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Sample records for 9732steel processing properties

  1. AISI/DOE Technology Roadmap Program: TRP 9732Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures

    SciTech Connect

    Srdan Simunovic; Gustavo Aramayo

    2002-01-31

    The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of Ultra Light Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. Crash modeling simulations show a clear effect of strain-rate sensitivity on high strength steel (HSS) intensive vehicle. The influence of a strain-rate model can be an incremental sensitivity due to the increased flow stress when similar structure collapse modes are predicted. However, significant differences in crash energy management capacity can be predicted if the change in loading on members alters the predicted collapse mode of the structure. From the material substitution study it can be concluded that HSS material substitution cannot be performed on the basis of the material yield point only and that, especially for advanced HSS vehicle designs, the entire region of material plastic response has to be considered. However, the problem of modeling of the overall dynamic crush process still remains open and requires further experimental and theoretical investigation. Crash modeling simulations show a moderate effect of forming on overall crash performance. The design is the determining factor on the vehicle performance and, therefore, the results of this research cannot provide measures that can be used in a general case. However, it has been shown that for materials that have modest strain hardening, the forming effect is observable and that when more complex forming operations are used, especially in combination with rapid strain hardening materials, forming effects should be taken in the consideration in the computational crash models. crash compatibility study between ULSAB and cars of similar geometric characteristics have shown that the U LSAB

  2. Processing - Property Relationship in Advanced Intermetallics

    DTIC Science & Technology

    1994-07-01

    AD-A285 262 - IlE I !!III Illl iIII c.,. Processing- Property Relationship I in Advanced Intermetallics Final Report For Period March 4,1991 through...through 03-03-94 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Processing- Property Relationship in Advanced Intermetallics; 4. AUTHOR(S) D.A. Hardwick and P.L...2 M echanical Properties ......................................................................... 9 3 C

  3. Structure, processing, and properties of potatoes

    NASA Technical Reports Server (NTRS)

    Lloyd, Isabel K.; Kolos, Kimberly R.; Menegaux, Edmond C.; Luo, Huy; Mccuen, Richard H.; Regan, Thomas M.

    1992-01-01

    The objective of this experiment and lesson intended for high school students in an engineering or materials science course or college freshmen is to demonstrate the relation between processing, structure, and thermodynamic and physical properties. The specific objectives are to show the effect of structure and structural changes on thermodynamic properties (specific heat) and physical properties (compressive strength); to illustrate the first law of thermodynamics; to compare boiling a potato in water with cooking it in a microwave in terms of the rate of structural change and the energy consumed to 'process' the potato; and to demonstrate compression testing.

  4. Audit of fuel processing restoration property

    SciTech Connect

    1995-10-01

    In April, 1992, due to a diminished need for reprocessed uranium, the Secretary of Energy terminated the Fuel Processing Restoration (FPR) project. The termination left management and operating (M&O) contractors at the Idaho National Engineering Laboratory (Laboratory) with over $54 million in tools, equipment and material to be retained, utilized or disposed of. The objectives of the audit were to determine whether FPR property was adequately accounted for and whether the property was properly redistributed or excessed when the FPR project was terminated.

  5. Properties of aerosol processed by ice clouds

    NASA Astrophysics Data System (ADS)

    Rudich, Y.; Adler, G.; Moise, T.; Erlick-Haspel, C.

    2012-12-01

    We suggest that highly porous aerosol (HPA) can form in the upper troposphere/lower stratosphere when ice particles encounter sub-saturation leading to ice sublimation similar to freeze drying. This process can occur at the lower layers of cirrus clouds (few km), at anvils of high convective clouds and thunderstorms, in clouds forming in atmospheric gravitational waves, in contrails and in high convective clouds injecting to the stratosphere. A new experimental system that simulates freeze drying of proxies for atmospheric aerosol at atmospheric pressure was constructed and various proxies for atmospheric soluble aerosol were studied. The properties of resulting HPA were characterized by various methods. It was found that the resulting aerosol have larger sizes (extent depends on substance and mixing), lower density (largevoid fraction), lower optical extinction and higher CCN activity and IN activity. Implication of HPA's unique properties and their atmospheric consequences to aerosol processing in ice clouds and to cloud cycles will be discussed.

  6. Advanced processing and properties of superhard materials

    SciTech Connect

    Narayan, J.

    1995-06-01

    The author reviews fundamental aspects of Superhard Materials with hardness close to that of diamond. These materials include cubic boron nitride (c-BN), carbon nitride ({beta}-C{sub 3}N{sub 4}) and diamondlike carbon. Since these materials are metastable at normal temperatures and pressures, novel methods of synthesis and processing of these materials are required. This review focuses on synthesis and processing, detailed materials characterization and properties of c-BN and {beta}C{sub 3}N{sub 4} and diamondlike carbon films.

  7. Viscoelastic properties of polymer composites during processing

    NASA Astrophysics Data System (ADS)

    O'Brien, Daniel James

    Residual stresses that are induced during processing of polymer matrix composites lead to warpage of structural parts and can produce microcracks and other forms of damage. Process models that track the development of residual stresses in composites during processing have received growing attention in recent years. An accurate and easy to implement simulation will help lower the manufacturing cost by enabling engineers to predict and prevent the warpage in parts due to residual stress. The critical feature of a process model is the development of an accurate material model to predict mechanical properties throughout the entire manufacturing cycle. Material models are very complex since the matrix changes from a fluid to a viscoelastic solid at the end of cure. In this work several aspects of the curing, viscoelastic, and cure shrinkage behavior of an aerospace grade epoxy resin were characterized and modeled for the purpose of composites process modeling. Measurement of matrix viscoelastic properties during cure was accomplished through two experimental approaches, each suited to a particular range of cure states. To investigate the material behavior during later stages of cure after gelation, small beam specimens were tested in three-point bending. During early stages of curing, samples were examined by shearing the material between parallel plates in a rheometer. Specimens for each configuration were manufactured at several cure states and tested at a range of temperatures. These data were used to develop a material model to predict the relaxation modulus of the matrix at any time during cure. Additionally, moire interferometry was successfully applied to the measurement of the viscoelastic Poisson's ratio of the matrix through its entire glassy-to-rubbery transition. The matrix viscoelastic material models were then used to predict composite viscoelastic properties and correlated with experimental results. In addition, the viscoelastic shrinkage behavior of the

  8. Textured silicon nitride: processing and anisotropic properties

    PubMed Central

    Zhu, Xinwen; Sakka, Yoshio

    2008-01-01

    Textured silicon nitride (Si3N4) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si3N4, with emphasis on the anisotropic and abnormal grain growth of β-Si3N4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for β-Si3N4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the texturing mechanisms and the factors affecting texture development. Also, methods of synthesizing the rodlike β-Si3N4 single crystals are presented. Various anisotropic properties of textured Si3N4 and their origins are thoroughly described and discussed, such as hardness, elastic modulus, bending strength, fracture toughness, fracture energy, creep behavior, tribological and wear behavior, erosion behavior, contact damage behavior and thermal conductivity. Models are analyzed to determine the thermal anisotropy by considering the intrinsic thermal anisotropy, degree of orientation and various microstructure factors. Textured porous Si3N4 with a unique microstructure composed of oriented elongated β-Si3N4 and anisotropic pores is also described for the first time, with emphasis on its unique mechanical and thermal-mechanical properties. Moreover, as an important related material, textured α-Sialon is also reviewed, because the presence of elongated α-Sialon grains allows the production of textured α-Sialon using the

  9. Textured silicon nitride: processing and anisotropic properties.

    PubMed

    Zhu, Xinwen; Sakka, Yoshio

    2008-07-01

    Textured silicon nitride (Si3N4) has been intensively studied over the past 15 years because of its use for achieving its superthermal and mechanical properties. In this review we present the fundamental aspects of the processing and anisotropic properties of textured Si3N4, with emphasis on the anisotropic and abnormal grain growth of β-Si3N4, texture structure and texture analysis, processing methods and anisotropic properties. On the basis of the texturing mechanisms, the processing methods described in this article have been classified into two types: hot-working (HW) and templated grain growth (TGG). The HW method includes the hot-pressing, hot-forging and sinter-forging techniques, and the TGG method includes the cold-pressing, extrusion, tape-casting and strong magnetic field alignment techniques for β-Si3N4 seed crystals. Each processing technique is thoroughly discussed in terms of theoretical models and experimental data, including the texturing mechanisms and the factors affecting texture development. Also, methods of synthesizing the rodlike β-Si3N4 single crystals are presented. Various anisotropic properties of textured Si3N4 and their origins are thoroughly described and discussed, such as hardness, elastic modulus, bending strength, fracture toughness, fracture energy, creep behavior, tribological and wear behavior, erosion behavior, contact damage behavior and thermal conductivity. Models are analyzed to determine the thermal anisotropy by considering the intrinsic thermal anisotropy, degree of orientation and various microstructure factors. Textured porous Si3N4 with a unique microstructure composed of oriented elongated β-Si3N4 and anisotropic pores is also described for the first time, with emphasis on its unique mechanical and thermal-mechanical properties. Moreover, as an important related material, textured α-Sialon is also reviewed, because the presence of elongated α-Sialon grains allows the production of textured α-Sialon using the

  10. Magnetic properties of friction stir processed composite

    SciTech Connect

    Das, Shamiparna; Martinez, Nelson Y.; Das, Santanu; Mishra, Rajiv S.; Grant, Glenn J.; Jana, Saumyadeep; Polikarpov, Evgueni

    2016-03-29

    There are many existing inspection systems each with their own advantages and drawbacks. These usually comprise of semi-remote sensors which frequently causes difficulty in reaching complex areas of a component. This study proposes to overcome that difficulty by developing embedded functional composites. Through this route, embedding can be achieved in virtually any component part and can be periodically interrogated by a reading device. The “reinforcement rich” processed areas can then be utilized to record properties like strain, temperature, stress state etc. depending on the reinforcement material. In this work, friction stir processing (FSP) was utilized to fabricate a magnetostrictive composite by embedding galfenol particles into a nonmagnetic aluminum (Al) matrix. It targets to develop a composite that produces strain in a varying magnetic field. Reinforcements were observed to be distributed uniformly in the matrix. Magnetization curves were studied using a vibrating sample magnetometer (VSM). A simple and cheap setup was developed to measure the magnetostrictive strain of the composites. Important factors affecting the magnetic properties were identified and ways to improve the magnetic properties discussed.

  11. Processing and properties of porous nickel titanium

    NASA Astrophysics Data System (ADS)

    Bansiddhi, Ampika

    Increasing interest in long-life bone implants with reduced mechanical properties reducing the stress-shielding effect and a structure mimicking bone porous architecture has encouraged study and development of fabrication methods for porous NiTi. The main objective of this work was to advance these goals by developing new processing procedures for porous NiTi that offer the following advances over existing technology: (i) controllable pore characteristics (porosity, pore size/shape, connectivity) to stimulate and accommodate a high level of bone ingrowth; (ii) mechanical properties (yield strength, stiffness, recovery strain) matching those of bone, to minimize stress-shielding effects; (iii) dense metal struts and walls, to prevent crack initiation and increase ductility; (iv) simplicity and low cost of production; and (v) capability for either shape-memory or superelasticity. A new strategy to fabricate porous NiTi with the above characteristics is presented. This strategy is based on densification by hot isostatic pressing (HIP) of a mixture of pre-alloyed NiTi powders and salt space holders, followed by removal of the salt. Using this strategy, the porosity of the NiTi is controllable by varying the volume fraction of the salt, and the pore size and shape can be tailored in accordance with the geometry of the salt used. The effects of using different space holders, i.e. sodium fluoride (NaF) and sodium chloride (NaCl), on the final porous product are examined. The influence of HIP temperature and further post-HIP sintering on foam properties is also presented. The high cost associated with HIP processing drove subsequent work towards new strategies to simplify porous NiTi synthesis while maintaining high-quality microstructures and mechanical properties. The strategy followed here involves combining the NaCl space holder technique with in situ transient liquid phase sintering of pre-alloyed NiTi and Nb powders, thereby integrating the densification of Ni

  12. Inferences of Ice Processes From Properties

    NASA Astrophysics Data System (ADS)

    Alley, R. B.; Wilen, L. A.; Spencer, M. K.; Hansen, D. P.; Fitzpatrick, J. J.

    2001-12-01

    Barclay Kamb's pioneering work on the physics and mineralogy of laboratory and natural ices has guided glaciological research spanning 40 years. Much of that research required extremely tedious use of optical universal stages to study thin sections of ice. Recent advances in digital systems have revolutionized data collection and offer great opportunities to use ice properties to infer processes that operate too slowly for proper laboratory investigation, leading toward a greatly improved understanding of the history of ice and its softness for further deformation (Wilen, 1999; Hansen and Wilen, in review; Wilen et al., this meeting). Patterns of nearest-neighbor c-axis orientations reveal the influence of nucleation-and-growth recrystallization (typically indicative of steady-state deformation) or polygonization. Combining these results with correlations between grain sizes and dust and chemical loadings reveals impurity effects on active processes. The relations between mean grain size and c-axis-fabric strength may show the importance of grain-boundary processes in deformation. Bubble sizes reveal climate conditions during firnification, and bubble shapes can provide information on in situ strain rates. These and many other possibilities should enhance our understanding of ice flow and of the paleoclimatic records archived in ice.

  13. Synthetic fuels handbook: properties, process and performance

    SciTech Connect

    Speight, J.

    2008-07-01

    The handbook is a comprehensive guide to the benefits and trade-offs of numerous alternative fuels, presenting expert analyses of the different properties, processes, and performance characteristics of each fuel. It discusses the concept systems and technology involved in the production of fuels on both industrial and individual scales. Chapters 5 and 7 are of special interest to the coal industry. Contents: Chapter 1. Fuel Sources - Conventional and Non-conventional; Chapter 2. Natural Gas; Chapter 3. Fuels From Petroleum and Heavy Oil; Chapter 4. Fuels From Tar Sand Bitumen; Chapter 5. Fuels From Coal; Chapter 6. Fuels From Oil Shale; Chapter 7. Fuels From Synthesis Gas; Chapter 8. Fuels From Biomass; Chapter 9. Fuels From Crops; Chapter 10. Fuels From Wood; Chapter 11. Fuels From Domestic and Industrial Waste; Chapter 12. Landfill Gas. 3 apps.

  14. Properties of the Bivariate Delayed Poisson Process

    DTIC Science & Technology

    1974-07-01

    Initial Conditions. The purpose and methodology of stationary Initial conditions for uni- varlate point processes have been described in Lawrance ... Lawrance , A. J. (1972). Some models for stationary series of univariate events. In Stochastic Point Processes: Statistical Analysis, Theory and

  15. The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 5. Processing and Miscellaneous Properties

    DTIC Science & Technology

    1993-04-01

    Processing and Mechanical Properties of High Texniperature/ High Performance Composites by A.G. Evans & F. Leckie University of California, Santa Barbara...University Carnegie Mellon University University of Virginia 93- 13752 Book 5of 5: PROCESSING AND MISCELLANEOUS PROPERTIES 93e • • SUMMARY OF TABLE OF...CONTENTS EXECUTIVE SUMMARY BOOK 1: CONSTITUENT PROPERTIES OF COMPOSITES BOOK 2: CONSTITUENT PROPERTIES AND MACROSCOPIC PERFORMANCE: CMCs BOOK 3

  16. Lunar fiberglass: Properties and process design

    NASA Technical Reports Server (NTRS)

    Dalton, Robert; Nichols, Todd

    1987-01-01

    A Clemson University ceramic engineering design for a lunar fiberglass plant is presented. The properties of glass fibers and metal-matrix composites are examined. Lunar geology is also discussed. A raw material and site are selected based on this information. A detailed plant design is presented, and summer experiments to be carried out at Johnson Space Center are reviewed.

  17. Excimer laser surface modification: Process and properties

    SciTech Connect

    Jervis, T.R.; Nastasi, M.; Hirvonen, J.P.

    1992-12-01

    Surface modification can improve materials for structural, tribological, and corrosion applications. Excimer laser light has been shown to provide a rapid means of modifying surfaces through heat treating, surface zone refining, and mixing. Laser pulses at modest power levels can easily melt the surfaces of many materials. Mixing within the molten layer or with the gas ambient may occur, if thermodynamically allowed, followed by rapid solidification. The high temperatures allow the system to overcome kinetic barriers found in some ion mixing experiments. Alternatively, surface zone refinement may result from repeated melting-solidification cycles. Ultraviolet laser light couples energy efficiently to the surface of metallic and ceramic materials. The nature of the modification that follows depends on the properties of the surface and substrate materials. Alloying from both gas and predeposited layer sources has been observed in metals, semiconductors, and ceramics as has surface enrichment of Cr by zone refinement of stainless steel. Rapid solidification after melting often results in the formation of nonequilibrium phases, including amorphous materials. Improved surface properties, including tribology and corrosion resistance, are observed in these materials.

  18. Process for restoring membrane permeation properties

    DOEpatents

    Pinnau, Ingo; Toy, Lora G.; Casillas, Carlos G.

    1997-05-20

    A process for restoring the selectivity of high-flee-volume, glassy polymer membranes for condensable components over less-condensable components or non-condensable components of a gas mixture. The process involves exposing the membrane to suitable sorbent vapor, such as propane or butane, thereby reopening the microvoids that make up the free volume. The selectivity of an aged membrane may be restored to 70-100% of its original value. The selectivity of a membrane which is known to age over time can also be maintained by keeping the membrane in a vapor environment when it is not in use.

  19. Process for restoring membrane permeation properties

    DOEpatents

    Pinnau, I.; Toy, L.G.; Casillas, C.G.

    1997-05-20

    A process is described for restoring the selectivity of high-free-volume, glassy polymer membranes for condensable components over less-condensable components or non-condensable components of a gas mixture. The process involves exposing the membrane to suitable sorbent vapor, such as propane or butane, thereby reopening the microvoids that make up the free volume. The selectivity of an aged membrane may be restored to 70--100% of its original value. The selectivity of a membrane which is known to age over time can also be maintained by keeping the membrane in a vapor environment when it is not in use. 8 figs.

  20. Effect of processing on Polymer/Composite structure and properties

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Advances in the vitality and economic health of the field of polymer forecasting are discussed. A consistent and rational point of view which considers processing as a participant in the underlying triad of relationships which comprise materials science and engineering is outlined. This triad includes processing as it influences material structure, and ultimately properties. Methods in processing structure properties, polymer science and engineering, polymer chemistry and synthesis, structure and modification and optimization through processing, and methods of melt flow modeling in processing structure property relations of polymer were developed. Mechanical properties of composites are considered, and biomedical materials research to include polymer processing effects are studied. An analysis of the design technology of advances graphite/epoxy composites is also reported.

  1. Processing and Properties of Airframe Materials.

    DTIC Science & Technology

    1984-02-01

    the first year of the three-year program to characterize the relationship between microstruc - ture and fatigue behavior of beta processed Ti-6A1-4V...determine how the microstructural variables affect the macroscopic deformation behavior . Experiments have been performed with 7475 Al having various grain...sizes. The flow stress vs strain rate behavior for the mixed grain size materials is best described using the iso-strain rate concept. Observations of

  2. Recycled Fiber Properties as Affected by Contaminants and Removal Processes.

    DTIC Science & Technology

    Five materials were applied to either a kraft pulp furnish or to a kraft paper and were removed by conventional removal processes. Uncontaminated... kraft paper subjected to the same removal processes determined that the process, not the contaminant, was responsible for changes in sheet properties

  3. Processing Conditions, Rice Properties, Health and Environment

    PubMed Central

    Roy, Poritosh; Orikasa, Takahiro; Okadome, Hiroshi; Nakamura, Nobutaka; Shiina, Takeo

    2011-01-01

    Rice is the staple food for nearly two-thirds of the world’s population. Food components and environmental load of rice depends on the rice form that is resulted by different processing conditions. Brown rice (BR), germinated brown rice (GBR) and partially-milled rice (PMR) contains more health beneficial food components compared to the well milled rice (WMR). Although the arsenic concentration in cooked rice depends on the cooking methods, parboiled rice (PBR) seems to be relatively prone to arsenic contamination compared to that of untreated rice, if contaminated water is used for parboiling and cooking. A change in consumption patterns from PBR to untreated rice (non-parboiled), and WMR to PMR or BR may conserve about 43–54 million tons of rice and reduce the risk from arsenic contamination in the arsenic prone area. This study also reveals that a change in rice consumption patterns not only supply more food components but also reduces environmental loads. A switch in production and consumption patterns would improve food security where food grains are scarce, and provide more health beneficial food components, may prevent some diseases and ease the burden on the Earth. However, motivation and awareness of the environment and health, and even a nominal incentive may require for a method switching which may help in building a sustainable society. PMID:21776212

  4. Processing, properties, and wear resistance of aluminides

    SciTech Connect

    Wright, R.N.; Rabin, B.H.; Wright, J.K.

    1993-03-01

    Fully dense alloys based on Fe{sub 3}Al were produced by reaction synthesis from low cost elemental powders using hot pressing, hot isostatic pressing or Ceracon process. The reaction proceeds by outward spreading of a transient liquid phase from the initial aluminum particle site and precipitation of the compound phase from the liquid. Combustion synthesized material has a very fine grain size that is resistant to coarsening at high temperature because of a high density of fine oxides from the prior particle boundaries. The fine grain size results in approximately twice the yield strength in the reaction synthesized material compared to hot extruded pre-alloyed powder. Combustion synthesis has also been successfully applied to joining Fe{sub 3}Al and to forming coatings on carbon steel substrates. Combustion synthesis has been shown to be viable for fabricating trialuminides from elemental powder compacts. Al{sub 3}Ti, Al{sub 73}Ti{sub 24}Cr{sub 3} and Al{sub 67}Ti{sub 25}Cr{sub 8} were examined. Fully dense, homogeneous materials exhibiting an equiaxed grain structure were produced by conducting reaction and homogenization under pressure, or in a furnace at ambient pressure and subsequently densifying the porous preform by hot consolidation. The tetragonal DO{sub 22} structure was the primary reaction product for all compositions. Most of the Cr remained undissolved after reaction and a homogenization heat treatment at 1200C or above was used to put the Cr into solution and form the desired L1{sub 2} phase.

  5. Process Formulations And Curing Conditions That Affect Saltstone Properties

    SciTech Connect

    Reigel, M. M.; Pickenheim, B. R.; Daniel, W. E.

    2012-09-28

    The first objective of this study was to analyze saltstone fresh properties to determine the feasibility of reducing the formulation water to premix (w/p) ratio while varying the amount of extra water and admixtures used during processing at the Saltstone Production Facility (SPF). The second part of this study was to provide information for understanding the impact of curing conditions (cure temperature, relative humidity (RH)) and processing formulation on the performance properties of cured saltstone.

  6. Processing dependence of mechanical properties of metallic glass nanowires

    SciTech Connect

    Zhang, Qi; Li, Mo; Li, Qi-Kai

    2015-02-16

    Compared to their crystalline counterparts, nanowires made of metallic glass have not only superb properties but also remarkable processing ability. They can be processed easily and cheaply like plastics via a wide range of methods. To date, the underlying mechanisms of how these different processing routes affect the wires' properties as well as the atomic structure remains largely unknown. Here, by using atomistic modeling, we show that different processing methods can greatly influence the mechanical properties. The nanowires made via focused ion beam milling and embossing exhibit higher strength but localized plastic deformation, whereas that made by casting from liquid shows excellent ductility with homogeneous deformation but reduced strength. The different responses are reflected sensitively in the underlying atomic structure and packing density, some of which have been observed experimentally. The presence of the gradient of alloy concentration and surface effect will be discussed.

  7. Radiation processing and functional properties of soybean ( Glycine max)

    NASA Astrophysics Data System (ADS)

    Pednekar, Mrinal; Das, Amit K.; Rajalakshmi, V.; Sharma, Arun

    2010-04-01

    Effect of radiation processing (10, 20 and 30 kGy) on soybean for better utilization was studied. Radiation processing reduced the cooking time of soybean and increased the oil absorption capacity of soy flour without affecting its proximate composition. Irradiation improved the functional properties like solubility, emulsification activity and foam stability of soybean protein isolate. The value addition effect of radiation processing has been discussed for the products (soy milk, tofu and tofu fortified patties) prepared from soybean.

  8. A Review on Biomass Torrefaction Process and Product Properties

    SciTech Connect

    Jaya Shankar Tumuluru; Shahab Sokhansanj; Christopher T. Wright; J. Richard Hess; Richard D. Boardman

    2011-08-01

    Biomass Torrefaction is gaining attention as an important preprocessing step to improve the quality of biomass in terms of physical properties and chemical composition. Torrefaction is a slow heating of biomass in an inert or reduced environment to a maximum temperature of approximately 300 C. Torrefaction can also be defined as a group of products resulting from the partially controlled and isothermal pyrolysis of biomass occurring in a temperature range of 200-280 C. Thus, the process can be called a mild pyrolysis as it occurs at the lower temperature range of the pyrolysis process. At the end of the torrefaction process, a solid uniform product with lower moisture content and higher energy content than raw biomass is produced. Most of the smoke-producing compounds and other volatiles are removed during torrefaction, which produces a final product that will have a lower mass but a higher heating value. The present review work looks into (a) torrefaction process and different products produced during the process and (b) solid torrefied material properties which include: (i) physical properties like moisture content, density, grindability, particle size distribution and particle surface area and pelletability; (ii) chemical properties like proximate and ultimate composition; and (iii) storage properties like off-gassing and spontaneous combustion.

  9. Processing, texture and mechanical properties of sintered silicon carbide

    NASA Technical Reports Server (NTRS)

    Landfermann, H.; Hausner, H.

    1988-01-01

    With regard to its favorable properties, in particular those shown at high temperatures, silicon carbide is of great interest for applications related to the construction of engines and turbines. Thus, silicon carbide could replace heat-resisting alloys with the objective to achieve a further increase in operational temperature. The present investigation is concerned with approaches which can provide silicon carbide material with suitable properties for the intended applications, taking into account the relations between characteristics of the raw material, material composition, sinter conditions, and results of the sintering process. The effects of density and texture formation on the mechanical properties are studied. It is found that a dense material with a fine-grained microstructure provides optimal mechanical properties, while any deviation from this ideal condition can lead to a considerable deterioration with respect to the material properties.

  10. Innovation adoption processes for third party property management companies

    SciTech Connect

    Shockman, Chris; Piette, Mary Ann

    2000-07-01

    Innovation adoption studies have never been applied to third party property management companies. These companies manage buildings for a fee as their primary business. Property management companies are influential in the adoption process for new technologies because they act as gatekeepers for technical information. This study analyzes radical and routine adoption process that are found in large, professionally operated property management companies. The process is explicated. The technical managers, and their role as technology gate keepers, are described. The distinction to the technical managers between routine and radical technology is that routine technologies do something in a new way and radical technologies do something new. Observations concerning evaluation and adoption of information technologies are described. The findings suggest methods of successfully tailoring and introducing technologies to this market.

  11. Processing and properties of low-aluminum alloy FAPY

    SciTech Connect

    Sikka, V.K.; Howell, C.R.; Hall, F.; Valykeo, J.

    1996-07-01

    This paper deals with the melting, processing, properties, and microstructure of three commercially melted heats of Fe-16 at. % Al alloy FAPY. All of the heats were air-induction melted (AIM), two at Hoskins Manufacturing Company (Hamburg, Michigan) and one at United Defense (Anniston, Alabama). One ingot from each of the heats was used for testing at the Oak Ridge National Laboratory. A 127-mm.-long section from each ingot was used for determining properties and microstructure in the as-cast, cast and hot-processed, and cold-rolled conditions. The fine-grained sheet showed 20% elongation at room temperature.

  12. Shaped Charge Liner Materials: Resources, Processes, Properties, Costs, and Applications

    DTIC Science & Technology

    1991-02-01

    SUBTITLE 5. FUNDING NUMBERS Shaped Charge Liner Materials: Resources, Processes, Properties, Costs, and Applications 2 6. AUTHOC Steven M. Buc 7...summaries of the mineral availability, Cq prmarymetal refinement processeb, material costs in raw form and as finished shaped charge liners , relevant... liner materials. 94-11479 gI 14, SUBJECT TERMS iSt NUMBER OF PAGIS 13chrg wrhad :xplosively formed penetrators material R. PRCE COEV" processing

  13. Process depending morphology and resulting physical properties of TPU

    NASA Astrophysics Data System (ADS)

    Frick, Achim; Spadaro, Marcel

    2015-12-01

    Thermoplastic polyurethane (TPU) is a rubber like material with outstanding properties, e.g. for seal applications. TPU basically provides high strength, low frictional behavior and excellent wear resistance. Though, due to segmented structure of TPU, which is composed of hard segments (HSs) and soft segments (SSs), physical properties depend strongly on the morphological arrangement of the phase separated HSs at a certain ratio of HSs to SSs. It is obvious that the TPU deforms differently depending on its bulk morphology. Basically, the morphology can either consist of HSs segregated into small domains, which are well dispersed in the SS matrix or of few strongly phase separated large size HS domains embedded in the SS matrix. The morphology development is hardly ruled by the melt processing conditions of the TPU. Depending on the morphology, TPU provides quite different physical properties with respect to strength, deformation behavior, thermal stability, creep resistance and tribological performance. The paper deals with the influence of important melt processing parameters, such as temperature, pressure and shear conditions, on the resulting physical properties tested by tensile and relaxation experiments. Furthermore the morphology is studied employing differential scanning calorimeter (DSC), transmission light microscopy (TLM), scanning electron beam microscopy (SEM) and transmission electron beam microscopy (TEM) investigations. Correlations between processing conditions and resulting TPU material properties are elaborated. Flow and shear simulations contribute to the understanding of thermal and flow induced morphology development.

  14. Process depending morphology and resulting physical properties of TPU

    SciTech Connect

    Frick, Achim Spadaro, Marcel

    2015-12-17

    Thermoplastic polyurethane (TPU) is a rubber like material with outstanding properties, e.g. for seal applications. TPU basically provides high strength, low frictional behavior and excellent wear resistance. Though, due to segmented structure of TPU, which is composed of hard segments (HSs) and soft segments (SSs), physical properties depend strongly on the morphological arrangement of the phase separated HSs at a certain ratio of HSs to SSs. It is obvious that the TPU deforms differently depending on its bulk morphology. Basically, the morphology can either consist of HSs segregated into small domains, which are well dispersed in the SS matrix or of few strongly phase separated large size HS domains embedded in the SS matrix. The morphology development is hardly ruled by the melt processing conditions of the TPU. Depending on the morphology, TPU provides quite different physical properties with respect to strength, deformation behavior, thermal stability, creep resistance and tribological performance. The paper deals with the influence of important melt processing parameters, such as temperature, pressure and shear conditions, on the resulting physical properties tested by tensile and relaxation experiments. Furthermore the morphology is studied employing differential scanning calorimeter (DSC), transmission light microscopy (TLM), scanning electron beam microscopy (SEM) and transmission electron beam microscopy (TEM) investigations. Correlations between processing conditions and resulting TPU material properties are elaborated. Flow and shear simulations contribute to the understanding of thermal and flow induced morphology development.

  15. Structure-Property Relationships of Solids in Pharmaceutical Processing

    NASA Astrophysics Data System (ADS)

    Chattoraj, Sayantan

    Pharmaceutical development and manufacturing of solid dosage forms is witnessing a seismic shift in the recent years. In contrast to the earlier days when drug development was empirical, now there is a significant emphasis on a more scientific and structured development process, primarily driven by the Quality-by-Design (QbD) initiatives of US Food and Drug Administration (US-FDA). Central to such an approach is the enhanced understanding of solid materials using the concept of Materials Science Tetrahedron (MST) that probes the interplay between four elements, viz., the structure, properties, processing, and performance of materials. In this thesis work, we have investigated the relationships between the structure and those properties of pharmaceutical solids that influence their processing behavior. In all cases, we have used material-sparing approaches to facilitate property assessment using very small sample size of materials, which is a pre-requisite in the early stages of drug development when the availability of materials, drugs in particular, is limited. The influence of solid structure, either at the molecular or bulk powder levels, on crystal plasticity and powder compaction, powder flow, and solid-state amorphization during milling, has been investigated in this study. Through such a systematic evaluation, we have captured the involvement of structure-property correlations within a wide spectrum of relevant processing behaviors of pharmaceutical solids. Such a holistic analysis will be beneficial for addressing both regulatory and scientific issues in drug development.

  16. Effect of processing pressure on the properties of graphite foam

    NASA Astrophysics Data System (ADS)

    Shah, Raviraj; Soni, Neha; Shrivastava, R.

    2013-06-01

    Graphite foam samples were prepared by heating mesophase pitch at different processing pressures followed by carbonization and graphitization under inert atmosphere. These samples were characterized for density, surface morphology and thermal conductivity. Microstructure of the samples indicate that processing pressure controls the evolution of volatiles from mesophase pitch to create a structure having optimum pore size, ligament thickness and junctions, which all are responsible for physical and thermal properties of resultant graphite foam. The study reveals that there is a relationship between processing pressure and the final density & thermal conductivity.

  17. Investigating face-property specific processing in the right OFA.

    PubMed

    Kadosh, Kathrin Cohen; Walsh, Vincent; Kadosh, Roi Cohen

    2011-01-01

    Within the neural face-processing network, the right occipital face area (rOFA) plays a prominent role, and it has been suggested that it receives both feed-forward and re-entrant feedback from other face sensitive areas. Its functional role is less well understood and whether the rOFA is involved in the initial analysis of a face stimulus or in the detailed integration of different face properties remains an open question. The present study investigated the functional role of the rOFA with regard to different face properties (identity, expression, and gaze) using transcranial magnetic stimulation (TMS). Experiment 1 showed that the rOFA integrates information across different face properties: performance for the combined processing of identity and expression decreased after TMS to the rOFA, while no impairment was seen in gaze processing. In Experiment 2 we examined the temporal dynamics of this effect. We pinpointed the impaired integrative computation to 170 ms post stimulus presentation. Together the results suggest that TMS to the rOFA affects the integrative processing of facial identity and expression at a mid-latency processing stage.

  18. Processing dependent properties of silica xerogels for interlayer dielectric applications

    NASA Astrophysics Data System (ADS)

    Jain, Anurag

    One of the current and near future research focus in microelectronics is to integrate copper with a new low dielectric constant (K) material. The traditional low K is dense SiO2 (K = 4). Introducing porosity in materials with silica backbone is promising as processing and integration methods are well known. This thesis focuses on studying silica xerogel, also known as nanoporous silica. A new low-K material has to be tested for an array of electrical, mechanical, thermal, and chemical properties before it is deemed successful to replace dense SiO2. These properties of silica xerogels are characterized using various analytical techniques and the effect of processing conditions is studied. The property data is explained by the models and mechanisms relating processing-structure-property behavior. The processing effects on thermal and mechanical properties are studied in great detail and the theories for generic porous low-K materials are developed. The xerogel films are processed at ambient conditions and crack free, thick (0.5--4 mum), highly porous (˜25--90%) films are obtained. Two methods of porosity control were used. One is the traditional single solvent (ethanol) method and another is a binary solvent (mixture of ethanol and ethylene glycol) method. The films underwent aging and silylation procedures to make the backbone stiff and hydrophobic. Sintering of xerogel films eliminates defects and organics and additional condensation reactions make matrix more connected, dense and ordered. Films were characterized for their refractive index, thickness, porosity, pore size and surface roughness. Dielectric constant measurements at 1 MHz show that K varies linearly with porosity. Dielectric loss tangents are low and breakdown strength meets the standards. FTIR and XPS analysis show that films are stable chemically and remain hydrophobic even after boiling in water. Mechanical and thermal properties of porous materials are dependent on the microstructure and various

  19. Food material properties and early hominin processing techniques.

    PubMed

    Zink, Katherine D; Lieberman, Daniel E; Lucas, Peter W

    2014-12-01

    Although early Homo is hypothesized to have used tools more than australopiths to process foods prior to consumption, it is unknown how much the food processing techniques they used altered the material properties of foods, and therefore the masticatory forces they generated, and how well they were able to comminute foods. This study presents experimental data on changes to food material properties caused by mechanical tenderization (pounding with a stone tool) and cooking (dry roasting) of two foods likely to have been important components of the hominin diet: meat and tubers. Mechanical tenderization significantly decreased tuber toughness by 42%, but had no effect on meat toughness. Roasting significantly decreased several material properties of tubers correlated with masticatory effort including toughness (49%), fracture stress (28%) and elastic modulus (45%), but increased the toughness (77%), fracture stress (50%-222%), and elastic modulus of muscle fibers in meat (308%). Despite increasing many material properties of meat associated with higher masticatory forces, roasting also decreased measured energy loss by 28%, which likely makes it easier to chew. These results suggest that the use of food processing techniques by early Homo probably differed for meat and tubers, but together would have reduced masticatory effort, helping to relax selection to maintain large, robust faces and large, thickly enameled teeth.

  20. Incoloy 908 database report: On process -- structure -- property relationship

    SciTech Connect

    Toma, L.S.; Hwang, I.S.; Steeves, M.M.

    1993-05-01

    Incoloy 908 is a nickel-iron base superalloy with a coefficient of expansion (COE) and mechanical properties that have been optimized for use in Nb{sub 3}Sn superconducting magnets. It has been proposed for use as a conduit material for the International Thermonuclear Experimental Reactor (ITER) magnets. The relationship between manufacturing processes, microstructures and mechanical properties of Incoloy 908 are characterized in support of the magnet fabrication and quality control. This report presents microhardness, microstructure, and yield and ultimate tensile strengths as functions of thermomechanical process variables including heat treatment, annealing and cold work for laboratory prepared Incoloy 908 specimens. Empirical correlations have been developed for the microhardness at room temperature and tensile strength at room temperature and at 4K. These results may be used for manufacturing quality control or for design.

  1. Processing and Properties of Chemically Derived Calcium Silicate Cements

    DTIC Science & Technology

    1992-02-27

    1991 Air Force Grant No. AFOSR-88-0184 Prepared for AIR FORCE OFFICE OF SCIENTIFIC RESEARCH ELECTRONIC AND MATERIAL SCIENCES DIRECTORATE Principal...Heiland, Processing and Properties of Chemically Derived Calcium Silicate Cement. Master of Science , Solid State Science , The Pennsylvania State...University, May 1990. Appendix IV Kelly Markowski, A Fundamental Study of the Surface Chemistry of Calcium Silicate Hydrate, Bachelor of Science Thesis

  2. Processing-structure-properties relationships in PLA nanocomposite films

    NASA Astrophysics Data System (ADS)

    Di Maio, L.; Scarfato, P.; Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Incarnato, L.

    2014-05-01

    This work deals on the possibility to improve performances of PLA-based nanocomposite films, for packaging applications, through conveniently tuning materials and processing conditions in melt compounding technology. In particular, two types of polylactic acid and different types of filler selected from montmorillonites and bentonites families were used to prepare the hybrid systems by using a twin-screw extruder. The effect of biaxial drawing on morphology and properties of the nanocomposites, produced by film blowing, was investigated.

  3. Backside EBR process performance with various wafer properties

    NASA Astrophysics Data System (ADS)

    Goto, Tomohiro; Shigemori, Kazuhito; Vangheluwe, Rik; Erich, Daub; Sanada, Masakazu

    2009-03-01

    In immersion lithography process, film stacking architecture will be necessary to avoid top coat film peeling. To achieve suitable stacking architecture for immersion lithography process, an EBR process that delivers tightly controlled film edge position and good uniformity around the wafer circumference is needed. We demonstrated a new bevel rinse system on a SOKUDO RF3 coat-and-develop track for immersion lithography. The performance of the new bevel rinse system for various wafer properties was evaluated. It was found that the bevel rinse system has a good controllability of film edge position and good uniformity around the wafer circumference. The results indicate that the bevel rinse system has a large margin for wafer centering accuracy, back side particles, wafer shape and substrates with good film edge position controllability, uniformity and clean apex. The system has been demonstrated to provide a suitable film stacking architecture for immersion lithography mass production process.

