c-Myc, and that PP2A activity is regulated by the Pin1 prolyl isomerase. Furthermore, the absence of

Elizabeth Yeh; Melissa Cunningham; Hugh Arnold; Dawn Chasse; Teresa Monteith; Giovanni Ivaldi; William C. Hahn; P. Todd Stukenberg; Shirish Shenolikar; Takafumi Uchida; Christopher M. Counter; Joseph R. Nevins; Anthony R. Means; Rosalie Sears

2004-01-01

414

P Bodies and the Control of mRNA Translation and Degradation  

Microsoft Academic Search

Recent results indicate that many untranslating mRNAs in somatic eukaryotic cells assemble into re- lated mRNPs that accumulate in specific cytoplasmic foci referred to as P bodies. Transcripts asso- ciated with P body components can either be degraded or return to translation. Moreover, P bodies are also biochemically and functionally related to some maternal and neuronal mRNA granules. This suggestsan

Roy Parker; Ujwal Sheth

2007-01-01

415

Quality control of human ABCG2 protein in the endoplasmic reticulum: Ubiquitination and proteasomal degradation  

Microsoft Academic Search

Human ATP-binding cassette (ABC) transporter ABCG2 (BCRP\\/MXR\\/ABCP) is a plasma membrane protein carrying intra- and inter-molecular disulfide bonds and an N-linked glycan. Both disulfide bond formation and N-glycosylation are critical check points determining the stability and degradation fate of ABCG2 protein in the endoplasmic reticulum (ER). Misfolded ABCG2 protein without those post-translational modifications is removed from the ER by retrotranslocation

Kanako Wakabayashi-Nakao; Ai Tamura; Tomoka Furukawa; Hiroshi Nakagawa; Toshihisa Ishikawa

2009-01-01

416

Degradation of porous poly(anhydride-co-imide) microspheres and implications for controlled macromolecule delivery.  

PubMed

The degradation properties of porous microspheres made using a new family of polyanhydride copolymers, the poly(anhydride-co-imides), were studied. Poly[trimellitylimido-L-tyrosine-co-sebacic acid-co-1,3-bis(carboxyphenoxy)propane] microspheres, with and without entrapped bovine serum albumin (BSA) as a model protein, were made using the double emulsion solvent evaporation process. Water penetration and anhydride bond cleavage (polymer degradation) occurred rapidly (< 5 days) compared to the time scale of overall microsphere erosion (weeks to months) with most polymer compositions. Subsequent to bond cleavage, the ultimate erosion of the microsphere and release of entrapped BSA was due mainly to the slow dissolution of the individual hydrophobic monomers (TMA-Tyr, SA and CPP) from the microsphere surface. BSA was released at approximately the same rate as the polymer eroded. Due to the fast degradation of anhydride bonds relative to microsphere erosion, initial polymer molecular weight did not have a significant effect on macromolecule release rates. Instead, monomer solubility correlated well with polymer erosion and BSA release rates. This erosion mechanism leads to predictable drug release rates which may be appropriate for the delivery of many protein therapeutics, including vaccine antigens. The anhydride-imide copolymers were well tolerated in acute toxicity studies in rats and therefore show promise as biomaterials. PMID:9678864

Hanes, J; Chiba, M; Langer, R

417

Plk1- and ?-TrCP-dependent degradation of Bora controls mitotic progression  

PubMed Central

Through a convergence of functional genomic and proteomic studies, we identify Bora as a previously unknown cell cycle protein that interacts with the Plk1 kinase and the SCF–?-TrCP ubiquitin ligase. We show that the Bora protein peaks in G2 and is degraded by proteasomes in mitosis. Proteolysis of Bora requires the Plk1 kinase activity and is mediated by SCF–?-TrCP. Plk1 phosphorylates a conserved DSGxxT degron in Bora and promotes its interaction with ?-TrCP. Mutations in this degron stabilize Bora. Expression of a nondegradable Bora variant prolongs the metaphase and delays anaphase onset, indicating a physiological requirement of Bora degradation. Interestingly, the activity of Bora is also required for normal mitotic progression, as knockdown of Bora activates the spindle checkpoint and delays sister chromatid segregation. Mechanistically, Bora regulates spindle stability and microtubule polymerization and promotes tension across sister kinetochores during mitosis. We conclude that tight regulation of the Bora protein by its synthesis and degradation is critical for cell cycle progression.