  4. Single crystal Processing and magnetic properties of gadolinium nickel

    SciTech Connect

    Shreve, Andrew John

    2012-01-01

    GdNi is a rare earth intermetallic material that exhibits very interesting magnetic properties. Spontaneous magnetostriction occurs in GdNi at T{sub C}, on the order of 8000ppm strain along the c-axis and only until very recently the mechanism causing this giant magnetostriction was not understood. In order to learn more about the electronic and magnetic structure of GdNi, single crystals are required for anisotropic magnetic property measurements. Single crystal processing is quite challenging for GdNi though since the rare-earth transition-metal composition yields a very reactive intermetallic compound. Many crystal growth methods are pursued in this study including crucible free methods, precipitation growths, and specially developed Bridgman crucibles. A plasma-sprayed Gd2O3 W-backed Bridgman crucible was found to be the best means of GdNi single crystal processing. With a source of high-quality single crystals, many magnetization measurements were collected to reveal the magnetic structure of GdNi. Heat capacity and the magnetocaloric effect are also measured on a single crystal sample. The result is a thorough report on high quality single crystal processing and the magnetic properties of GdNi.

  5. Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys.

    PubMed

    Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

    2016-12-01

    Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties.

  6. Optical properties of polydimethylsiloxane (PDMS) during nanosecond laser processing

    NASA Astrophysics Data System (ADS)

    Stankova, N. E.; Atanasov, P. A.; Nikov, Ru. G.; Nikov, R. G.; Nedyalkov, N. N.; Stoyanchov, T. R.; Fukata, N.; Kolev, K. N.; Valova, E. I.; Georgieva, J. S.; Armyanov, St. A.

    2016-06-01

    This article presents experimental investigations of effects of the process parameters on the medical grade polydimethylsiloxane (PDMS) elastomer processed by laser source with irradiation at UV (266 and 355 nm), VIS (532 nm) and NIR (1064 nm). Systematic experiments are done to characterize how the laser beam parameters (wavelength, fluence, and number of pulses) affect the optical properties and the chemical composition in the laser treated areas. Remarkable changes of the optical properties and the chemical composition are observed. Despite the low optical absorption of the native PDMS for UV, VIS and NIR wavelengths, successful laser treatment is accomplished due to the incubation process occurring below the polymer surface. With increasing of the fluence and the number of the pulses chemical transformations are revealed in the entire laser treated area and hence decreasing of the optical transmittance is observed. The incubation gets saturation after a certain number of pulses and the laser ablation of the material begins efficiently. At the UV and VIS wavelengths the number of the initial pulses, at which the optical transmittance begins to reduce, decreases from 16 up to 8 with increasing of the laser fluence up to 1.0, 2.5 and 10 J cm-2 for 266, 355 and 532 nm, respectively. In the case of 1064 nm the optical transmittance begins to reduce at 11th pulse incident at a fluence of 13 J cm-2 and the number of the pulses decreases to 8 when the fluence reaches value of 16 J cm-2. The threshold laser fluence needed to induce incubation process after certain number of pulses of 8 is different for every wavelength irradiation as the values increase from 1.0 for 266 nm up to 16 J cm-2 for 1064 nm. The incubation and the ablation processes occur in the PDMS elastomer material during its pulsed laser treatment are a complex function of the wavelength, fluence, number of pulses and the material properties as well.

  7. Process design of press hardening with gradient material property influence

    SciTech Connect

    Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

    2011-05-04

    Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

  8. Influence of wheat kernel physical properties on the pulverizing process.

    PubMed

    Dziki, Dariusz; Cacak-Pietrzak, Grażyna; Miś, Antoni; Jończyk, Krzysztof; Gawlik-Dziki, Urszula

    2014-10-01

    The physical properties of wheat kernel were determined and related to pulverizing performance by correlation analysis. Nineteen samples of wheat cultivars about similar level of protein content (11.2-12.8 % w.b.) and obtained from organic farming system were used for analysis. The kernel (moisture content 10 % w.b.) was pulverized by using the laboratory hammer mill equipped with round holes 1.0 mm screen. The specific grinding energy ranged from 120 kJkg(-1) to 159 kJkg(-1). On the basis of data obtained many of significant correlations (p < 0.05) were found between wheat kernel physical properties and pulverizing process of wheat kernel, especially wheat kernel hardness index (obtained on the basis of Single Kernel Characterization System) and vitreousness significantly and positively correlated with the grinding energy indices and the mass fraction of coarse particles (> 0.5 mm). Among the kernel mechanical properties determined on the basis of uniaxial compression test only the rapture force was correlated with the impact grinding results. The results showed also positive and significant relationships between kernel ash content and grinding energy requirements. On the basis of wheat physical properties the multiple linear regression was proposed for predicting the average particle size of pulverized kernel.

  9. Mechanical and tribological properties of ion beam-processed surfaces

    SciTech Connect

    Kodali, Padma

    1998-01-01

    The intent of this work was to broaden the applications of well-established surface modification techniques and to elucidate the various wear mechanisms that occur in sliding contact of ion-beam processed surfaces. The investigation included characterization and evaluation of coatings and modified surfaces synthesized by three surface engineering methods; namely, beam-line ion implantation, plasma-source ion implantation, and DC magnetron sputtering. Correlation among measured properties such as surface hardness, fracture toughness, and wear behavior was also examined. This dissertation focused on the following areas of research: (1) investigating the mechanical and tribological properties of mixed implantation of carbon and nitrogen into single crystal silicon by beam-line implantation; (2) characterizing the mechanical and tribological properties of diamond-like carbon (DLC) coatings processed by plasma source ion implantation; and (3) developing and evaluating metastable boron-carbon-nitrogen (BCN) compound coatings for mechanical and tribological properties. The surface hardness of a mixed carbon-nitrogen implant sample improved significantly compared to the unimplanted sample. However, the enhancement in the wear factor of this sample was found to be less significant than carbon-implanted samples. The presence of nitrogen might be responsible for the degraded wear behavior since nitrogen-implantation alone resulted in no improvement in the wear factor. DLC coatings have low friction, low wear factor, and high hardness. The fracture toughness of DLC coatings has been estimated for the first time. The wear mechanism in DLC coatings investigated with a ruby slider under a contact stress of 1 GPa was determined to be plastic deformation. The preliminary data on metastable BCN compound coatings indicated high friction, low wear factor, and high hardness.

  10. Electron Beam-Cure Polymer Matrix Composites: Processing and Properties

    NASA Technical Reports Server (NTRS)

    Wrenn, G.; Frame, B.; Jensen, B.; Nettles, A.

    2001-01-01

    Researchers from NASA and Oak Ridge National Laboratory are evaluating a series of electron beam curable composites for application in reusable launch vehicle airframe and propulsion systems. Objectives are to develop electron beam curable composites that are useful at cryogenic to elevated temperatures (-217 C to 200 C), validate key mechanical properties of these composites, and demonstrate cost-saving fabrication methods at the subcomponent level. Electron beam curing of polymer matrix composites is an enabling capability for production of aerospace structures in a non-autoclave process. Payoffs of this technology will be fabrication of composite structures at room temperature, reduced tooling cost and cure time, and improvements in component durability. This presentation covers the results of material property evaluations for electron beam-cured composites made with either unidirectional tape or woven fabric architectures. Resin systems have been evaluated for performance in ambient, cryogenic, and elevated temperature conditions. Results for electron beam composites and similar composites cured in conventional processes are reviewed for comparison. Fabrication demonstrations were also performed for electron beam-cured composite airframe and propulsion piping subcomponents. These parts have been built to validate manufacturing methods with electron beam composite materials, to evaluate electron beam curing processing parameters, and to demonstrate lightweight, low-cost tooling options.

  11. Effect of heat processing on selected grain amaranth physicochemical properties

    PubMed Central

    Muyonga, John H; Andabati, Brian; Ssepuuya, Geoffrey

    2014-01-01

    Grain amaranth is a pseudocereal with unique agricultural, nutritional, and functional properties. This study was undertaken to determine the effect of different heat-processing methods on physicochemical and nutraceutical properties in two main grain amaranth species, of Amaranthus hypochondriacus L. and Amaranthus cruentus L. Grains were prepared by roasting and popping, milled and analyzed for changes in in vitro protein digestibility, gruel viscosity, pasting characteristics, antioxidant activity, flavonoids, and total phenolics. In vitro protein digestibility was determined using the pepsin-pancreatin enzyme system. Viscosity and pasting characteristics of samples were determined using a Brookfield Viscometer and a Rapid Visco Analyzer, respectively. The grain methanol extracts were analysed for phenolics using spectrophotometry while antioxidant activity was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Heat treatment led to a reduction in protein digestibility, the effect being higher in popped than in roasted samples. Viscosities for roasted grain amaranth gruels were significantly higher than those obtained from raw and popped grain amaranth gruels. The results for pasting properties were consistent with the results for viscosity. In both A. hypochondriacus L. and A. cruentus L., the order of the viscosity values was roasted>raw>popped. The viscosities were also generally lower for A. cruentus L. compared to A. hypochondriacus L. Raw samples for both A. hypochondriacus L. and A. cruentus L. did not significantly differ in total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant activity values. Thermal processing led to an increase in TFC and antioxidant activity. However, TPC of heat-processed samples remained unchanged. From the results, it can be concluded that heat treatment enhances antioxidant activity of grain amaranth and causes rheological changes dependent on the nature of heat treatment. PMID

  12. Processing and property evaluation of metal matrix superconducting materials

    NASA Technical Reports Server (NTRS)

    Rao, Appajosula S.

    1995-01-01

    Metal - superconductor (YBCO) systems have been prepared and characterized by resistivity, ac susceptibility and dc SQUID magnetic moment measurements. The silver composites showed superconducting transition for all the composites processed and the superconducting transition temperature tends to depend upon the concentration of the silver in the composite. Aluminum composites showed an unusual resistivity results with two transitions around 90 K and 120 K. The superconducting property of silver composites can be explained qualitatively in terms of the proximity theory that has been suggested for the low temperature superconductors.

  13. Structure-property-processing relationships in Kevlar fibers

    SciTech Connect

    Lacks, D.J.

    1996-12-31

    Molecular simulations are carried out to elucidate the differences in the properties of the commercial fibers Kevlar 29, Kevlar 49 and Kevlar 149, which are manufactured under different processing conditions, and are composed of poly(p-phenylene teraphthalamide) (PPTA). In going from Kevlar 29 to Kevlar 49 to Kevlar 149, the axial Young`s modulus increases significantly and the torsion modulus decreases significantly, while the compressive strength stays roughly the same. Previous investigators have shown that the increase in the Young`s modulus arises from increased axial orientation. The present paper addresses the torsion modulus and compressive strength of the fibers.

  14. Processing and properties of FeAl-bonded composites

    SciTech Connect

    Schneibel, J.H.; Subramanian, R.; Alexander, K.B.; Becher, P.F.

    1996-12-31

    Iron aluminides are thermodynamically compatible with a wide range of ceramics such as carbides, borides, oxides, and nitrides, which makes them suitable as the matrix in composites or cermets containing fine ceramic particulates. For ceramic contents varying from 30 to 60 vol.%, composites of Fe-40 at. % Al with WC, TiC, TiB{sub 2}, and ZrB{sub 2} were fabricated by conventional liquid phase sintering of powder mixtures. For ceramic contents from 70 to 85 vol.%, pressureless melt infiltration was found to be a more suitable processing technique. In FeAl-60 vol.% WC, flexure strengths of up to 1.8 GPa were obtained, even though processing defects consisting of small oxide clusters were present. Room temperature fracture toughnesses were determined by flexure testing of chevron-notched specimens. FeAl/WC and FeAl/TiC composites containing 60 vol.% carbide particles exhibited K{sub Q} values around 20 MPa m{sup 1/2}. Slow crack growth measurements carried out in water and in dry oxygen suggest a relatively small influence of water-vapor embrittlement. It appears therefore that the mechanical properties of iron aluminides in the form of fine ligaments are quite different from their bulk properties. Measurements of the oxidation resistance, dry wear resistance, and thermal expansion of iron aluminide composites suggest many potential applications for these new materials.

  15. Processing parameters matching effects upon Rhizobium tropici biopolymers' rheological properties.

    PubMed

    Pimenta, Flávia Duta; Lopes, Léa Maria de Almeida; de França, Francisca Pessôa

    2008-07-01

    The combined effects of the processing parameters upon rheological properties of biopolymers produced by Rhizobium tropici were studied as a function of the Ca(+2) ions' concentration variation, yeast extract concentration added to the medium, aeration, and agitation, maintaining the mannitol concentration in 10 g/L. The experiments were carried out using a fermenter with 20-L capacity as a reactor. All processing parameters were monitored online. The temperature [(30 +/- 1) degrees C] and pH values (7.0) were kept constant throughout the experimental time. As a statistical tool, a complete 2(3) factorial design with central point and response surface was used to investigate the interactions between relevant variables of the fermentation process: calcium carbonate concentration, yeast extract concentration, aeration, and agitation. The processing parameter setup for reaching the maximum response for rheological propriety production was obtained when applying mannitol concentration of 10.0 g/L, calcium carbonate concentration 1.0 g/L, yeast extract concentration 1.0 g/L, aeration 1.30 vvm, and agitation 800 rpm. The viscosimetric investigation of polysaccharide solutions exposed their shear-thinning behavior and polyelectrolytic feature.

  16. Processing and Properties of a Phenolic Composite System

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Bai, J. M.; Baughman, James M.

    2006-01-01

    Phenolic resin systems generate water as a reaction by-product via condensation reactions during curing at elevated temperatures. In the fabrication of fiber reinforced phenolic resin matrix composites, volatile management is crucial in producing void-free quality laminates. A commercial vacuum-bag moldable phenolic prepreg system was selected for this study. The traditional single-vacuum-bag (SVB) process was unable to manage the volatiles effectively, resulting in inferior voidy laminates. However, a double vacuum bag (DVB) process was shown to afford superior volatile management and consistently yielded void-free quality parts. The DVB process cure cycle (temperature /pressure profiles) for the selected composite system was designed, with the vacuum pressure application point carefully selected, to avoid excessive resin squeeze-outs and achieve the net shape and target resin content in the final consolidated laminate parts. Laminate consolidation quality was characterized by optical photomicrography for the cross sections and measurements of mechanical properties. A 40% increase in short beam shear strength, 30% greater flexural strength, 10% higher tensile and 18% higher compression strengths were obtained in composite laminates fabricated by the DVB process.

  17. Structure-process-property relations in excimer laser surface processed Ti-6Al-4V alloy

    SciTech Connect

    Jervis, T.R.; Zocco, T.G.; Steele, J.H. Jr.

    1990-01-01

    Excimer laser processing results in very rapid solidification of metal surfaces. In addition to mixing or segregation processes, rapid heat treatment can result in phase transformations which yield beneficial surface properties. We have investigated the effect of pulsed excimer laser radiation on the microstructure and surface hardness of Ti-6Al-4V alloy. This material undergoes a well defined martensite transformation during rapid quenching from temperatures in the {beta} phase field. The depth of the transformed layer is thus a marker for the temperature profile during processing. We find that the depth of the transformed layer agrees well with a simple 1-D calculation of heat flow following the laser pulse. As measured by the nanoindenter, we find that the surface martensite is softer than the as-rolled alloy. Multiple pulse processing at high fluences results in an increase in surface hardness, but at a depth much less than that of the martensite, suggesting an independent mechanism. 10 refs., 4 figs.

  18. Accelerating the FE-Simulation of Roll Forming Processes with the Aid of specific Process's Properties

    NASA Astrophysics Data System (ADS)

    Abrass, Ahmad; Özel, Mahmut; Groche, Peter

    2011-08-01

    Roll forming is an effective and economical sheet forming process that is well-established in industry for the manufacturing of large quantities of profile-shaped products. In cold-roll forming, a metal sheet is fed through successive pairs of forming rolls until it is formed into the desired cross-sectional profile. The deformation of the sheet is complex. For this reason, the theoretical analysis is very difficult, especially, if the strain distribution and the occurring forces are to be determined [1]. The design of roll forming processes depends upon a large number of variables, which mainly relies upon experience based knowledge [2]. In order to overcome the challenges and to optimize these processes, FE-simulations are used. The simulation of these processes is time-consuming. The main objective of this work is to accelerate the simulation of roll forming processes by taking advantage of their steady state properties. These properties allow the transformation of points on the sheet metal according to a mathematical function. This transformation function is determined with the help of the finite element method and then the next forming steps are computed, based on the generated function. With the aid of this developed method, the computational time can be reduced effectively. The details of the FE-model and new numerical algorithms will be described. Furthermore, the results of numerical simulations with and without the application of the developed method will be compared regarding computational time and numerical results.

  19. Applications of polybenzoxazines for improvement in processability and property

    NASA Astrophysics Data System (ADS)

    Jin, Lin

    Polybenzoxazines obtained from the polymerization of benzoxazine monomers or oligomers has been used for various applications: to simplify the technology adopted for protection, to improve the processability of high performance material and to replace the environmental hazards in resins. Novel siloxane-containing benzoxazine oligomers with benzoxazine rings in the main chain have been synthesized and mixed with octasilane polyhedral silsesquioxane (OctaSilane POSS) and glass sphere to form a thermo-oxidatively stable coating on a carbon/carbon composite after polymerization and baking. The coating method is very simple and inexpensive compared with the conventional approaches, such as chemical vapor deposition. The effectiveness of the coating has also been demonstrated. A new class of benzoxazine-containing monomers, namely bis(benzoxazinemaleimide)s have been synthesized to improve the poor processability of bismaleimides. A new approach of using high boiling point nonpolar solvent has been developed to prepare the monomer, which is difficult to synthesize using the traditional method of synthesizing benzoxazines. In the meantime, by the combination of two types of polymers: benzoxazine and bismaleimides, high thermally stable thermosets with high Tg have been obtained. Benzoxazine monomers have also been introduced into vinyl ester resins to replace styrene for environmental concern. With the incorporation of allyl-containing benzoxazines, the dynamic mechanical property and the thermal stability of the resins have been improved, while the processability of the resin is maintained.

  20. Enhancement of Stainless Steel's Mechanical Properties via Carburizing Process

    NASA Astrophysics Data System (ADS)

    Ahmad, S.; Alias, S. K.; Abdullah, B.; Hafiz Mohd Bakri, Mohd.; Hafizuddin Jumadin, Muhammad; Mat Shah, Muhammad Amir

    2016-11-01

    Carburizing process is a method to disperse carbon into the steel surface in order to enhance its mechanical properties such as hardness and wear resistance. This paper study investigates the effect of carburizing temperature to the carbon dispersion layer in stainless steel. The standard AISI 304 stainless steel was carburized in two different temperatures which were 900°C and 950°C. The effect of carbon dispersion layers were observed and the results indicated that the increasing value of the average dispersion layer from 1.30 mm to 2.74 mm thickness was found to be related to increment of carburizing holding temperature . The increment of carbon thickness layer also resulted in improvement of hardness and tensile strength of carburized stainless steel.

  1. Fuel property effects on engine combustion processes. Final report

    SciTech Connect

    Cernansky, N.P.; Miller, D.L.

    1995-04-27

    A major obstacle to improving spark ignition engine efficiency is the limitations on compression ratio imposed by tendency of hydrocarbon fuels to knock (autoignite). A research program investigated the knock problem in spark ignition engines. Objective was to understand low and intermediate temperature chemistry of combustion processes relevant to autoignition and knock and to determine fuel property effects. Experiments were conducted in an optically and physically accessible research engine, static reactor, and an atmospheric pressure flow reactor (APFR). Chemical kinetic models were developed for prediction of species evolution and autoignition behavior. The work provided insight into low and intermediate temperature chemistry prior to autoignition of n-butane, iso-butane, n-pentane, 1-pentene, n-heptane, iso-octane and some binary blends. Study of effects of ethers (MTBE, ETBE, TAME and DIPE ) and alcohols (methanol and ethanol) on the oxidation and autoignition of primary reference fuel (PRF) blends.

  2. Properties and processing of nanocrystalline materials. Quarterly report

    SciTech Connect

    Valiev, R.Z.

    1996-01-22

    The present Report completes the investigations in the frame of the project for the first year. It is important to estimate our achievements in the investigation of properties of nanocrystalline materials obtained by severe plastic deformation and their production. We think that the main results obtained can be summarized as follows: (1) We performed an improvement of the die-set for equal channel (ECA) pressing and torsion under high pressure with the aim to increase dimensions of the samples produced and to conduct processing of low ductile materials. (2) It was established that in pure metals severe plastic deformation led to the formation of an ultra fine-grained structure with a mean grain size of 100-200 nm, while in alloys due to severe plastic deformation and/or special methods of treatment (a decrease in the temperature of deformation, an increase of the pressure applied etc.) the grain size could be decreased down to a few tens of manometers.

  3. Tribological properties of silicon carbide in metal removal process

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1980-01-01

    Material properties are considered as they relate to adhesion, friction, and wear of single crystal silicon carbide in contact with metals and alloys that are likely to be involved in a metal removal process such as grinding. Metal removal from adhesion between sliding surfaces in contact and metal removal as a result of the silicon carbide sliding against a metal, indenting into it, and plowing a series of grooves or furrows are discussed. Fracture and deformation characteristics of the silicon carbide surface are also covered. The adhesion, friction, and metal transfer to silicon carbide is related to the relative chemical activity of the metals. The more active the metal, the higher the adhesion and friction, and the greater the metal transfer to silicon carbide. Atomic size and content of alloying elements play a dominant role in controlling adhesion, friction, and abrasive wear properties of alloys. The friction and abrasive wear (metal removal) decrease linearly as the shear strength of the bulk metal increases. They decrease as the solute to solvent atomic radius ratio increases or decreases linearly from unity, and with an increase of solute content. The surface fracture of silicon carbide is due to cleavages of 0001, 10(-1)0, and/or 11(-2)0 planes.

  4. Opponent process properties of self-administered cocaine.

    PubMed

    Ettenberg, Aaron

    2004-01-01

    Over the past decade, data collected in our laboratory have demonstrated that self-administered cocaine produces Opponent-Process-like behavioral effects. Animals running a straight alley once each day for IV cocaine develop over trials an approach-avoidance conflict about re-entering the goal box. This conflict behavior is characterized by a stop in forward locomotion (usually at the very mouth of the goal box) followed by a turn and 'retreat' back toward the goal box. The results of a series of studies conducted over the past decade collectively suggest that the behavioral ambivalence exemplified by rats running the alley for IV cocaine stems from concurrent and opponent positive (rewarding) and negative (anxiogenic) properties of the drug--both of which are associated with the goal box. These opponent properties of cocaine have been shown to result from temporally distinct affective states. Using a conditioned place preference test, we have been able to demonstrate that while the initial immediate effects of IV cocaine are reinforcing, the state present 15 min post-injection is aversive. In our most recent work, the co-administration of IV cocaine with either oral ethanol or IV heroin was found to greatly diminish the development and occurrence of retreat behaviors in the runway. It may therefore be that the high incidence of co-abuse of cocaine with either ethanol or heroin, stems from the users' motivation to alleviate some of the negative side effects of cocaine. It would seem then that the Opponent Process Theory has provided a useful conceptual framework for the study of the behavioral consequences of self-administered cocaine including the notion that both positive and negative reinforcement mechanisms are involved in the development and maintenance of cocaine abuse.

  5. Modeling the thermal properties and processing of composite materials

    SciTech Connect

    Pitchumani, R.

    1992-01-01

    The manufacture of partially cured, thermoset matrix composite systems is modeled. A generalized analysis, applicable to almost all the fiber-resin systems encountered in practice, is carried out in terms of four key dimensionless groups formed of the process and the product parameters - (1) the Damkohler number (K(sub o)) which is a relative measure of the conduction and the reaction time scales, (2) the dimensionless activation energy (E(sub o)), (3) the adiabatic reaction temperature (B(sub o)) which represents the temperature rise potential in the composite due to the heat of the cure reaction, and (4) the Biot number (B(sub i)) which characterizes the post-cure convective cooling of the composite product. Optimal cure cycles which yield a homogeneous cure in the composite, are obtained as a function of the dimensionless parameters. Design plots for the optimal cure temperature and duration are presented. Their use in practical situations is illustrated in the context of a commercially available graphite-epoxy prepreg from Hercules, which is widely used in the aerospace industry. The thermal properties of the composite namely, the transient thermal diffusivity and the steady state thermal conductivity, are essential parameters in the process modeling studies, as well for the design of composite materials for several high temperature applications. Transient heat conduction in fibrous composites is investigated with the aim of devising a criterion for the validity of the analysis of composite materials as homogeneous media having the effective thermal properties. A homogeneity criterion based on the composite thickness is derived in terms of the fiber volume fraction and the fiber diameter. The criterion, which is the first of its kind for fibrous composites, is valid in the practical range of composite parameters. An analytical means for evaluating the effective thermal diffusivity is also presented.

  6. Processing, properties, and applications of sol-gel silica optics

    NASA Astrophysics Data System (ADS)

    Nogues, Jean-Luc R.; LaPaglia, Anthony J.

    1989-12-01

    For many years the market share maintained by U.S. optics manufacturers has been declining continuously caused in part by intense competition principally from countries in the Far East, and in part by the lack of a highly trained cadre of opticians to replace the current generation. This fact could place in jeopardy the defense system of the United States in case of international war. For example, in 1987, optical glass component imports accounted for approximately 50 percent of the Department of Defense (DOD) consumption. GELTECH's sol-gel technology is a new process for making a high quality optical glass and components for commercial and military uses. This technology offers in addition to being a local source of optics, the possibility to create new materials for high-tech optical applications, and the elimination of the major part of grinding and polishing for which the skill moved off-shore. This paper presents a summary of the solgel technology for the manufacture of high quality optical glass and components. Properties of pure silica glass made by solgel process (Type V and Type VI silicas) are given and include: ultraviolet, visible and near infrared spectrophotometry, optical homogeneity and thermal expansion. Many applications such as near net shape casting or Fresnel lens surface replication are discussed. Several potential new applications offered by the solgel technology such as organic-inorganic composites for non linear optics or scintillation detection are also reported in this paper.

  7. Additive manufacturing of Inconel 718 using electron beam melting: Processing, post-processing, & mechanical properties

    NASA Astrophysics Data System (ADS)

    Sames, William James, V.

    Additive Manufacturing (AM) process parameters were studied for production of the high temperature alloy Inconel 718 using Electron Beam Melting (EBM) to better understand the relationship between processing, microstructure, and mechanical properties. Processing parameters were analyzed for impact on process time, process temperature, and the amount of applied energy. The applied electron beam energy was shown to be integral to the formation of swelling defects. Standard features in the microstructure were identified, including previously unidentified solidification features such as shrinkage porosity and non-equilibrium phases. The as-solidified structure does not persist in the bulk of EBM parts due to a high process hold temperature (˜1000°C), which causes in situ homogenization. The most significant variability in as-fabricated microstructure is the formation of intragranular delta-phase needles, which can form in samples produced with lower process temperatures (< 960°C). A novel approach was developed and demonstrated for controlling the temperature of cool down, thus providing a technique for in situ heat treatment of material. This technique was used to produce material with hardness of 478+/-7 HV with no post-processing, which exceeds the hardness of peak-aged Inconel 718. Traditional post-processing methods of hot isostatic pressing (HIP) and solution treatment and aging (STA) were found to result in variability in grain growth and phase solution. Recrystallization and grain structure are identified as possible mechanisms to promote grain growth. These results led to the conclusion that the first step in thermal post-processing of EBM Inconel 718 should be an optimized solution treatment to reset phase variation in the as-fabricated microstructure without incurring significant grain growth. Such an optimized solution treatment was developed (1120°C, 2hr) for application prior to aging or HIP. The majority of as-fabricated tensile properties met ASTM

  8. Physical Properties and Processing of Asteroid Regoliths and Interiors

    NASA Astrophysics Data System (ADS)

    Lee, Pascal Clayton-Clyde

    1997-11-01

    Four aspects of the physical properties and processing of asteroid regoliths and interiors are examined: (1) impact cratering, (2) thermal cycling, (3) electrostatic processing, and (4) asteroid densities. These aspects contribute to understanding the production, emplacement, redistribution, segregation, disruption, loss, and overall state of regoliths on asteroids. Impact cratering (Chapter 2) is considered through a study of the scaling characteristics and distribution of the large blocks revealed on 243 Ida in Galileo images. The blocks are interpreted as coarse impact ejecta fragments, most of them remaining within or in the vicinity of the large impact structures from which they were excavated. Alternative origins and the probable age of the blocks are discussed. Extrapolation of ejecta scaling laws applicable to Ida lead to predicting maximum ejecta blocks sizes on other asteroids. Thermal cycling, the periodic stressing and straining of asteroid regolith materials due to insolation-induced diurnal and orbital temperature variations, is investigated as another process whereby asteroid regoliths might be disrupted (thermal weathering and disaggregation; thermal quakes), and transported (thermal creep) (Chapter 3). Thermal cycling is found to be of minor significance in the evolution of asteroid regoliths. Electrostatic processing, the levitation, transport, and/or ejection of charged dust under electrostatic fields produced on resistive surfaces by insolation-induced photoelectron emission, is proposed as a contributing mechanism whereby asteroid regoliths may be sorted, redistributed, and winnowed of their finest particle size fraction (Chapter 4). The process may help explain differences in regolith texture between asteroids and the Moon, and among various types of asteroids. Finally, asteroid and meteorite density data are reviewed and interpreted to constrain the internal structure of asteroids (Chapter 5). A relation between meteorite and asteroid

  9. Processing, structure, and properties of nanostructured multifunctional tribological coatings.

    PubMed

    Lin, Jianliang; Park, In-Wook; Mishra, Brajendra; Pinkas, Malki; Moore, John J; Anton, Jennifer M; Kim, Kwang Ho; Voevodin, Andrey A; Levashov, Evgeny A

    2009-07-01

    Nanostructured, nanocomposite binary (TiC-a:C), ternary (Cr-Al-N), quaternary (Ti-B-C-N) and quinternary (Ti-Si-B-C-N) multicomponent films have been deposited using unbalanced magnetron sputtering (UBMS) and closed field unbalanced magnetron sputtering (CFUBMS) from both elemental and composite targets. Approaches to control the film chemistry, volume fraction and size of the multicomponent species, and pulsed ion energy (ion flux) bombardment to tailor the structure and properties of the films for specific tribological applications, e.g., low friction coefficient and low wear rate, are emphasized. The synthesized films are characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nanoindentation, and microtribometry. The relationships between processing parameters (pulsed ion energy and ion flux), thin film microstructure, mechanical and tribological properties are being investigated in terms of the nanocrystalline-nanocrystalline and nanocrystalline-amorphous composite thin film systems that are generated. In the Ti-Si-B-C-N films, nanocomposites of solid solutions, e.g., nanosized (Ti,C,N)B2 and Ti(C,N) crystallites are embedded in an amorphous TiSi2 and SiC matrix including some carbon, SiB4, BN, CN(x), TiO2 and B2O3 components. The Ti-Si-B-C-N coating with up to 150 W Si target power exhibited a hardness of about 35 GPa, a high H/E ratio of 0.095, and a low wear rate of from approximately 3 to approximately 10 x 10(-6) mm3/(Nm). In another aspect, using increased ion energy and ion flux, which are generated by pulsing the power of the target(s) in a closed field arrangement, to provide improved ion bombardment on tailoring the structure and properties of TiC-a:C and Cr-Al-N coatings are demonstrated. It was found that highly energetic species (up to hundreds eV) were found in the plasma by pulsing the power of the target(s) during magnetron sputtering

  10. Current Computational Challenges for CMC Processes, Properties, and Structures

    NASA Technical Reports Server (NTRS)

    DiCarlo, James

    2008-01-01

    In comparison to current state-of-the-art metallic alloys, ceramic matrix composites (CMC) offer a variety of performance advantages, such as higher temperature capability (greater than the approx.2100 F capability for best metallic alloys), lower density (approx.30-50% metal density), and lower thermal expansion. In comparison to other competing high-temperature materials, CMC are also capable of providing significantly better static and dynamic toughness than un-reinforced monolithic ceramics and significantly better environmental resistance than carbon-fiber reinforced composites. Because of these advantages, NASA, the Air Force, and other U.S. government agencies and industries are currently seeking to implement these advanced materials into hot-section components of gas turbine engines for both propulsion and power generation. For applications such as these, CMC are expected to result in many important performance benefits, such as reduced component cooling air requirements, simpler component design, reduced weight, improved fuel efficiency, reduced emissions, higher blade frequencies, reduced blade clearances, and higher thrust. Although much progress has been made recently in the development of CMC constituent materials and fabrication processes, major challenges still remain for implementation of these advanced composite materials into viable engine components. The objective of this presentation is to briefly review some of those challenges that are generally related to the need to develop physics-based computational approaches to allow CMC fabricators and designers to model (1) CMC processes for fiber architecture formation and matrix infiltration, (2) CMC properties of high technical interest such as multidirectional creep, thermal conductivity, matrix cracking stress, damage accumulation, and degradation effects in aggressive environments, and (3) CMC component life times when all of these effects are interacting in a complex stress and service

  11. Processing, characterization and properties of oxide based nanocomposites

    NASA Astrophysics Data System (ADS)

    Bhaduri, Sutapa

    The synthesis, characterization and mechanical properties of oxide based nanocomposites are reported in this dissertation. Two binary systems are studied: Alsb2Osb3-MgO and Alsb2Osb3-ZrOsb2. Alsb2Osb3-MgO was chosen because of its relatively large field of solid solubilities at a moderate temperature. On the other hand, Alsb2Osb3-ZrOsb2 was chosen because it shows minimal solid solubility of the constituents. A novel "Auto Ignition" process using suitable fuels and oxidizers was utilized in the synthesis of nanocomposites and solid solutions. Thermodynamic calculations were carried out in predicting end point adiabatic temperatures (Tsbad) for each composition in both systems. Combustion temperatures were experimentally measured by means of a data acquisition system. Characterizations of the powders were carried out by x-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive analysis (EDAX) and differential thermal analysis (DTA). Heat treatment experiments were carried out to study the grain growth behavior. A hot isostatic pressing (HIP) model was developed for the present nanoceramics. Input parameters were carefully chosen for such nanomaterials. The as-synthesized nanocrystalline powders were consolidated to near theoretical density by hot isostatic pressing (HIPing) while retaining fine grain size. The experimental results were compared with the predictions of the model. Mechanical properties, such as room temperature toughness, low temperatures well as high temperature hardness, were determined for both systems. Room temperature hardness values were (2.89-7.79) GPa and fracture toughness was between 2.7 and 5.82 MPa.msp{1/2} for various compositions in the Alsb2Osb3-MgO system. Room temperature hardness values were between 5.33 and 8.71 GPa and fracture toughness values ranged from (5.3-9.62) MPa.msp{1/2} for various compositions in the Alsb2Osb3-ZrOsb2 system. Nanoindentation experiments were carried out to further explore the room

  12. The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 3. Constituent Properties and Macroscopic Performance: MMCs

    DTIC Science & Technology

    1993-04-01

    April 1993 "DTIC ELECTE-NJUN21 9199 The Processing and Mechanical Properties of High Temperature/ High Performance Composites by A.G. Evans & F. Leckie...CONSTITUENT PROPERTIES AND MACROSCOPIC PERFORMANCE: MMCs SUMMARY OF TABLE OF CONTENTS EXECUTIVE SUMMARY BOOK 1: CONSTITUENT PROPERTIES OF COMPOSITES ...PROPERTIES AND MACROSCOPIC PERFORMANCE: MMCs 34. Mode I Fatigue Cracking in a Fiber D.P. Walls Reinforced Metal Matrix Composite G. Bao F.W. Zok 35

  13. Microstructure and mechanical properties of SPD processed nanocrystalline tantalum

    NASA Astrophysics Data System (ADS)

    Li, Gang

    In this study, the refractory metal, Tantalum (Ta), having a Body Centered Cubic (BCC) structure is selected as a model material. Bulk nanocrystalline Ta (NC-Ta) is used to study the process-microstructure-property relationship for a nano-structured BCC metal. For the first time, high pressure torsion (HPT) technique was applied to produce NC-Ta. Microstructural features of HPT NC-Ta were characterized by X-ray Diffraction (XRD) and Transmission Electron Microcopy (TEM). The resulting microstructures show nano-size grains (grain size smaller than 100 nm) together with high angle grain boundaries. The grain size was estimated to be around 35 nm based on the broadening of the (110) peak of XRD, while a few tens of nanometers based on TEM observation. A high density of atomic steps and ledges were observed along the grain boundaries while a large population of edge dislocations within the grains by high resolution TEM. It shows the non-equilibrium and high-energy nature of the grain boundaries. The mechanical properties of HPT NC-Ta were investigated using instrumented nanoindentation and micro-compression techniques, respectively. Instrumented nanoindentation intends to study the uniformity of the distribution of mechanical properties, the strain rate effect, and the thermally activated processes associated with plastic deformation. The results show that the elastic modulus of HPT NC-Ta is considerably reduced compared to the coarse-grain counterparts. The results are explained based on the hypothesis that in the HPT NC-Ta greatly increased populations of grain boundaries (GBs) and triple junctions (TJs) have been induced along with a high concentration of lattice vacancies in the severely deformed metal. The microhardness measurement shows a peak across the radial direction. It is believed this indicates an inverse Hall-Petch effect. Also, the nanoindentation hardness measurement, independent of the indentation depth, indicates the absence of indentation size effect

  14. Processing, Microstructure, and Properties of Multiphase Mo Silicide Alloys

    SciTech Connect

    Heatherly, L.; Liu, C.T.; Schneibel, J.H.

    1998-11-30

    Multiphase Mo silicide alloys containing T2 (Mo{sub 5}SiB{sub 2}), Mo{sub 3}Si and Mo phases where prepared by both melting and casting (M and C) and powder metallurgical (PM) processes. Glassy phases are observed in PM materials but not in M and C materials. Microstructural studies indicate that the primary phase is Mo-rich solid solution in alloys containing {le}(9.4Si+13.8B, at. %) and T2 in alloys with {ge}(9.8Si+14.6B). An eutectic composition is estimated to be close to Mo-9.6Si-14.2B. The mechanical properties of multiphase silicide alloys were determined by hardness, tensile and bending tests at room temperature. The multiphase alloy MSB-18 (Mo-9.4Si-13.8B) possesses a flexure strength distinctly higher than that of MoSi{sub 2} and other Mo{sub 5}Si{sub 3} silicide alloys containing no Mo particles. Also, MSB-18 is tougher than MoSi{sub 2} by a factor of 4.

  15. Unconventional secretory processing diversifies neuronal ion channel properties

    PubMed Central

    Hanus, Cyril; Geptin, Helene; Tushev, Georgi; Garg, Sakshi; Alvarez-Castelao, Beatriz; Sambandan, Sivakumar; Kochen, Lisa; Hafner, Anne-Sophie; Langer, Julian D; Schuman, Erin M

    2016-01-01

    N-glycosylation – the sequential addition of complex sugars to adhesion proteins, neurotransmitter receptors, ion channels and secreted trophic factors as they progress through the endoplasmic reticulum and the Golgi apparatus – is one of the most frequent protein modifications. In mammals, most organ-specific N-glycosylation events occur in the brain. Yet, little is known about the nature, function and regulation of N-glycosylation in neurons. Using imaging, quantitative immunoblotting and mass spectrometry, we show that hundreds of neuronal surface membrane proteins are core-glycosylated, resulting in the neuronal membrane displaying surprisingly high levels of glycosylation profiles that are classically associated with immature intracellular proteins. We report that while N-glycosylation is generally required for dendritic development and glutamate receptor surface expression, core-glycosylated proteins are sufficient to sustain these processes, and are thus functional. This atypical glycosylation of surface neuronal proteins can be attributed to a bypass or a hypo-function of the Golgi apparatus. Core-glycosylation is regulated by synaptic activity, modulates synaptic signaling and accelerates the turnover of GluA2-containing glutamate receptors, revealing a novel mechanism that controls the composition and sensing properties of the neuronal membrane. DOI: http://dx.doi.org/10.7554/eLife.20609.001 PMID:27677849

  16. On the processing and properties of binary compound insertion electrodes

    NASA Astrophysics Data System (ADS)

    Sarakonsri, Thapanee

    This dissertation explores the processing/structure/property relationship for binary compounds used as negative electrode material. A solution route method for synthesis of binary compound electrodes, InSb, Cu2Sb, and Cu6Sn5 will be introduced. The material characterization using XRD and TEM techniques suggests the formation of an amorphous phase in the reaction products. The amorphous phase was decomposed under an annealing process and under direct exposure to the electron beam. The precipitation of different phases in the form of small particles was observed. The electrochemical analysis of InSb from the solution route will be compared with ball milled and single crystal InSb electrodes. The structure simulation of the ternary phase Li3xIn1-xSb, which exists in the Li-In-Sb phase diagram at 400°C proposed by W. Sitte and W. Weppner [1], was used to confirm the occurrence of ternary compounds after an initial lithium insertion into the InSb zinc-blende structure. The charge-discharge voltage profile of Li/InSb under OCV conditions shows chemical potential changing with time in the two-phase region, indicating a series of ternary phase formation according to the phase diagram. This is an experimental result confirming the existence of ternary phases, which is consistent with the simulation models. The electrochemical analysis of Cu2Sb and Cu6Sn 5 solution route electrodes will be discussed. The Cu extrusion from Cu2Sb and Cu6Sn5 structures was reported to occur during the lithiation process [2, 3]. The post mortem analysis of a Cu2Sb electrode then was conducted to examine the Cu extrusion. The electrochemical behavior of InSb from solution route and Cu 6Sn5 from both solution route and ball milling exhibits a local minimum voltage in the first discharge. It was suggested that the occurrence of a local voltage minimum was due to the slow nucleation of a stable phase [4]. The growth analysis of Johnson-Mehl-Avrami [5] combined with Butler-Volmer [6] electrode

  17. Metastable zirconia-yttria-alumina ceramics: Structure, processing and properties

    NASA Astrophysics Data System (ADS)

    Zhou, Xinzhang

    2002-09-01

    properties. Thirdly, reduced phase transformation temperatures will also find their applications in ceramic processing.

  18. Effect of processing temperature on the properties of a polyvinyl chloride maxillofacial elastomer.

    PubMed

    Yu, R; Koran, A; Powers, J M

    1983-10-01

    Mechanical properties and color of a plasticized polyvinyl chloride (PVC) maxillofacial elastomer were evaluated at processing temperatures from 140 to 190 degrees C. The properties were dependent on processing temperature. Specimens prepared at 170 degrees C had optimum mechanical properties with minimal discoloration.

  19. The Processing and Mechanical Properties of High Temperature/ High Performance Composites. Processing/Property Correlations. Book 4

    DTIC Science & Technology

    1994-03-01

    34Dispersion Strengthened Copper Properties and Applications," in High Conductivity Copper and Aluminum Alloys E. Ling and P. W. Taubenblat, eds., AIME...Novel ODS Copper Alloys from Rapidly- M. S. Nagorka Solidified Precursors--I: Creep G. E. Lucas Behavior C. G. Levi 60. Mechanical Properties of...fiber’s elastic deflection and we have shown that this has a complex dependence upon matrix and fiber properties . Manyfibers and matrix alloys are

  20. Bioactive phytochemicals in wheat: Extraction, analysis, processing, and functional properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole wheat provides a rich source of bioactive phytochemicals namely, phenolic acids, carotenoids, tocopherols, alkylresorcinols, arabinoxylans, benzoxazinoids, phytosterols, and lignans. This review provides information on the distribution, extractability, analysis, and nutraceutical properties of...

  1. Processing effects on the mechanical properties of tungsten heavy alloys

    NASA Technical Reports Server (NTRS)

    Kishi, Toshihito; German, R. M.

    1990-01-01

    Tungsten heavy alloys exhibit significant mechanical property sensitivities to the fabrication variables. These sensitivities are illustrated in this examination of vacuum sintering and the effects of composition, sintering temperature, and sintering time on the mechanical properties of tungsten heavy alloys. Measurements were conducted to assess the density, strength, hardness, and elongation dependencies. A detrimental aspect of vacuum sintering is matrix phase evaporation, although vacuum sintering does eliminate the need for postsintering heat treatments.

  2. Textile Processes for Engineering Tissues with Biomimetic Architectures and Properties.

    PubMed

    Fallahi, Afsoon; Khademhosseini, Ali; Tamayol, Ali

    2016-09-01

    Textile technologies in which fibers containing biological factors and cells are formed and assembled into constructs with biomimetic properties have attracted significant attention in the field of tissue engineering. This Forum article highlights the most prominent advances of the field in the areas of fiber fabrication and construct engineering.

  3. Transport processes in partially saturate concrete: Testing and liquid properties

    NASA Astrophysics Data System (ADS)

    Villani, Chiara

    The measurement of transport properties of concrete is considered by many to have the potential to serve as a performance criterion that can be related to concrete durability. However, the sensitivity of transport tests to several parameters combined with the low permeability of concrete complicates the testing. Gas permeability and diffusivity test methods are attractive due to the ease of testing, their non-destructive nature and their potential to correlate to in-field carbonation of reinforced concrete structures. This work was aimed at investigating the potential of existing gas transport tests as a way to reliably quantify transport properties in concrete. In this study gas permeability and diffusivity test methods were analyzed comparing their performance in terms of repeatability and variability. The influence of several parameters was investigated such as moisture content, mixture proportions and gas flow. A closer look to the influence of pressure revealed an anomalous trend of permeability with respect to pressure. An alternative calculation is proposed in an effort to move towards the determination of intrinsic material properties that can serve as an input for service life prediction models. The impact of deicing salts exposure was also analyzed with respect to their alteration of the degree of saturation as this may affect gas transport in cementitious materials. Limited information were previously available on liquid properties over a wide range of concentrations. To overcome this limitation, this study quantified surface tension, viscosity in presence of deicing salts in a broad concentration range and at different temperatures. Existing models were applied to predict the change of fluid properties during drying. Vapor desorption isotherms were obtained to investigate the influence of deicing salts presence on the non-linear moisture diffusion coefficient. Semi-empirical models were used to quantify the initiation and the rate of drying using liquid

  4. Correlation of Process Parameters and Part Properties in Laser Sintering using Response Surface Modeling

    NASA Astrophysics Data System (ADS)

    Wegner, Andreas; Witt, Gerd

    Due to the advancements during the last decade, the laser sintering process has achieved a high technical level, allowing for Rapid Manufacturing in some applications. However, processes still show poor repeatability of part quality, process interruptions or defective parts. The knowledge needed to avoid such problems is still insufficient. Literature provides only few detailed correlations between process parameters and part properties. Therefore, an approach using response surface methodology was chosen to correlate part properties with main influencing factors. Aim of the analyses was to predict and to improve part properties based on an enhanced process understanding.

  5. 24 CFR 203.664 - Processing defaulted mortgages on property located on Indian land.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... property located on Indian land. 203.664 Section 203.664 Housing and Urban Development Regulations Relating... Responsibilities Mortgages in Default on Property Located on Indian Reservations § 203.664 Processing defaulted mortgages on property located on Indian land. Before a mortgagee requests that the Secretary...

  6. 24 CFR 203.665 - Processing defaulted mortgages on property located on Hawaiian home lands.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... property located on Hawaiian home lands. 203.665 Section 203.665 Housing and Urban Development Regulations... Responsibilities Mortgages in Default on Property Located on Hawaiian Home Lands § 203.665 Processing defaulted mortgages on property located on Hawaiian home lands. Before a mortgagee requests the Secretary to...

  7. 24 CFR 203.665 - Processing defaulted mortgages on property located on Hawaiian home lands.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... property located on Hawaiian home lands. 203.665 Section 203.665 Housing and Urban Development Regulations... Responsibilities Mortgages in Default on Property Located on Hawaiian Home Lands § 203.665 Processing defaulted mortgages on property located on Hawaiian home lands. Before a mortgagee requests the Secretary to...

  8. 24 CFR 203.664 - Processing defaulted mortgages on property located on Indian land.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... property located on Indian land. 203.664 Section 203.664 Housing and Urban Development Regulations Relating... Responsibilities Mortgages in Default on Property Located on Indian Reservations § 203.664 Processing defaulted mortgages on property located on Indian land. Before a mortgagee requests that the Secretary...

  9. Localized Mechanical Properties of Friction Stir Processed Sensitized 5456-H116 Al

    DTIC Science & Technology

    2013-04-01

    FSP is applied to a sensitized 5456-H116 aluminum plate and the resulting microstructure is linked to local mechanical properties (0.2% yield...have negatively affected the mechanical properties 15. SUBJECT TERMS Aluminum Alloys, Friction Stir Processing, Sensitization, Mechanical Testing... aluminum 5456-H116 (wt. %) ..............................................3 Table 2. Bulk base material properties for H116, O, and sensitized H116

  10. Processing-property relationships of polypropylene/ciprofloxacin fibers

    NASA Astrophysics Data System (ADS)

    Botta, L.; Scaffaro, R.

    2015-12-01

    In this work we prepared polypropylene (PP) fibers incorporating an antibiotic, i.e. ciprofloxacin (CFX), by melt spinning. In particular, PP has been compounded with CFX at different concentrations by using a counter-rotating twin screw compounder. The PP/CFX fibers have been spun by using a capillary rheometer operating under a constant extrusion speed. The effect of "online" hot drawing during the melt spinning or of an "offline" cold drawing on the properties of PP/CFX fibers were evaluated. In particular, the influence of the drawing conditions on the mechanical properties and the release kinetics were studied. Moreover, the rheological behavior in non-isothermal elongation flow has been assessed.

  11. Process dependent thermoelectric properties of EDTA assisted bismuth telluride

    NASA Astrophysics Data System (ADS)

    Kulsi, Chiranjit; Kargupta, Kajari; Banerjee, Dipali

    2016-04-01

    Comparison between the structure and thermoelectric properties of EDTA (Ethylene-diamine-tetra-acetic acid) assisted bismuth telluride prepared by electrochemical deposition and hydrothermal route is reported in the present work. The prepared samples have been structurally characterized by high resolution X-ray diffraction spectra (HRXRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopic images (HRTEM). Crystallite size and strain have been determined from Williamson-Hall plot of XRD which is in conformity with TEM images. Measurement of transport properties show sample in the pellet form (S1) prepared via hydrothermal route has higher value of thermoelectric power (S) than the electrodeposited film (S2). But due to a substantial increase in the electrical conductivity (σ) of the film (S2) over the pellet (S1), the power factor and the figure of merit is higher for sample S2 than the sample S1 at room temperature.

  12. Regulatory gene networks and the properties of the developmental process

    NASA Technical Reports Server (NTRS)

    Davidson, Eric H.; McClay, David R.; Hood, Leroy

    2003-01-01

    Genomic instructions for development are encoded in arrays of regulatory DNA. These specify large networks of interactions among genes producing transcription factors and signaling components. The architecture of such networks both explains and predicts developmental phenomenology. Although network analysis is yet in its early stages, some fundamental commonalities are already emerging. Two such are the use of multigenic feedback loops to ensure the progressivity of developmental regulatory states and the prevalence of repressive regulatory interactions in spatial control processes. Gene regulatory networks make it possible to explain the process of development in causal terms and eventually will enable the redesign of developmental regulatory circuitry to achieve different outcomes.

  13. Processing and properties of molybdenum silicide intermetallics containing boron

    SciTech Connect

    Schneibel, J.H.; Liu, C.T.; Heatherly, L.; Wright, J.L.; Carmichael, C.A.

    1997-08-01

    Molybdenum-silicon-boron intermetallics with the composition Mo-10.5 Si-1.1 B, wt% (Mo-26.7 Si-7.3 B, at. %) were fabricated by several processing techniques. Powder processing (PM) resulted in macrocrack-free material containing no or only few microcracks. The PM materials contained quasi-equilibrium pores and large concentrations of oxygen. Average room temperature flexure strengths of 270 MPa were obtained. At 1,200 C in air, flexure strengths as high as 600 MPa were observed. These high values are attributed to crack healing and incipient plasticity. Ingot metallurgy (IM) materials contained much less oxygen than their PM counterparts. Depending on the cooling rate during solidification, they developed either mostly macrocracks or mostly microcracks. Due to the high flaw densities, the room temperature flexure strengths were only of the order of 100 MPa. However, the flexure strengths at 1,200 C were up to 3 times higher than those at room temperature. Again, this is attributed to crack healing and incipient plasticity. The IM materials will require secondary processing to develop their full potential. A preliminary examination of secondary processing routes included isothermal forging and hot extrusion.

  14. Processing and physical properties of chia-oat hydrocolloids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chia-oat dry blended composites and their processed hydrocolloids containing omega-3 and omega-6 fatty acids from chia along with soluble ß-glucan from three oat products were developed and studied. Chia’s omega-3 fatty acids and soluble ß-glucan from oat products are recognized for preventing heart...

  15. Aerosol physical properties and their impact on climate change processes

    NASA Astrophysics Data System (ADS)

    Strzalkowska, Agata; Zielinski, Tymon; Petelski, Tomasz; Makuch, Przemyslaw; Pakszys, Paulina; Markuszewski, Piotr; Piskozub, Jacek; Drozdowska, Violetta; Gutowska, Dorota; Rozwadowska, Anna

    2013-04-01

    Characterizing aerosols involves the specification of not only their spatial and temporal distributions but their multi-component composition, particle size distribution and physical properties as well. Due to their light attenuation and scattering properties, aerosols influence radiance measured by satellite for ocean color remote sensing. Studies of marine aerosol production and transport are important for many earth sciences such as cloud physics, atmospheric optics, environmental pollution studies, and interaction between ocean and atmosphere. It was one of the reasons for the growth in the number of research programs dealing with marine aerosols. Sea salt aerosols are among the most abundant components of the atmospheric aerosol, and thus it exerts a strong influence on radiation, cloud formation, meteorology and chemistry of the marine atmosphere. An accurate understanding and description of these mechanisms is crucial to modeling climate and climate change. This work provides information on combined aerosol studies made with lidars and sun photometers onboard the ship and in different coastal areas. We concentrate on aerosol optical thickness and its variations with aerosol advections into the study area. We pay special attention to the problem of proper data collection and analyses techniques. We showed that in order to detect the dynamics of potential aerosol composition changes it is necessary to use data from different stations where measurements are made using the same techniques. The combination of such information with air mass back-trajectories and data collected at stations located on the route of air masses provides comprehensive picture of aerosol variations in the study area both vertically and horizontally. Acknowledgements: The support for this study was provided by the project Satellite Monitoring of the Baltic Sea Environment - SatBałtyk founded by European Union through European Regional Development Fund contract No. POIG 01

  16. Thermodynamic properties of pulverized coal during rapid heating devolatilization processes

    SciTech Connect

    Proscia, W.M.; Freihaut, J.D.; Rastogi, S.; Klinzing, G.E.

    1994-07-01

    The thermodynamic properties of coal under conditions of rapid heating have been determined using a combination of UTRC facilities including a proprietary rapid heating rate differential thermal analyzer (RHR-DTA), a microbomb calorimeter (MBC), an entrained flow reactor (EFR), an elemental analyzer (EA), and a FT-IR. The total heat of devolatilization, was measured for a HVA bituminous coal (PSOC 1451D, Pittsburgh No. 8) and a LV bituminous coal (PSOC 1516D, Lower Kittaning). For the HVA coal, the contributions of each of the following components to the overall heat of devolatilization were measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Morphological characterization of coal and char samples was performed at the University of Pittsburgh using a PC-based image analysis system, BET apparatus, helium pcynometer, and mercury porosimeter. The bulk density, true density, CO{sub 2} surface area, pore volume distribution, and particle size distribution as a function of extent of reaction are reported for both the HVA and LV coal. Analyses of the data were performed to obtain the fractal dimension of the particles as well as estimates for the external surface area. The morphological data together with the thermodynamic data obtained in this investigation provides a complete database for a set of common, well characterized coal and char samples. This database can be used to improve the prediction of particle temperatures in coal devolatilization models. Such models are used both to obtain kinetic rates from fundamental studies and in predicting furnace performance with comprehensive coal combustion codes. Recommendations for heat capacity functions and heats of devolatilization for the HVA and LV coals are given. Results of sample particle temperature calculations using the recommended thermodynamic properties are provided.

  17. A Study on the Influence of Process Parameters on the Viscoelastic Properties of ABS Components Manufactured by FDM Process

    NASA Astrophysics Data System (ADS)

    Dakshinamurthy, Devika; Gupta, Srinivasa

    2016-06-01

    Fused Deposition Modelling (FDM) is a fast growing Rapid Prototyping (RP) technology due to its ability to build parts having complex geometrical shape in reasonable time period. The quality of built parts depends on many process variables. In this study, the influence of three FDM process parameters namely, slice height, raster angle and raster width on viscoelastic properties of Acrylonitrile Butadiene Styrene (ABS) RP-specimen is studied. Statistically designed experiments have been conducted for finding the optimum process parameter setting for enhancing the storage modulus. Dynamic Mechanical Analysis has been used to understand the viscoelastic properties at various parameter settings. At the optimal parameter setting the storage modulus and loss modulus of the ABS-RP specimen was 1008 and 259.9 MPa respectively. The relative percentage contribution of slice height and raster width on the viscoelastic properties of the FDM-RP components was found to be 55 and 31 % respectively.

  18. Handbook of refractory carbides and nitrides: Properties, characteristics, processing and applications

    SciTech Connect

    Pierson, H.O.

    1997-12-31

    This reference work provides a complete review of the structure properties, processing and applications of refractory carbides and nitrides. The contents include: the refractory carbides; interstitial carbides, structure and composites; titanium, zirconium, and hafnium carbides; vanadium, niobium and tantalum carbides; chromium, molybdenum, and tungsten carbides; covalent carbides--structure and composition; characteristics and properties of silicon carbide and boron carbide; the refractory nitrides; interstitial nitrides--structure and composition; interstitial nitrides--properties and general characteristics; covalent nitrides--composition and structure; covalent nitrides--properties and general characteristics; processing of refractory carbides and nitrides and applications of refractory carbides and nitrides.

  19. 41 CFR 102-37.50 - What is the general process for requesting surplus property for donation?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... process for requesting surplus property for donation? 102-37.50 Section 102-37.50 Public Contracts and... REGULATION PERSONAL PROPERTY 37-DONATION OF SURPLUS PERSONAL PROPERTY General Provisions Donation Overview § 102-37.50 What is the general process for requesting surplus property for donation? The process...

  20. Growth, processing and properties of CVD diamond for optical applications

    NASA Astrophysics Data System (ADS)

    Snail, Keith A.

    1992-11-01

    In recent years there has been an increased need for optical materials for use in adverse chemical, thermal, abrasive, and/or radiation environments. Diamond is a natural candidate for many of these applications because of its radiation hardness, superb resistance to chemical attack and abrasive wear, high thermal conductivity, and low absorption coefficient throughout the visible and much of the infrared. The use of synthetic (high pressure-high temperature) and natural diamond in optical components has been limited by the size and shapesof available crystals, and the inability to coat optical elements. The chemical vapor deposition (CVD) of polycrystalline diamond does not suffer the same limitations, and is therefore the focus of an expanding worldwide research effort. CVD diamond is not without its own shortcomings, however, and in this paper a status report is given on the obstacles and current research related to using CVD diamond as an optical material. Natural diamond's relevant physical properties and the optical applications envisioned for CVD diamond are also discussed.

  1. Mechanical Properties of Human Cells Change during Neoplastic Processes

    NASA Astrophysics Data System (ADS)

    Guthold, Martin; Guo, Xinyi; Bonin, Keith; Scarpinato, Karin

    2014-03-01

    Using an AFM with a spherical probe of 5.3 μm, we determined mechanical properties of individual human mammary epithelial cells that have progressed through four stages of neoplastic transformation: normal, immortal, tumorigenic, and metastatic. Measurements on cells in all four stages were taken over both the nucleus and the cytoplasm. Moreover, the measurements were made for cells outside of a colony (isolated), on the periphery of a colony, and inside a colony. By fitting the AFM force vs. indentation curves to a Hertz model, we determined the Young's modulus, E. We found a distinct contrast in the influence a cell's colony environment has on its stiffness depending on whether the cells are normal or cancer cells. We also found that cells become softer as they advance to the tumorigenic stage and then stiffen somewhat in the final step to metastatic cells. For cells averaged over all locations the stiffness values of the nuclear region for normal, immortal, tumorigenic, and metastatic cells were (mean +/- sem) 880 +/- 50, 940+/-50, 400 +/- 20, and 600 +/-20 Pa respectively. Cytoplasmic regions followed a similar trend. These results point to a complex picture of the mechanical changes that occur as cells undergo neoplastic transformation. This work is supported by NSF Materials and Surface Engineering grant CMMI-1152781.

  2. Pyroelectric Materials for Uncooled Infrared Detectors: Processing, Properties, and Applications

    NASA Technical Reports Server (NTRS)

    Aggarwal, M. D.; Batra, A. K.; Guggilla, P.; Edwards, M. E.; Penn, B. G.; Currie, J. R., Jr.

    2010-01-01

    Uncooled pyroelectric detectors find applications in diverse and wide areas such as industrial production; automotive; aerospace applications for satellite-borne ozone sensors assembled with an infrared spectrometer; health care; space exploration; imaging systems for ships, cars, and aircraft; and military and security surveillance systems. These detectors are the prime candidates for NASA s thermal infrared detector requirements. In this Technical Memorandum, the physical phenomena underlying the operation and advantages of pyroelectric infrared detectors is introduced. A list and applications of important ferroelectrics is given, which is a subclass of pyroelectrics. The basic concepts of processing of important pyroelectrics in various forms are described: single crystal growth, ceramic processing, polymer-composites preparation, and thin- and thick-film fabrications. The present status of materials and their characteristics and detectors figures-of-merit are presented in detail. In the end, the unique techniques demonstrated for improving/enhancing the performance of pyroelectric detectors are illustrated. Emphasis is placed on recent advances and emerging technologies such as thin-film array devices and novel single crystal sensors.

  3. Influence of the processed sunflower oil on the cement properties

    NASA Astrophysics Data System (ADS)

    Fleysher, A. U.; Tokarchuk, V. V.; Sviderskiy, V. A.

    2015-01-01

    Used oils (vegetable oil, animal oil, engine oil, etc.), which are essentially industrial wastes, have found application as secondary raw materials in some braches of industry. In particular, the only well-known and commonly-used way of utilizing wastes of vegetable oils is to apply them as raw materials in the production of biodiesel. The goal of the present study is to develop a conceptually new way of vegetable oil wastes utilization in the building industry. The test admixture D-148 was obtained from the processing of wastes of sunflower oil and it mainly consists of fatty acid diethanolamide. The test admixture was added to the cement system for the purpose of studying its influence on water demand, flowability, setting times, compressive strength and moisture adsorption. The test admixture D-148 at the optimal content 0. 2 weight % causes 10% decrease in water demand, 1.7 time increase in flowability (namely spread diameter), 23% increase in grade strength and 34% decrease in moisture adsorption. The results of the present investigation make it possible to consider the final product of the waste sunflower oil processing as multifunctional plasticizing-waterproofing admixture.

  4. Processing, microstructure evolution and properties of nanoscale aluminum alloys

    NASA Astrophysics Data System (ADS)

    Han, Jixiong

    In this project, phase transformations and precipitation behavior in age-hardenable nanoscale materials systems, using Al-Cu alloys as model materials, were first studied. The Al-Cu nanoparticles were synthesized by a Plasma Ablation process and found to contain a 2˜5 nm thick adherent aluminum oxide scale, which prevented further oxidation. On aging of the particles, a precipitation sequence consisting of, nearly pure Cu precipitates to the metastable theta' to equilibrium theta was observed, with all three forming along the oxide-particle interface. The structure of theta' and its interface with the Al matrix has been characterized in detail. Ultrafine Al-Cu nanoparticles (5˜25 nm) were also synthesized by inert gas condensation (IGC) and their aging behavior was studied. These particles were found to be quite stable against precipitation. Secondly, pure Al nanoparticles were prepared by the Exploding Wire process and their sintering and consolidation behavior were studied. It was found that nanopowders of Al could be processed to bulk structures with high hardness and density. Sintering temperature was found to have a dominant effect on density, hardness and microstructure. Sintering at temperatures >600°C led to breakup of the oxide scale, leading to an interesting nanocomposite composed of 100˜200 nm Al oxide dispersed in a bimodal nanometer-micrometer size Al matrix grains. Although there was some grain growth, the randomly dispersed oxide fragments were quite effective in pinning the Al grain boundaries, preventing excessive grain growth and retaining high hardness. Cold rolling and hot rolling were effective methods for attaining full densification and high hardness. Thirdly, the microstructure evolution and mechanical behavior of Al-Al 2O3 nanocomposites were studied. The composites can retain high strength at elevated temperature and thermal soaking has practically no detrimental effect on strength. Although the ductility of the composite remains

  5. Metric Properties of Discrete Time Exclusion Type Processes in Continuum

    NASA Astrophysics Data System (ADS)

    Blank, Michael

    2010-07-01

    A new class of exclusion type processes acting in continuum with synchronous updating is introduced and studied. Ergodic averages of particle velocities are obtained and their connections to other statistical quantities, in particular to the particle density (the so called Fundamental Diagram) is analyzed rigorously. The main technical tool is a "dynamical" coupling applied in a nonstandard fashion: we do not prove the existence of the successful coupling (which even might not hold) but instead use its presence/absence as an important diagnostic tool. Despite that this approach cannot be applied to lattice systems directly, it allows to obtain new results for the lattice systems embedding them to the systems in continuum. Applications to the traffic flows modelling are discussed as well.

  6. Using tomograms for quantitative interpretation of processes and properties

    NASA Astrophysics Data System (ADS)

    Day-Lewis, F. D.; Johnson, T. C.; Singha, K.; Henderson, R. D.; Lane, J. W.

    2008-12-01

    Changes in subsurface hydrologic conditions that result from remediation or natural processes increasingly are monitored with near-surface geophysical imaging. In particular, time-lapse electrical resistivity tomography (ERT) and radar tomography (RT) are well suited to monitoring fluid-conductivity changes associated with injection of amendments for biostimulation, freshwater/saltwater dynamics in coastal aquifers, and aquifer-storage and recovery (ASR). Quantifying results from tomograms is complicated by limited resolution and estimation uncertainty that are inherent to geophysical inverse problems. Hydrologic and engineering parameters are difficult to estimate because survey geometry, measurement physics, experimental errors, regularization strategy, prior information, and parameterization also affect interpretation of geophysical measurements. Here, we review recent work to address the problem of "correlation loss" and to directly extract information about transport processes from geophysical time series. Both synthetic and field-experimental examples are presented. Case studies include applications of (1) time-lapse ERT and RT to monitor biostimulation injections at a former Department of Defense site in Brandywine, MD; (2) time-lapse ERT to monitor submarine ground-water discharge at Cape Cod, MA; and (3) time-lapse ERT to monitor an ASR experiment in Charleston, SC. In the first study, a spatially variable calibration between ERT-estimated bulk and sampled fluid conductivity was developed and applied to three-dimensional tomograms to infer the evolution of fluid conductivity after injections of amendments and pH adjustment. In the second study, the ability to resolve subsurface salinity contrasts is shown to vary strongly as a function of tide level. In the third study, electrical methods are used to monitor rate-limited mass transfer, and hydrologic parameters are estimated from the temporal moments of fluid and ERT-estimated conductivity; however, the

  7. Effect of thermal processing practices on the properties of superplastic Al-Li alloys. Final report

    SciTech Connect

    Hales, S.J.; Lippard, H.E.

    1993-09-01

    The effect of thermal processing on the mechanical properties of superplastically formed structural components fabricated from three aluminum-lithium alloys was evaluated. The starting materials consisted of 8090, 2090, and X2095 (Weldalite(TM) 049), in the form of commercial-grade superplastic sheet. The experimental test matrix was designed to assess the impact on mechanical properties of eliminating solution heat treatment and/or cold water quenching from post-forming thermal processing. The extensive hardness and tensile property data compiled are presented as a function of aging temperature, superplastic strain and temper/quench rate for each alloy. The tensile properties of the materials following superplastic forming in two T5-type tempers are compared with the baseline T6 temper. The implications for simplifying thermal processing without degradation in properties are discussed on the basis of the results.

  8. Effect of thermal processing practices on the properties of superplastic Al-Li alloys

    NASA Technical Reports Server (NTRS)

    Hales, Stephen J.; Lippard, Henry E.

    1993-01-01

    The effect of thermal processing on the mechanical properties of superplastically formed structural components fabricated from three aluminum-lithium alloys was evaluated. The starting materials consisted of 8090, 2090, and X2095 (Weldalite(TM) 049), in the form of commercial-grade superplastic sheet. The experimental test matrix was designed to assess the impact on mechanical properties of eliminating solution heat treatment and/or cold water quenching from post-forming thermal processing. The extensive hardness and tensile property data compiled are presented as a function of aging temperature, superplastic strain and temper/quench rate for each alloy. The tensile properties of the materials following superplastic forming in two T5-type tempers are compared with the baseline T6 temper. The implications for simplifying thermal processing without degradation in properties are discussed on the basis of the results.

  9. Physicochemical properties and oral bioavailability of ursolic acid nanoparticles using supercritical anti-solvent (SAS) process.

    PubMed

    Yang, Lei; Sun, Zhen; Zu, Yuangang; Zhao, Chunjian; Sun, Xiaowei; Zhang, Zhonghua; Zhang, Lin

    2012-05-01

    The objective of the study was to prepare ursolic acid (UA) nanoparticles using the supercritical anti-solvent (SAS) process and evaluate its physicochemical properties and oral bioavailability. The effects of four process variables, pressure, temperature, drug concentration and drug solution flow rate, on drug particle formation during SAS process, were investigated. Particles with mean particle size ranging from 139.2±19.7 to 1039.8±65.2nm were obtained by varying the process parameters. The UA was characterised by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, specific surface area, dissolution test and bioavailability test. It was concluded that physicochemical properties and bioavailability of crystalline UA could be improved by physical modification, such as particle size reduction and generation of amorphous state using SAS process. Further, SAS process was a powerful methodology for improving the physicochemical properties and bioavailability of UA.

  10. High Temperature Advanced Structural Composites. Volume 2. Ceramic Matrix Composites, Fiber Processing and Properties, and Interfaces

    DTIC Science & Technology

    1993-04-02

    our computed properties of hot pressed aluminum nitride. Ceram. Int. 8 value is a few orders of magnitude lower than the 1 (1982) pp 34-40 observed one...prospect of alloying SiC with other covalencly bonded refractory materials, such as AlN, to achieve microstructural control or alter properties has...specialty applica- tions. In this review the processing, properties . and uses of the end-member compounds. silicon dioxide (SiO.) and aluminum oxide

  11. Markovian nature, completeness, regularity and correlation properties of generalized Poisson-Kac processes

    NASA Astrophysics Data System (ADS)

    Giona, Massimiliano; Brasiello, Antonio; Crescitelli, Silvestro

    2017-02-01

    We analyze some basic issues associated with generalized Poisson–Kac (GPK) stochastic processes, starting from the extended notion of the Markovian condition. The extended Markovian nature of GPK processes is established, and the implications of this property derived: the associated adjoint formalism for GPK processes is developed essentially in an analogous way as for the Fokker–Planck operator associated with Langevin equations driven by Wiener processes. Subsequently, the regularity of trajectories is addressed: the occurrence of fractality in the realizations of GPK is a long-term emergent property, and its implication in thermodynamics is discussed. The concept of completeness in the stochastic description of GPK is also introduced. Finally, some observations on the role of correlation properties of noise sources and their influence on the dynamic properties of transport phenomena are addressed, using a Wiener model for comparison.

  12. CHEMISTRY AND PHYSICAL PROPERTIES OF MELT PROCESSED- AND SOLUTION-CROSS LINKED CORN ZEIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn zein was cross linked with glutaraldehyde (GDA) and with glacial acetic acid (HAc) as catalyst with the objective to enhance the mechanical properties of poured films which were compared with the physical properties of compression molded tensile bars from melt processed zein with GDA. A reacti...

  13. Structure/property development in aPET during large strain, solid phase polymer processing

    NASA Astrophysics Data System (ADS)

    Martin, Peter; Mohamed, Raja Roslan Raja

    2015-12-01

    Amorphous Polyethylene terephthalate (aPET) is increasingly of interest for the polymer packaging industry due to its blend of excellent mechanical properties and most importantly its ease of recyclability. Among the major commercial polymers it is almost unique in the degree of improvement in mechanical properties that can be obtained through process-induced strain. For many years these unique properties have been very successfully exploited in the injection stretch blow molding process, where it is deliberately stretched to very large strains using extremely high pressures. However, the material is now also being used in much lower pressure processes such as thermoforming where its properties are often not fully exploited. In this work the change in structure and properties of aPET with strain is systematically investigated using a high speed biaxial stretching machine. The aim was to demonstrate how the properties of the material could be controlled by large strain, high temperature biaxial stretching processes such as thermoforming and blow molding. The results show that property changes in the material are driven by orientation and the onset of rapid strain hardening at large strains. This in turn is shown to vary strongly with process-induced parameters such as the strain rate and the mode and magnitude of biaxial deformation.

  14. Interface Effects of the Properties and Processing of Graded Composite Aluminum Alloys

    DTIC Science & Technology

    2015-08-31

    Final Report: Interface effects of the properties and processing of graded composite aluminum alloys Report Title The objective of this STIR program...architecturally graded aluminum composite with a diffuse interface between alloys 5456 and 7055. The program supported the education and training of one graduate...2015 Approved for Public Release; Distribution Unlimited Final Report: Interface effects of the properties and processing of graded composite aluminum

  15. DWPF (Defense Waste Processing Facility) glass composition control based on glass properties

    SciTech Connect

    Carter, J T; Brown, K G; Bickford, D F

    1988-01-01

    The Defense Waste Processing Facility (DWPF) will immobilize Savannah River Plant (SRP) High Level Waste as a durable borosilicate glass for permanent disposal in a civilian repository. The DWPF will be controlled based on glass composition. The waste glass physical and chemical properties, such as viscosity, liquidus temperature, and durability are functions of glass chemistry. Preliminary models have been developed to evaluate the effects of feed composition variability on the glass properties. These properties are presently being related to the waste glass composition in order to develop process control paradigms that include batching algorithms, hold points, and transfer limits. 3 refs., 6 tabs.

  16. Processing and Properties Of Refractory Zirconium Diboride Composites For Use In High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Stackpoole, Margaret; Gusman, M.; Ellerby, D.; Johnson, S. M.; Arnold, Jim (Technical Monitor)

    2001-01-01

    The Thermal Protection Materials and Systems Branch at NASA Ames Research Center is involved in the development of a class of refractory oxidation-resistant diboride composites termed Ultra High Temperature Ceramics or UHTCs. These composites have good high temperature properties making them candidate materials for thermal protection system (TPS) applications. The current research focuses on improving processing methods to develop more reliable composites with enhanced thermal and mechanical properties. This presentation will concentrate on the processing of ZrB2/SiC composites. Some preliminary mechanical properties and oxidation data will also be presented.

  17. A statistical property of multiagent learning based on Markov decision process.

    PubMed

    Iwata, Kazunori; Ikeda, Kazushi; Sakai, Hideaki

    2006-07-01

    We exhibit an important property called the asymptotic equipartition property (AEP) on empirical sequences in an ergodic multiagent Markov decision process (MDP). Using the AEP which facilitates the analysis of multiagent learning, we give a statistical property of multiagent learning, such as reinforcement learning (RL), near the end of the learning process. We examine the effect of the conditions among the agents on the achievement of a cooperative policy in three different cases: blind, visible, and communicable. Also, we derive a bound on the speed with which the empirical sequence converges to the best sequence in probability, so that the multiagent learning yields the best cooperative result.

  18. The NBS: Processing/Microstructure/Property Relationships in 2024 Aluminum Alloy Plates

    NASA Technical Reports Server (NTRS)

    Ives, L. K.; Swartzendruber, W. J.; Boettinger, W. J.; Rosen, M.; Ridder, S. D.

    1983-01-01

    As received plates of 2024 aluminum alloy were examined. Topics covered include: solidification segregation studies; microsegregation and macrosegregation in laboratory and commercially cast ingots; C-curves and nondestructive evaluation; time-temperature precipitation diagrams and the relationships between mechanical properties and NDE measurements; transmission electron microscopy studies; the relationship between microstructure and properties; ultrasonic characterization; eddy-current conductivity characterization; the study of aging process by means of dynamic eddy current measurements; and Heat flow-property predictions, property degradations due to improve quench from the solution heat treatment temperature.

  19. Influence of processing sequence on the tribological properties of VGCF-X/PA6/SEBS composites

    NASA Astrophysics Data System (ADS)

    Osada, Yu; Nishitani, Yosuke; Kitano, Takeshi

    2016-03-01

    In order to develop the new tribomaterials for mechanical sliding parts with sufficient balance of mechanical and tribological properties, we investigated the influence of processing sequence on the tribological properties of the ternary nanocomposites: the polymer blends of polyamide 6 (PA6) and styrene-ethylene/butylene-styrene copolymer (SEBS) filled with vapor grown carbon fiber (VGCF-X), which is one of carbon nanofiber (CNF) and has 15nm diameter and 3μm length. Five different processing sequences: (1) VGCF-X, PA6 and SEBS were mixed simultaneously (Process A), (2) Re-mixing (Second compounding) of the materials prepared by Process A (Process AR),(3) SEBS was blended with PA6 (PA6/SEBS blends) and then these blends were mixed with VGCF-X (Process B), (4) VGCF-X was mixed with PA6 (VGCF-X/PA6 composites) and then these composites were blended with SEBS (Process C), and (5) VGCF-X were mixed with SEBS (VGCF-X/SEBS composites) and then these composites were blended with PA6 (Process D) were attempted for preparing of the ternary nanocomposites (VGCF-X/PA6/SEBS composites). These ternary polymer nanocomposites were extruded by a twin screw extruder and injection-molded. Their tribological properties were evaluated by using a ring-on-plate type sliding wear tester under dry condition. The tribological properties such as the frictional coefficient and the specific wear rate were influenced by the processing sequence. These results may be attributed to the change of internal structure formation, which is a dispersibility of SEBS particle and VGCF-X in ternary nanocomposites (VGCF-X/PA6/SEBS) by different processing sequences. In particular, the processing sequences of AR, B and D, which are those of re-mixing of VGCF-X, have a good dispersibility of VGCF-X for the improvement of tribological properties.

  20. Effects of uniquely processed cowpea and plantain flours on wheat bread properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of incorporating uniquely processed whole-seed cowpeas or plantain flours at 10 or 20 g/100 g in all-purpose flour on paste viscosity and bread-baking properties in model bread was determined. Flours from plantains processed as follows: unblanched plantains dried at 60 degrees C (PLC), so...

  1. 41 CFR 102-36.130 - What are our responsibilities in processing transfer orders of excess personal property?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What are our responsibilities in processing transfer orders of excess personal property? 102-36.130 Section 102-36.130 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION PERSONAL PROPERTY...

  2. 41 CFR 102-36.35 - What is the typical process for disposing of excess personal property?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is the typical process for disposing of excess personal property? 102-36.35 Section 102-36.35 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION PERSONAL PROPERTY 36-DISPOSITION OF...

  3. Influence of different processing techniques on the mechanical properties of used tires in embankment construction.

    PubMed

    Edinçliler, Ayşe; Baykal, Gökhan; Saygili, Altug

    2010-06-01

    Use of the processed used tires in embankment construction is becoming an accepted way of beneficially recycling scrap tires due to shortages of natural mineral resources and increasing waste disposal costs. Using these used tires in construction requires an awareness of the properties and the limitations associated with their use. The main objective of this paper is to assess the different processing techniques on the mechanical properties of used tires-sand mixtures to improve the engineering properties of the available soil. In the first part, a literature study on the mechanical properties of the processed used tires such as tire shreds, tire chips, tire buffings and their mixtures with sand are summarized. In the second part, large-scale direct shear tests are performed to evaluate shear strength of tire crumb-sand mixtures where information is not readily available in the literature. The test results with tire crumb were compared with the other processed used tire-sand mixtures. Sand-used tire mixtures have higher shear strength than that of the sand alone and the shear strength parameters depend on the processing conditions of used tires. Three factors are found to significantly affect the mechanical properties: normal stress, processing techniques, and the used tire content.