Seki, Akiko; Coppinger, Judith A.; Du, Haining; Jang, Chang-Young; Yates, John R.; Fang, Guowei

2008-01-01

418

10 CFR 76.111 - Physical security, material control and accounting, and protection of certain information.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Physical security, material control and accounting...Safeguards and Security § 76.111 Physical security, material control and accounting...certification of the Corporation 2 for physical security and material control...

2013-01-01

419

10 CFR 60.78 - Material control and accounting records and reports.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Material control and accounting records and reports...and Inspections § 60.78 Material control and accounting records and reports...shall implement a program of material control and accounting (and...

2013-01-01

420

10 CFR 63.78 - Material control and accounting records and reports.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Material control and accounting records and reports...and Inspections § 63.78 Material control and accounting records and reports...shall implement a program of material control and accounting (and...

2013-01-01

421

Threading dislocation-governed degradation in crystal quality of heteroepitaxial materials: The case of InAlN nearly lattice-matched to GaN  

NASA Astrophysics Data System (ADS)

The crystal qualities of InAlN nearly lattice-matched (LM) to GaN with different thicknesses have been investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that the crystal quality of InAlN starts to degrade when the InAlN thickness exceeds several hundred nanometers, forming a structure consisting of two sub-layers with one sub-layer coherent to GaN and the other being degraded. Moreover, the degradation was found to be governed by the threading dislocations (TDs) propagation from the underlying GaN layer, rather than by the misfit strain between InAlN and GaN. Based on TEM observations, the growth evolution of the two-sub-layer structure is proposed, which is different from those conventional mechanisms of crystal-quality degradation in heteroepitaxial material. The results of InAlN nearly LM to GaN are suggested to be helpful in understanding the growths of lattice-mismatched systems of other In-contained III-nitrides, including InGaN/GaN.

Chen, Z. T.; Fujita, K.; Ichikawa, J.; Egawa, T.

2012-03-01

422

Control of degradation of spent LWR (light-water reactor) fuel during dry storage in an inert atmosphere  

SciTech Connect

Dry storage of Zircaloy-clad spent fuel in inert gas (referred to as inerted dry storage or IDS) is being developed as an alternative to water pool storage of spent fuel. The objectives of the activities described in this report are to identify potential Zircaloy degradation mechanisms and evaluate their applicability to cladding breach during IDS, develop models of the dominant Zircaloy degradation mechanisms, and recommend cladding temperature limits during IDS to control Zircaloy degradation. The principal potential Zircaloy cladding breach mechanisms during IDS have been identified as creep rupture, stress corrosion cracking (SCC), and delayed hydride cracking (DHC). Creep rupture is concluded to be the primary cladding breach mechanism during IDS. Deformation and fracture maps based on creep rupture were developed for Zircaloy. These maps were then used as the basis for developing spent fuel cladding temperature limits that would prevent cladding breach during a 40-year IDS period. The probability of cladding breach for spent fuel stored at the temperature limit is less than 0.5% per spent fuel rod. 52 refs., 7 figs., 1 tab.

Cunningham, M.E.; Simonen, E.P.; Allemann, R.T.; Levy, I.S.; Hazelton, R.F.

1987-10-01

423

APC/C (Cdh1) controls the proteasome-mediated degradation of E2F3 during cell cycle exit.  

PubMed

E2F transcription factors regulate gene expression in concert with the retinoblastoma tumor suppressor family. These transcriptional complexes are master regulators of cell cycle progression and, in addition, control the expression of genes involved in DNA repair, G 2/M checkpoint and differentiation. E2F3 has recently attracted particular attention, because it is amplified in various human tumors. Here we show that E2F3 becomes unstable as cells exit the cell cycle. E2F3 degradation is mediated by the anaphase-promoting complex/cyclosome and its activator Cdh1 (APC/C (Cdh1) ). E2F3 interacts with Cdh1 but not Cdc20, the other APC/C activator. Enforced expression of Cdh1 results in proteasome-dependent degradation of E2F3, whereas the overexpression of Cdc20 has no effect on E2F3 turnover. Finally, silencing of Cdh1 by RNA interference stabilizes E2F3 in differentiating neuroblastoma cells. These findings indicate that the APC/C (Cdh1) ubiquitin ligase targets E2F3 for proteasome-dependent degradation during cell cycle exit and neuronal differentiation. PMID:22580460

Ping, Zhen; Lim, Ratna; Bashir, Tarig; Pagano, Michele; Guardavaccaro, Daniele

2012-05-15

424

Influence of support material on the immobilization of biomass for the degradation of linear alkylbenzene sulfonate in anaerobic reactors.  