  4. Process, properties, and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, Richard C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  5. Process, properties and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  6. The Processing and Mechanical Properties of High Temperature/ High Performance Composites. Stress Redistribution and Notch Properties. Book 2

    DTIC Science & Technology

    1994-03-01

    The Processing and Mechanical Properties of High Temperature/ High Performance Composites by A.G. Evans & F. Leckie - 4 University of California...Chan Ceramic Layered Composites M. Y He J. W. Hutchinson 20. Notch Sensitivity and Stress T. J. Mackin Redistribution in CMCs T. E. Purcell M. YHe A...G. Evans 2 1. Notch-Sensitivity and Shear Bands in M. -Y. He Brittle Matrix Composites B. Wu Z. Suo 22. On Large Scale Sliding in Fiber- Z. C. XMa

  7. Coastal Benthic Optical Properties (COBOP): Characteristics and Processes Related to Optical Properties of Benthic Marine Organisms and Substrates

    DTIC Science & Technology

    1998-01-01

    coral reef cnidarians in particular. We wish to determine both how biological processes act to determine the optical properties and how optical measurements can be used to provide insight into biological state or process. The objectives for this year’s work were to: (1) Evaluate several methods for separating the fluorescence and reflectance components contributing to spectral signatures under daylight illumination; and (2) Locate specimens that contain only one of each of the coral fluorescent pigments and make excitation and emission measurements for use as

  8. Microstructures and mechanical properties of Ti5553 alloy processed by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Jiang, B. Z.; Emura, S.; Tsuchiya, K.

    2014-08-01

    In the present research, the effects of high-pressure torsion (HPT) processing on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr (Ti5553) alloy were studied. HPT processing produced a white etching layer (WEL) in the middle section of the cross-section and numerous shear bands in the surface region of the cross-section. And the thickness of the WEL increased with increasing the HPT revolutions. TEM observation of the WEL revealed an ultrafine-grained structure with high degree of lattice distortions. The mechanical properties measurements showed that the hardness and ultimate tensile strength increased by HPT processing, accompanied with a decrease in the elongation to failure. It is considered that the mechanical properties of HPT processed Ti5553 alloy are mostly dominated by the shear banded region and the WEL where have the finest grain size and high density of dislocations.

  9. Processing Characteristics and Properties of the Cellular Products Made by Using Special Foaming Agents

    NASA Astrophysics Data System (ADS)

    Garbacz, Tomasz; Dulebova, Ludmila

    2012-12-01

    The paper describes the manufacturing process of extruded products by the cellular extrusion method, and presents specifications of the blowing agents used in the extrusion process as well as process conditions. The process of cellular extrusion of thermoplastic materials is aimed at obtaining cellular shapes and coats with reduced density, presenting no hollows on the surface of extruder product and displaying minimal contraction under concurrent maintenance of properties similar to properties of products extruded by means of the conventional method. In order to obtain cellular structure, the properties of extruded product are modified by applying suitable plastic or inserting auxiliary agents.

  10. Physical oceanographic processes influence bio-optical properties in the Tasman Sea

    NASA Astrophysics Data System (ADS)

    Cherukuru, Nagur; Davies, Peter L.; Brando, Vittorio E.; Anstee, Janet M.; Baird, Mark E.; Clementson, Lesley A.; Doblin, Martina A.

    2016-04-01

    Remote sensing observations show optical signatures to conform to the physical oceanographic patterns in the Tasman Sea. To test the link between physical oceanographic processes and bio-optical properties we investigated an in situ bio-optical dataset collected in the Tasman Sea. Analysis of in situ observations showed the presence of four different water masses in the Tasman Sea, formed by the relatively warm and saline East Australia Current (EAC) water, a mesoscale cold core eddy on the continental slope, cooler Tasman Sea water on the shelf and river plume water. The distribution of suspended substances and their inherent optical properties in these water masses were distinctly different. Light absorption and attenuation budgets indicate varying optical complexity between the water masses. Specific inherent optical properties of suspended particulate and dissolved substances in each group were different as they were influenced by physical and biogeochemical processes specific to that water mass. Remote sensing reflectance signature varied in response to changing bio-optical properties between the water masses; thus providing the link between physical oceanographic processes, bio-optical properties and the optical signature. Findings presented here extend our knowledge of the Tasman Sea, its optical environment and the role of physical oceanographic processes in influencing the inherent optical properties and remote sensing signature in this complex oceanographic region.

  11. Effect of Process Parameters on Microstructural Evolution, Mechanical Properties and Corrosion Behavior of Friction Stir Processed Al 7075 Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, Atul; Sharma, Sandan Kumar; Pal, Kaushik; Mula, Suhrit

    2017-02-01

    Aim of the present study is to investigate the effect of process parameters on microstructural evolution, mechanical properties and corrosion behavior of an age-hardenable Al 7075 alloy. The alloy plates (6 mm thickness) were friction stir processed (FSPed) at various traverse speed, namely 25, 45, 65, 85, 100 and 150 mm/min at 2 different rpm of 508 and 720. The optimized result in terms of defect-free processed zone with refined microstructure was obtained only at a rotational speed of 720 rpm for a traverse speed of 25, 45, 65 and 85 mm/min. The microstructural evolution was investigated using optical, scanning and transmission electron microscopy. The grain size of the nugget zone was found to decrease with increase in the traverse speed from 25 to 85 mm/min at a constant rpm of 720. The mechanical properties were evaluated by Vickers hardness measurements, tensile and wear testing. Yield strength was found to be the maximum ( 366 MPa) for the FSPed sample processed at 85 mm/min. The hardness values also followed the similar increasing trend with increase in the traverse speed. The wear volume loss decreased by 38% for the sample processed at a traverse speed of 85 mm/min as compared to that of the sample processed at 25 mm/min. The friction coefficient was found to substantiate well with the wear track morphology. The improvement in mechanical properties is ascertained to the refinement of grain size at higher traverse speed (due to less heat input). The FSPed samples showed inferior corrosion resistance in contrast to that of the base metal. This is possibly due to the coarsening of precipitates and depletion of solutes in the matrix. The morphology of the corroded samples corroborated well with the corrosion behavior of the corresponding specimen.

  12. Effect of Process Parameters on Microstructural Evolution, Mechanical Properties and Corrosion Behavior of Friction Stir Processed Al 7075 Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, Atul; Sharma, Sandan Kumar; Pal, Kaushik; Mula, Suhrit

    2017-03-01

    Aim of the present study is to investigate the effect of process parameters on microstructural evolution, mechanical properties and corrosion behavior of an age-hardenable Al 7075 alloy. The alloy plates (6 mm thickness) were friction stir processed (FSPed) at various traverse speed, namely 25, 45, 65, 85, 100 and 150 mm/min at 2 different rpm of 508 and 720. The optimized result in terms of defect-free processed zone with refined microstructure was obtained only at a rotational speed of 720 rpm for a traverse speed of 25, 45, 65 and 85 mm/min. The microstructural evolution was investigated using optical, scanning and transmission electron microscopy. The grain size of the nugget zone was found to decrease with increase in the traverse speed from 25 to 85 mm/min at a constant rpm of 720. The mechanical properties were evaluated by Vickers hardness measurements, tensile and wear testing. Yield strength was found to be the maximum ( 366 MPa) for the FSPed sample processed at 85 mm/min. The hardness values also followed the similar increasing trend with increase in the traverse speed. The wear volume loss decreased by 38% for the sample processed at a traverse speed of 85 mm/min as compared to that of the sample processed at 25 mm/min. The friction coefficient was found to substantiate well with the wear track morphology. The improvement in mechanical properties is ascertained to the refinement of grain size at higher traverse speed (due to less heat input). The FSPed samples showed inferior corrosion resistance in contrast to that of the base metal. This is possibly due to the coarsening of precipitates and depletion of solutes in the matrix. The morphology of the corroded samples corroborated well with the corrosion behavior of the corresponding specimen.

  13. Reverse engineering nuclear properties from rare earth abundances in the r process

    NASA Astrophysics Data System (ADS)

    Mumpower, M. R.; McLaughlin, G. C.; Surman, R.; Steiner, A. W.

    2017-03-01

    The bulk of the rare earth elements are believed to be synthesized in the rapid neutron capture process or r process of nucleosynthesis. The solar r-process residuals show a small peak in the rare earths around A∼ 160, which is proposed to be formed dynamically during the end phase of the r process by a pileup of material. This abundance feature is of particular importance as it is sensitive to both the nuclear physics inputs and the astrophysical conditions of the main r process. We explore the formation of the rare earth peak from the perspective of an inverse problem, using Monte Carlo studies of nuclear masses to investigate the unknown nuclear properties required to best match rare earth abundance sector of the solar isotopic residuals. When nuclear masses are changed, we recalculate the relevant β-decay properties and neutron capture rates in the rare earth region. The feedback provided by this observational constraint allows for the reverse engineering of nuclear properties far from stability where no experimental information exists. We investigate a range of astrophysical conditions with this method and show how these lead to different predictions in the nuclear properties influential to the formation of the rare earth peak. We conclude that targeted experimental campaigns in this region will help to resolve the type of conditions responsible for the production of the rare earth nuclei, and will provide new insights into the longstanding problem of the astrophysical site(s) of the r process.

  14. Electrical and mechanical properties as a processing condition in polyvinylchloride multi walled carbon nanotube composites.

    PubMed

    Song, Byung Ju; Ahn, Jin Woo; Cho, Kwon Koo; Roh, Jae Seung; Lee, Dong Yun; Yang, Yong Suk; Lee, Jae Beom; Hwang, Dae Youn; Kim, Hye Sung

    2013-11-01

    We investigated the electrical conductivity (sigma) and mechanical property of polyvinylchloride/carbon nanotube composites as a function of the CNT content and processing time during a solid-state process of high speed vibration mixing (HSVM) and high energy ball milling (HEBM). Both processes were suggested to avoid high temperatures, solvents, chemical modification of carbon nanotubes. In this study, the percolation threshold (phi(c)) for electrical conduction is about 1 wt% CNT with a sigma value of 0.21 S/m, and the electrical conductivity is higher value than that reported by other researchers from melt mixing process or obtained from the other solid-state processes. We found that the dispersion of CNTs and morphology change from CNT breaking are closely related to sigma. Especially, a large morphology change in the CNTs was occurred at the specific processing time, and a significant decrease in the electrical conductivity of polyvinylchloride/carbon nanotube composite occurred in this condition. A meaningful increase of electrical properties and mechanical property is observed in the sample with about 1-2 wt% CNT contents sintered at 200 degrees C after the milling for 20 min by HEBM process. Our study indicates the proper process condition required to improve sigma of PVC/CNT composites.

  15. Effect of Mg-Zr substitution and microwave processing on magnetic properties of barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Sharma, Manju; Kashyap, Subhash C.; Gupta, H. C.

    2014-09-01

    The effect of substitution of Mg-Zr for Fe in M-type barium hexaferrite (BHF) and of processing technique on the magnetic properties and microstructure has been reported in the present paper. Significant changes in magnetic properties have been observed on substituting Fe ions by Mg and Zr ions in M-type barium hexaferrite, i.e. BaFe12O19 as well as by single mode microwave processing. The single mode microwave processing of the undoped sample reduced the coercivity to nearly 25% of the value for the sintered sample along with the enhancement in magnetization, thereby making it suitable for memory devices. The improvement in magnetic properties is explained on the basis of microstructure. The addition of substituents, though assisted in the formation of single phase, it, however, degraded the magnetization besides decreasing the coercivity, possibly due to substitution at the octahedral sites.

  16. Relationships between processing-structure-migration properties for recycled polypropylene in food packaging.

    PubMed

    Incarnato, L; Di Maio, L; Acierno, D; Denaro, M; Arrivabene, L

    1998-01-01

    In this work the relationships between processing, structure and migration properties of recycled polypropylene (PP) were analysed in relation to the possible use of recycled PP in food packaging applications. PP containers used in food packaging were contaminated with food and then washed, reduced into a processable size, dried and reprocessed by injection moulding. Gel Permeation Chromatography (GPC) analysis, mechanical, and total migration tests were performed on injection moulded samples to verify the effect of the recycling process on the structure and properties of PP. In order to evaluate the effect of the molecular weight on the properties of the recycled polymer, the study was conducted on containers produced by injection moulding made from a low molecular weight (LMW) PP and on containers produced by thermoforming made from a high molecular weight (HMW) PP.

  17. Continuous melt granulation: Influence of process and formulation parameters upon granule and tablet properties.

    PubMed

    Monteyne, Tinne; Vancoillie, Jochem; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-10-01

    The pharmaceutical industry has a growing interest in alternative manufacturing models allowing automation and continuous production in order to improve process efficiency and reduce costs. Implementing a switch from batch to continuous processing requires fundamental process understanding and the implementation of quality-by-design (QbD) principles. The aim of this study was to examine the relationship between formulation-parameters (type binder, binder concentration, drug-binder miscibility), process-parameters (screw speed, powder feed rate and granulation temperature), granule properties (size, size distribution, shape, friability, true density, flowability) and tablet properties (tensile strength, friability, dissolution rate) of four different drug-binder formulations using Design of experiments (DOE). Two binders (polyethylene glycol (PEG) and Soluplus®) with a different solid state, semi-crystalline vs amorphous respectively, were combined with two model-drugs, metoprolol tartrate (MPT) and caffeine anhydrous (CAF), both having a contrasting miscibility with the binders. This research revealed that the granule properties of miscible drug-binder systems depended on the powder feed rate and barrel filling degree of the granulator whereas the granule properties of immiscible systems were mainly influenced by binder concentration. Using an amorphous binder, the tablet tensile strength depended on the granule size. In contrast, granule friability was more important for tablet quality using a brittle binder. However, this was not the case for caffeine-containing blends, since these phenomena were dominated by the enhanced compression properties of caffeine Form I, which was formed during granulation. Hence, it is important to gain knowledge about formulation behavior during processing since this influences the effect of process parameters onto the granule and tablet properties.

  18. Numerical Prediction of Microstructure and Mechanical Properties During the Hot Stamping Process

    NASA Astrophysics Data System (ADS)

    Kan, Dongbin; Liu, Lizhong; Hu, Ping; Ma, Ning; Shen, Guozhe; Han, Xiaoqiang; Ying, Liang

    2011-08-01

    Numerical simulation and prediction of microstructures and mechanical properties of products is very important in product development of hot stamping parts. With this method we can easily design changes of hot stamping products' properties prior to the manufacturing stage and this offers noticeable time and cost savings. In the present work, the hot stamping process of a U-channel with 22MnB5 boron steels is simulated by using a coupled thermo-mechanical FEM program. Then with the temperature evolution results obtained from the simulation, a model is applied to predict the microstructure evolution during the hot stamping process and mechanical properties of this U-channel. The model consists of a phase transformation model and a mechanical properties prediction model. The phase transformation model which is proposed by Li et al is used to predict the austenite decomposition into ferrite, pearlite, and bainite during the cooling process. The diffusionless austenite-martensite transformation is modeled using the Koistinen and Marburger relation. The mechanical properties prediction model is applied to predict the products' hardness distribution. The numerical simulation is evaluated by comparing simulation results with the U-channel hot stamping experiment. The numerically obtained temperature history is basically in agreement with corresponding experimental observation. The evaluation indicates the feasibility of this set of methods to be used to guide the optimization of hot stamping process parameters and the design of hot stamping tools.

  19. The effect of processing conditions on the properties of poly(methyl methacrylate) fibers.

    PubMed

    Wright, Debra D; Lautenschlager, Eugene P; Gilbert, Jeremy L

    2002-01-01

    Brittle failure of bone cement remains a problem for the long-term stability of hip prostheses. Fibers have been developed from poly(methyl methacrylate) (PMMA) that retain the chemistry of bone cement, but improve the mechanical properties greatly. To fabricate the fibers, a polymer melt is extruded out of a small die (spinneret) and pulled onto a take-up wheel. Varying the speed of extrusion and temperature of the melt can control the viscosity of the molten polymer. This study examines the effect of melt viscosity on the resultant properties of fibers fabricated from PMMA. The goals are to optimize fiber processing and determine processing-structure--property relationships. Resultant fibers had moderate to high levels of retained molecular orientation, and ultimate tensile strengths (UTS) ranging from 60 to 225 MPa, moduli from 1.5 to 3.5 GPa, and strain to failure from 10 to 40%. Fibers fabricated at a constant viscosity and draw velocity had identical properties, whereas decreasing the viscosity generally increased the mechanical properties and retained orientation. Linear regression models were constructed to predict how the processing variables affect the structure (orientation) of the fiber and how the structure affects the UTS. This can be used to design efficient processing methods for PMMA fibers.

  20. Properties of Aluminum Deposited by a High-Velocity Oxygen-Fueled Process

    SciTech Connect

    Chow, R; Decker, T A; Gansert, R V; Gansert, D; Lee, D

    2001-06-12

    Aluminum coatings deposited by a HVOF process have been demonstrated and relevant coating properties evaluated according to two deposition parameters, the spray distance and the oxygen-to-fuel flow ratio. The coating porosity, surface roughness, and microhardness are measured. The coating properties are fairly insensitive to spray distance, the distance between the nozzle and the workpiece, and fuel ratios, the oxygen-to-fuel flow. Increasing the fuel content does appear to improve the process productivity in terms of surface roughness. Minimization of nozzle loading is discussed.

  1. Hydrothermal carbonization of biomass from landscape management - Influence of process parameters on soil properties of hydrochars.

    PubMed

    Röhrdanz, Michael; Rebling, Tammo; Ohlert, Jan; Jasper, Jan; Greve, Thomas; Buchwald, Rainer; von Frieling, Petra; Wark, Michael

    2016-05-15

    Besides pyrolysis the technology of hydrothermal carbonization (HTC) is tested to produce hydrochars for soil improvement. The chemical and physical properties of the hydrochars mainly depend on the feedstock and the process parameters reaction time and process temperature. Systematic investigations on the influences of these process parameters on soil properties of hydrochars like water holding capacity (WHC) and cation exchange capacity (CEC) are missing. In this study, a rush-rich biomass was carbonized within defined HTC process conditions under variation of reaction time and process temperature to produce hydrochars. Analysis of WHC, CEC, the elemental composition and Fourier-transform infrared spectroscopy (FT-IR) were performed to evaluate the influence of HTC process conditions on the pedological hydrochar properties. The results indicated that at increasing reaction severity (reaction time and process temperature) WHC and CEC decreased as well as the elemental O/C ratio. The decrease of WHC and CEC is based on the decrease of the hydrochar surface polarity. However, even the lowest WHC and CEC of investigated hydrochars still exceeded those of pure quartz sand by factors of 5-10. An application of hydrochars produced at severe HTC conditions could improve WHC and CEC of sandy soils. This has to be investigated in further studies.

  2. End Uses Mechanical Properties Settled By The Modified Sintering Conditions Of The Metal Injection Molding Process

    NASA Astrophysics Data System (ADS)

    Marray, Tarek; Jaccquet, Philippe; Moinard-Checot, Delphine; Fabre, Agnès; Barrallier, Laurent

    2011-01-01

    Most common mechanical applications require parts with specific properties as hard faced features. It is well known that treating parts under suitable atmospheres may improve hardness and strength yield of steels. Heat treatment process and more particularly thermo-chemical diffusion processes (such as carburizing or its variation: carbonitriding) can be performed to reach the industrial hardness profile requirements. In this work, a low-alloyed steel feedstock based on water soluble binder system is submitted to the MIM process steps (including injection molding, debinding and sintering). As-sintered parts are then treated under a low pressure carbonitriding treatment. This contribution focuses on preliminary results such as microstructural analyses and mechanical properties which are established at each stage of the process to determine and monitor changes.

  3. End Uses Mechanical Properties Settled By The Modified Sintering Conditions Of The Metal Injection Molding Process

    SciTech Connect

    Marray, Tarek; Jaccquet, Philippe; Moinard-Checot, Delphine; Fabre, Agnes; Barrallier, Laurent

    2011-01-17

    Most common mechanical applications require parts with specific properties as hard faced features. It is well known that treating parts under suitable atmospheres may improve hardness and strength yield of steels. Heat treatment process and more particularly thermo-chemical diffusion processes (such as carburizing or its variation: carbonitriding) can be performed to reach the industrial hardness profile requirements. In this work, a low-alloyed steel feedstock based on water soluble binder system is submitted to the MIM process steps (including injection molding, debinding and sintering). As-sintered parts are then treated under a low pressure carbonitriding treatment. This contribution focuses on preliminary results such as microstructural analyses and mechanical properties which are established at each stage of the process to determine and monitor changes.

  4. Sensitivity analysis of roll load, torque and material properties in the roll forming process

    NASA Astrophysics Data System (ADS)

    Abeyrathna, Buddhika; Rolfe, Bernard; Hodgson, Peter; Weiss, Matthias

    2013-12-01

    Advanced High Strength Steel (AHSS) and Ultra High Strength Steel (UHSS) are increasingly used in the current automotive industry because of their high strength and weight saving potential. As a sheet forming process, roll forming is capable of forming such materials with precise dimensions, however a small change in processing may results in significant change in the material properties such as yield strength and hardening exponent from coil to coil or within the same coil. This paper presents the effect of yield strength and the hardening exponent on roll load, torque of the roll forming process and the longitudinal bow. The roll forming process is numerically simulated, and then the regression analysis and Analysis of Variance (ANOVA) techniques are employed to establish the relationships among the aforementioned parameters and to determine the percentage influence of material properties on longitudinal bow, roll load and torque.

  5. Tailoring the physical properties of homopolymers and polymer nanocomposites via solid-state processing

    NASA Astrophysics Data System (ADS)

    Pierre, Cynthia

    Numerous approaches can be used to modify polymer properties. In this thesis, it is demonstrated that an innovative, continuous, industrially scalable process called solid-state shear pulverization (SSSP) can be used to enhance polymer properties with and without the addition of nanofillers. The SSSP process employs a modified twin-screw extruder in which the barrel is cooled rather than heated, resulting in the polymer being processed at a temperature below its glass transition temperature, if the polymer is amorphous, or its melt transition temperature, if the polymer is semi-crystalline. The material processed via SSSP experiences high levels of shear and compressive stresses, resulting in many repeated fragmentation and fusion steps during pulverization, which can lead to mechanochemistry. This research provides the first in-depth study on the effect of SSSP processing on the molecular structure as well as physical properties of homopolymers. Rheological characterization has demonstrated an increase in the melt viscosity of pulverized poly(ethylene terephthalate) (PET), which can be ascribed to the in situ formation of lightly branched PET. Further evidence of branched PET is provided via a dramatic increase in the rate of crystallization of the pulverized samples. These results suggest that SSSP processing can enhance the reuse and recyclability of PET. While SSSP processing has dramatic effects on the structure of polyesters and consequently their properties, a mild effect is observed for polyolefins. This thesis also demonstrates via a combination of methods that the well-exfoliated state can be achieved via SSSP processing of various polymer nanocomposites, using as-received, unmodified fillers. For example, extensive comparisons are made concerning the thermal stability in air or nitrogen atmosphere of polypropylene (PP)/clay, PP/graphite, and PP/carbon nanotube (CNT) nanocomposites made by SSSP. These comparisons suggest that the mechanism by which CNTs

  6. Process induced electroactive β-polymorph in PVDF: effect on dielectric and ferroelectric properties.

    PubMed

    Sharma, Maya; Madras, Giridhar; Bose, Suryasarathi

    2014-07-28

    The effects of various processing conditions, like annealing, poling, mechanical rolling and their combinations, on the dielectric and ferroelectric properties of PVDF [poly(vinylidene fluoride)] were systematically studied in this work. Further, the effect of processing sequence on the structure and properties was investigated. While all the processing conditions adopted here resulted in phase transformation of the α- to electroactive β-polymorph in PVDF, the fraction of β-phase developed was observed to be strongly contingent on the adopted process. The transformation of α to electroactive β-polymorph was determined by X-ray diffraction and FTIR. The neat PVDF showed only α-phase, whereas mechanically rolled samples exhibited the highest ca. 85% β-phase in PVDF. Both the permittivity and the loss tangent decreased in the samples which had undergone different processing conditions. The polarization-electric field (P-E) loops for all the samples were evaluated. Interestingly, the energy density, estimated from the electrical displacement-electric field (D-E) loops, was observed to be highest for the poled samples which were initially rolled. The results indicate that various processing conditions can influence the dielectric and the ferroelectric properties differently.

  7. Acquisition of material properties in production for sheet metal forming processes

    SciTech Connect

    Heingärtner, Jörg; Hora, Pavel; Neumann, Anja; Hortig, Dirk; Rencki, Yasar

    2013-12-16

    In past work a measurement system for the in-line acquisition of material properties was developed at IVP. This system is based on the non-destructive eddy-current principle. Using this system, a 100% control of material properties of the processed material is possible. The system can be used for ferromagnetic materials like standard steels as well as paramagnetic materials like Aluminum and stainless steel. Used as an in-line measurement system, it can be configured as a stand-alone system to control material properties and sort out inapplicable material or as part of a control system of the forming process. In both cases, the acquired data can be used as input data for numerical simulations, e.g. stochastic simulations based on real world data.

  8. Impact of further processing on dielectric properties of broiler poultry meat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently in the U.S. more than 90% of the turkeys and more than 70% of the broilers are processed beyond the normal ready-to-cook stage. Up to 50% of raw poultry meat is marinated with mixtures of water, salts, and phosphates. Physical properties of foods provide essential data to the food industr...

  9. Chemistry and Physical Properties of Melt Processed- and Solution- Cross Linked Corn Zein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn zein was cross linked with the glutaraldehyde (GDA) using glacial acetic acid (HAc) as catalyst. The objectives are to enhance the mechanical properties of poured films and to compare them with compression molded tensile bars from melt processed zein. Chemistry of the cross linking reaction w...

  10. Influence of formulation and preparation process on ambroxol hydrochloride dry powder inhalation characteristics and aerosolization properties.

    PubMed

    Ren, Yachao; Yu, Chaoqun; Meng, Kangkang; Tang, Xing

    2008-09-01

    The objective of this study is to evaluate the influence of formulation and preparation process on ambroxol hydrochloride (AH) dry powder inhalation (DPI) characteristics and aerosolization properties. Spray-dried samples of AH, AH/leucine, and AH/leucine/mannitol were prepared from their corresponding water solutions under the same conditions to study the influence of the composition, and the AH/leucine/mannitol (2.5/0.5/1 by weight) formulation was used for investigation of the effect of the preparation process. Following spray-drying, the resulting powders were characterized using scanning electron microscopy, laser diffraction, tapped density, and angle of repose measurements, and the aerosolization performance was determined using a twin-stage liquid impinger. AH/leucine/mannitol (2.5/0.5/1 by weight) obtained by cospray-drying improved the AH aerosolization properties. The AH/leucine/mannitol (2.5/0.5/1 by weight) preparation exhibited the following properties: 62.34% yield, 0.34 g/cm(3) tap density, 2.71 microm d(ae), 33.45 degrees angle of repose, and 30.93% respirable fraction. The influence of the preparation process on DPI characteristics and aerosolization properties was relatively small, but the influence of the composition was relatively large. Optimization of DPI can be achieved by selecting the most appropriate formulation and preparation process.

  11. Effect of food processing on the physicochemical properties of dietary fibre.

    PubMed

    Ozyurt, Vasfiye Hazal; Ötles, Semih

    2016-01-01

    Products derived from the manufacturing or processing of plant based foods: cereals, fruits, vegetables, as well as algae, are sources of abundant dietary fibre. Diets high in dietary fibre have been associated with the reduced risk of cardiovascular disease, diabetes, hypertension, obesity, and gastrointestinal disorders. These fibre-rich products and byproducts can also fortify foods, increase their dietary fibre content and result in healthy products, low in calories, cholesterol and fat. Traditionally, consumers have chosen foods such as whole grains, fruits and vegetables as sources of dietary fibre. Recently, food manufacturers have responded to consumer demand for foods with a higher fibre content by developing products in which highfibre ingredients are used. Different food processing methods also increase the dietary fiber content of food. Moreover, its chemical and physical properties may be affected by food processing. Some of them might even improve the functionality of fibre. Therefore, they may also be applied as functional ingredients to improve physical properties like the physical and structural properties of hydration, oil-holding capacity, viscosity. This study was conducted to examine the effect of different food processing methods on the physicochemical properties of dietary fibre.

  12. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    NASA Astrophysics Data System (ADS)

    Shin, Boo Young; Kim, Jae Hong

    2015-07-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity.

  13. The Psychometric Properties of the Swedish Version of the EB Process Assessment Scale

    ERIC Educational Resources Information Center

    Nyström, Siv; Åhsberg, Elizabeth

    2016-01-01

    Objective: This study examines whether the psychometric properties of the short version of the Evidence-Based Practice Process Assessment Scale (EBPPAS) remain satisfactory when translated and transferred to the context of Swedish welfare services. Method: The Swedish version of EBPPAS was tested on a sample of community-based professionals in…

  14. Neutrino properties deduced from the study of lepton number violating processes at low and high energies

    SciTech Connect

    Stoica, Sabin

    2012-11-20

    There is nowadays a significant progress in understanding the neutrino properties. The results of the neutrino oscillation experiments have convincingly showed that neutrinos have mass and oscillate, in contradiction with the Standard Model (SM) assumptions, and these are the first evidences of beyond SM physics. However, fundamental properties of the neutrinos like their absolute mass, their character (are they Dirac or Majorana particles?), their mass hierarchy, the number of neutrino flavors, etc., still remain unknown. In this context there is an increased interest in the study of the lepton number violating (LNV) processes, since they could complete our understanding on the neutrino properties. Since recently, the neutrinoless double beta decay was considered the only process able to distinguish between Dirac or Majorana neutrinos and to give a hint on the absolute mass of the electron neutrino. At present, the increased luminosity of the LHC experiments makes feasible the search of LNV processes at high energy as well. In this lecture I will make a brief review on our present knowledge of the neutrino properties, on the present status of the double-beta decay studies and on the first attempts to search LNV processes at LHC.

  15. Structure-property-processing correlations in freeze-cast composite scaffolds.

    PubMed

    Hunger, Philipp M; Donius, Amalie E; Wegst, Ulrike G K

    2013-05-01

    Surprisingly few reports have been published, to date, on the structure-property-processing correlations observed in freeze-cast materials directionally solidified from polymer solutions, or ceramic or metal slurries. The studies that exist focus on properties of sintered ceramics, that is materials whose structure was altered by further processing. In this contribution, we report first results on correlations observed in alumina-chitosan-gelatin composites, which were chosen as a model system to test and compare the effect of particle size and processing parameters on their mechanical properties at a specific composition. Our study reveals that highly porous (>90%) hybrid materials can be manufactured by freeze casting, through the self-assembly of a polymer and a ceramic phase that occurs during directional solidification, without the need of additional processing steps such as sintering or infiltration. It further illustrates that the properties of freeze-cast hybrid materials can independently be tailored at two levels of their structural hierarchy, allowing for the simultaneous optimization of both mechanical and structural requirements. An increase in freezing rate resulted in decreases in lamellar spacing, cell wall thickness, pore aspect ratio and cross-sectional area, as well as increases in both Young's modulus and compressive yield strength. The mechanical properties of the composite scaffolds increased with an increasing particle size. The results show that both structure and mechanical properties of the freeze-cast composites can be custom-designed and that they are thus ideally suited for a large variety of applications that require high porosity at low or medium load-bearing capacity.

  16. Characterizing biotic and abiotic properties of landscape and their implications for ecohydrological processes across scales

    NASA Astrophysics Data System (ADS)

    Kumar, J.; Langford, Z.; Hoffman, F. M.

    2015-12-01

    Ecohydrological processes governing the dynamics of terrestrial ecosystems and its response and feedback to climate change occur at diverse spatial and temporal scales. To accurately capture the dynamics of ecohydrological processes in the model, its critically important to capture the subgrid scale heterogeneity of the landscape and develop scale aware process representation and parameterization. This study focused on the Arctic tundra landscape at Seward Peninsula of Alaska. Ecohydrological processes in this sensitive landscape are strongly governed by the physical and structural properties (like topography, soil, permafrost, geomorphology etc.) of the landscape, environmental conditions (like temperature, precipitation, light, radiation) and biotic conditions (vegetation, above/below biomass and organic matter, disturbance history etc.). From site to watershed to regional (scale at which models often operate), landscape is a complex mosaic of a range of biotic and abiotic properties. We have developed and applied a hierarchical characterization and classification approach to segment the landscape in distinct units which can be used to develop and parameterize process models at local scale. We also analyze how the distribution and organization of the landscape units as building blocks influence and interact with ecosystem processes across scales. Our goals is understand the landscape organization principles and their roles to inform and improve process based models of ecohydrological processes in Arctic tundra landscape.

  17. Process parameters, orientation, and functional properties of melt-processed bulk Y-Ba-Cu-O superconductors

    NASA Astrophysics Data System (ADS)

    Zakharchenko, I. V.; Terryll, K. M.; Rao, K. V.; Balachandran, U.

    1995-12-01

    This study compared the microstructure, texturing, and functional properties (critical currents) of YBa2Cu3O7-x-based bulk pellets that were prepared by the quench-melt-growth-process (QMGP), melt-textured growth, and conventional solid-state reaction approaches. Using two x-ray diffraction methods, θ-2θ, and rocking curves, we found that the individual grains of two melt-processed pellets exhibited remarkable preferred orientational alignment (best rocking curve width < 3.2‡). However, the direction of the preferred orientation among the grains was random. Among the three types of bulk materials studied, the QMGP sample was found to have the best Jc values, ≈4500 A/cm2 at 77K in a field of 2 kG, as determined from superconducting quantum interference device magnetic data.

  18. Effects of Manufacturing Processes and In-Service Temperature Variations on the Properties of TRIP Steels

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-04-30

    This paper examines key aspects of the manufacturing process that “Transformation Induced Plasticity” (TRIP) steels would be exposed to, and systematically evaluate how the forming and thermal histories affect final strength and ductility of the material. The paper evaluates in-service temperature variations, such as under hood and hot/cold cyclic conditions, to determine whether these conditions influence final strength, ductility and energy absorption characteristics of several available TRIP steel grades. As part of the manufacturing thermal environment evaluations, stamping process thermal histories are included in the studies. As part of the in-service conditions, different pre-straining levels are also included. Materials from four steel suppliers world wide are examined. The material properties are established over a full range of expected thermal histories and selected loading modes. Establishing these relationships will allow OEM designers to select TRIP steels for proper vehicle applications, and to specify manufacturing process conditions that yield reliable final material property levels.

  19. Improvement of Structural and Mechanical Properties of Al-1100 Alloy via Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Mosallaee, M.; Dehghan, M.

    2014-10-01

    In the present study, the relationship between structural and mechanical properties of friction stir processed Al-1100 alloy and process parameters (tool rotation rate: ω and traverse speed: ν) was studied to get an better understanding and optimizing the friction stir processing (FSP) condition of this alloy. Microstructural studies revealed that increasing of ω up to 720 rpm resulted in grain refinement in the stirred zone (SZ), but higher increasing of ω caused grain growth in this zone. These variations of SZ grain size illustrated that the prevailing factor that determined the SZ grain size was plastic deformation at first and thereafter, peak temperature in the SZ. Mechanical properties investigations were in accordance with microstructural findings and illustrated that optimized FSP condition for Al-1100 alloy was 720 rpm and 20 mm/min. Optimized FSP condition resulted in a significant improvement of tensile strength and elongation up to 22 and 8% of those of base metal, respectively.

  20. Identification of physical properties for the retrieval data quality objective process

    SciTech Connect

    Gates, C.M.; Beckette, M.R.

    1995-06-01

    This activity supports the retrieval data quality objective (DQO) process by identifying the material properties that are important to the design, development, and operation of retrieval equipment; the activity also provides justification for characterizing those properties. These properties, which control tank waste behavior during retrieval operations, are also critical to the development of valid physical simulants for designing retrieval equipment. The waste is to be retrieved in a series of four steps. First, a selected retrieval technology breaks up or dislodges the waste into subsequently smaller pieces. Then, the dislodged waste is conveyed out of the tank through the conveyance line. Next, the waste flows into a separator unit that separates the gaseous phase from the liquid and solid phases. Finally, a unit may be present to condition the slurried waste before transporting it to the treatment facility. This document describes the characterization needs for the proposed processes to accomplish waste retrieval. Baseline mobilization technologies include mixer pump technology, sluicing, and high-pressure water-jet cutting. Other processes that are discussed in this document include slurry formation, pneumatic conveyance, and slurry transport. Section 2.0 gives a background of the DQO process and the different retrieval technologies. Section 3.0 provides the mechanistic descriptions and material properties critical to the different technologies and processes. Supplemental information on specific technologies and processes is provided in the appendices. Appendix A contains a preliminary sluicing model, and Appendices B and C cover pneumatic transport and slurry transport, respectively, as prepared for this document. Appendix D contains sample calculations for various equations.

  1. Microstructure and Mechanical Properties of Microwave Post-processed Ni Coating

    NASA Astrophysics Data System (ADS)

    Zafar, Sunny; Sharma, Apurbba Kumar

    2017-03-01

    Flame-sprayed coatings are widely used in the industries attributed to their low cost and simple processing. However, the presence of porosity and poor adhesion with the substrate requires suitable post-processing of the as-sprayed deposits. In the present work, post-processing of the flame-sprayed Ni-based coating has been successfully attempted using microwave hybrid heating. Microwave post-processing of the flame-sprayed coatings was carried out at 2.45 GHz in a 1 kW multimode industrial microwave applicator. The microwave-processed and as-sprayed deposits were characterized for their microstructure, porosity, fracture toughness and surface roughness. The properties of the coatings were correlated with their abrasive wear behavior using a sliding abrasion test on a pin-on-disk tribometer. Microwave post-processing led to healed micropores and microcracks, thus causing homogenization of the microstructure in the coating layer. Therefore, microwave post-processed coating layer exhibits improved mechanical and tribological properties compared to the as-sprayed coating layer.

  2. Microstructure and Mechanical Properties of Microwave Post-processed Ni Coating

    NASA Astrophysics Data System (ADS)

    Zafar, Sunny; Sharma, Apurbba Kumar

    2017-02-01

    Flame-sprayed coatings are widely used in the industries attributed to their low cost and simple processing. However, the presence of porosity and poor adhesion with the substrate requires suitable post-processing of the as-sprayed deposits. In the present work, post-processing of the flame-sprayed Ni-based coating has been successfully attempted using microwave hybrid heating. Microwave post-processing of the flame-sprayed coatings was carried out at 2.45 GHz in a 1 kW multimode industrial microwave applicator. The microwave-processed and as-sprayed deposits were characterized for their microstructure, porosity, fracture toughness and surface roughness. The properties of the coatings were correlated with their abrasive wear behavior using a sliding abrasion test on a pin-on-disk tribometer. Microwave post-processing led to healed micropores and microcracks, thus causing homogenization of the microstructure in the coating layer. Therefore, microwave post-processed coating layer exhibits improved mechanical and tribological properties compared to the as-sprayed coating layer.

  3. The viscoelastic properties of processed cheeses depend on their thermal history and fat polymorphism.

    PubMed

    Gliguem, Hela; Lopez, Christelle; Michon, Camille; Lesieur, Pierre; Ollivon, Michel

    2011-04-13

    Both the composition and the thermal kinetics that are applied to processed cheeses can affect their texture. This study investigated the effect of the storage conditions and thermal history on the viscoelastic properties of processed cheese and the physical properties of the fat phase. The microstructure of processed cheese has been characterized. Using a combination of physical techniques such as rheometry, differential scanning calorimetry, and X-ray diffraction, the partial crystallization of fat and the polymorphism of triacylglycerols (TG; main constituents of milk fat) were related to changes in the elastic modulus and tan δ as a function of temperature. In the small emulsion droplets (<1 μm) dispersed in processed cheeses, the solid fat phase was studied at a molecular level and showed differences as a function of the thermal history. Storage of processed cheese at 4 °C and its equilibration at 25 °C lead to partial crystallization of the fat phase, with the formation of a β' 2 L (40.9 Å) structure; on cooling at 2 °C min(-1), the formation of an α 3 L (65.8 Å) structure was characterized. The cooling of processed cheese from 60 to -10 °C leads to the formation of a single type of crystal: α 3 L (72 Å). Structural reorganizations of the solid fat phase characterized on heating allowed the interpretation of the elastic modulus evolution of processed cheese. This study evidenced polymorphism of TG in a complex food product such as processed cheese and allowed a better understanding of the viscoelastic properties as a function of the thermal history.

  4. The effect of thermal processing on microstructure and mechanical properties in a nickel-iron alloy

    NASA Astrophysics Data System (ADS)

    Yang, Ling

    The correlation between processing conditions, resulted microstructure and mechanical properties is of interest in the field of metallurgy for centuries. In this work, we investigated the effect of thermal processing parameters on microstructure, and key mechanical properties to turbine rotor design: tensile yield strength and crack growth resistance, for a nickel-iron based superalloy Inconel 706. The first step of the designing of experiments is to find parameter ranges for thermal processing. Physical metallurgy on superalloys was combined with finite element analysis to estimate variations in thermal histories for a large Alloy 706 forging, and the results were adopted for designing of experiments. Through the systematic study, correlation was found between the processing parameters and the microstructure. Five different types of grain boundaries were identified by optical metallography, fractography, and transmission electron microscopy, and they were found to be associated with eta precipitation at the grain boundaries. Proportions of types of boundaries, eta size, spacing and angle respect to the grain boundary were found to be dependent on processing parameters. Differences in grain interior precipitates were also identified, and correlated with processing conditions. Further, a strong correlation between microstructure and mechanical properties was identified. The grain boundary precipitates affect the time dependent crack propagation resistance, and different types of boundaries have different levels of resistance. Grain interior precipitates were correlated with tensile yield strength. It was also found that there is a strong environmental effect on time dependent crack propagation resistance, and the sensitivity to environmental damage is microstructure dependent. The microstructure with eta decorated on grain boundaries by controlled processing parameters is more resistant to environmental damage through oxygen embrittlement than material without eta

  5. Effect of radiation processing on nutritional, functional, sensory and antioxidant properties of red kidney beans

    NASA Astrophysics Data System (ADS)

    Marathe, S. A.; Deshpande, R.; Khamesra, Arohi; Ibrahim, Geeta; Jamdar, Sahayog N.

    2016-08-01

    In the present study dry red kidney beans (Phaseolus vulgaris), irradiated in the dose range of 0.25-10.0 kGy were evaluated for proximate composition, functional, sensory and antioxidant properties. Radiation processing up to 10 kGy did not affect proximate composition, hydration capacity and free fatty acid value. All the sensory attributes were unaffected at 1.0 kGy dose. The dose of 10 kGy, showed lower values for odor and taste, however, they were in acceptable range. Significant improvement in textural quality and reduction in cooking time was observed at dose of 10 kGy. Antioxidant activity of radiation processed samples was also assessed after normal processing such as soaking and pressure cooking. Both phenolic content and antioxidant activity evaluated in terms of DPPH free radical scavenging assay and inhibition in lipid peroxidation using rabbit erythrocyte ghost system, were marginally improved (5-10%) at the dose of 10 kGy in dry and cooked samples. During storage of samples for six months, no significant change was observed in sensory, cooking and antioxidant properties. Thus, radiation treatment of 1 kGy can be applied to get extended shelf life of kidney beans with improved functional properties without impairing bioactivity; nutritional quality and sensory property.

  6. Relationship between microstructure, material distribution, and mechanical properties of sheep tibia during fracture healing process.

    PubMed

    Gao, Jiazi; Gong, He; Huang, Xing; Fang, Juan; Zhu, Dong; Fan, Yubo

    2013-01-01

    The aim of this study was to investigate the relationship between microstructural parameters, material distribution, and mechanical properties of sheep tibia at the apparent and tissue levels during the fracture healing process. Eighteen sheep underwent tibial osteotomy and were sacrificed at 4, 8, and 12 weeks. Radiographs and micro-computed tomography (micro-CT) scanning were taken for microstructural assessment, material distribution evaluation, and micro-finite element analysis. A displacement of 5% compressive strain on the longitudinal direction was applied to the micro-finite element model, and apparent and tissue-level mechanical properties were calculated. Principle component analysis and linear regression were used to establish the relationship between principle components (PCs) and mechanical parameters. Visible bony callus formation was observed throughout the healing process from radiographic assessment. Apparent mechanical property increased at 8 weeks, but tissue-level mechanical property did not increase significantly until 12 weeks. Three PCs were extracted from microstructural parameters and material distribution, which accounted for 87.592% of the total variation. The regression results showed a significant relationship between PCs and mechanical parameters (R>0.8, P<0.05). Results of this study show that microstructure and material distribution based on micro-CT imaging could efficiently predict bone strength and reflect the bone remodeling process during fracture healing, which provides a basis for exploring the fracture healing mechanism and may be used as an approach for fractured bone strength assessment.

  7. Graphene transport properties upon exposure to PMMA processing and heat treatments

    NASA Astrophysics Data System (ADS)

    Gammelgaard, Lene; Caridad, José M.; Cagliani, Alberto; Mackenzie, David M. A.; Petersen, Dirch H.; Booth, Timothy J.; Bøggild, Peter

    2014-12-01

    The evolution of graphene's electrical transport properties due to processing with the polymer polymethyl methacrylate (PMMA) and heat are examined in this study. The use of stencil (shadow mask) lithography enables fabrication of graphene devices without the usage of polymers, chemicals or heat, allowing us to measure the evolution of the electrical transport properties during individual processing steps from the initial as-exfoliated to the PMMA-processed graphene. Heating generally promotes the conformation of graphene to SiO2 and is found to play a major role for the electrical properties of graphene while PMMA residues are found to be surprisingly benign. In accordance with this picture, graphene devices with initially high carrier mobility tend to suffer a decrease in carrier mobility, while in contrast an improvement is observed for low carrier mobility devices. We explain this by noting that flakes conforming poorly to the substrate will have a higher carrier mobility which will however be reduced as heat treatment enhance the conformation. We finally show the electrical properties of graphene to be reversible upon heat treatments in air up to 200 °C.

  8. Nitinol laser cutting: microstructure and functional properties of femtosecond and continuous wave laser processing

    NASA Astrophysics Data System (ADS)

    Biffi, C. A.; Tuissi, A.

    2017-03-01

    Thermal processing can affect the properties of smart materials, and the correct selection of the best manufacturing technology is fundamental for producing high tech smart devices, containing embedded functional properties. In this work cutting of thin superelastic Nitinol plates using a femtosecond (fs) and continuous wave (CW) laser was studied. Diamond shaped elements were cut to characterize the kerf qualitative features; microstructural analysis of the cross sections allowed identification of thermal damage characteristics introduced into the material during the laser processes. A thermally undamaged microstructure was observed for fs laser cutting, while CW was seen to be characterized by a large heat-affected zone. Functional properties were investigated by differential scanning calorimetry and tensile testing of laser cut microelements and of the reference material. It was seen that the martensitic transformation behavior of Nitinol is not affected by fs regime, while cw cutting provokes an effect equivalent to a high temperature thermal treatment in the material surrounding the cutting kerf, degradating the material properties. Finally, tensile testing indicated that superelastic performances were guaranteed by fs regime, while strong reduction of the recoverable strain was detected in the CW processed sample.

  9. Chemistry and physical properties of melt-processed and solution-cross-linked corn zein.

    PubMed

    Sessa, David J; Mohamed, Abdellatif; Byars, Jeffrey A

    2008-08-27

    Corn zein was cross-linked with glutaraldehyde (GDA) using glacial acetic acid (HAc) as catalyst. The objectives are to evaluate the swelling characteristics of GDA cross-linked zein gels in water, ethanol, and their combinations. Similar formulations, upon solvent evaporation, form films. The mechanical properties of the films are compared to compression molded tensile bars from GDA melt-processed zein as a second objective. Chemistry of the cross-linking reaction was based on the aldehyde binding characteristics defined by use of fluorescence spectroscopy; sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to demonstrate the cross-linking reaction; FTIR to observe absorption differences of the cross-linked product; differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis to assess thermal properties; and the use of Instron Universal Testing Machine to evaluate mechanical properties. A reaction mechanism for acid catalyzed GDA cross-linking of zein is proposed. Thermal and mechanical properties of tensile bars cut from either film or formed by compression molding were similar, where both showed increased tensile strengths, ductility and stiffness when compared with unmodified controls. Samples that were reacted with 8% GDA by weight based on weight of zein from either process retained their integrity when tensile bars from each were subjected to boiling water for 10 min or soaking in either water or HAc for 24 h. The melt-processed, cross-linked zein is a more environmentally friendly method that would eliminate the need for HAc recovery.

  10. Life Distribution Properties of Devices Subject to a Levy Wear Process.

    DTIC Science & Technology

    1982-01-01

    and1 Pr,)schan A . , it suff ices to provi. tl,, properties of ) t(-rtns of those, of Vanm) -, and tnen draw thca conclu’- on for tlhV non-stat ionarv...AD1A27 062 LFOSTRIBUTION PROPERTIES OF DEVICES SUBJECT 0O A 1 LEVY WEAR PROCESS(U) NORTH CAROLINA UNIV AT CHAPEL HIL DEPT OF MATHEMATICS M ABOEL...BUREAU OF STANDARDS-1963- A AFOSR-TR. 83-0261 , - LECTE Department ’ A ,2.- ’..<APR 2 2 1983. >- of " C’- Q. of A C.’) Mathematics __J The

  11. Structural and mechanical properties of nanocrystalline titanium processed by severe plastic deformation

    SciTech Connect

    Popov, A.A.; Pyshmintsev, I.Y.; Demakov, S.L.; Illarionov, A.G.; Lowe, T.C.; Sergeyeva, A.V.; Valiev, R.Z.

    1997-10-01

    Recent investigations have demonstrated that materials with ultrafine grain (UFG) structure (nano- and submicron crystalline) can be processed by severe plastic deformation. One advantage of this method is that it can be applied to both pure metals and alloys. Moreover, it produces samples that have no residual porosity so that meaningful measurements of the physical and mechanical properties are possible. Investigations of ultrafine grain copper and aluminum alloys have revealed a number of specific features of their mechanical behavior, namely extremely high hardness and strength, the absence of strain hardening, and deviation form the Hall-Petch relationship. In this work the authors investigate the mechanical properties and thermal stability of UFG titanium.

  12. Geotechnical Properties of Oil Shale Retorted by the PARAHO and TOSCO Processes.

    DTIC Science & Technology

    1979-11-01

    outlet size set by consideration of particle interlucking, flow rate, etc. 235 .," Material Oil shale B. With vibrating equipment ] Material not suited...AD-AB.a 317 ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG--ETC F/S 8/7 GEOTECHNICAL PROPERTIES OF OIL SHALE RETORTED BY THE PARAHO AND-ETC(U...lEEllllElhllIE MEJ I .LEVEL. TECHNICAL REPORT 66-79-22 GEOTECHNICAL PROPERTIES OF OILas SHALE RETORTED BY THE PARAHO AND C TOSCO PROCESSES by ( Frank C

  13. Processing, properties, and in vitro bioactivity of polysulfone-bioactive glass composites.

    PubMed

    Oréfice, Rodrigo; Clark, Arthur; West, Jon; Brennan, Anthony; Hench, Larry

    2007-03-01

    The mismatch between the mechanical properties of bioceramics and natural tissue has restricted in several cases a wider application of ceramics in medical and dental fields. To overcome this problem, polymer matrix composites can be designed to combine bioactive properties of some bioceramics with the superior mechanical properties of some engineering plastics. In this work, polymer particulate composites composed of a high mechanical-property polymer and bioactive glass particles were produced and both the in vitro bioactivity and properties of the system were investigated. Composites with different volume fraction and particle size were prepared. In vitro tests showed that hydroxy-carbonate-apatite can be deposited on the surface of a composite as early as 20 h in a simulated body fluid. Ionic evolution from a composite with 40% volume fraction of particles was demonstrated to be similar to bulk bioactive glasses. The mechanical properties of some of the obtained composites had values comparable with the ones reported for bone. Moreover, a physical model based on dynamical mechanical tests showed evidences that the interface of the composite was aiding in the stress transfer process.

  14. Ti Alloys Processed By Selective Laser Melting And By Laser Cladding: Microstructures And Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Mertens, Anne; Contrepois, Quentin; Dormal, Thierry; Lemaire, Olivier; Lecomte-Beckers, Jacqueline

    2012-07-01

    In this study, samples of alloy Ti-6Al-4V have been processed by Selective Laser Melting (SLM) and by Laser Cladding (LC), two layer-by-layer near-net-shape processes allowing for economic production of complex parts. The resulting microstructures have been characterised in details, so as to allow for a better understanding of the solidification process and of the subsequent phase transformations taking place upon cooling for both techniques. On the one hand, a new “MesoClad” laser with a maximum power of 300 W has been used successfully to produce thin wall samples by LC. On the other hand, the influence of processing parameters on the mechanical properties was investigated by means of uniaxial tensile testing performed on samples produced by SLM with different orientations with respect to the direction of mechanical solicitation. A strong anisotropy in mechanical behaviour was thus interpreted in relations with the microstructures and processing conditions.

  15. Wear Resistant Carbide-based Thermal Sprayed Coatings: Process, Properties, Mechanical Degradation and Wear

    NASA Astrophysics Data System (ADS)

    Ghabchi, Arash

    Thermally sprayed ceramic-metallic composite (CerMet) materials consist of ceramic particles mainly in form of carbides reinforced by metallic binder exhibit unique microstructural and mechanical characteristics. Such structure brings in a novel combination of hardness and toughness enabling application of this class of material in wear resistant surfaces. Final deposit microstructure that defines the mechanical properties and wear performance of material depends on process parameters and starting material characteristics. Complex interaction of in-flight particles with supersonic flame, formation of complex defective deposit structure comprising of pores, cracks and splat boundaries make comprehending of interrelation of process, microstructure, properties and performance a difficult task. Additional challenge is development of systematic understanding on mechanical degradation, damage and wear mechanisms of cermet coatings due to their complex structure. This dissertation attempts to address these issues first by taking a systematic step by step approach, process map, to establish a correlation between process, particle state, microstructure and properties. Different strategies were proposed and examined to control the high velocity thermal spray process. This strategy assessment enabled a better control over in-flight particles state in high velocity thermal spray process and provided better understanding on interaction of in-flight particles with the flame. Further, possible advantages of reducing the carbide particle size from micron to nano in terms of mechanical properties and different wear performance were explored. It was suggested that poor wear performance of nano-structured coating is due to presence of brittle phases and less available binder promotes the excessive stress detrimental to load carrying capability of material. Material damage and wear mechanisms of coating under different tribological conditions were examined. The results suggest a

  16. Study on properties of CFRP fabricated by VA-RTM process

    NASA Astrophysics Data System (ADS)

    Jeoung, Sun Kyoung; Hwang, Ye Jin; Lee, Hyun Wook; Son, Soon Keun; Kim, Hyung Sik; Ha, Jin Uk

    2016-03-01

    Carbon fiber reinforced plastics (CFRP) have a lot of attention from industry and academia due to its excellent mechanical property. It has been used for aircraft, automotive and so on, since it can replace metallic materials and reduce total weight with increased physical properties. However, the manufacturing process and the material cost are still challenging to be commercialized in the automotive market. Therefore, many researchers are trying to minimize materials and process cost for broadening their applications. In this study, thermoset epoxy resins were used for binder of CFRP. Epoxy resins were investigated in order to figure out optimized curing speed under vacuum assisted resin transfer molding (VARTM) processing condition. Mechanical properties of CFRP with different carbon fiber orientation and woven carbon fiber were compared to mathematically simulated results. In order to develop the application of automobile component, reliability tests of CFRP were carried out. Tensile strength of CFRP is increased when the orientation angle between fiber and axis of load was decreased (90°→ 0°). It is considered that epoxy and carbon fiber absorbed the tensile energy because the orientation of fiber and the load bearing are matched with axis direction. In addition, the CFRP automobile engine hood was fabricated by VARTM process. Drop weight impact tests (20kg & 100kg weight) were carried out in order to simulate crash performance of CFRP engine hoods.

  17. Moss Mediates the Influence of Shrub Species on Soil Properties and Processes in Alpine Tundra

    PubMed Central

    Williamson, Scott N.; Barrio, Isabel C.; Helgadóttir, Ágústa; HiK, David S.

    2016-01-01

    In tundra ecosystems, bryophytes influence soil processes directly and indirectly through interactions with overstory shrub species. We experimentally manipulated moss cover and measured seasonal soil properties and processes under two species of deciduous shrubs with contrasting canopy structures, Salix planifolia pulchra and Betula glandulosa-nana complex. Soil properties (seasonal temperature, moisture and C:N ratios) and processes (seasonal litter decomposition and soil respiration) were measured over twelve months. Shrub species identity had the largest influence on summer soil temperatures and soil respiration rates, which were higher under Salix canopies. Mosses were associated with lower soil moisture irrespective of shrub identity, but modulated the effects of shrubs on winter soil temperatures and soil C:N ratios so that moss cover reduced differences in soil winter temperatures between shrub species and reduced C:N ratios under Betula but not under Salix canopies. Our results suggest a central role of mosses in mediating soil properties and processes, with their influence depending on shrub species identity. Such species-dependent effects need to be accounted for when forecasting vegetation dynamics under ongoing environmental changes. PMID:27760156

  18. Electromagnetic and absorbing property of CIPs/resin composite using the 3D forming process

    NASA Astrophysics Data System (ADS)

    Xu, Yonggang; Liang, Zichang; Wang, Xiaobing; Yuan, Liming; Li, Xinghao

    2016-08-01

    The absorbing composite filled with the flaky carbonyl iron particles (CIPs) were prepared using a three-dimensional (3D) forming process, in which the forming powder was fabricated using a milling process. The surface morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer, and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 4-18 GHz. With the variable thickness was set, the reflection loss (RL) was simulated to analyze the absorbing property of the composite. The results showed that the forming powder was uniformly dispersed in the absorber, and the saturation magnetization and the grain structure of the CIPs in the forming powder nearly did not change in the milling process. With the same volume content CIPs added, the average permittivity and the imaginary permeability of the samples added the powder was smaller than the directly mixing sample due to the aggregation effect. The RL results showed that the absorbing composites using the 3D forming process with thickness 6 or 8 mm had an better absorbing property (minimum RL -13.58 and -21.85 dB) in 4-18 GHz.

  19. Influence of Water Content on Mechanical Properties of Rock in Both Saturation and Drying Processes

    NASA Astrophysics Data System (ADS)

    Zhou, Zilong; Cai, Xin; Cao, Wenzhuo; Li, Xibing; Xiong, Cheng

    2016-08-01

    Water content has a pronounced influence on the properties of rock materials, which is responsible for many rock engineering hazards, such as landslides and karst collapse. Meanwhile, water injection is also used for the prevention of some engineering disasters like rock-bursts. To comprehensively investigate the effect of water content on mechanical properties of rocks, laboratory tests were carried out on sandstone specimens with different water contents in both saturation and drying processes. The Nuclear Magnetic Resonance technique was applied to study the water distribution in specimens with variation of water contents. The servo-controlled rock mechanics testing machine and Split Hopkinson Pressure Bar technique were used to conduct both compressive and tensile tests on sandstone specimens with different water contents. From the laboratory tests, reductions of the compressive and tensile strength of sandstone under static and dynamic states in different saturation processes were observed. In the drying process, all of the saturated specimens could basically regain their mechanical properties and recover its strength as in the dry state. However, for partially saturated specimens in the saturation and drying processes, the tensile strength of specimens with the same water content was different, which could be related to different water distributions in specimens.

  20. Effect of electric pulse processing on physical and chemical properties of inorganic materials

    NASA Astrophysics Data System (ADS)

    Sakipova, S. E.; Nussupbekov, B. R.; Ospanova, D.; Khassenov, A.; Sakipova, Sh E.

    2015-04-01

    This article analyzes various aspects of the practical application of electric pulse technology of industrial raw materials processing as a result of a spark electric discharge in a liquid solution of the raw material under processing. The object of the study are samples of technogenic materials from a deposit in Central Kazakhstan, which are crushed and ground to particles with a preset degree of fragmentation. The electric pulse processing is performed by using different numbers of discharges. The effect of electric pulse processing with different electrical parameters is carried out on the basis of comparison of the properties and structure of metal-containing and industrial raw materials after machining and electric pulse processing. The X-ray spectral microanalysis was performed using a scanning microscope. The researchers obtained data on changes in the microstructure and elemental composition of inorganic material samples as a result of electric pulse processing. It was established that the technology of electric pulse crushing and grinding of inorganic materials makes it possible to obtain not only a final product with desired size of dispersed particles, but also to change their physical and chemical properties.

  1. Laser engineered net shaping (LENS{trademark}) process: Optimization of surface finish and microstructural properties

    SciTech Connect

    Smugeresky, J.E.; Keicher, D.M.; Romero, J.A.; Griffith, M.L.; Harwell, L.D.

    1997-11-01

    Rapid prototyping (RP) has revolutionized the approach to fabricating geometrically complex hardware from a CAD solid model. The various RP techniques allow component designers to directly fabricate conceptual models in plastics and polymer coated metals; however, each of the techniques requires additional processes, e.g. investment casting, to allow the fabrication of functional metallic hardware. This limitation has provided the impetus for further development of solid freeform fabrication technologies which enable fabrication of functional metallic hardware directly from the CAD solid model. The Laser Engineered Net Shaping (LENS{trademark}) process holds promise in satisfying this need. This newly emerging technology possesses the capability to fabricate fully dense components with good dimensional accuracy and with unique materials properties. Relatively complex geometrical shapes have been fabricated using this technology. In continuing to develop the LENS{trademark} process, further advancements are required. The functional dependence of the component surface finish and microstructural characteristics on process parameters including power size and size distribution are being evaluated. A set of statistically designed experiments is being used to sort through the various process parameters and identify significant process variables for improving surface finish and achieving optimum material microstructural properties.

  2. Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing

    NASA Astrophysics Data System (ADS)

    Mansoor, Bilal

    The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

  3. Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Young; Shim, Chun Sik; Sturtevant, Caleb; Kim, Dave (Dae-Wook); Song, Ha Cheol

    2014-09-01

    Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

  4. Process-Dependent Properties in Colloidally Synthesized “Giant” Core/Shell Nanocrystal Quantum Dots

    SciTech Connect

    Hollingsworth, Jennifer A.; Ghosh, Yagnaseni; Dennis, Allison M.; Mangum, Benjamin D.; Park, Young-Shin; Kundu, Janardan; Htoon, Han

    2012-06-07

    Due to their characteristic bright and stable photoluminescence, semiconductor nanocrystal quantum dots (NQDs) have attracted much interest as efficient light emitters for applications from single-particle tracking to solid-state lighting. Despite their numerous enabling traits, however, NQD optical properties are frustratingly sensitive to their chemical environment, exhibit fluorescence intermittency ('blinking'), and are susceptible to Auger recombination, an efficient nonradiative decay process. Previously, we showed for the first time that colloidal CdSe/CdS core/shell nanocrystal quantum dots (NQDs) comprising ultrathick shells (number of shell monolayers, n, > 10) grown by protracted successive ionic layer adsorption and reaction (SILAR) leads to remarkable photostability and significantly suppressed blinking behavior as a function of increasing shell thickness. We have also shown that these so-called 'giant' NQDs (g-NQDs) afford nearly complete suppression of non-radiative Auger recombination, revealed in our studies as long biexciton lifetimes and efficient multiexciton emission. The unique behavior of this core/shell system prompted us to assess correlations between specific physicochemical properties - beyond shell thickness - and functionality. Here, we demonstrate the ability of particle shape/faceting, crystalline phase, and core size to determine ensemble and single-particle optical properties (quantum yield/brightness, blinking, radiative lifetimes). Significantly, we show how reaction process parameters (surface-stabilizing ligands, ligand:NQD ratio, choice of 'inert' solvent, and modifications to the SILAR method itself) can be tuned to modify these function-dictating NQD physical properties, ultimately leading to an optimized synthetic approach that results in the complete suppression of blinking. We find that the resulting 'guiding principles' can be applied to other NQD compositions, allowing us to achieve non-blinking behavior in the near

  5. Bioactive and functional properties of protein hydrolysates from fish frame processing waste using plant proteases.

    PubMed

    Gajanan, Phadke Girija; Elavarasan, Krishnamoorthy; Shamasundar, Bangalore Aswathnarayan

    2016-12-01

    Enzymatic conversion of fish frame waste of threadfin breams (Nemipterus japonicus) to protein hydrolysate could be a solution for minimizing the pollution issues related to seafood processing operations and a way for the value addition to processing by-products. Protein hydrolysates from fish frame waste (FW) of thread fin breams (N. japonicus) were prepared and evaluated for bioactive properties such as angiotensin-I-converting enzyme (ACE) inhibitory activity and antioxidant and functional properties as a function of degree of hydrolysis (DH). Two different plant proteases, papain and bromelain, were used to prepare fish protein hydrolysates (FPH) and designated as HP (hydrolysates prepared using papain) and HB (hydrolysates prepared using bromelain). The ACE inhibitory activity of HP samples was higher at 5 and 10 % DH than that of the HB samples at DH 15 %, and there was no significant difference (p < 0.05). Antioxidant properties (2, 2 diphenyl-1-picrylhydrazyl [DPPH] radical scavenging activity, ferric reducing power and lipid peroxidation inhibition) of hydrolysates increased with increase in DH. The HB samples at DH 15 % had significantly higher antioxidant properties than HP samples (p < 0.05). The solubility of HP and HB samples was high in a wide range of pH and increased with DH. The functional properties of HP and HB samples decreased significantly with increase in DH (p < 0.05). The fractionation of the HB-DH 15 % sample yielded three peptide fractions with the approximate molecular weight of peptides in the range of 7562-812 Da. Relatively, bromelain enzyme is more effective in producing the FPH with desirable bioactive and functional properties.

  6. The influence of processing on microstructure and properties of iron aluminides

    SciTech Connect

    Wright, R.N.; Wright, J.K.

    1995-08-01

    An Fe-28%Al alloy containing 5% Cr has been synthesized by reaction of elemental powders, followed by consolidation using hot isostatic pressing or hot extrusion. The resulting materials are fully dense, homogeneous, and have a grain size of less than 5{mu}m. Processing strongly influences the propensity toward secondary recrystallization. While HIPped material is extremely resistant to grain growth, under some circumstances hot extruded material undergoes secondary recrystallization, resulting in grain sizes as large as 25 millimeters. Elevated temperature tensile properties and strain rate sensitivities are reported for fine and very coarse grained materials. Grain boundary sliding is not a significant deformation mode for any of the materials. The properties are compared to those of Fe{sub 3}Al processed from conventional hot extruded prealloyed. powder. It has been found that the reaction synthesized materials generally have superior elevated temperature tensile strength.

  7. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 1, Overview

    SciTech Connect

    Butner, R.S.; Elliott, D.C.; Sealock, L.J. Jr.; Pyne, J.W.

    1988-12-01

    Pacific Northwest Laboratory has completed an initial investigation of the effects of physical and chemical properties of biomass feedstocks relative to their performance in biomass energy conversion systems. Both biochemical conversion routes (anaerobic digestion and ethanol fermentation) and thermochemical routes (combustion, pyrolysis, and gasification) were included in the study. Related processes including chemical and physical pretreatment to improve digestibility, and size and density modification processes such as milling and pelletizing were also examined. This overview report provides background and discussion of feedstock and conversion relationships, along with recommendations for future research. The recommendations include (1) coordinate production and conversion research programs; (2) quantify the relationship between feedstock properties and conversion priorities; (3) develop a common framework for evaluating and characterizing biomass feedstocks; (4) include conversion effects as part of the criteria for selecting feedstock breeding programs; and (5) continue emphasis on multiple feedstock/conversion options for biomass energy systems. 9 refs., 3 figs., 2 tabs.

  8. Processing, properties, and applications of Ni{sub 3}Al-based alloys

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Liu, C.T.

    1997-06-01

    The Ni{sub 3}Al-based alloys represent a quantum jump in advanced alloys for structural applications at elevated temperatures. These alloys offer benefits of oxidation, carburization, and chlorination resistance, and significantly higher strength than many commercially used alloys. The commercial applications of the Ni{sub 3}Al-based alloys have begun to occur because of their comprehensive development This paper is to provide a review of. (1) alloy development, (2) melting, casting, and processing of alloys, (3) property data, (4) welding process and weldment properties, and (5) case histories of current applications. It is concluded that the cast alloy IC-221M is on its way to commercialization. 22 refs., 8 figs., 2 tabs.

  9. Photophysical properties and photoisomerization processes of Methyl Red embedded in rigid polymer

    NASA Astrophysics Data System (ADS)

    Lee, Geon Joon; Kim, Dongho; Lee, Minyung

    1995-01-01

    The photophysical properties of Methyl Red molecules embedded in a poly(methyl methacrylate) (PMMA) matrix were investigated with photoinduced absorption, absorption kinetics, steady-state, and time-resolved luminescence spectroscopy. The excited singlet (S1) state lifetimes for trans and cis isomers of Methyl Red in PMMA at room temperature have been measured as 35 and 420 ps, respectively. The excited triplet (T1) state energy level and its lifetime at 77 K were also obtained. A slow trans-cis isomerization process having a time constant of a few hundred seconds was observed for the illuminated Methyl Red in rigid polymer. Based on measured photophysical properties and dynamic processes, an energy-level diagram for Methyl Red molecules in rigid polymer is introduced to explain these observations.

  10. Investigation of test methods, material properties and processes for solar cell encapsulants

    NASA Technical Reports Server (NTRS)

    Willis, P. B.; Baum, B.

    1977-01-01

    The potentially useful encapsulating materials for Task 3 of the Low-Cost Silicon Solar Array project were studied to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. Materials for study were chosen on the basis of existing knowledge of generic chemical types having high resistance to environmental weathering. The materials varied from rubbers to thermoplastics and presented a broad range of mechanical properties and processing requirements. Basic physical and optical properties were measured on the polymers and were redetermined after exposure to indoor artificial accelerated aging conditions covering four time periods. Strengths and weaknesses of the various materials were revealed and data was accumulated for the development of predictive methodologies. To date, silicone rubbers, fluorocarbons, and acrylic polymers appear to have the most promising combination of characteristics. The fluorocarbons may be used only as films, however, because of their high cost.

  11. Influence of process variables on the properties of laccase biobleached pulps.

    PubMed

    Martin-Sampedro, Raquel; Miranda, Jesús; García-Fuentevilla, Luisa L; Hernández, Manuel; Arias, Maria E; Diaz, Manuel J; Eugenio, Maria E

    2015-01-01

    A laccase stage can be used as a pre-treatment of a standard chemical bleaching sequence to reduce environmental concerns associated to this process. The importance of each independent variable and its influence on the properties of the bleached pulp have been studied in depth in this work, using an adaptive network-based fuzzy inference system (ANFIS) with four independent variables (laccase, buffer, mediator and oxygen) as input. Eucalyptus globulus kraft pulp was biobleached using a laccase from Pycnoporus sanguineus and a natural mediator (acetosyringone). Later, an alkaline extraction and a hydrogen peroxide treatment were applied. Most biobleaching processes showed a decrease in kappa number and an increase in brightness with no significant impact on the viscosity values, compared with the control. Oxygen was the variable with the smallest influence on the final pulp properties while the laccase and buffer solution showed a significant influence.

  12. Multifunctional PLA-PHB/cellulose nanocrystal films: processing, structural and thermal properties.

    PubMed

    Arrieta, M P; Fortunati, E; Dominici, F; Rayón, E; López, J; Kenny, J M

    2014-07-17

    Cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose by acid hydrolysis were added into poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends to improve the final properties of the multifunctional systems. CNC were also modified with a surfactant (CNCs) to increase the interfacial adhesion in the systems maintaining the thermal stability. Firstly, masterbatch pellets were obtained for each formulation to improve the dispersion of the cellulose structures in the PLA-PHB and then nanocomposite films were processed. The thermal stability as well as the morphological and structural properties of nanocomposites was investigated. While PHB increased the PLA crystallinity due to its nucleation effect, well dispersed CNC and CNCs not only increased the crystallinity but also improved the processability, the thermal stability and the interaction between both polymers especially in the case of the modified CNCs based PLA-PHB formulation. Likewise, CNCs were better dispersed in PLA-CNCs and PLA-PHB-CNCs, than CNC.

  13. Microlayer coextrusion process as a way to improve thermomechanical properties of ABS/PC blends

    NASA Astrophysics Data System (ADS)

    Sollogoub, C.; Grandmontagne, A.; Guinault, A.

    2011-05-01

    ABS/PC blends have always presented a great interest both in industrial and academic contexts, since they combine the most desirable properties of both ABS and PC. Melt blends are classically prepared using a twin screw extruder. In this study, ABS/PC blends of two compositions were prepared with two blending techniques: coextrusion mixing method (CM) and microlayer coextrusion method (MC), designed to better control the blend morphology, and then injection molded. SEM observations show that different blend morphologies have been obtained, depending on the blending technique. It was shown that microlayer coextrusion process can lead to orientated morphology phase (fibrillar and lamellar structures), whereas coextrusion mixing method leads only to nodular morphology. These morphologies have been correlated with thermomechanical properties (tensile tests and DMTA). Improved mechanical performances are achieved with the microlayer coextrusion process.

  14. Optical properties of selected components of mineral dust aerosol processed with organic acids and humic material

    NASA Astrophysics Data System (ADS)

    Alexander, Jennifer M.; Grassian, V. H.; Young, M. A.; Kleiber, P. D.

    2015-03-01

    Visible light scattering phase function and linear polarization profiles of mineral dust components processed with organic acids and humic material are measured, and results are compared to T-matrix simulations of the scattering properties. Processed samples include quartz mixed with humic material, and calcite reacted with acetic and oxalic acids. Clear differences in light scattering properties are observed for all three processed samples when compared to the unprocessed dust or organic salt products. Results for quartz processed with humic acid sodium salt (NaHA) indicate the presence of both internally mixed quartz-NaHA particles and externally mixed NaHA aerosol. Simulations of light scattering suggest that the processed quartz particles become more moderate in shape due to the formation of a coating of humic material over the mineral core. Experimental results for calcite reacted with acetic acid are consistent with an external mixture of calcite and the reaction product, calcium acetate. Modeling of the light scattering properties does not require any significant change to the calcite particle shape distribution although morphology changes cannot be ruled out by our data. It is expected that calcite reacted with oxalic acid will produce internally mixed particles of calcite and calcium oxalate due to the low solubility of the product salt. However, simulations of the scattering for the calcite-oxalic acid system result in rather poor fits to the data when compared to the other samples. The poor fit provides a less accurate picture of the impact of processing in the calcite-oxalic acid system.

  15. Investigating ionomer morphologies with STEM and SAXS: Toward rigorous processing-structure-property relationships

    NASA Astrophysics Data System (ADS)

    Benetatos, Nicholas M.

    Due to their extraordinary chemical and physical properties, ionomers have found wide-ranging applications including chemically resistant thermoplastics, robust coatings, and selectively permeable ion-transport membranes. The unique properties of ionomers result directly from the self-assembly/organization of ionic functional groups and counterions into nanoscale aggregates which act as transient physical crosslinks. For more than a half century, significant effort has been devoted toward understanding these structurally complex multi-component polymers, however, a complete description of their processing-structure-property relationships remains elusive. Quantifying these relationships will provide an important step toward the rational design, synthesis, and preparation of superior ionomeric materials. In order to rigorously advance the study of ionomer morphology, we combine traditional small angle X-ray scattering (SAXS) approaches with cutting-edge real space imaging via scanning transmission electron microscopy (STEM). This technique has provides high resolution imaging capability in which the image contrast is generated by differences in local average atomic number. Our work has shown that these characterization methods can be used to obtain complementary morphological information regarding the size, shape, and spatial distribution of the nanoscale ionic aggregates that control the physical properties of ionomers. With this information, we evaluate the validity of prevalent structural/morphological models and systematically explore how the nanoscale morphology is affected by changes in polymer backbone structure, materials chemistry, and processing.

  16. Effect of high-pressure food processing on the physical properties of synthetic and biopolymer films.

    PubMed

    Galotto, M J; Ulloa, P A; Guarda, A; Gavara, R; Miltz, J

    2009-08-01

    The effect of high-pressure processing on 2 plastic food packaging films, a biopolymer (PLASiOx/PLA) and a synthetic polymer (PET-AlOx), was studied. Samples in direct contact with olive oil, as a fatty food simulant, and distilled water, as an aqueous simulant, were subjected to a pressure of 500MPa for 15 min at 50 degrees C. The mechanical, thermal, and gas barrier properties of both films were evaluated after the high-pressure processing (HPP) and compared to control samples that have not undergone this treatment. Significant changes in all properties were observed in both films after the HPP treatment and in contact with the food simulants. In both films an induced crystallization was noticed. In the PLASiOx/PLA film the changes were larger when in contact with water that probably acted as a plasticizer. In the PET-AlOx film the changes in properties were attributed to the formation of pinholes and cracks during the HPP treatment. In this film, most of the properties changed more in the presence of oil as the food simulant.

  17. Process for improving mechanical properties of epoxy resins by addition of cobalt ions

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K. (Inventor)

    1984-01-01

    A resin product useful as an adhesive, composite or casting resin is described as well as the process used in its preparation to improve its flexural strength mechanical property characteristics. Improved flexural strength is attained with little or no change in density, thermal stability or moisture resistance by chemically incorporating 1.2% to 10.6% by weight Co(3) ions in an epoxidized resin system.

  18. Methacrylic resin having a high solar radiant energy absorbing property and process for producing the same

    SciTech Connect

    Abe, K.; Kamada, K.; Nakai, Y.

    1981-10-20

    A methacrylic resin having a high solar radiant energy absorbing property wherein an organic compound (A) containing cupric ion and a compound (B) having at least one p-o-h bond in a molecule are contained into the methacrylic resin selected from poly(Methyl methacrylate) or methacrylic polymers containing at least 50% by weight of a methyl methacrylate unit. A process for producing said methacrylic resin is also disclosed.

  19. A Study of Thermal Properties and the Heating Process in Asphaltic Concrete.

    DTIC Science & Technology

    1984-02-01

    PROPERTIES AND THE HEATING FINAL PROCESS IN ASPHALTIC CONCRETE 1 Jul 1982 - 31 Dec. 19R3 6. PERFORMING O1G. REPORT NUMBER 7. AUTHOR(e) 8. CONTRACT OR GRANT...OFFICE NAME AND ADDRESS 12. REPORT DATE AIR FORCE OFFICE OF SCIENTIFIC RESEARCH /NA February 1984 BOLLING AFB, DC 20332 15. NUMBEROFPAGES 157 14...asphalt and asphaltic concrete have been reported in the literature for at least 55 years (14), much of the data is un- documented in that variables

  20. Processing-structure-property relationships in electron beam physical vapor deposited yttria stabilized zirconia coatings

    SciTech Connect

    Rao, D. Srinivasa; Valleti, Krishna; Joshi, S. V.; Janardhan, G. Ranga

    2011-05-15

    The physical and mechanical properties of yttria stabilized zirconia (YSZ) coatings deposited by the electron beam physical vapor deposition technique have been investigated by varying the key process variables such as vapor incidence angle and sample rotation speed. The tetragonal zirconia coatings formed under varying process conditions employed were found to have widely different surface and cross-sectional morphologies. The porosity, phase composition, planar orientation, hardness, adhesion, and surface residual stresses in the coated specimens were comprehensively evaluated to develop a correlation with the process variables. Under transverse scratch test conditions, the YSZ coatings exhibited two different crack formation modes, depending on the magnitude of residual stress. The influence of processing conditions on the coating deposition rate, column orientation angle, and adhesion strength has been established. Key relationships between porosity, hardness, and adhesion are also presented.

  1. The effect of silane addition timing on mixing processability and properties of silica reinforced rubber compound

    NASA Astrophysics Data System (ADS)

    Jeong, Hee-Hoon; Jin, Hyun-Ho; Ha, Sung-Ho; Jang, Suk-Hee; Kang, Yong-Gu; Han, Min-Hyun

    2016-03-01

    A series of experiments were performed to determine an optimum balance between processability and performance of a highly loaded silica compound. The experiments evaluated 4 different silane injection times. All mixing related to silane addition was conducted with a scaled up "Tandem" mixer line. With exception to silane addition timing, almost all operating conditions were controlled between experimental features. It was found that when the silane addition was introduced earlier in the mixing cycle both the reaction was more complete and the bound rubber content was higher. But processability indicators such as sheet forming and Mooney plasticity were negatively impacted. On the other hand, as silane injection was delayed to later in the mixing process the filler dispersion and good sheet forming was improved. However both the bound rubber content and Silane reaction completion were decreased. With the changes in silane addition time, the processability and properties of a silica compound can be controlled.

  2. Remote Laser Processing of Composite Materials with Different Opto-Thermic Properties

    NASA Astrophysics Data System (ADS)

    Fürst, A.; Klotzbach, A.; Hühne, S.; Hauptmann, J.; Beyer, E.