PubMed

Two horizontal-flow anaerobic immobilized biomass reactors (HAIB) were used to study the degradation of the LAS surfactant: one filled with charcoal (HAIB1) and the other with a mixed bed of expanded clay and polyurethane foam (HAIB2). The reactors were fed with synthetic substrate supplemented with 14 mg l(-1)of LAS, kept at 30+/-2 degrees C and operated with a hydraulic retention time (HRT) of 12h. The surfactant was quantified by HPLC. Spatial variation analyses were done to quantify organic matter and LAS consumption along the reactor length. The presence of the surfactant in the load did not affect the removal of organic matter (COD), which was close to 90% in both reactors for an influent COD of 550 mg l(-1). The results of a mass balance indicated that 28% of all LAS added to HAIB1 was removed by degradation. HAIB2 presented 27% degradation. Molecular biology techniques revealed microorganisms belonging the uncultured Holophaga sp., uncultured delta Proteobacterium, uncultured Verrucomicrobium sp., Bacteroides sp. and uncultured gamma Proteobacterium sp. The reactor with biomass immobilized on charcoal presented lower adsorption and a higher kinetic degradation coefficient. So, it was the most suitable support for LAS anaerobic treatment. PMID:18814953

Lima de Oliveira, Lorena; Silveira Duarte, Iolanda Cristina; Sakamoto, Isabel Kimiko; Amâncio Varesche, Maria Bernadete

2008-09-23

425

Preprocessing and Quality Control Strategies for Illumina DASL Assay-Based Brain Gene Expression Studies with Semi-Degraded Samples  

PubMed Central

Available statistical preprocessing or quality control analysis tools for gene expression microarray datasets are known to greatly affect downstream data analysis, especially when degraded samples, unique tissue samples, or novel expression assays are used. It is therefore important to assess the validity and impact of the assumptions built in to preprocessing schemes for a dataset. We developed and assessed a data preprocessing strategy for use with the Illumina DASL-based gene expression assay with partially degraded postmortem prefrontal cortex samples. The samples were obtained from individuals with autism as part of an investigation of the pathogenic factors contributing to autism. Using statistical analysis methods and metrics such as those associated with multivariate distance matrix regression and mean inter-array correlation, we developed a DASL-based assay gene expression preprocessing pipeline to accommodate and detect problems with microarray-based gene expression values obtained with degraded brain samples. Key steps in the pipeline included outlier exclusion, data transformation and normalization, and batch effect and covariate corrections. Our goal was to produce a clean dataset for subsequent downstream differential expression analysis. We ultimately settled on available transformation and normalization algorithms in the R/Bioconductor package lumi based on an assessment of their use in various combinations. A log2-transformed, quantile-normalized, and batch and seizure-corrected procedure was likely the most appropriate for our data. We empirically tested different components of our proposed preprocessing strategy and believe that our results suggest that a preprocessing strategy that effectively identifies outliers, normalizes the data, and corrects for batch effects can be applied to all studies, even those pursued with degraded samples.

Chow, Maggie L.; Winn, Mary E.; Li, Hai-Ri; April, Craig; Wynshaw-Boris, Anthony; Fan, Jian-Bing; Fu, Xiang-Dong; Courchesne, Eric; Schork, Nicholas J.

2012-01-01

426

Preprocessing and Quality Control Strategies for Illumina DASL Assay-Based Brain Gene Expression Studies with Semi-Degraded Samples.  

PubMed

Available statistical preprocessing or quality control analysis tools for gene expression microarray datasets are known to greatly affect downstream data analysis, especially when degraded samples, unique tissue samples, or novel expression assays are used. It is therefore important to assess the validity and impact of the assumptions built in to preprocessing schemes for a dataset. We developed and assessed a data preprocessing strategy for use with the Illumina DASL-based gene expression assay with partially degraded postmortem prefrontal cortex samples. The samples were obtained from individuals with autism as part of an investigation of the pathogenic factors contributing to autism. Using statistical analysis methods and metrics such as those associated with multivariate distance matrix regression and mean inter-array correlation, we developed a DASL-based assay gene expression preprocessing pipeline to accommodate and detect problems with microarray-based gene expression values obtained with degraded brain samples. Key steps in the pipeline included outlier exclusion, data transformation and normalization, and batch effect and covariate corrections. Our goal was to produce a clean dataset for subsequent downstream differential expression analysis. We ultimately settled on available transformation and normalization algorithms in the R/Bioconductor package lumi based on an assessment of their use in various combinations. A log2-transformed, quantile-normalized, and batch and seizure-corrected procedure was likely the most appropriate for our data. We empirically tested different components of our proposed preprocessing strategy and believe that our results suggest that a preprocessing strategy that effectively identifies outliers, normalizes the data, and corrects for batch effects can be applied to all studies, even those pursued with degraded samples. PMID:22375143