    Near net shape preforms with a minimum of material consumption are required to increase the acceptance of fibre reinforced polymers in the industry, This should be accompanied with appropriate, fast and flexible processes. The 21/2 D beam deflection expands the area of possible kinds of processing strategies, wherefore the laser can be a tool for the future. The development of remote laser processing is strongly connected with the understanding of the interaction between tool and material. Within the paper investigations on opto - thermic properties of the components as a function of the wavelength of the beam source were shown. The results of the measurements are fundamental for processing composite structures made of glass- or carbon fibre and polymer matrices.

  3. Thermodynamic properties of adsorbed water on silica gel - Exergy losses in adiabatic sorption processes

    NASA Astrophysics Data System (ADS)

    Worek, W. M.; Zengh, W.; San, J.-Y.

    1991-09-01

    In order to perform exergy analyses to optimize the transient heat and mass transfer processes involving sorption by solid adsorbents, the thermodynamic properties of adsorbed water must be determined. In this paper, the integral enthalpy and entropy are determined directly from isotherm data of water adsorbed on silica gel particles and silica gel manufactured in the form of a felt with 25 percent cotton as a support and Teflon as a binder. These results are then used to evaluate the exergy losses, due to the sorption and the convective heat and mass transfer processes, that occur in each portion of an adiabatic desiccant dehumidificaton cycle.

  4. Effect of thermomechanical processing on mechanical properties of Fe-16 at. % Al alloy

    SciTech Connect

    Sikka, V.K.

    1994-12-31

    An iron-aluminum alloy containing 16 at. % Al, which is essentially free from environmental effect on its ductility, has been developed. This alloy has over 20% elongation at room temperature. This paper presents in detail the effect of vacuum versus air melting on the properties of Fe-16 at. % Al alloy. The comparative results have shown air-induction melting to produce lower room-temperature ductility for the identical processing steps. Additional processing steps required to improve the ductility of air-melted material are also identified.

  5. Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties

    SciTech Connect

    Beardsley, M B

    2008-03-26

    The feasibility to coat large SNF/HLW containers with a structurally amorphous material (SAM) was demonstrated on sub-scale models fabricated from Type 316L stainless steel. The sub-scale model were coated with SAM 1651 material using kerosene high velocity oxygen fuel (HVOF) torch to thicknesses ranging from 1 mm to 2 mm. The process parameters such as standoff distance, oxygen flow, and kerosene flow, were optimized in order to improve the corrosion properties of the coatings. Testing in an electrochemical cell and long-term exposure to a salt spray environment were used to guide the selection of process parameters.

  6. Structure and properties of polypropylene cast films: Polymer type and processing effects

    NASA Astrophysics Data System (ADS)

    Mileva, Daniela; Gahleitner, Markus; Gloger, Dietrich

    2016-05-01

    The influence of processing parameters in a cast film extrusion process of thin films of isotactic polypropylene homopolymer and random propylene-ethylene copolymer was analyzed. Variation of the chill roll temperature allowed changing the supercooling of the melt and thus the generation of different crystal polymorphs of iPP. Additional focus was placed on the effect of flow induced crystallization via changing the output rate of the line. The crystal structure and morphology of the materials were evaluated and correlated to selected optical and mechanical properties.

  7. Influence of Hemp Fibers Pre-processing on Low Density Polyethylene Matrix Composites Properties

    NASA Astrophysics Data System (ADS)

    Kukle, S.; Vidzickis, R.; Zelca, Z.; Belakova, D.; Kajaks, J.

    2016-04-01

    In present research with short hemp fibres reinforced LLDPE matrix composites with fibres content in a range from 30 to 50 wt% subjected to four different pre-processing technologies were produced and such their properties as tensile strength and elongation at break, tensile modulus, melt flow index, micro hardness and water absorption dynamics were investigated. Capillary viscosimetry was used for fluidity evaluation and melt flow index (MFI) evaluated for all variants. MFI of fibres of two pre-processing variants were high enough to increase hemp fibres content from 30 to 50 wt% with moderate increase of water sorption capability.

  8. Impact of pulse thermal processing on the properties of inkjet printed metal and flexible sensors

    DOE PAGES

    Joshi, Pooran C.; Kuruganti, Teja; Killough, Stephen M.

    2015-03-11

    In this paper, we report on the low temperature processing of environmental sensors employing pulse thermal processing (PTP) technique to define a path toward flexible sensor technology on plastic, paper, and fabric substrates. Inkjet printing and pulse thermal processing technique were used to realize mask-less, additive integration of low-cost sensors on polymeric substrates with specific focus on temperature, humidity, and strain sensors. The printed metal line performance was evaluated in terms of the electrical conductivity characteristics as a function of post-deposition thermal processing conditions. The PTP processed Ag metal lines exhibited high conductivity with metal sheet resistance values below 100more » mΩ/{whitesquare} using a pulse width as short as 250 μs. The flexible temperature and relative humidity sensors were defined on flexible polyimide substrates by direct printing of Ag metal structures. The printed resistive temperature sensor and capacitive humidity sensor were characterized for their sensitivity with focus on future smart-building applications. Strain gauges were printed on polyimide substrate to determine the mechanical properties of the silver nanoparticle films. Finally, the observed electrical properties of the printed metal lines and the sensitivity of the flexible sensors show promise for the realization of a high performance print-on-demand technology exploiting low thermal-budget PTP technique.« less

  9. Impact of pulse thermal processing on the properties of inkjet printed metal and flexible sensors

    SciTech Connect

    Joshi, Pooran C.; Kuruganti, Teja; Killough, Stephen M.

    2015-03-11

    In this paper, we report on the low temperature processing of environmental sensors employing pulse thermal processing (PTP) technique to define a path toward flexible sensor technology on plastic, paper, and fabric substrates. Inkjet printing and pulse thermal processing technique were used to realize mask-less, additive integration of low-cost sensors on polymeric substrates with specific focus on temperature, humidity, and strain sensors. The printed metal line performance was evaluated in terms of the electrical conductivity characteristics as a function of post-deposition thermal processing conditions. The PTP processed Ag metal lines exhibited high conductivity with metal sheet resistance values below 100 mΩ/{whitesquare} using a pulse width as short as 250 μs. The flexible temperature and relative humidity sensors were defined on flexible polyimide substrates by direct printing of Ag metal structures. The printed resistive temperature sensor and capacitive humidity sensor were characterized for their sensitivity with focus on future smart-building applications. Strain gauges were printed on polyimide substrate to determine the mechanical properties of the silver nanoparticle films. Finally, the observed electrical properties of the printed metal lines and the sensitivity of the flexible sensors show promise for the realization of a high performance print-on-demand technology exploiting low thermal-budget PTP technique.

  10. Influence of Process Parameters on Microstructure and Mechanical Properties of Friction-Stir-Processed Mg-Gd-Y-Zr Casting

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Xiao, B. L.; Ma, Z. Y.

    2012-06-01

    Mg-10Gd-3Y-0.5Zr (wt pct) casting was subjected to friction stir processing (FSP) at a constant rotation rate of 800 rpm and varied travel speeds of 25, 50, and 100 mm/minute. FSP resulted in the generation of fine-grained microstructure and fundamental dissolution of coarse Mg5(Gd,Y) phase at the grain boundaries, thereby enhancing the tensile properties significantly at both room and elevated temperatures. The grain size of the FSP samples decreased with the increasing travel speed, whereas the microstructure heterogeneity with the banded structure (onion rings) became evident at a higher travel speed. Tensile elongation of the FSP samples increased as the travel speed increased, whereas the highest strengths were obtained at the medium travel speed of 50 mm/minute. Higher strengths and greater elongations were observed for the FSP samples in the transverse direction (TD) than in the longitudinal direction (LD). After post-FSP aging, the strengths of the FSP samples were increased significantly with the TD and LD exhibiting the same strengths; however, the elongation was decreased remarkably with the TD having higher elongation than the LD. A variation of the tensile properties was discussed in detail based on the microstructure heterogeneity and fracture surfaces.

  11. Effect of sodium hexametaphosphate concentration and cooking time on the physicochemical properties of pasteurized process cheese.

    PubMed

    Shirashoji, N; Jaeggi, J J; Lucey, J A

    2010-07-01

    Sodium hexametaphosphate (SHMP) is commonly used as an emulsifying salt (ES) in process cheese, although rarely as the sole ES. It appears that no published studies exist on the effect of SHMP concentration on the properties of process cheese when pH is kept constant; pH is well known to affect process cheese functionality. The detailed interactions between the added phosphate, casein (CN), and indigenous Ca phosphate are poorly understood. We studied the effect of the concentration of SHMP (0.25-2.75%) and holding time (0-20min) on the textural and rheological properties of pasteurized process Cheddar cheese using a central composite rotatable design. All cheeses were adjusted to pH 5.6. The meltability of process cheese (as indicated by the decrease in loss tangent parameter from small amplitude oscillatory rheology, degree of flow, and melt area from the Schreiber test) decreased with an increase in the concentration of SHMP. Holding time also led to a slight reduction in meltability. Hardness of process cheese increased as the concentration of SHMP increased. Acid-base titration curves indicated that the buffering peak at pH 4.8, which is attributable to residual colloidal Ca phosphate, was shifted to lower pH values with increasing concentration of SHMP. The insoluble Ca and total and insoluble P contents increased as concentration of SHMP increased. The proportion of insoluble P as a percentage of total (indigenous and added) P decreased with an increase in ES concentration because of some of the (added) SHMP formed soluble salts. The results of this study suggest that SHMP chelated the residual colloidal Ca phosphate content and dispersed CN; the newly formed Ca-phosphate complex remained trapped within the process cheese matrix, probably by cross-linking CN. Increasing the concentration of SHMP helped to improve fat emulsification and CN dispersion during cooking, both of which probably helped to reinforce the structure of process cheese.

  12. Physical and processing properties of milk, butter, and cheddar cheese from cows fed supplemental fish meal.

    PubMed

    Avramis, C A; Wang, H; McBride, B W; Wright, T C; Hill, A R

    2003-08-01

    Physical, chemical, sensory and processing properties of milk produced by feeding a rumen-undegradable fish meal protein supplement to Holstein cows were investigated. The supplement contained (as fed basis) 25% soft-white wheat, 60% herring meal, and 15% feather meal. The total fat level in the milk decreased to 2.43%. For both pasteurized and ultra-high temperature processed drinking milk, no difference was found between fish meal (FM) milk and control milk in terms of color, flavor and flavor stability; in particular, no oxidized flavor was observed. Cheddar cheese made from FM milk ripened faster after 3 mo of ripening and developed a more desirable texture and stronger Cheddar flavor. The yield efficiencies for FM and control cheese, 94.4 (+/- 2.44 SE) and 96.4 (+/- 2.26 SE), respectively, were not different. Relative to controls, average fat globule size was smaller in FM milk and churning time of FM cream was longer. FM butter had softer texture and better cold spreadability, and butter oils from FM enriched milk had lower dropping points compared to control butter oil (average 32.89 versus 34.06 degrees C). These differences in physical properties of butter fat were greater than expected considering that iodine values were not different. This study demonstrates the feasibility of producing high quality products from milk naturally supplemented with FM, but the results also show that dietary changes affect processing properties.

  13. Sintering Process and Mechanical Property of MWCNTs/HDPE Bulk Composite

    PubMed Central

    Tze-Chi, Hsu; Jie-Ren, Zheng

    2009-01-01

    Studies have proved that increasing polymer matrices by carbon nanotubes to form structural reinforcement and electrical conductivity have significantly improved mechanical and electrical properties at very low carbon nanotubes loading. In other words, increasing polymer matrices by carbon nanotubes to form structural reinforcement can reduce friction coefficient and enhance anti-wear property. However, producing traditional MWCNTs in polymeric materix is an extremely complicated process. Using melt-mixing process or in situ polymerization leads to better dispersion effect on composite materials. In this study, therefore, to simplify MWCNTs /HDPE composite process and increase dispersion, powder was used directly to replace pellet to mix and sinter with MWCNTs. The composite bulks with 0, 0.5, 1, 2 and 4% nanotube content by weight was analyzed under SEM to observe nanotubes dispersion. At this rate, a MWCNTs/HDPE composite bulk with uniformly dispersed MWCNTs was achieved, and through the wear bench (Pin-on-Disk), the wear experiment has accomplished. Accordingly, the result suggests the sintered MWCNTs/HDPE composites amplify the hardness and wear-resist property. PMID:19730688

  14. Enhancing the functional properties and nutritional quality of ice cream with processed amla (Indian gooseberry).

    PubMed

    Goraya, Rajpreet Kaur; Bajwa, Usha

    2015-12-01

    Amla (Indian gooseberry) and its processed products are rich source of vitamin C, phenols, dietary fibre and antioxidants. In contrast, ice cream is a poor source of these phytochemicals and antioxidants; therefore, the present investigation was undertaken to enhance the functional properties and nutritional quality of ice cream with the incorporation of processed amla. Ice cream was prepared using amla shreds, pulp, preserve and candy at 5 to 20 % and powder at 0.5 to 2.0 % levels in ice cream mix prior to freezing. Inclusion of amla products at augmented levels resulted in significant changes in physico-chemical properties and phytochemical content of ice cream. The total solids decreased on addition of shreds and pulp and increased with preserve, candy and powder in ice cream at increasing levels. The functional constituents i.e. fibre, total phenols, tannins, ascorbic acid and antioxidant activity increased with greater level of inclusion. Incorporation of processed amla raised the melting resistance of ice cream and decreased the overrun. The samples with 5 % shreds and pulp, 10 % preserve and candy and 0.5 % powder were found to have highest overall acceptability scores. Inclusion of amla in all the forms i.e. shreds, pulp, preserve, candy and powder enhanced the functional properties and nutritional value of ice cream.

  15. Processing-property relationships in autocalve-cured graphite-fiber/epoxy-resin composites

    SciTech Connect

    Wang, H.T.

    1988-01-01

    Research was conducted to model processing and investigate relationships between processing and physical/mechanical properties in autoclave-cured unidirectional graphite/epoxy composites. Particular attention was given to the cure kinetics, the temperature distribution inside the composite during cure, the chemorheology, the resin flow, and the physical/mechanical properties of the neat resin and its composites. The TGDDM/DDS epoxy system and unidirectional graphite fiber-reinforced composites were chosen for the study. The kinetics of neat resin and its prepreg were evaluated. Changes in temperature distribution in a composite during cure as a function of cure time and position were predicted by solving an energy-balance equation. A modified WLF equation was proposed as a theoretical model to predict changes of the chemoviscosity during cure; experimental data were generated from a cone-and-plate rheometer. Resin flow during cure was characterized by investigating the cross-section area of the composite. Finally, the effect of the curing process on the physical/mechanical properties of neat resin and composite was evaluated. Matrix-dominated failure mode was assessed. Both strength characterization and fracture mechanics test methods were performed.

  16. Effects of material variables and process parameters on properties of investment casting shells

    NASA Astrophysics Data System (ADS)

    Tumurugoti, Priyatham

    Manufacture of investment casting shells is a complex process. The choice of raw materials - refractory powders or grains, binders and additives - affects the properties of investment casting shells. In this study, different systems of shells were prepared, according to a design of experiments, with commercially available raw materials that differ in chemistry, particle size or particle size distribution. Shell strength was measured in green, fired and cooled, and hot conditions and the results were analyzed for strength -- material property relation. Various microstructures of polished cross sections of these shells were characterized using scanning electron microscope. It was determined that the amount of matrix holding the stucco grains was dominant factor affecting green strength. Fired and hot strengths were observed to vary depending on interactions between different phases of matrix and stucco. In addition to the material properties, control of shell building parameters is critical to achieve quality shells. Process parameters affect strength of the shell by providing a means to change the relative amounts of stucco, slurry and porosity. To study the microstructural variations, shells were prepared by varying process parameters like slurry viscosity and stucco size. Data from image analysis of different microstructures were correlated to their respective fired strengths. It was determined that the shells prepared from high viscosity slurry and fine stucco had the highest strength.

  17. Rheology, processing, and mechanical properties of thermoplastic/graphite fiber composites

    SciTech Connect

    Scobbo, J.J. Jr.

    1989-01-01

    Various cause and effect relations between the rheology, processing and mechanical properties of poly(ether ether ketone) (PEEK) and poly(arylene sulfide) (PAS) matrix composites were studied. The test methods and characterization schemes used emphasize novel techniques for characterizing composites that have not been used previously. A dynamic mechanical analyzer has been modified and used to characterize transition temperatures of the neat matrix resins and the 60 volume percent continuous graphite fiber reinforced composites. Transitions related to local order may have been found in PEEK at 380{degree}C and PAS at 345{degree}C. Transitions such as these have not been reported previously using dynamic mechanical analysis. Basic rheological behavior of the resins has been studied using dynamic mechanical analysis. Similar dynamic tests were performed on PEEK and PAS matrix unidirectional prepreg tape-based laminates. Tests were performed for the first time in simple shear with the matrix in the melt state. Simple shear deformation is of interest because it represents flow behavior of laminated composites in processing operations such as thermoforming. A simple model of resin layers between fibrous plates describes the observed behavior. A bending mode dynamic test has been developed to determine laminate softening temperatures. This test has been shown to be beneficial in the characterization of composite elastic properties at room temperature. The test requires less material and labor than other more common mechanical property tests. Processing studies were conducted where the radiative heating of laminates was simulated to determine optimum thermoforming cycle times.

  18. Fatigue properties of magnesium alloy AZ91 processed by severe plastic deformation.

    PubMed

    Fintová, Stanislava; Kunz, Ludvík

    2015-02-01

    Fatigue properties of cast AZ91 magnesium alloy processed by severe plastic deformation were investigated and compared with the properties of the initial cast state. The severe plastic deformation was carried out by equal channel angular pressing (ECAP). The ECAP treatment resulted in a bimodal structure. The bimodality consists in a coexistence of fine grained areas with higher content of Mg17Al12 particles and areas exhibiting larger grains and lower density of Mg17Al12 particles. Improvement of the basic mechanical properties of AZ91 (yield stress, tensile strength and ductility) by ECAP was significant. Also the improvement of the fatigue life in the low-cycle fatigue region was substantial. However the improvement of the fatigue strength in the high-cycle fatigue region was found to be negligible. The endurance limit based on 10(7) cycles for the cast alloy was 80 MPa and for the alloy processed by ECAP 85 MPa. The cyclic plastic response in both states was qualitatively similar; initial softening was followed by a long cyclic hardening. Fatigue cracks in cast alloy initiate in cyclic slip bands which were formed in areas of solid solution. In the case of severe plastic deformed material with bimodal structure two substantially different mechanisms of crack initiation were observed. Crack initiation in slip bands was a preferred process in the areas with large grains whereas the grain boundaries cracking was a characteristic mechanism in the fine grained regions.

  19. Dynamical properties of the two-process model for sleep-wake cycles in infantile autism.

    PubMed

    Matsuura, Hirotsune; Tateno, Katsumi; Aou, Shuji

    2008-09-01

    The two-process model is a scheme for the timing of sleep that consists of homeostatic (Process S) and circadian (Process C) variables. The two-process model exhibits abnormal sleep patterns such as internal desynchronization or sleep fragmentation. Early infants with autism often experience sleep difficulties. Large day-by-day changes are found in the sleep onset and waking times in autistic children. Frequent night waking is a prominent property of their sleep. Further, the sleep duration of autistic children is often fragmented. These sleep patterns in infants with autism are not fully understood yet. In the present study, the sleep patterns in autistic children were reproduced by a modified two-process model using nonlinear analysis. A nap term was introduced into the original two-process model to reproduce the sleep patterns in early infants. The nap term and the time course of Process S are mentioned in the present study. Those parameters led to bifurcation of the sleep-wake cycle in the modified two-process model. In a certain range of these parameter sets, a small external noise was amplified, and an irregular sleep-wake cycle appeared. The short duration of sleep led to another irregular sleep onset or waking. Consequently, an irregular sleep-wake cycle appeared in early infantile autism.

  20. 24 CFR 203.666 - Processing defaulted mortgages on property in Allegany Reservation of Seneca Nation of Indians.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... property in Allegany Reservation of Seneca Nation of Indians. 203.666 Section 203.666 Housing and Urban... INSURANCE Servicing Responsibilities Assignment and Forbearance-Property in Allegany Reservation of Seneca Indians § 203.666 Processing defaulted mortgages on property in Allegany Reservation of Seneca Nation...

  1. 24 CFR 203.666 - Processing defaulted mortgages on property in Allegany Reservation of Seneca Nation of Indians.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... property in Allegany Reservation of Seneca Nation of Indians. 203.666 Section 203.666 Housing and Urban... INSURANCE Servicing Responsibilities Assignment and Forbearance-Property in Allegany Reservation of Seneca Indians § 203.666 Processing defaulted mortgages on property in Allegany Reservation of Seneca Nation...

  2. Structure-Property-Processing Correlations in Freeze-Cast Hybrid Scaffolds

    NASA Astrophysics Data System (ADS)

    Hunger, Philipp Malte

    Porous materials are highly sought after for applications ranging from catalyst carriers to tissue scaffolds. Most applications require clearly defined structural features and a specific mechanical performance. Therefore, it is essential to establish systematic structure-property-processing correlations to be able to tailor both structure and mechanical properties for a particular application. Because the introduction of porosity is detrimental to the mechanical performance of highly porous structures, it is necessary to generate a structure that allows for the mechanical properties to be maximized. One example for such a structure are honeycombs. In addition to the porosity and pore morphology, the scaffold's performance depends on the properties inherent to the material from which it is made. Polymeric foams possess high toughness but low stiffness, whereas ceramic foams possess high stiffness but low toughness. Natural composites like bone, antler and nacre have both high stiffness and high toughness. This unusual set of mechanical properties is thought to be intricately linked to the multi-level hierarchical composite structure present in these materials. Great potential for the fabrication of stiff, strong and tough porous scaffolds is thus seen in nacre-like composite materials with a hierarchical, honeycomb-like structure. Freeze casting is a method with which such hybrid materials can be made, adding the third dimension to nacre by forming a highly porous, hierarchical bulk material, with dense, nacre-like cell walls. The nacre-like cell walls self-assemble during the directional freezing of a water-based ceramic-polymer slurry. Reported here are structure-property-processing correlations observed in these materials. They are unusual, because they are, like nacre, solely glued by a polymeric phase and not processed further by sintering. The results illustrate several pathways to control both structure and mechanical properties in freeze-cast composites and

  3. Effect of wastewater treatment processes on the pyrolysis properties of the pyrolysis tars from sewage sludges

    NASA Astrophysics Data System (ADS)

    Wu, Xia; Xie, Li-Ping; Li, Xin-Yu; Dai, Xiao-Hong; Fei, Xue-Ning; Jiang, Yuan-Guang

    2011-06-01

    The pyrolysis properties of five different pyrolysis tars, which the tars from 1# to 5# are obtained by pyrolyzing the sewage sludges of anaerobic digestion and indigestion from the A2/O wastewater treatment process, those from the activated sludge process and the indigested sludge from the continuous SBR process respectively, were studied by thermal gravimetric analysis at a heating rate of 10 °C/min in the nitrogen atmosphere. The results show that the pyrolysis processes of the pyrolysis tars of 1#, 2#, 3# and 5# all can be divided into four stages: the stages of light organic compounds releasing, heavy polar organic compounds decomposition, heavy organic compounds decomposition and the residual organic compounds decomposition. However, the process of 4# pyrolysis tar is only divided into three stages: the stages of light organic compounds releasing, decomposition of heavy polar organic compounds and the residual heavy organic compounds respectively. Both the sludge anaerobic digestion and the "anaerobic" process in wastewater treatment processes make the content of light organic compounds in tars decrease, but make that of heavy organic compounds with complex structure increase. Besides, both make the pyrolysis properties of the tars become worse. The pyrolysis reaction mechanisms of the five pyrolysis tars have been studied with Coats-Redfern equation. It shows that there are the same mechanism functions in the first stage for the five tars and in the second and third stage for the tars of 1#, 2#, 3# and 5#, which is different with the function in the second stage for 4# tar. The five tars are easy to volatile.

  4. Effect of emulsifying salts on the physicochemical properties of processed cheese made from Mozzarella.

    PubMed

    Chen, L; Liu, H

    2012-09-01

    The aim of this study was to investigate the effect of different types and concentrations of emulsifying salts (trisodium citrate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and disodium orthophosphate) on the physicochemical properties of processed cheese. The physicochemical composition, texture profile, degree of casein dissociation, fat particle size, color, and nuclear magnetic resonance profile (NMR) of processed cheese were determined. Hardness, degree of casein dissociation, and pH increased as the concentration of emulsifying salts increased. The fat particle size of processed cheese was significantly influenced by the type of emulsifying salts, with processed cheese made with sodium hexametaphosphate having larger particles (4.68 µm) than cheeses made with the other salts (from 2.71 to 3.30 µm). The processed cheese prepared with trisodium citrate was whiter than those prepared with the other emulsifying salts. The NMR analysis showed that the relaxation time of processed cheese of 10 to 100 ms accounted for a major proportion, indicating that the moisture in processed cheese was mainly bound water combined with the fat globule and hydrated casein.

  5. Casein peptization, functional properties, and sensory acceptance of processed cheese spreads made with different emulsifying salts.

    PubMed

    Cunha, Clarissa R; Viotto, Walkiria H

    2010-01-01

    "Requeijão cremoso" is a traditional Brazilian processed cheese spread, showing ample acceptance on the national market. Emulsifying salts (ES) are an important factor influencing the characteristics of processed cheeses, but the literature presents conflicting results about their action on cheese functionality. Requeijão cremoso obtained from anhydrous ingredients allows the study of the influence of each type of ES on the cheese properties, since it can be treated as a model system where the variables are limited and well known. The objective of this study was to evaluate the effect of different types of ES (TSC-sodium citrate, SHMP-sodium hexametaphosphate, STPP-sodium tripolyphosphate, and TSPP-tetrasodium pyrophosphate) on the sensory and functional characteristics of requeijão cremoso-processed cheeses obtained from anhydrous ingredients. The physicochemical composition, degree of casein dissociation, fat particle size, melting index, color, texture profile, and sensory acceptance of the cheeses were determined. The functional behavior of processed cheeses was strongly influenced by the type of ES and its physicochemical properties including its ability to bind Ca, the casein dispersion during cooking, and the possible creation of cross-links with casein during cooling. The cheese made with SHMP was the one most differentiated from the others, presenting lower melting index, whiter color, and higher values for hardness, gumminess, and adhesiveness. The differences in texture had an impact on sensory acceptance: with the exception of the sample manufactured with sodium hexametaphosphate, all the samples presented good sensory acceptance.

  6. Ionization Properties of Molecules Commonly Used for Plasma Processing of Semi-Conductors

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.

    2000-01-01

    Two types of processes are involved in plasma processing of semi-conductors. They are: plasma etching or cleaning and plasma deposition of the semi-conducting materials. For plasma etching of semi-conductors mostly halogen containing gases are used as additives to gases such as O2 and N2. For plasma deposition gases such as C2H2, SiH4, Si2H6 have been tested in the past. For an optimal performance of a reactor it is important to model the plasma. In this modeling effort electron impact excitation and ionization cross sections play a central role. For ionization balance calculations values of ionization cross sections are needed. Ion molecule reactions determine the ultimate composition of the plasma. Recently it has been discovered that the by products of many of these plasmas are per fluro hydrocarbons (PFCs) which are highly infrared absorbing species and have long life times in the atmosphere. They cause global warming. A lot of research is being pursued at the present time to find alternative molecules which do not produce global warming gases as the and product of the plasma processing reactor. There is also interest in the ionization and dissociative ionization properties of these molecules from the point view of the plasma abatement of the pollutant gases at the exhaust of the semi-conductor processing reactors. At the conference ionization and dissociative ionization properties of some of these molecules will be presented.

  7. Effect of extrusion processing on immune activation properties of hazelnut protein in a mouse model.

    PubMed

    Ortiz, Tina; Para, Radhakrishna; Gonipeta, Babu; Reitmeyer, Mike; He, Yingli; Srkalovic, Ines; Ng, Perry K W; Gangur, Venu

    2016-09-01

    Although food processing can alter food allergenicity, the impact of extrusion processing on in vivo hazelnut allergenicity is unknown. Here, we tested the hypothesis that extrusion processing will alter the immune activation properties of hazelnut protein (HNP) in mice. Soluble extrusion-processed HNP (EHNP) was prepared and evaluated for immune response using an established transdermal sensitization mouse model. Mice were sensitized with identical amounts of EHNP versus raw HNP. After confirming systemic IgE, IgG1 and IgG2a antibody responses, oral hypersensitivity reaction was quantified by hypothermia shock response (HSR). Mechanism was studied by measuring mucosal mast cell (MMC) degranulation. Compared to raw HNP, the EHNP elicited slower but similar IgE antibody (Ab) response, lower IgG1 but higher IgG2a Ab response. The EHNP exhibited significantly lower oral HSR as well as MMC degranulation capacity. These results demonstrate that the extrusion technology can be used to produce soluble HNP with altered immune activation properties.

  8. Study on parameters affecting the mechanical properties of dry fiber bundles during continuous composite manufacturing processes

    NASA Astrophysics Data System (ADS)

    Maier, A.; Schledjewski, R.

    2016-07-01

    For continuous manufacturing processes mechanical preloading of the fibers occurs during the delivery of the fibers from the spool creel to the actual manufacturing process step. Moreover preloading of the dry roving bundles might be mandatory, e.g. during winding, to be able to produce high quality components. On the one hand too high tensile loads within dry roving bundles might result in a catastrophic failure and on the other hand the part produced under too low pre-tension might have low quality and mechanical properties. In this work, load conditions influencing mechanical properties of dry glass fiber bundles during continuous composite manufacturing processes were analyzed. Load conditions, i.e. fiber delivery speed, necessary pre-tension and other effects of the delivery system during continuous fiber winding, were chosen in process typical ranges. First, the strain rate dependency under static tensile load conditions was investigated. Furthermore different free gauge lengths up to 1.2 m, interactions between fiber points of contact regarding influence of sizing as well as impregnation were tested and the effect of twisting on the mechanical behavior of dry glass fiber bundles during the fiber delivery was studied.

  9. The influence of stoichiometry on electrical properties of silicon carbide grown by physical vapor transport process

    NASA Astrophysics Data System (ADS)

    Li, Qiang

    The purposes of this thesis were to investigate the influence of the vapor phase stoichiometry in the ambient on electrical properties of silicon carbide grown by physical vapor transport (PVT) process in order to provide a better understanding of the nature of the compensation mechanisms in semi-insulating SiC crystals. Standard PVT and hydrogen-assisted PVT processes have been used to grow SiC single crystals. Chemical elemental analysis, contactless resistivity mapping (COREMA), temperature dependent Hall measurements (TDH), deep level transient spectroscopy (DLTS), and minority diffusion length measurements were performed to characterize the properties of SiC wafers. The nitrogen contamination, the net carrier concentrations, and the concentrations of the major deep traps in the undoped and nitrogen-doped SiC crystals were found to substantially decrease during the standard PVT growth when moving from seed to tail of the crystal. Addition of hydrogen to the growth ambient changed all the properties in the same direction. As a consequence of the doping and deep traps variations, the electrical properties including resistivity, Fermi energy, and minority carrier lifetime continuously changed during the growth. The results of the hydrogen-assisted PVT growth and the virtual reactor growth modeling indicated that the electrical properties change as a function of stoichiometry in the vapor phase, and the carbon transport efficiency can be enhanced by the reactions of hydrogen with the SiC charge material and the graphite parts of the crucible. Thermodynamic calculation of the vapor phase stoichiometry and the studies of the properties of H2-assisted PVT-grown crystals have shown that hydrogen can be used as a key factor controlling the vapor phase stoichiometry in the PVT process; in this manner the purity, electrical uniformities and the yield of the semi-insulating wafers can be improved to a great extent. The electron mobility values were found unusually low in

  10. Microstructural and bulk property changes in hardened cement paste during the first drying process

    SciTech Connect

    Maruyama, Ippei; Nishioka, Yukiko; Igarashi, Go; Matsui, Kunio

    2014-04-01

    This paper reports the microstructural changes and resultant bulk physical property changes in hardened cement paste (hcp) during the first desorption process. The microstructural changes and solid-phase changes were evaluated by water vapor sorption, nitrogen sorption, ultrasonic velocity, and {sup 29}Si and {sup 27}Al nuclear magnetic resonance. Strength, Young's modulus, and drying shrinkage were also examined. The first drying process increased the volume of macropores and decreased the volume of mesopores and interlayer spaces. Furthermore, in the first drying process globule clusters were interconnected. During the first desorption, the strength increased for samples cured at 100% to 90% RH, decreased for 90% to 40% RH, and increased again for 40% to 11% RH. This behavior is explained by both microstructural changes in hcp and C–S–H globule densification. The drying shrinkage strains during rapid drying and slow drying were compared and the effects of the microstructural changes and evaporation were separated.

  11. Properties of Nb3Al Wires Processed by Double Rapid Heating and Quenching

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Kikuchi, A.; Takeuchi, T.; Banno, N.; Iijima, Y.; Nimori, S.; Takigawa, H.; Yoshida, M.; Tomita, K.; Kato, S.; Takao, T.; Nakamoto, T.; Nakagawa, K.

    We have been developing Nb3Al wires processed by rapid heating and quenching for a number of years as promising candidates for use in future high-field accelerator magnets. These wires have better strain and stress tolerances than Nb3Sn wires do, but to meet the demands of future accelerator magnet designs, it is necessary to further improve their performance. In particular,it is necessary to increase their non-copper critical current density in 12-20T fields. To pursue this goal, we introduced double rapid heating and quenching (DRHQ) treatment into the fabrication process for Nb3Al wires, and studied the mechanical and superconducting properties of the resulting DRHQ-processed wires.

  12. Developments in the processing and properties of particulate Al-Si composites

    NASA Astrophysics Data System (ADS)

    Ejiofor, J. U.; Reddy, R. G.

    1997-11-01

    In the past ten years, materials R&D has shifted from monolithic to composite materials, adjusting to the global need for reduced weight, low cost, quality, and high performance in structural materials. This article reviews developments in the molten processing of particulate Al-Si alloy composites and their respective properties. Existing and emerging processing innovations are discussed, and the reinforcement phases in prominent R&D activities are identified. The vortex (or mixing) method continues to be the most popular processing method in use because of its ease of operation, total production cost, and suitability, while the infiltration, compocasting (or rheocasting), in-situ, and spray atomization and codeposition techniques receive less attention.

  13. Thermoelectric plastics: from design to synthesis, processing and structure–property relationships

    PubMed Central

    Kroon, Renee; Mengistie, Desalegn Alemu; Kiefer, David; Hynynen, Jonna; Ryan, Jason D.; Yu, Liyang

    2016-01-01

    Thermoelectric plastics are a class of polymer-based materials that combine the ability to directly convert heat to electricity, and vice versa, with ease of processing. Potential applications include waste heat recovery, spot cooling and miniature power sources for autonomous electronics. Recent progress has led to surging interest in organic thermoelectrics. This tutorial review discusses the current trends in the field with regard to the four main building blocks of thermoelectric plastics: (1) organic semiconductors and in particular conjugated polymers, (2) dopants and counterions, (3) insulating polymers, and (4) conductive fillers. The design and synthesis of conjugated polymers that promise to show good thermoelectric properties are explored, followed by an overview of relevant structure–property relationships. Doping of conjugated polymers is discussed and its interplay with processing as well as structure formation is elucidated. The use of insulating polymers as binders or matrices is proposed, which permit the adjustment of the rheological and mechanical properties of a thermoelectric plastic. Then, nanocomposites of conductive fillers such as carbon nanotubes, graphene and inorganic nanowires in a polymer matrix are introduced. A case study examines poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, which up to now have shown the most promising thermoelectric performance. Finally, a discussion of the advantages provided by bulk architectures e.g. for wearable applications highlights the unique advantages that thermoelectric plastics promise to offer. PMID:27385496

  14. Thermoelectric plastics: from design to synthesis, processing and structure-property relationships.

    PubMed

    Kroon, Renee; Mengistie, Desalegn Alemu; Kiefer, David; Hynynen, Jonna; Ryan, Jason D; Yu, Liyang; Müller, Christian

    2016-11-07

    Thermoelectric plastics are a class of polymer-based materials that combine the ability to directly convert heat to electricity, and vice versa, with ease of processing. Potential applications include waste heat recovery, spot cooling and miniature power sources for autonomous electronics. Recent progress has led to surging interest in organic thermoelectrics. This tutorial review discusses the current trends in the field with regard to the four main building blocks of thermoelectric plastics: (1) organic semiconductors and in particular conjugated polymers, (2) dopants and counterions, (3) insulating polymers, and (4) conductive fillers. The design and synthesis of conjugated polymers that promise to show good thermoelectric properties are explored, followed by an overview of relevant structure-property relationships. Doping of conjugated polymers is discussed and its interplay with processing as well as structure formation is elucidated. The use of insulating polymers as binders or matrices is proposed, which permit the adjustment of the rheological and mechanical properties of a thermoelectric plastic. Then, nanocomposites of conductive fillers such as carbon nanotubes, graphene and inorganic nanowires in a polymer matrix are introduced. A case study examines poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, which up to now have shown the most promising thermoelectric performance. Finally, a discussion of the advantages provided by bulk architectures e.g. for wearable applications highlights the unique advantages that thermoelectric plastics promise to offer.

  15. Structures, properties, and energy-storage mechanisms of the semi-lunar process cuticles in locusts.

    PubMed

    Wan, Chao; Hao, Zhixiu; Feng, Xiqiao

    2016-10-17

    Locusts have excellent jumping and kicking abilities to survive in nature, which are achieved through the energy storage and release processes occurring in cuticles, especially in the semi-lunar processes (SLP) at the femorotibial joints. As yet, however, the strain energy-storage mechanisms of the SLP cuticles remain unclear. To decode this mystery, we investigated the microstructure, material composition, and mechanical properties of the SLP cuticle and its remarkable strain energy-storage mechanisms for jumping and kicking. It is found that the SLP cuticle of adult Locusta migratoria manilensis consists of five main parts that exhibit different microstructural features, material compositions, mechanical properties, and biological functions in storing strain energy. The mechanical properties of these five components are all transversely isotropic and strongly depend on their water contents. Finite element simulations indicate that the two parts of the core region of the SLP cuticle likely make significant contributions to its outstanding strain energy-storage ability. This work deepens our understanding of the locomotion behaviors and superior energy-storage mechanisms of insects such as locusts and is helpful for the design and fabrication of strain energy-storage devices.

  16. Structures, properties, and energy-storage mechanisms of the semi-lunar process cuticles in locusts

    PubMed Central

    Wan, Chao; Hao, Zhixiu; Feng, Xiqiao

    2016-01-01

    Locusts have excellent jumping and kicking abilities to survive in nature, which are achieved through the energy storage and release processes occurring in cuticles, especially in the semi-lunar processes (SLP) at the femorotibial joints. As yet, however, the strain energy-storage mechanisms of the SLP cuticles remain unclear. To decode this mystery, we investigated the microstructure, material composition, and mechanical properties of the SLP cuticle and its remarkable strain energy-storage mechanisms for jumping and kicking. It is found that the SLP cuticle of adult Locusta migratoria manilensis consists of five main parts that exhibit different microstructural features, material compositions, mechanical properties, and biological functions in storing strain energy. The mechanical properties of these five components are all transversely isotropic and strongly depend on their water contents. Finite element simulations indicate that the two parts of the core region of the SLP cuticle likely make significant contributions to its outstanding strain energy-storage ability. This work deepens our understanding of the locomotion behaviors and superior energy-storage mechanisms of insects such as locusts and is helpful for the design and fabrication of strain energy-storage devices. PMID:27748460

  17. Structures, properties, and energy-storage mechanisms of the semi-lunar process cuticles in locusts

    NASA Astrophysics Data System (ADS)

    Wan, Chao; Hao, Zhixiu; Feng, Xiqiao

    2016-10-01

    Locusts have excellent jumping and kicking abilities to survive in nature, which are achieved through the energy storage and release processes occurring in cuticles, especially in the semi-lunar processes (SLP) at the femorotibial joints. As yet, however, the strain energy-storage mechanisms of the SLP cuticles remain unclear. To decode this mystery, we investigated the microstructure, material composition, and mechanical properties of the SLP cuticle and its remarkable strain energy-storage mechanisms for jumping and kicking. It is found that the SLP cuticle of adult Locusta migratoria manilensis consists of five main parts that exhibit different microstructural features, material compositions, mechanical properties, and biological functions in storing strain energy. The mechanical properties of these five components are all transversely isotropic and strongly depend on their water contents. Finite element simulations indicate that the two parts of the core region of the SLP cuticle likely make significant contributions to its outstanding strain energy-storage ability. This work deepens our understanding of the locomotion behaviors and superior energy-storage mechanisms of insects such as locusts and is helpful for the design and fabrication of strain energy-storage devices.

  18. Processing and Properties of Vacuum Assisted Resin Transfer Molded Phenylethynyl Terminated Imide Composites

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Ghose, Sayata; Watson, Kent A.; Chunchu, Prasad B.; Jensen, Brian J.; Connell, John W.

    2012-01-01

    Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems that can be processed without the use of an autoclave for advanced aerospace applications. Due to their low melt viscosities and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature vacuum assisted resin transfer molding (HT-VARTM). VARTM has shown the potential to reduce the manufacturing cost of composite structures. In the current study, two PETI resins, LARC(Trademark) PETI-330 and LARC(Trademark) PETI-9, were infused into carbon fiber preforms at 260 C and cured at temperatures up to 371 C. Photomicrographs of polished cross sections were taken and void contents, determined by acid digestion, were below 4.5%. Mechanical properties including short block compression (SBC), compression after impact (CAI), and open hole compression (OHC) were determined at room temperature, 177 C, and 288 C. Both PETI-9 and PETI-330 composites demonstrated very good retention of mechanical properties at elevated temperatures. SBC and OHC properties after aging for 1000 hours at temperatures up to 288 C were also determined.

  19. The Lognormal Race: A Cognitive-Process Model of Choice and Latency with Desirable Psychometric Properties.

    PubMed

    Rouder, Jeffrey N; Province, Jordan M; Morey, Richard D; Gomez, Pablo; Heathcote, Andrew

    2015-06-01

    We present a cognitive process model of response choice and response time performance data that has excellent psychometric properties and may be used in a wide variety of contexts. In the model there is an accumulator associated with each response option. These accumulators have bounds, and the first accumulator to reach its bound determines the response time and response choice. The times at which accumulator reaches its bound is assumed to be lognormally distributed, hence the model is race or minima process among lognormal variables. A key property of the model is that it is relatively straightforward to place a wide variety of models on the logarithm of these finishing times including linear models, structural equation models, autoregressive models, growth-curve models, etc. Consequently, the model has excellent statistical and psychometric properties and can be used in a wide range of contexts, from laboratory experiments to high-stakes testing, to assess performance. We provide a Bayesian hierarchical analysis of the model, and illustrate its flexibility with an application in testing and one in lexical decision making, a reading skill.

  20. Psychometric properties of the Norwegian version of the Care Process Self-Evaluation Tool.

    PubMed

    Størkson, Sverre; Biringer, Eva; Hartveit, Miriam; Aßmus, Jörg; Vanhaecht, Kris

    2016-11-01

    The Care Process Self-Evaluation Tool (CPSET) assesses key characteristics of well-organised care processes in hospitals from an interprofessional team perspective. The present study investigated the psychometric properties of the CPSET in terms of factor structure, convergent and discriminant validity, and reliability in Norwegian language and context. After a pilot test, the Norwegian version of the questionnaire was administered as a web form to 501 health professionals in public general hospitals and mental health specialist services; 301 completed forms (response rate 60%) were returned, and 268 (54%) forms representing 27 care processes (19 from somatic care and 8 from mental healthcare) were included in the valid sample. A confirmatory factor analysis (CFA) confirmed the original five-factor structure. All model fit indices, including the standardised root mean square residual (SRMR), which is independent of the χ(2)-test, met the criteria for an acceptable model fit. Internal consistencies within sub-scales as measured by Cronbach's alpha were high (range 0.83-0.94). As expected, some redundancy between factors existed (in particular among the PO (Patient-focused organisation), COR (Coordination of the care process), COM (Communication with patient and family), and PO (Follow-up of the care process) factors). In conclusion, the Norwegian CPSET scale showed acceptable psychometric properties in terms of convergent validity and reliability, and fit indices from the CFA confirmed the original factor structure. Based on these findings, we recommend the Norwegian version of the CPSET for use in the assessment of interprofessional teamwork in care processes in specialist healthcare.

  1. Comparisons of chemical and physical properties of catfish oils prepared from different extracting processes.

    PubMed

    Sathivel, S; Yin, H; Prinyawiwatkul, W; King, J M

    2009-03-01

    Four different catfish oil extraction processes were used to extract oil from catfish viscera: process CF1 involved a mixture of ground catfish viscera and water, no heat treatment, and centrifugation; process CF2 involved ground catfish viscera (no added water), heat treatment, and centrifugation; process CF3 involved a mixture of ground catfish viscera and water, heat treatment, and centrifugation; process CF4 involved ground catfish viscera, enzymatic hydrolysis, and centrifugation. Chemical and physical properties of the resulting of catfish oils were evaluated. The CF4 process recovered significantly higher amounts of crude oil from catfish viscera than the other 3 extraction methods. The CF4 oil contained a higher percent of free fatty acid and peroxide values than CF1, CF2, and CF3 oils. Oleic acid in catfish oil was the predominant fatty acid accounting for about 50% of total fatty acids. Weight loss of oils increased with increasing temperatures between 250 and 500 degrees C. All the catfish oil samples melted around -32 degrees C regardless of the extraction methods. The flow behavior index of all the oil samples was less than 1, which indicated that the catfish oils exhibited non-Newtonian fluid behavior. The apparent viscosity at -5 and 0 degrees C was significantly higher (P < 0.05) than those at 5, 10, 15, 20, 25, and 30 degrees C. The average magnitude of activation energy for apparent viscosity of the oil was higher for CF2 than CF1, CF3, and CF4.

  2. Influence of thermal processing on the properties of chlorpheniramine maleate tablets containing an acrylic polymer.

    PubMed

    Zhu, Yucun; Shah, Navnit H; Malick, A Waseem; Infeld, Martin H; McGinity, James W

    2002-11-01

    The purpose of this investigation was to determine the effects of thermal processing and post-processing thermal treatment on the release properties of chlorpheniramine maleate (CPM) from matrix tablets containing Eudragit RS PO and triethyl citrate (TEC). CPM tablets containing Eudragit RS PO with and without TEC were prepared by direct compression (DC), high shear hot-melt granulation (HMG), and hot-melt extrusion (HME). X-ray diffraction patterns showed that the CPM was distributed in Eudragit RS PO at the molecular level following HME. The thermogravimetry analysis (TGA) profiles of CPM, Eudragit RS PO, and TEC demonstrated that these materials were thermally stable during both the high shear HMG and HME processes. The tablets were subjected to post-processing thermal treatment by storing the tablets at 60 degrees C in open containers for 24 hr. Tablets prepared by DC showed the highest drug release rate constant of 36.2% hr-1/2. When 4% TEC was incorporated into the formulation, the drug release rate constant for the directly compressed tablets decreased to 32.4% hr-1/2. After high shear HMG and HME of the powder blend containing 4% TEC, the drug release rate constant decreased to 30.8 and 13.8% hr-1/2 for the respective processes. The drug release rate constants for all tablets decreased following post-processing thermal treatment. The reduction in release rate was due to an increase in the intermolecular binding and entanglement between drug molecules and polymer molecules that occurred during thermal processing. Post-processing thermal treatment of the hot-melt extrudates had a minimal effect on the drug release rate since the HME process enhanced the drug and polymer entanglement to a greater extent.

  3. Effect of tetrasodium pyrophosphate concentration and cooking time on the physicochemical properties of process cheese.

    PubMed

    Shirashoji, N; Aoyagi, H; Jaeggi, J J; Lucey, J A

    2016-09-01

    Tetrasodium pyrophosphate (TSPP) is widely used as an emulsifying salt (ES) in process cheese. Previous reports have indicated that TSPP exhibits some unusual properties, including the gelation of milk proteins at specific ES concentrations. We studied the effect of various concentrations (0.25-2.75%) of TSPP and cooking times (0-20min) on the rheological, textural, and physical properties of pasteurized process Cheddar cheese using a central composite rotatable experimental design. Cheeses were made with a constant pH value to avoid pH as a confounding factor. Modeling of the textural properties of process cheese made with TSPP exhibited complex behavior, with polynomial models (cubic) giving better predictions (higher coefficient of determination values) than simpler quadratic models. Meltability indices (degree of flow from the UW MeltProfiler (University of Wisconsin-Madison), loss tangent value at 60°C from rheological testing, and Schreiber melt area) initially decreased with increasing TSPP concentrations, but above a critical ES concentration (~1.0%) meltability increased at higher TSPP concentrations. The storage modulus values measured at 70°C for process cheese initially increased with increasing TSPP concentration, but above a concentration of 1% ES, the storage modulus values decreased. Cooking time had little effect on the various melting or rheological properties. With an increase in TSPP concentration, the insoluble Ca and P contents increased, suggesting that TSPP addition resulted in the formation of insoluble calcium pyrophosphate complexes; some of which were likely associated with caseins. A portion of the added TSPP remained in the soluble phase. The acid-base buffering profiles also indicated that calcium pyrophosphate complexes were formed in cheese made with TSPP. In milk systems, low levels of TSPP have been shown to induce protein crosslinking and gelation, whereas at higher TSPP concentrations milk gelation was inhibited due to

  4. The structure-property relationships of powder processed Fe-Al-Si alloys

    SciTech Connect

    Prichard, Paul D.

    1998-02-23

    Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) process to obtain a high fraction of metal injection molding (MIM) quality powder (D84 < 32 μm). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 μm. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 μm to 104 μm. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase α + DO3 structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

  5. Investigation of radiation keeping property of barite coated cloth via image processing method

    SciTech Connect

    Kilincarslan, S.; Akkurt, I.; Molla, T.; Akarslan, F.

    2012-09-06

    Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

  6. Microstructural characteristics and mechanical properties of Al-2024 alloy processed via a rheocasting route

    NASA Astrophysics Data System (ADS)

    Rahimi, Behnam; Khosravi, Hamed; Haddad-Sabzevar, Mohsen

    2015-01-01

    This article reports the effects of stirring speed and T6 heat treatment on the microstructure and mechanical properties of Al-2024 alloy synthesized by a rheocasting process. There was a decrease in grain size of α-Al particles corresponding to an increase in stirring speed. By increasing the stirring speed, however, the globularity of matrix particles first increased and then declined. It was also found that the hardness, compressive strength, and compressive strain increased with the increase of stirring speed. Microstructural studies revealed the presence of nonsoluble Al15(CuFeMn)3Si2 phase in the vicinity of CuAl2 in the rheocast samples. The required time for the solution treatment stage was also influenced by stirring speed; the solution treatment time decreased with the increase in stirring speed. Furthermore, the rheocast samples required a longer homogenization period compared to conventionally wrought alloys. Improvements in hardness and compressive properties were observed after T6 heat treatment.

  7. Mechanical properties of metals for biomedical applications using powder metallurgy process: A review

    NASA Astrophysics Data System (ADS)

    Dewidar, Montasser Marasy; Yoon, Ho-Chel; Lim, Jae Kyoo

    2006-06-01

    The uses of biomaterials have been revolutionizing the biomedical field in deployment as implants for humans. During the past five decades, many implant materials made of metals have been put into practical use. Powder metallurgy techniques have been used to produce controlled porous structures, such as porous coatings applied for dental and orthopedic surgical implants, which allow bony tissue ingrowth within the implant surface, thereby improving fixation. This paper examines various important metals using powder metallurgy technology to produce elements of a total hip replacement. These alloys are 316L stainless steel alloy, Co-Cr-Mo alloy, and Ti-6Al-4V alloy. Also, this paper examines current information on the mechanical properties. Mechanical properties are discussed as a function of type of materials and process of fabrication. This article addresses the engineering aspects concerning the advantages and disadvantages of each type of material.

  8. Chemical composition, functional properties and processing of carrot-a review.

    PubMed

    Sharma, Krishan Datt; Karki, Swati; Thakur, Narayan Singh; Attri, Surekha

    2012-02-01

    Carrot is one of the important root vegetables rich in bioactive compounds like carotenoids and dietary fibers with appreciable levels of several other functional components having significant health-promoting properties. The consumption of carrot and its products is increasing steadily due to its recognition as an important source of natural antioxidants having anticancer activity. Apart from carrot roots being traditionally used in salad and preparation of curries in India, these could commercially be converted into nutritionally rich processed products like juice, concentrate, dried powder, canned, preserve, candy, pickle, and gazrailla. Carrot pomace containing about 50% of β-carotene could profitably be utilized for the supplementation of products like cake, bread, biscuits and preparation of several types of functional products. The present review highlights the nutritional composition, health promoting phytonutrients, functional properties, products development and by-products utilization of carrot and carrot pomace along with their potential application.

  9. Nanosilver Biocidal Properties and Their Application in Disinfection of Hatchers in Poultry Processing Plants.

    PubMed

    Banach, Marcin; Tymczyna, Leszek; Chmielowiec-Korzeniowska, Anna; Pulit-Prociak, Jolanta

    2016-01-01

    The aim of this study was to use aqueous suspensions of silver nanoparticles with a wide spectrum of particle sizes, variable morphology, high stability, and appropriate physicochemical properties to examine their bactericidal and fungicidal properties against microorganisms present in poultry processing plants. At the same time, the particles were tested for preventing the production of odorogenous pollutants during incubation and thereby reducing the emission of harmful gases from such types of facilities. The results show that the use of nanosilver preparations in order to disinfect eggs and hatchers reduced microbiological contamination. The bactericidal and fungicidal efficacy of the applied preparation was comparable to UV radiation and its effectiveness increasing during the incubation. Good results were achieved in terms of the level of organic gaseous contaminants, which decreased by 86% after the application of the nanosilver preparation.

  10. Nanosilver Biocidal Properties and Their Application in Disinfection of Hatchers in Poultry Processing Plants

    PubMed Central

    Banach, Marcin; Tymczyna, Leszek; Chmielowiec-Korzeniowska, Anna; Pulit-Prociak, Jolanta

    2016-01-01

    The aim of this study was to use aqueous suspensions of silver nanoparticles with a wide spectrum of particle sizes, variable morphology, high stability, and appropriate physicochemical properties to examine their bactericidal and fungicidal properties against microorganisms present in poultry processing plants. At the same time, the particles were tested for preventing the production of odorogenous pollutants during incubation and thereby reducing the emission of harmful gases from such types of facilities. The results show that the use of nanosilver preparations in order to disinfect eggs and hatchers reduced microbiological contamination. The bactericidal and fungicidal efficacy of the applied preparation was comparable to UV radiation and its effectiveness increasing during the incubation. Good results were achieved in terms of the level of organic gaseous contaminants, which decreased by 86% after the application of the nanosilver preparation. PMID:26903785

  11. Studies of Thermophysical Properties of Metals and Semiconductors by Containerless Processing Under Microgravity

    NASA Technical Reports Server (NTRS)

    Seidel, A.; Soellner, W.; Stenzel, C.

    2012-01-01

    Electromagnetic levitation under microgravity provides unique opportunities for the investigation of liquid metals, alloys and semiconductors, both above and below their melting temperatures, with minimized disturbances of the sample under investigation. The opportunity to perform such experiments will soon be available on the ISS with the EML payload which is currently being integrated. With its high-performance diagnostics systems EML allows to measure various physical properties such as heat capacity, enthalpy of fusion, viscosity, surface tension, thermal expansion coefficient, and electrical conductivity. In studies of nucleation and solidification phenomena the nucleation kinetics, phase selection, and solidification velocity can be determined. Advanced measurement capabilities currently being studied include the measurement and control of the residual oxygen content of the process atmosphere and a complementary inductive technique to measure thermophysical properties.

  12. Method of manipulating the chemical properties of water to improve the effectiveness of a desired process

    DOEpatents

    Hawthorne, Steven B.; Miller, David J.; Lagadec, Arnaud Jean-Marie; Hammond, Peter James; Clifford, Anthony Alan

    2002-01-01

    The method of the present invention is adapted to manipulate the chemical properties of water in order to improve the effectiveness of a desired process. The method involves heating the water in the vessel to subcritical temperatures between 100.degree. to 374.degree. C. while maintaining sufficient pressure to the water to maintain the water in the liquid state. Various physiochemical properties of the water can be manipulated including polarity, solute solubility, surface tension, viscosity, and the disassociation constant. The method of the present invention has various uses including extracting organics from solids and semisolids such as soil, selectively extracting desired organics from liquids, selectively separating organics using sorbent phases, enhancing reactions by controlling the disassociation constant of water, cleaning waste water, removing organics from water using activated carbon or other suitable sorbents, and degrading various compounds.

  13. Preparation of silica thin films by novel wet process and study of their optical properties.

    PubMed

    Im, Sang-Hyeok; Kim, Nam-Jin; Kim, Dong-Hwan; Hwang, Cha-Won; Yoon, Duck-Ki; Ryu, Bong-Ki

    2012-02-01

    Silicon dioxide (SiO2) thin films have gained considerable attention because of their various industrial applications. For example, SiO2 thin films are used in superhydrophilic self-cleaning surface glass, UV protection films, anti-reflection coatings, and insulating materials. Recently, many processes such as vacuum evaporation, sputtering, chemical vapor deposition, and spin coating have been widely applied to prepare thin films of functionally graded materials. However, these processes suffer from several engineering problems. For example, a special apparatus is required for the deposition of films, and conventional wet processes are not suitable for coating the surfaces of substrates with a large surface area and complex morphology. In this study, we investigated the film morphology and optical properties of SiO2 films prepared by a novel technique, namely, liquid phase deposition (LPD). Images of the SiO2 films were obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in order to study the surface morphology of these films: these images indicate that films deposited with different reaction times were uniform and dense and were composed of pure silica. Optical properties such as refractive index and transmittance were estimated by UV-vis spectroscopy and ellipsometry. SiO2 films with porous structures at the nanometer scale (100-250 nm) were successfully produced by LPD. The deposited film had excellent transmittance in the visible wavelength region.

  14. Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.

    1986-01-01

    Dynamic Dielectric measurements made over a wide range of frequency provide a sensitive and convenient means for monitoring the cure process in thermosets and thermoplastics. The measurement of dielectric relaxation is one of only a few instrumental techniques available for studying molecular properties in both the liquid and solid states. Furthermore, it is probably the only convenient experimental technique for studying the polymerization process of going from a monomeric liquid of varying viscosity to a crosslinked, insoluble, high temperature solid. The objective of the research is to develop on-line dielectric instrumentation for quantitative nondestructive material evaluation and closed loop smart cure cycle control. The key is to relate the chemistry of the cure cycle process to the dielectric properties of the polymer system by correlating the time, temperature, and frequency dependent dielectric measurements with chemical characterization measurements. Measurement of the wide variation in magnitude of the complex permittivity with both frequency and state of cure, coupled with chemical characterization work, have been shown in the laboratory to have the potential to determine: resin quality, composition and age; cure cycle window boundaries; onset of flow and point of maximum flow; extent of and completion of reaction; evolution of volatiles; T sub g; and, crosslinking and molecular weight buildup.

  15. Block Copolymer Modified Epoxy Amine System for Reactive Rotational Molding: Structures, Properties and Processability

    NASA Astrophysics Data System (ADS)

    Lecocq, Eva; Nony, Fabien; Tcharkhtchi, Abbas; Gérard, Jean-François

    2011-05-01

    Poly(styrene-butadiene-methylmethacrylate) (SBM) and poly(methylmethacrylate-butyle-acrylate-methylmethacrylate) (MAM) triblock copolymers have been dissolved in liquid DGEBA epoxy resin which is subsequently polymerized by meta-xylene diamine (MXDA) or Jeffamine EDR-148. A chemorheology study of these formulations by plate-plate rheology and by thermal analysis has allowed to conclude that the addition of these copolymer blocks improve the reactive rotational moulding processability without affecting the processing time. Indeed, it prevents the pooling of the formulation at the bottom of the mould and a too rapid build up of resin viscosity of these thermosetting systems. The morphology of the cured blends examined by scanning electron microscopy (SEM) shows an increase of fracture surface area and thereby a potential increase of the toughness with the modification of epoxy system. Dynamic mechanical spectroscopy (DMA) and opalescence of final material show that the block PMMA, initially miscible, is likely to induce phase separation from the epoxy-amine matrix. Thereby, the poor compatibilisation between the toughener and the matrix has a detrimental effect on the tensile mechanical properties. The compatibilisation has to be increased to improve in synergy the processability and the final properties of these block copolymer modified formulations. First attempts could be by adapting the length and ratio of each block.

  16. High-pressure processing inactivates Listeria innocua yet compromises Queso Fresco crumbling properties.

    PubMed

    Hnosko, J; San-Martin Gonzalez, M F; Clark, S

    2012-09-01

    The objective of this study was to determine the effectiveness of high-pressure processing to inactivate Listeria innocua (a Listeria monocytogenes surrogate) in Queso Fresco, and to study the effects of the high-pressure treatment on cheese-crumbling properties. Queso Fresco was made with pasteurized, homogenized milk, lactic acid bacterial starter culture, chymosin, and flake salt. Cheeses were pressed (0.1 MPa) for 1h before crumbling and inoculation with a cocktail of 3 strains of L. innocua, and then pressed for 12 h (0.1 MPa). High-pressure processing treatments of sliced cheese rounds included pressure from 400 to 600 MPa for 1 to 25 min. Cheese sample temperatures, initially approximately 21°C, increased during pressurization and decreased gradually during the holding time. The highest temperature increase was to 23.6°C at 600 MPa. Greater than 5-log reductions occurred at set-point pressures of 500, 550, or 600 MPa when held for at least 15, 3, or 1 min, respectively. However, because inactivation was neither complete nor permanent and crumbling properties were not maintained under the conditions tested in this study, high-pressure processing is not recommended for Queso Fresco applications.

  17. Nonlinear Optical Properties of Organic and Polymeric Thin Film Materials of Potential for Microgravity Processing Studies

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Paley, Mark S.; Penn, Benjamin; Witherow, William K.; Bank, Curtis; Shields, Angela; Hicks, Rosline; Ashley, Paul R.

    1996-01-01

    In this paper, we will take a closer look at the state of the art of polydiacetylene, and metal-free phthalocyanine films, in view of the microgravity impact on their optical properties, their nonlinear optical properties and their potential advantages for integrated optics. These materials have many attractive features with regard to their use in integrated optical circuits and optical switching. Thin films of these materials processed in microgravity environment show enhanced optical quality and better molecular alignment than those processed in unit gravity. Our studies of these materials indicate that microgravity can play a major role in integrated optics technology. Polydiacetylene films are produced by UV irradiation of monomer solution through an optical window. This novel technique of forming polydiacetylene thin films has been modified for constructing sophisticated micro-structure integrated optical patterns using a pre-programmed UV-Laser beam. Wave guiding through these thin films by the prism coupler technique has been demonstrated. The third order nonlinear parameters of these films have been evaluated. Metal-free phthalocyanine films of good optical quality are processed in our laboratories by vapor deposition technique. Initial studies on these films indicate that they have excellent chemical, laser, and environmental stability. They have large nonlinear optical parameters and show intrinsic optical bistability. This bistability is essential for optical logic gates and optical switching applications. Waveguiding and device making investigations of these materials are underway.

  18. Processing, properties and applications of composites using powder-coated epoxy towpreg technology

    NASA Technical Reports Server (NTRS)

    Bayha, T. D.; Osborne, P. P.; Thrasher, T. P.; Hartness, J. T.; Johnston, N. J.; Marchello, J. M.; Hugh, M. K.

    1993-01-01

    Composite manufacturing using the current prepregging technology of impregnating liquid resin into three-dimensionally reinforced textile preforms can be a costly and difficult operation. Alternatively, using polymer in the solid form, grinding it into a powder, and then depositing it onto a carbon fiber tow prior to making a textile preform is a viable method for the production of complex textile shapes. The powder-coated towpreg yarn is stable, needs no refrigeration, contains no solvents and is easy to process into various woven and braided preforms for later consolidation into composite structures. NASA's Advanced Composites Technology (ACT) program has provided an avenue for developing the technology by which advanced resins and their powder-coated preforms may be used in aircraft structures. Two-dimensional braiding and weaving studies using powder-coated towpreg have been conducted to determine the effect of resin content, towpreg size and twist on textile composite properties. Studies have been made to customize the towpreg to reduce friction and bulk factor. Processing parameters have been determined for three epoxy resin systems on eight-harness satin fabric, and on more advanced 3-D preform architectures for the downselected resin system. Processing effects and the resultant mechanical properties of these textile composites will be presented and compared.

  19. Aerosol Properties and Processes: A Path from Field and Laboratory Measurements to Global Climate Models

    SciTech Connect

    Ghan, Steven J.; Schwartz, Stephen E.

    2007-07-01

    Aerosols exert a substantial influence on climate and climate change through a variety of complex mechanisms. Consequently there is a need to represent aerosol effects in global climate models, and models have begun to include representations of these effects. However, the treatment of aerosols in current global climate models is presently highly simplified, omitting many important processes and feedbacks. Consequently there is need for substantial improvement. Here we describe the U. S. Department of Energy strategy for improving the treatment of aerosol properties and processes in global climate models. The strategy begins with a foundation of field and laboratory measurements that provide the basis for modules of selected aerosol properties and processes. These modules are then integrated in regional aerosol models, which are evaluated by comparing with field measurements. Issues of scale are then addressed so that the modules can be applied to global aerosol models, which are evaluated by comparing with global satellite measurements. Finally, the validated set of modules are applied to global climate models for multi-century simulations. This strategy can be applied to successive generations of global climate models.

  20. Properties and processing characteristics of low density carbon cloth phenolic composites

    NASA Technical Reports Server (NTRS)

    Wang, C. Jeff

    1993-01-01

    Ply-lift and pocketing are two critical anomalies of carbon cloth phenolic composites (CCPC) in rocket nozzle applications. Ply lift occurs at low temperatures when the A/P and in-plane permeabilities of the composite materials are still very low and in-plane porous paths are blocked. Pocketing occurs at elevated temperatures when in-plane permeability is reduced by the A/P compressive stress. The thermostructural response of CCPC in a rapid heating environment involves simultaneous heat, mass, and momentum transfer along with the degradation of phenolic resin in a multiphase system with temperature- and time-dependent material properties as well as dynamic processing conditions. Three temperature regions represent the consequent chemical reactions, material transformations, and property transitions, and provide a quick qualitative method for characterizing the thermostructural behavior of a CCPC. In order to optimize the FM5939 LDCCP (low density carbon cloth phenolic) for the nozzle performance required in the Advanced Solid Rocket Motor (ASRM) program, a fundamental study on LDCCP materials was conducted. The cured composite has a density of 1.0 +/- 0.5 gm/cc which includes 10 to 25 percent void volume. The weight percent of carbon microballoon is low (7-15 percent). However, they account for approximately one third of the volume and historically their percentages have not been controlled very tightly. In addition, the composite properties show no correlation with microballoon weight percent or fiber properties (e.g. fiber density or fiber moisture adsorption capacity). Test results concerning the ply-lift anomaly in the MNASA motor firings were: (1) Steeper ply angle (shorter path lenght) designs minimized/eliminated by lifting, (2) material with higher void volume ply lifted less frequently, (3) materials with high (greater than 9 percent) microballoon content had a higher rate of ply lifting, and (4) LDCCP materials failed at microballoon-resin interfaces

  1. Effect of silica nanoparticles on polyurethane foaming process and foam properties

    NASA Astrophysics Data System (ADS)

    Francés, A. B.; Navarro Bañón, M. V.

    2014-08-01

    Flexible polyurethane foams (FPUF) are commonly used as cushioning material in upholstered products made on several industrial sectors: furniture, automotive seating, bedding, etc. Polyurethane is a high molecular weight polymer based on the reaction between a hydroxyl group (polyol) and isocyanate. The density, flowability, compressive, tensile or shearing strength, the thermal and dimensional stability, combustibility, and other properties can be adjusted by the addition of several additives. Nanomaterials offer a wide range of possibilities to obtain nanocomposites with specific properties. The combination of FPUF with silica nanoparticles could develop nanocomposite materials with unique properties: improved mechanical and thermal properties, gas permeability, and fire retardancy. However, as silica particles are at least partially surface-terminated with Si-OH groups, it was suspected that the silica could interfere in the reaction of poyurethane formation.The objective of this study was to investigate the enhancement of thermal and mechanical properties of FPUF by the incorporation of different types of silica and determining the influence thereof during the foaming process. Flexible polyurethane foams with different loading mass fraction of silica nanoparticles (0-1% wt) and different types of silica (non treated and modified silica) were synthesized. PU/SiO2 nanocomposites were characterized by FTIR spectroscopy, TGA, and measurements of apparent density, resilience and determination of compression set. Addition of silica nanoparticles influences negatively in the density and compression set of the foams. However, resilience and thermal stability of the foams are improved. Silica nanoparticles do not affect to the chemical structure of the foams although they interfere in the blowing reaction.

  2. Effects of phytase-assisted processing method on physicochemical and functional properties of soy protein isolate.

    PubMed

    Wang, Hongjian; Chen, Yeming; Hua, Yufei; Kong, Xiangzhen; Zhang, Caimeng

    2014-11-12

    Phytate is an important antinutritional factor in food products. In this study, a phytase-assisted processing method was used to produce low-phytate soybean protein isolate (SPI) samples, and their physicochemical and functional properties were examined. Hydrolysis condition at low temperature (room temperature) and pH 5.0 was better than that recommended by manufacturer (pH 5.0, 55 °C) at keeping the properties of SPI, so the former condition was selected to prepare SPI samples with phytate contents of 19.86-0.11 mg/g by prolonging hydrolysis time (0 (traditional method), 5, 10, 20, 40, and 60 min). Ash content (R(2) = 0.940), solubility (R(2) = 0.983), ζ-potential value (R(2) = 0.793), denaturation temperatures (β-conglycinin, R(2) = 0.941; glycinin, R(2) = 0.977), emulsifying activity index (R(2) = 0.983), foaming capacity (R(2) = 0.955), and trypsin inhibitor activity (R(2) = 0.821) of SPI were positively correlated with phytate content, whereas protein content (R(2) = 0.876), protein recovery (R(2) = 0.781), emulsifying stability index (R(2) = 0.953), foaming stability (R(2) = 0.919), gel hardness (R(2) = 0.893), and in vitro digestibility (R(2) = 0.969) were negatively correlated with phytate content. Simulated gastrointestinal digestion and subsequent dialysis showed that percentages of dialyzable Zn and Ca were increased with decreasing phytate content, whereas the amounts of dialyzable Zn and Ca revealed different behaviors: the former was increased and the latter was decreased. Circular dichroism spectra showed that secondary structure of SPI was changed by phytase. Compared with traditional processing method, the phytase-assisted processing method could produce SPI with lower phytate and higher protein contents, which had better in vitro digestibility and could be used to prepare gels with higher hardness by partially losing some other functional properties.

  3. A Preliminary Analysis of Precipitation Properties and Processes during NASA GPM IFloodS

    NASA Technical Reports Server (NTRS)

    Carey, Lawrence; Gatlin, Patrick; Petersen, Walt; Wingo, Matt; Lang, Timothy; Wolff, Dave

    2014-01-01

    The Iowa Flood Studies (IFloodS) is a NASA Global Precipitation Measurement (GPM) ground measurement campaign, which took place in eastern Iowa from May 1 to June 15, 2013. The goals of the field campaign were to collect detailed measurements of surface precipitation using ground instruments and advanced weather radars while simultaneously collecting data from satellites passing overhead. Data collected by the radars and other ground instruments, such as disdrometers and rain gauges, will be used to characterize precipitation properties throughout the vertical column, including the precipitation type (e.g., rain, graupel, hail, aggregates, ice crystals), precipitation amounts (e.g., rain rate), and the size and shape of raindrops. The impact of physical processes, such as aggregation, melting, breakup and coalescence on the measured liquid and ice precipitation properties will be investigated. These ground observations will ultimately be used to improve rainfall estimates from satellites and in particular the algorithms that interpret raw data for the upcoming GPM mission's Core Observatory satellite, which launches in 2014. The various precipitation data collected will eventually be used as input to flood forecasting models in an effort to improve capabilities and test the utility and limitations of satellite precipitation data for flood forecasting. In this preliminary study, the focus will be on analysis of NASA NPOL (S-band, polarimetric) radar (e.g., radar reflectivity, differential reflectivity, differential phase, correlation coefficient) and NASA 2D Video Disdrometers (2DVDs) measurements. Quality control and processing of the radar and disdrometer data sets will be outlined. In analyzing preliminary cases, particular emphasis will be placed on 1) documenting the evolution of the rain drop size distribution (DSD) as a function of column melting processes and 2) assessing the impact of range on ground-based polarimetric radar estimates of DSD properties.

  4. Transport properties of proton-exchange membranes: Effect of supercritical-fluid processing and chemical functionality

    NASA Astrophysics Data System (ADS)

    Pulido Ayazo

    NafionRTM membranes commonly used in direct methanol fuel cells (DMFC), are tipically limited by high methanol permeability (also known as the cross-over limitation). These membranes have phase segregated sulfonated ionic domains in a perfluorinated backbone, which makes processing challenging and limited by phase equilibria considerations. This study used supercritical fluids (SCFs) as a processing alternative, since the gas-like mass transport properties of SCFs allow a better penetration into the membranes and the use of polar co-solvents influenced their morphology, fine-tuning the physical and transport properties in the membrane. Measurements of methanol permeability and proton conductivity were performed to the NafionRTM membranes processed with SCFs at 40ºC and 200 bar and the co-solvents as: acetone, tetrahydrofuran (THF), isopropyl alcohol, HPLC-grade water, acetic acid, cyclohexanone. The results obtained for the permeability data were of the order of 10 -8-10-9 cm2/s, two orders of magnitude lower than unprocessed Nafion. Proton conductivity results obtained using AC impedance electrochemical spectroscopy was between 0.02 and 0.09 S/cm, very similar to the unprocessed Nafion. SCF processing with ethanol as co-solvent reduced the methanol permeability by two orders of magnitude, while the proton conductivity was only reduced by 4%. XRD analysis made to the treated samples exhibited a decreasing pattern in the crystallinity, which affects the transport properties of the membrane. Also, SAXS profiles of the Nafion membranes processed were obtained with the goal of determining changes produced by the SCF processing in the hydrophilic domains of the polymer. With the goal of searching for new alternatives in proton exchange membranes (PEMs) triblock copolymer of poly(styrene-isobutylene-styrene) (SIBS) and poly(styrene-isobutylene-styrene) SEBS were studied. These sulfonated tri-block copolymers had lower methanol permeabilities, but also lower proton

  5. Locust bean gum: processing, properties and food applications--a review.

    PubMed

    Barak, Sheweta; Mudgil, Deepak

    2014-05-01

    Locust bean gum or carob gum is a galactomannan obtained from seed endosperm of carob tree i.e. Ceratonia siliqua. It is widely utilized as an additive in various industries such as food, pharmaceuticals, paper, textile, oil well drilling and cosmetics. Industrial applications of locust bean gum are due to its ability to form hydrogen bonding with water molecule. It is also beneficial in the control of many health problems like diabetes, bowel movements, heart disease and colon cancer due to its dietary fiber action. This article focuses on production, processing, composition, properties, food applications and health benefits of locust bean gum.

  6. Effect of processing temperature on structure and photocatalytic properties of g-C3N4

    NASA Astrophysics Data System (ADS)

    Papailias, I.; Giannakopoulou, T.; Todorova, N.; Demotikali, D.; Vaimakis, T.; Trapalis, C.

    2015-12-01

    Graphitic carbon nitride (g-C3N4) photocatalysts were synthesized by thermal polycondensation of melamine at different temperatures (450 °C, 550 °C and 650 °C). The crystalline structure, morphology, porosity, composition and light absorption of the materials were thoroughly investigated. Furthermore, their photocatalytic activity was evaluated by NO oxidation under UV and visible light irradiation. The results showed that the structural and optical properties highly depend on the process temperature and thus the degree of polycondensation. The best photocatalytic activity was exhibited by the sample prepared at 450 °C and the possible reasons were discussed.

  7. Investigation of test methods, material properties and processes for solar cell encapsulants

    NASA Technical Reports Server (NTRS)

    Willis, P. B.

    1985-01-01

    The historical development of ethylene vinyl acetate (EVA) is presented, including the functional requirements, polymer selection, curing, stabilization, production and module processing. The construction and use of a new method for the accelerated aging of polymers is detailed. The method more closely resembles the conditions that may be encountered in actual module field exposure and additionally may permit service life to be predicted accurately. The use of hardboard as a low cost candidate substrate material is studied. The performance of surface antisoiling treatments useful for imparting a self cleaning property to modules is updated.

  8. Effects of the poling process on dielectric, piezoelectric, and ferroelectric properties of lead zirconate titanate

    NASA Astrophysics Data System (ADS)

    Prewitt, Anderson D.

    Smart materials are widely used in many of today's relevant technologies such as nano and micro electromechanical systems (NEMS and MEMS), sensors, actuators, nonvolatile memory, and solid state devices. Many of these systems rely heavily on the electromechanical properties of certain smart materials, such as piezoelectricity and ferroelectricity. By definition, piezoelectricity is a mechanical stress in a material that produces an electric displacement (known as the direct piezoelectric effect) or electrical charge in a material which produces a mechanical strain (known as the converse piezoelectric effect). Ferroelectricity is a sub-class of piezoelectricity in which the polarization occurs spontaneously and the dipoles can be reoriented. Domain walls are the nanoscale regions separating two finite distinctively polarized areas in a ferroelectric. The reorientation of polarization in a material is called the poling process and many factors can influence the effectiveness of this process. A more fundamental understanding of how electrical and mechanical loading changes the domain structure of these materials could lead to enhanced properties such as increased energy transduction and decreased nonlinear behavior. This research demonstrates the influence of mechanical pressure and electrical field during and after the poling process on domain walls. The effects of strong mechanical forces on large-scale domain switching and weak cyclic forces on small-scale domain wall motion are investigated to show how they affect the macroscopic behavior of these materials. Commercial lead zirconate titanate ceramics were studied under various poling conditions and the effect of domain wall motion on the piezoelectric, dielectric, and ferroelectric properties was investigated. Polarization and strain measurements from samples poled at specific conditions and converse piezoelectric coefficient and dielectric permittivity data was extracted and interpreted in the context of

  9. Conducting Properties of Polyaniline in the THz Region: Investigations of Various Processing Conditions

    NASA Astrophysics Data System (ADS)

    Tapia, Alvin Karlo G.; Tominaga, Keisuke

    2017-02-01

    The conduction properties of polyaniline (PAni) with various processing conditions were demonstrated using terahertz time-domain spectroscopy. The effects of protonation were observed by varying the doping time and annealing time. The measurements agreed with the Mott-Davis hopping model with the exponent varying inversely with the protonation conditions. Also, the density of the samples increased with compression pressure thereby increasing the inter-chain and inter-particle charge transport. Lastly, the THz response on PAni-polyethylene pellets showed dominant contribution of PAni network.

  10. Rheological properties of the product slurry of the Nitrate to Ammonia and Ceramic (NAC) process

    SciTech Connect

    Muguercia, I.; Yang, G.; Ebadian, M.A.; Lee, D.D.; Mattus, A.J.; Hunt, R.D.

    1995-03-01

    The Nitrate to Ammonia and Ceramic (NAC) process is an innovative technology for immobilizing the liquid from Low Level radioactive Waste (LLW). An experimental study was conducted to measure the rheological properties of the pipe flow of the NAC product slurry. Test results indicate that the NAC product slurry has a profound rheological behavior. At low solids concentration, the slurry exhibits a typical dilatant fluid (or shear thinning)fluid. The transition from dilatant fluid to pseudo-plastic fluid will occur at between 25% to 30% solids concentration in temperature ranges of 50--80{degree}C. Correlation equations are developed based on the test data.