Chow, Maggie L; Winn, Mary E; Li, Hai-Ri; April, Craig; Wynshaw-Boris, Anthony; Fan, Jian-Bing; Fu, Xiang-Dong; Courchesne, Eric; Schork, Nicholas J

2012-02-24

427

Population dynamics in controlled unsteady-state systems: An application to the degradation of glyphosate in a sequencing batch reactor  

SciTech Connect

Control over population dynamics and organism selection in a biological waste treatment system provides an effective means of engineering process efficiency. Examples of applications of organism selection include control of filamentous organisms, biological nutrient removal, industrial waste treatment requiring the removal of specific substrates, and hazardous waste treatment. Inherently, full scale biological waste treatment systems are unsteady state systems due to the variations in the waste streams and mass flow rates of the substrates. Some systems, however, have the capacity to impose controlled selective pressures on the biological population by means of their operation. An example of such a system is the Sequencing Batch Reactor (SBR) which was the experimental system utilized in this research work. The concepts of organism selection were studied in detail for the biodegradation of a herbicide waste stream, with glyphosate as the target compound. The SBR provided a reactor configuration capable of exerting the necessary selective pressures to select and enrich for a glyphosate degrading population. Based on results for bench scale SBRs, a hypothesis was developed to explain population dynamics in glyphosate degrading systems.

Devarakonda, M.S.

1988-01-01

428

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

2011-05-12

429

Material Selection for Controlling Stress-Corrosion Cracking.  

National Technical Information Service (NTIS)

Criteria are given for use in selecting materials for spacecraft and associated equipment and facilities so that failure resulting from stress corrosion can be prevented. Three categories of materials are listed: metal alloys with, (1) high, (2) moderate ...

1981-01-01

430

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

431

Criteria for Determination of Material Control and Accountability System Effectiveness  

SciTech Connect

The Nevada Test Site (NTS) is a test bed for implementation of the Safeguards First Principles Initiative (SFPI), a risk-based approach to Material Control & Accountability (MC&A) requirements. The Comprehensive Assessment of Safeguards Strategies (COMPASS) model is used to determine the effectiveness of MC&A systems under SFPI. Under this model, MC&A is divided into nine primary elements. Each element is divided into sub-elements. Then each sub-element is assigned two values, effectiveness and contribution, that are used to calculate the rating. Effectiveness is a measure of subelement implementation and how well it meets requirements. Contribution is a relative measure of the importance, and functions as a weighting factor. The COMPASS model provides the methodology for calculation of sub-element and element ratings, but not the actual criteria. Each site must develop its own criteria. For the rating to be meaningful, the effectiveness criteria must be objective and based on explicit, measurable criteria. Contribution (weights) must reflect the importance within the MC&A program. This paper details the NTS approach to system effectiveness and contribution values, and will cover the following: the basis for the ratings, an explanation of the contribution “weights,” and the objective, performance based effectiveness criteria. Finally, the evaluation process will be described.

John Wright

2008-03-01

432

Structural control in the synthesis of inorganic porous materials  

Microsoft Academic Search

Mesoporous (2.0--50.0 nm pore diameter) and macroporous (50.0 nm on up) materials have been the basis of my studies. These materials, for many years, possessed large pore size distributions. Recently, however, it has been possible to synthesize both mesoporous and macroporous materials that possess highly ordered uniform pores throughout the material. Workers at Mobil Corporation in 1992 discovered a hexagonally

Brian Thomas Holland

1999-01-01

433

Reflectance of laser-damaged spacecraft thermal control materials  

Microsoft Academic Search

Damage to materials by continuous wave (CW) irradiation of an infrared (IR) laser is dependent on thermal transfer, resulting from absorption of laser energy into the material. Under laser illumination conditions, the thermal radiative properties of a material are often not constant. Reflectance, for example, can vary dramatically as a result of thermal decomposition of paints and coatings. The Air

Robert K. Freeman; Fred A. Rigby; Steve E. Doerr; Lawrence E. Grimes; Daniel B. Ward

1998-01-01

434

Degradation of Weathered Oil by Mixed Marine Bacteria and the Toxicity of Accumulated Water-Soluble Material to Two Marine Crustacea  

Microsoft Academic Search

.   Artificially weathered crude oil was degraded by four diverse cultures of mixed marine bacteria under optimized conditions\\u000a for 7 and 14 days. Loss in