  11. Processing-structure-property relations in PEEK/carbon composites made from comingled fabric and prepreg

    SciTech Connect

    Vu-khanh, T.; Denault, J. )

    1991-10-01

    The effects of the conditions of the processing of PEEK/carbon prepregs and comingled fabric on the microstructure and mechanical characteristics of the resulting composites were investigated. Results showed that, in the comingled fabric system, the fiber/matrix adhesion depends on the molding temperature, the residence time at the melt temperature, and the cooling rate. Too high molding temperature resulted in degradation of the PEEK matrix, which affected the crystallization behavior of the composites, the fiber/matrix adhesion, and the matrix properties. This effect was most important in the case of comingled systems containing sized carbon fibers. 17 refs.

  12. Mechanical properties and structure of AZ61 magnesium alloy processed by equal channel angular pressing

    NASA Astrophysics Data System (ADS)

    Hilšer, O.; Rusz, S.; Tański, T.; Snopiński, P.; Džugan, J.; Kraus, M.

    2017-02-01

    An equal channel angular pressing (ECAP) procedure has been developed to produce a fine-grained AZ61 magnesium alloy. The results show that the microstructure can be effectively refined with increasing equivalent strain during ECAP. For increasing ECAP process efficiency was conventional tool as a helix in the horizontal part of channel built. This fine-grained alloy has an excellent strength accompanied by reasonable good tensile ductility. The success of the development of this ECAP procedure can offer a good opportunity for the development of magnesium alloys with good mechanical properties.

  13. Home-Processed Red Beetroot (Beta vulgaris L.) Products: Changes in Antioxidant Properties and Bioaccessibility.

    PubMed

    Guldiken, Burcu; Toydemir, Gamze; Nur Memis, Kubra; Okur, Sena; Boyacioglu, Dilek; Capanoglu, Esra

    2016-06-01

    In this study, the effects of home-processing on the antioxidant properties and in vitro bioaccessibility of red beetroot bioactives were investigated. For this purpose, fresh red beetroot and six different home-processed red beetroot products-including boiled, oven-dried, pickled, pureed, juice-processed, and jam-processed-were analyzed and compared for their total phenolic (TP) and total flavonoid (TF) contents, total antioxidant capacities (TAC), and individual anthocyanin contents. In addition, bioaccessibility of red beetroot antioxidants was determined using an in vitro simulated gastrointestinal digestion method. Dried, pureed, and fresh red beetroot samples had the highest TP, TF, and TAC values, which were 347 ± 23 mg gallic acid equivalent (GAE)/100 g, 289 ± 53 mg rutin equivalent (RE)/100 g, 3889 ± 982 mg trolox equivalent antioxidant capacity (TEAC)/100 g, respectively. The in vitro digestion method revealed the highest recovery for TP (16%) and TAC (1.3%) in jam. This study provides comparative data to evaluate the effects of various home-processing techniques on antioxidant potential of red beetroot products.

  14. The influence of nanoadditives on the tribological properties of process fluids

    NASA Astrophysics Data System (ADS)

    Bakalova, T.; Svobodová, L.; Borůvková, K.; Louda, P.; Voleský, L.

    2016-04-01

    Tribology deals with interaction of surfaces in relative motion depending on their design, friction, wear and lubrication. The proper use of process fluids or lubricants can bring a significant reduction in friction and the amount of wear, thereby leading to a reduction in power consumption. During different technological operations contamination of used process fluids or lubricants occurs. Such contamination leads not only to a reduction of the lifetime of the lubricants but it can also change the functional properties and increase the health risks for operators. The quality of the process fluid is among other things influenced by bacterial attacks. The use of nanoadditives is one method for inhibiting the bacteria and improving the bioavailability and stability of the technological fluids. Nanolubricant is a new system composed of nanometer-sized particles dispersed in a base lubricant. The doping of lubricants with nanoparticles is one of the ways to solve problems with the removal of bacteria, whereby improving the biological, chemical and technological stability of process fluids. In the article, we monitor the effects of doping process fluids with nanoparticles of silica (SiO2), titanium dioxide (TiO2), silver nitrate (AgNO3) and ascorbic acid (C6H8O6) on the friction coefficient and on the wear of friction pairs of Si3N4 balls against steel 16MnCr5, EN 10084-94.

  15. Influence of dehydration process in Castellano chickpea: changes in bioactive carbohydrates and functional properties.

    PubMed

    Aguilera, Yolanda; Benítez, Vanesa; Mollá, Esperanza; Esteban, Rosa M; Martín-Cabrejas, María A

    2011-11-01

    Changes in bioactive carbohydrates, functional, and microstructural characteristics that occurred in chickpea under soaking, cooking, and industrial dehydration processing were evaluated. Raw chickpea exhibited important levels of raffinose family of oligosaccharides (RFOs), resistant starch (RS) and total dietary fibre (TDF), being insoluble dietary fibre (IDF) the main fraction (94%). The dehydration process increased RFOs (43%), RS (47%) and soluble dietary fiber (SDF) (59%) levels significantly. In addition, a noticeable increase in both fibre fractions was observed, being higher in soluble fibre in (SDF) (59%). The minimum nitrogen solubility of raw flours was at pH 4, and a high degree of protein insolubilization (80%) was observed in dehydrated flours. The raw and processed flours exhibited low oil-holding capacities (1.10 mg/ml), and did not show any change by thermal processing, whereas water-holding capacities rose to 5.50 mg/ml of sample. Cooking and industrial dehydration process reduced emulsifying activity and foaming capacity of chickpea flour. The microstructural observations were consistent with the chemical results. Thus, the significant occurrence of these bioactive carbohydrate compounds along with the interesting functional properties of the dehydrated flours could be considered useful as functional ingredients for food formulation.

  16. Estimation of environment-related properties of chemicals for design of sustainable processes: development of group-contribution+ (GC+) property models and uncertainty analysis.

    PubMed

    Hukkerikar, Amol Shivajirao; Kalakul, Sawitree; Sarup, Bent; Young, Douglas M; Sin, Gürkan; Gani, Rafiqul

    2012-11-26

    of the developed property models for the estimation of environment-related properties and uncertainties of the estimated property values is highlighted through an illustrative example. The developed property models provide reliable estimates of environment-related properties needed to perform process synthesis, design, and analysis of sustainable chemical processes and allow one to evaluate the effect of uncertainties of estimated property values on the calculated performance of processes giving useful insights into quality and reliability of the design of sustainable processes.

  17. Processing and Dynamic-Mechanical Properties of Polybuthylene Therephtalate Based Nanocomposites

    NASA Astrophysics Data System (ADS)

    Russo, P.; Acierno, D.; Gallo, E.

    2008-08-01

    The influence of relevant replacements of a traditional phosphinate based fire retardant additive with metal oxide nanoparticles on the processability, fire performance and dynamic mechanical properties of a commercial polybuthylene therephtalate resin was investigated. Results have demonstrated that the addition of 2 wt% of iron or antimonium oxide nanoparticles with a simultaneous significant reduction, from 20 wt% to 8 wt% or also to 5 wt%, of a phosphorous based fire retardant (Exolit OP1240) concentrations deals to a clear improvement of the matrix processability by lowering its shear viscosity while maintaining fire performances of products. Dynamic-mechanical measurements showed an increase of the material stiffness, especially in presence of iron oxide nanoparticles, no effect on the glass transition temperature of the matrix and a widening and raising of loss modulus signals as a sign of more heterogeneous structures formation.

  18. Investigation of test methods, material properties, and processes for solar cell encapsulants

    NASA Astrophysics Data System (ADS)

    Willis, P. B.

    Progress in solar energy technology is reported in the following areas: aging and life prediction methodology and devices for solar cell encapsulation; the function of adhesion chemistry, primers, and a new diagnostic technique for estimations of bond durability; a study of fire retardant formulations for decreasing the potential flammability of solar modules; initial studies of the electrical insulating properties of encapsulation materials and measurement of the intrinsic dielectric strength; antisoiling compounds for the prevention of soil build-up on the outer surface of the module; and low temperature processing encapsulants that permit module fabrication at temperatures less than 100 C. Another area of study has been added to determine the degree to which formulation and processes affect the module quality and manufacturing yield.

  19. Microstructure/property studies supporting development of low cost processes for TiAl automotive valves

    SciTech Connect

    Jones, P.E.; Porter, W.J. III; Keller, M.M.; Eylon, D.

    1995-07-01

    Lightweight gamma titanium aluminide automotive valves may significantly improve engine performance and fuel economy. However, low cost mass production processes must be developed to realize these gains. Permanent mold casting processes and low cost heat treatments are being developed to enable commercial introduction of TiAl automotive valves. Microstructural development, tensile, creep, and high cycle fatigue properties of permanent mold Ti-47Al-2Nb-1.75Cr (at%) castings are compared with investment castings of similar size. A recommendation is made to use as-HIP castings for components not designed to damage tolerant criteria. This work was performed as pan of a vertically integrated team effort to transfer aerospace TiAl technology to the automotive market.

  20. Structure-processing-property relationships for polymer interphases in fiber reinforced composite materials

    SciTech Connect

    Drzal, L.T.

    1995-12-31

    When polymer matrix composite materials are fabricated, polymers are processed to surround each reinforcing element while they are fluid and then they solidify in intimate contact with the reinforcement surface. For thermoset matrices, chemisorption of constituents, segregation of components. and processing constraints all can influence the resulting structure of the polymer in its solidified state. For thermoplastic matrices, segregation by molecular weight, morphological changes resulting from crystallization or additive segregation can also control the final matrix structure. In addition the surface of the fibers is coated with chemical agents that can also interact with the polymer. Examples will be given to illustrate the effect of the structure of this polymer interphase on adhesion. It will be shown that in some cases if the resulting polymer structure is known, adhesion and composite properties can be predicted.

  1. Novel pre-alloyed powder processing of modified alnico 8: Correlation of microstructure and magnetic properties

    SciTech Connect

    Anderson, I. E.; Kassen, A. G.; White, E. M. H.; Zhou, L.; Tang, W.; Palasyuk, A.; Dennis, K. W.; McCallum, R. W.; Kramer, M. J.

    2015-04-13

    Progress is reviewed on development of an improved near-final bulk magnet fabrication process for alnico 8, as a non-rare earth permanent magnet with promise for sufficient energy density and coercivity for electric drive motors. This study showed that alnico bulk magnets in near-final shape can be made by simple compression molding from spherical high purity gas atomized pre-alloyed powder. Dwell time at peak sintering temperature (1250°C) greatly affected grain size of the resulting magnet alloys. This microstructure transformation was demonstrated to be useful for gaining partially aligned magnetic properties and boosting energy product. Furthermore, while a route to increased coercivity was not identified by these experiments, manufacturability of bulk alnico magnet alloys in near-final shapes was demonstrated, permitting further processing and alloy modification experiments that can target higher coercivity and better control of grain anisotropy during grain growth.

  2. Novel pre-alloyed powder processing of modified alnico 8: Correlation of microstructure and magnetic properties

    DOE PAGES

    Anderson, I. E.; Kassen, A. G.; White, E. M. H.; ...

    2015-04-13

    Progress is reviewed on development of an improved near-final bulk magnet fabrication process for alnico 8, as a non-rare earth permanent magnet with promise for sufficient energy density and coercivity for electric drive motors. This study showed that alnico bulk magnets in near-final shape can be made by simple compression molding from spherical high purity gas atomized pre-alloyed powder. Dwell time at peak sintering temperature (1250°C) greatly affected grain size of the resulting magnet alloys. This microstructure transformation was demonstrated to be useful for gaining partially aligned magnetic properties and boosting energy product. Furthermore, while a route to increased coercivitymore » was not identified by these experiments, manufacturability of bulk alnico magnet alloys in near-final shapes was demonstrated, permitting further processing and alloy modification experiments that can target higher coercivity and better control of grain anisotropy during grain growth.« less

  3. Manufacturing and Process-based Property Analysis of Textile-Reinforced Thermoplastic Spacer Composites

    NASA Astrophysics Data System (ADS)

    Hufenbach, Werner; Adam, Frank; Füßel, René; Krahl, Michael; Weck, Daniel

    2012-12-01

    Novel woven spacer fabrics based on hybrid yarns are suitable for an efficient fabrication of three-dimensional composite structures in high volume production. In this paper, an innovative manufacturing process with short cycle times and high automatisation is introduced for textile-reinforced thermoplastic spacer structures suited for bending load cases. The different process steps hybrid yarn fabrication, weaving technology for three-dimensional textile preforms and consolidation with unique kinematics and hot pressing technology are described in detail. The bending properties of the manufactured spacer structures are evaluated by means of experiments as well as finite element simulations. Numerical parametric studies are performed in order to validate the influence of manufacturing tolerances on the bending stiffness of the spacer structures.

  4. Thermomechanical Properties of Quartz Intended for Carbothermic Process for Silicon Production

    NASA Astrophysics Data System (ADS)

    Kefaifi, Aissa; Sahraoui, Tahar; Kheloufi, Abdelkrim; Berbar, Yacine; Drouiche, Nadjib

    The technology of solar grade silicon production intended for solar cells manufacturing consists in three successive stages: silica raw material ore enrichment, carbothermic reduction of silica to obtain metallurgical silicon grade (MG-Si) and purification of metallurgical silicon grade for obtaining the silicon solar grade (SoG-Si). Our work was focused on the preparation of the charge (SiO2 and C) to obtain the metallurgical silicon grade, which aims to study the silica thermo-mechanical properties as raw material for the carbothermic process. Various experiments at laboratory scale were developed on quartz samples as the explosion tests, heat tests, and mechanical tests in order to derive friability indices, thermal resistance and heat index. The results have allowed us to make a preliminary conclusion on silica intended for carbothermic process based on its thermo-mechanical characteristics as well as its better performance in the muffle furnace.

  5. TiO2 film properties as a function of processing temperature, volume 3

    NASA Technical Reports Server (NTRS)

    Fitzgibbons, E. T.; Sladek, K. J.; Hartwig, W. H.

    1972-01-01

    Thin film TiO2 was produced at 150 C by chemical vapor deposition using hydrolysis of tetraisopropyl titanate. Films were amorphous as grown, but annealing in air caused crystallization, with anatase formed beginning at 350 C and rutile at 700 C. Density and index of refraction increased substantially with increasing anneal temperature, while etch susceptibility in HF and H2SO4 decreased. Comparison with literature data showed two groups of processes. One group yields films having properties that gradually approach those of rutile with increasing process temperature. The other group gives rutile directly at moderate temperatures. Deposition of amorphous film followed by etching and annealing is suggested as a means for pattern definition.

  6. Morphology and mixing state of atmospheric particles: Links to optical properties and cloud processing

    NASA Astrophysics Data System (ADS)

    China, Swarup

    Atmospheric particles are ubiquitous in Earth's atmosphere and impact the environment and the climate while affecting human health and Earth's radiation balance, and degrading visibility. Atmospheric particles directly affect our planet's radiation budget by scattering and absorbing solar radiation, and indirectly by interacting with clouds. Single particle morphology (shape, size and internal structure) and mixing state (coating by organic and inorganic material) can significantly influence the particle optical properties as well as various microphysical processes, involving cloud-particle interactions and including heterogeneous ice nucleation and water uptake. Conversely, aerosol cloud processing can affect the morphology and mixing of the particles. For example, fresh soot has typically an open fractal-like structure, but aging and cloud processing can restructure soot into more compacted shapes, with different optical and ice nucleation properties. During my graduate research, I used an array of electron microscopy and image analysis tools to study morphology and mixing state of a large number of individual particles collected during several field and laboratory studies. To this end, I investigated various types of particles such as tar balls (spherical carbonaceous particles emitted during biomass burning) and dust particles, but with a special emphasis on soot particles. In addition, I used the Stony Brook ice nucleation cell facility to investigate heterogeneous ice nucleation and water uptake by long-range transported particles collected at the Pico Mountain Observatory, in the Archipelago of the Azores. Finally, I used ice nucleation data from the SAAS (Soot Aerosol Aging Study) chamber study at the Pacific Northwest National Laboratory to understand the effects that ice nucleation and supercooled water processing has on the morphology of residual soot particles. Some highlights of our findings and implications are discussed next. We found that the

  7. Investigation of test methods, material properties, and processes for solar cell encapsulants

    NASA Technical Reports Server (NTRS)

    Willis, P. B.

    1985-01-01

    Progress in solar energy technology is reported in the following areas: aging and life prediction methodology and devices for solar cell encapsulation; the function of adhesion chemistry, primers, and a new diagnostic technique for estimations of bond durability; a study of fire retardant formulations for decreasing the potential flammability of solar modules; initial studies of the electrical insulating properties of encapsulation materials and measurement of the intrinsic dielectric strength; antisoiling compounds for the prevention of soil build-up on the outer surface of the module; and low temperature processing encapsulants that permit module fabrication at temperatures less than 100 C. Another area of study has been added to determine the degree to which formulation and processes affect the module quality and manufacturing yield.

  8. Structural and magnetic properties of nanocrystalline Fe-Co-Ni alloy processed by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Raanaei, Hossein; Eskandari, Hossein; Mohammad-Hosseini, Vahid

    2016-01-01

    In this present work, a nanostructured iron-cobalt-nickel alloy with Fe50Co30Ni20 composition has been processed by mechanical alloying. The structural and magnetic properties have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. It is shown that the crystallize size reaches to about 18.7 nm after 32 h milling time. A remarkable decrease in coercivity after 16 h milling time and also a continuous increase in remanent magnetization during the mechanical alloying process are observed. Heat treatment of the samples milled at 32 and 48 h demonstrates the crystalline constituent elements and also Fe3O4 crystalline phase.

  9. Novel pre-alloyed powder processing of modified alnico 8: Correlation of microstructure and magnetic properties

    SciTech Connect

    Anderson, I. E. Kassen, A. G.; White, E. M. H.; Zhou, L.; Tang, W.; Palasyuk, A.; Dennis, K. W.; McCallum, R. W.; Kramer, M. J.

    2015-05-07

    Progress is reviewed on development of an improved near-final bulk magnet fabrication process for alnico 8, as a non-rare earth permanent magnet with promise for sufficient energy density and coercivity for electric drive motors. This study showed that alnico bulk magnets in near-final shape can be made by simple compression molding from spherical high purity gas atomized pre-alloyed powder. Dwell time at peak sintering temperature (1250 °C) greatly affected grain size of the resulting magnet alloys. This microstructure transformation was demonstrated to be useful for gaining partially aligned magnetic properties and boosting energy product. While a route to increased coercivity was not identified by these experiments, manufacturability of bulk alnico magnet alloys in near-final shapes was demonstrated, permitting further processing and alloy modification experiments that can target higher coercivity and better control of grain anisotropy during grain growth.

  10. Morphologies, Processing and Properties of Ceramic Foams and Their Potential as TPS Materials

    NASA Technical Reports Server (NTRS)

    Stackpoole, Mairead; Simoes, Conan R.; Johnson, Sylvia M.

    2002-01-01

    The current research is focused on processing ceramic foams with compositions that have potential as a thermal protection material. The use of pre-ceramic polymers with the addition of sacrificial blowing agents or sacrificial fillers offers a viable approach to form either open or closed cell insulation. Our work demonstrates that this is a feasible method to form refractory ceramic foams at relatively low processing temperatures. It is possible to foam complex shapes then pyrolize the system to form a ceramic while retaining the shape of the unfired foam. Initial work focused on identifying suitable pre-ceramic polymers with desired properties such as ceramic yield and chemical make up of the pyrolysis product after firing. We focused on making foams in the Si system (Sic, Si02, Si-0-C), which is in use in current acreage TPS systems. Ceramic foams with different architectures were formed from the pyrolysis of pre-ceramic polymers at 1200 C in different atmospheres. In some systems a sacrificial polyurethane was used as the blowing agent. We have also processed foams using sacrificial fillers to introduce controlled cell sizes. Each sacrificial filler or blowing agent leads to a unique morphology. The effect of different fillers on foam morphologies and the characterization of these foams in terms of mechanical and thermal properties are presented. We have conducted preliminary arc jet testing on selected foams with the materials being exposed to typical re-entry conditions for acreage TPS and these results will be discussed. Foams processed using these approaches have bulk densities ranging from 0.15 to 0.9 g/cm3 and cell sizes ranging from 5 to 500 pm. Compression strengths ranged from 2 to 7 MPa for these systems. Finally, preliminary oxidation studies have been conducted on selected systems and will be discussed.

  11. Electromagnetic absorbing property of the flaky carbonyl iron particles by chemical corrosion process

    NASA Astrophysics Data System (ADS)

    Zheng, Dianliang; Liu, Ting; Zhou, Li; Xu, Yonggang

    2016-12-01

    The flaky carbonyl iron particles (CIPs) were prepared using a milling process at the first step, then the chemical corrosion process was done to optimize the particle shape. The particle morphology was characterized by the scanning electron microscopy, the static magnetic property was evaluated on a vibrating sample magnetometer and X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The complex permittivity and permeability were measured using a vector network analyzer in the frequency range of 2-18 GHz and the reflection loss (RL) was calculated. The results showed that the saturation magnetization value of the CIPs decreased as the CIPs was corroded to the small flakes in chemical corrosion process. The diffraction peaks of the single α-Fe existed in the XRD pattern of CIPs, and the characteristic peaks was more obvious and the intensity of the diffraction pattern was lower by corrosion. The permittivity and the permeability of the corroded milling CIPs was a little larger than the milling CIPs, it was due to the larger aspect ratio based on the fitting calculation process. At thickness 0.6 mm and 0.8 mm, the corroded milling CIPs composite had the better absorbing property than the other two samples. The frequency band (RL<-5 dB) could be widened to 8.96-18 GHz at 0.6 mm and 5.92-18 GHz at 0.8 mm, and RL less than -8 dB began to exist in 8.96-14.72 GHz at 0.8 mm.

  12. Crystallization and polymorphism of triacylglycerols contribute to the rheological properties of processed cheese.

    PubMed

    Gliguem, Hela; Ghorbel, Dorra; Lopez, Christelle; Michon, Camille; Ollivon, Michel; Lesieur, Pierre

    2009-04-22

    The thermal, rheological, and structural behaviors of a spreadable processed cheese were studied by complementary techniques including differential scanning calorimetry (DSC), rheology, and X-ray diffraction as a function of temperature. In this product, fat is present as a dispersed phase. Thermal and rheological properties were studied at different cooling rates between 0.5 and 10 degrees C min(-1) from 60 to 3 degrees C. Crystallization properties of fat were monitored at a cooling rate of -2 degrees C min(-1) from 60 to -10 degrees C. Fat triacylglycerols (TGs) crystallized at 15 degrees C in a triple-chain length 3Lalpha (72 A) structure correlated to exothermic events and to the sudden increase in the rheological moduli G' and G''. Upon heating at 2 degrees C min(-1), the polymorphic transition of TGs evidence the melting of the 3Lalpha structure and the formation of a 2Lbeta' (36.7-41.5 A) structure. Melting of the latter follows. These transformations coincide with thermal events observed by DSC and the decrease in two steps of the rheological moduli. The influence of fat crystallization, melting, and polymorphism upon the viscoelastic properties is clearly demonstrated upon both heating and cooling.

  13. Springtime cloud properties in the Taiwan Strait: synoptic controls and local processes

    NASA Astrophysics Data System (ADS)

    Kueh, Mien-Tze; Lin, Pay-Liam

    2014-05-01

    This paper examines the springtime cloud properties in the Taiwan Strait (TS), with emphases on their dependence on synoptic controls and local processes, using a suite of in situ and remote sensing observations. Cloud properties in the TS are inferred from a combination of MODIS and in situ observations and further classified into two synoptic conditions: continental cold air surge and frontal system. The study reveals a predominance of synoptic-scale controls in regulating the cloud properties in the TS. The sensitivity of clouds to the local thermodynamic mechanisms as well as the underlying surface conditions is fundamentally dependent on synoptic-scale flow patterns. The springtime clouds over the TS are commonly a mixture of stratocumulus and alto clouds. More precisely, there is a preponderance of stratocumulus over the strait. A preferential occupancy of stratiform alto clouds is recognized during cold air surge, whereas vertical development of cloud layers (mostly the stratocumulus) is commonly observed with frontal passage. The most distinct difference between the local clouds formation associated with the two synoptic conditions is the suppression of very low cloud and fog along with cold air surge. Stratus clouds and fog are present within the northward prefrontal airflow from warmer to colder water sites, along with an increase in stability relating to lower altitudes of boundary layer clouds. Although the rainfall occurrences are about the same for both synoptic conditions, the frontal rain amounts are larger on average.

  14. Relationship of solvent to the photopolymerization process, properties, and structure in model dentin adhesives

    PubMed Central

    Ye, Qiang; Spencer, Paulette; Wang, Yong; Misra, Anil

    2007-01-01

    The ratio of the double-bond content of monomer to polymer, i.e. degree of conversion (DC) has been used frequently as a convenient means of comparing the behavior and properties of dental composites and adhesives. The purpose of this investigation was to study the relationship of photopolymerization processes, bulk properties, and structure using model dentin adhesives cured in the presence of different ethanol content as an example. There was little difference in the DC of model BisGMA-based adhesives cured in the presence of ethanol concentrations ranging from 0 to 40 wt %, but there were substantial differences in the mechanical properties. Ultimate tensile strength (UTS) and modulus of elasticity decreased with an increase in ethanol content. Polymer structure was revealed by thermal behavior in the glass transition temperature (Tg) region; these measurements were obtained by modulated temperature differential scanning calorimetry (MTDSC) technology, which removes the competing irreversible effects associated with release of volatiles and residual curing. Glass transition temperature of model adhesives decreased substantially with an increase in ethanol content. The DC based on the quantity of remaining double bond has been used extensively to characterize and provide a relative assessment of the quality of dentin adhesives and dental composites. Since polymers differing in linearity, and therefore crosslink density, may have a similar degree of conversion, the measurement of monomer/polymer conversion does not necessarily provide complete representation of the quality or durability of the polymer structure. PMID:17001655

  15. Relationship between the electrical and rheological properties of potato tuber tissue after various forms of processing.

    PubMed

    Dejmek, Petr; Miyawaki, Osato

    2002-06-01

    The impedance at frequencies of 1-1000 kHz and dynamic bending storage modulus measured by the vibrating reed method were compared for potato tuber tissue, which had been processed by various methods. Raw potato tuber tissue strips were either heated for 30 min up to 100 degrees C or frozen-thawed. Some samples were osmotically dehydrated in a mannitol solution up to a concentration of 0.7 mol/l. The electrical reactance correlated well with the storage modulus of heated or frozen-thawed potato tissues, but not with the storage modulus of the mannitol-treated tissue. The storage modulus appeared to be strongly dependent on the turgor pressure of the cells which was drastically decreased by the heating, freezing-thawing, and osmotic treatments. The electrical properties reflect the cell integrity, and a large difference was observed between the change in impedance after heating or freezing-thawing, and that after the osmotic treatment. A significant change in the electric properties was also observed for a starch suspension at the gelatinization temperature. However, the contribution due to gelatinization did not appear to play an important role in the change of electrical properties of potato tissue by heating.

  16. Property and process correlations for iron-enriched basalt waste forms

    SciTech Connect

    Grandy, J.D.; Eddy, T.L.; Anderson, G.L.

    1993-02-01

    Correlations of thermodynamic properties and process parameters of high-temperature slag for a range of compositions of iron-enriched basalt are presented. The quantification of the properties of this complex mixture can assist in the design and monitoring of high-temperature melting systems for the treatment of radioactive and hazardous wastes at the Idaho National Engineering Laboratory. The buried and stored wastes at the INEL Radioactive Waste Management Complex have a similar composition to iron-enriched basalt after oxidation of organics. The properties correlated are the viscosity, electrical conductivity, refractory corrosion, and recrystallization temperature. The correlations are expressed as a function of input waste-soil mixture composition, alkali concentration, and slag temperature. An application to determine the effect of alkali flux on slag temperature, leach rate, and volume reduction is presented. Though the correlations are for mixtures of soil and waste with average transuranic-contaminated waste compositions, it appears that good approximations for other waste streams and glass-ceramic waste forms can be obtained because of similarities in composition.

  17. Processing and properties of superclean ASTM A508 Cl. 4 forgings

    SciTech Connect

    Hinkel, A.V.; Handerhan, K.J.; Manzo, G.J.; Simkins, G.P.

    1988-12-31

    Steels with improved resistance to temper embrittlement are now being produced using ``superclean`` steelmaking technology. This technology involves the use of scrap control, proper electric arc furnace and ladle refining furnace practices to produce steel with very low Mn, Si, P, S and other residual impurities such as Sn, As and Sb. This technology has been applied on a production basis to modified ASTM A508 Cl- 4 material intended for high temperature pressure vessel forgings. Processing and properties of this superclean material are reviewed. In addition, the cleanliness and mechanical properties are compared to conventionally melted A508 Cl. 4 material. The ``superclean`` A508 Cl. 4 mod. was found to meet all specification requirements. In addition, the superclean material was found to possess superior upper shelf CVN properties, a lower FATT{sub 50} and NDTT, along with superior microcleanliness compared to conventional material. Finally, the superclean material was found to be immune to temper embrittlement based on the short-term embrittlement treatments examined.

  18. Processing effects for integrated PZT: Residual stress, thickness, and dielectric properties

    NASA Astrophysics Data System (ADS)

    Ong, Ryan Jason

    This dissertation focuses on the integration of lead zirconate titanate (PZT) films on Pt/Ti/SiO2//Si, and the effect of on properties. Direct deposition of PZT on Si will lead to on-chip power capacitors, non-volatile memory cells, and vibration sensors. However, previous research indicates that the dielectric, ferroelectric and piezoelectric response characteristics for the devices are often inferior to bulk specimens. Property variations have been attributed to changes in several major variables including, chemical composition, phase content, grain size, crystallographic orientation, film thickness, and stress, each of which, in turn, can depend on processing. The first goal of this work was to design a sol-gel processing methodology to control all major variables except film thickness and stress, thus isolating their respective effects on properties. All specimens were verified to be of the Pb(Zr0.53Ti0.47)O3 composition, in the perovskite structure, with a constant grain size of 110nm, and with (111) fiber texture. PZT film thickness was varied from 95nm to 500nm and residual stress was measured to be either 150 or 180MPa, biaxial tensile, depending on thickness. These specimens allowed for new insights into the fundamental differences between bulk materials and thin films. A series-capacitor model accounted for the observed dilution in room-temperature K from >900 to ˜600 as film thickness decreased, but could not account for the absence of the expected dielectric anomaly at high temperatures. Instead, a stress-induced distributed phase transformation related to the polycrystalline nature of the film was proposed to account for the observed behavior. Residual stress reduced the spontaneous polarization values in these specimens to 32muC/cm 2 from the predicted stress-free value of 50muC/cm2. An increase in coercive field was attributed to interfacial capacitance and residual stress, whereas a decrease of 30MPa tensile stress resulted in an increase of d33

  19. Effect of carbon nanotubes and processing methods on the properties of carbon nanotube/polypropylene composites.

    PubMed

    Sahoo, Nanda Gopal; Thet, Naing Tun; Tan, Qing Hao; Li, Lin; Chan, Siew Hwa; Zhao, Jianhong; Yu, Suzhu

    2009-10-01

    The effect of multi-walled carbon nanotubes (MWCNTs) and processing methods on the morphological, crystalline, dynamic mechanical, mechanical and electrical properties of MWCNT/polypropylene (PP) composites has been investigated by using field emission scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile and electric conductivity tests. The MWCNTs have been functionalized covalently and noncovalently for better dispersion in the PP matrix. A homogeneous dispersion of MWCNTs was achieved in the PP matrix as evidenced by scanning electron microscopy. Differential scanning calorimetric (DSC) results confirmed that the incorporation of the MWCNTs effectively enhanced the crystallization of the PP matrix through heterogeneous nucleation. The glass transition temperature increased from 8 degrees C for the pure PP to 26 degrees C for the composite with 10 wt% MWCNT-COOH. The present investigation revealed that the mechanical, thermal as well as electrical properties of carbon nanotubes filled polymer composites were strongly dependent on the state of dispersion, mixing and processing methods.

  20. Growth process and magnetic properties of α-FeSe nanostructures

    NASA Astrophysics Data System (ADS)

    Li, S. J.; Li, D.; Jiang, J. J.; Liu, G. B.; Ma, S.; Liu, W.; Zhang, Z. D.

    2014-05-01

    Growth process and magnetic properties of PbO-type α-FexSe nanostructures with shape changing from nanocacti to nanopetals and then to nanosheets are investigated. With iron acetylacetonate [Fe(acac)3] and Se powder as raw materials, the diffusion process of Fe atoms dominates the synthesis of α-FexSe nanocacti following phase transitions from FeSe2 to Fe3Se4 and finally to α-FexSe. When a mixed solution containing Se precursor and Fe(acac)3 was used as the raw material, the formation of FeSe2 and Fe3Se4 can be avoided and, bended α-FexSe nanopetals can be prepared at 345 °C, which became flat nanosheets with a [001] preferred orientation as extending the reaction time from 1 to 4 h. No superconducting transition occurs in the α-FexSe (0.84 ≤ x ≤ 1.05) nanostructures due to composition heterogeneity or size effect. Magnetic measurements indicate that an antiferromagnetic component with a Néel point at about 45 K dominates the magnetic properties of the α-Fe0.87Se nanosheets.

  1. Growth process and magnetic properties of α-FeSe nanostructures

    SciTech Connect

    Li, S. J.; Li, D. Jiang, J. J.; Liu, G. B.; Ma, S.; Liu, W.; Zhang, Z. D.

    2014-05-07

    Growth process and magnetic properties of PbO-type α-Fe{sub x}Se nanostructures with shape changing from nanocacti to nanopetals and then to nanosheets are investigated. With iron acetylacetonate [Fe(acac){sub 3}] and Se powder as raw materials, the diffusion process of Fe atoms dominates the synthesis of α-Fe{sub x}Se nanocacti following phase transitions from FeSe{sub 2} to Fe{sub 3}Se{sub 4} and finally to α-Fe{sub x}Se. When a mixed solution containing Se precursor and Fe(acac){sub 3} was used as the raw material, the formation of FeSe{sub 2} and Fe{sub 3}Se{sub 4} can be avoided and, bended α-Fe{sub x}Se nanopetals can be prepared at 345 °C, which became flat nanosheets with a [001] preferred orientation as extending the reaction time from 1 to 4 h. No superconducting transition occurs in the α-Fe{sub x}Se (0.84 ≤ x ≤ 1.05) nanostructures due to composition heterogeneity or size effect. Magnetic measurements indicate that an antiferromagnetic component with a Néel point at about 45 K dominates the magnetic properties of the α-Fe{sub 0.87}Se nanosheets.

  2. Modification of solid-state property of sulfasalazine by using the supercritical antisolvent process

    NASA Astrophysics Data System (ADS)

    Wu, Wei-Yi; Su, Chie-Shaan

    2017-02-01

    In this study, the supercritical antisolvent (SAS) process was used to recrystallize an active pharmaceutical ingredient, sulfasalazine, to modify the solid-state properties including particle size, crystal habit and polymorphic form. Supercritical CO2 and tetrahydrofuran were used as the antisolvent and solvent, respectively. SAS results obtained from different operating temperatures (35, 45, 55 and 65 °C) were compared and discussed. The results indicate that at 55 °C, spherical sulfasalazine crystals were produced and that their mean particle size was micronized to approximately 1 μm. In addition, according to the analytical results of powder X-ray diffractometry (PXRD), a novel polymorphic form of sulfasalazine was obtained after SAS. Furthermore, the spectroscopic and thermal behavior of produced sulfasalazine crystals were also studied by Fourier transform infrared spectrometry (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Finally, SAS results obtained from different operating temperature was discussed on the basis of the mixture critical point (MCP) of CO2 and tetrahydrofuran. Operation at slightly higher than the MCP is favorable for recrystallization of sulfasalazine through SAS. These results demonstrate that the SAS process is an efficient tool for controlling and modifying the solid-state property of sulfasalazine.

  3. Processing and thermal properties of filament wound carbon-carbon composites for impact shell application

    NASA Astrophysics Data System (ADS)

    Zee, Ralph; Romanoski, Glenn; Gale, H. Shyam; Wang, Hsin

    2001-02-01

    The performance and safety of the radioisotope power source depend in part on the thermal and impact properties of the materials used in the general purpose heat source (GPHS) through the use of an impact shell, thermal insulation and an aeroshell. Results from an earlier study indicate the importance of circumferential fibers to the mechanical properties of cylindrical filament wound carbon-carbon composites for the impact shell application. Based on this study, an investigation was initiated to determine the processing characteristics and the mechanical and thermal response of three filament wound configurations with different percentages of circumferential fibers: 50%, 66% and 80%. The performs were fabricated using a 3-D filament winding machine followed by five cycles of resin impregnation and carbonization. In this paper, the processing sequence and the resulting microstructures of the composites will be described. The thermal conductivity values of the composites as a function of fiber configuration and density will be discussed. These results will be compared with the fine-weave pierced-fabric (FWPF) material and carbon-bonded carbon-fiber insulation. Finally, the relevance of the new configurations for applications in the general purpose heat source (GPHS) will also be inferred. .

  4. Rennet Coagulation and Cheesemaking Properties of Thermally Processed Milk: Overview and Recent Developments.

    PubMed

    Kethireddipalli, Prashanti; Hill, Arthur R

    2015-11-04

    Thermally induced changes in milk proteins and minerals, particularly interactions among caseins and denatured whey proteins, influence important properties of dairy products in both positive and negative ways. Whereas the extensive protein connectivity and increased water-holding capacity resulting from such heat-induced protein modification account for the much desired firmness of acid gels of yogurt, thermal processing, on the other hand, severely impairs clotting and adversely affects the cheesemaking properties of rennet-coagulated cheeses. In technological terms, the principal ongoing challenge in the cheese industry is to take advantage of the water-holding capacity of thermally aggregated whey proteins without compromising the rennetability of cheese milk or the textural and functional attributes of cheese. Including some recent data from the authors' laboratory, this paper will discuss important aspects and current literature on the use of thermally processed milk in the production of rennet-coagulated cheeses and also some of the potential alternatives available for inclusion of whey proteins in cheese, such as the addition of microparticulated whey proteins to cheese milk.

  5. Interpreting food processing through dietary mechanical properties: a Lemur catta case study.

    PubMed

    Yamashita, Nayuta; Cuozzo, Frank P; Sauther, Michelle L

    2012-06-01

    Knowledge of dietary mechanical properties can be informative about physical consequences to consumers during ingestion and mastication. In this article, we examine how Tamarindus indica fruits can affect dental morphology in a population of ring-tailed lemurs (Lemur catta) at Beza Mahafaly special reserve in southwestern Madagascar. Ring-tailed lemurs in tamarind dominated gallery forests exhibit extreme wear and tooth loss on their postcanine dentition that has been related to processing T. indica fruits. We measured and compared mechanical properties of individual food parts in the diet of ring-tailed lemurs in different seasons in 1999-2000, 2008, and 2010. Fracture toughness, hardness, and modulus of foods were measured with a portable mechanical tester. The ripe fruits of T. indica are indeed the toughest and hardest foods ingested by the lemurs. In addition, they are among the largest foods consumed, require high numbers of ingestive bites to process, and are the most frequently eaten by volume. During controlled cutting tests of the ripe fruit shell, multiple runaway side cracks form alongside the cut. Similarly, the lemurs repeatedly bite the ripe shell during feeding and thereby introduce multiple cracks that eventually fragment the shell. Studies of enamel microstructure (e.g., Lucas et al.: BioEssays 30 (2008) 374-385; Campbell et al., 2011) advance the idea that the thin enamel of ring-tailed lemur teeth is susceptible to substantial micro-cracking that rapidly erodes the teeth. We conclude that micro-cracking from repeated loads, in combination with the mechanical and physical properties of the fruit, is primarily responsible for the observed dental damage.

  6. Improving the spatial representation of soil properties and hydrology using topographically derived watershed model initialization processes

    NASA Astrophysics Data System (ADS)

    Easton, Z. M.; Fuka, D.; Collick, A.; Kleinman, P. J. A.; Auerbach, D.; Sommerlot, A.; Wagena, M. B.

    2015-12-01

    Topography exerts critical controls on many hydrologic, geomorphologic, and environmental biophysical processes. Unfortunately many watershed modeling systems use topography only to define basin boundaries and stream channels and do not explicitly account for the topographic controls on processes such as soil genesis, soil moisture distributions and hydrological response. We develop and demonstrate a method that uses topography to spatially adjust soil morphological and soil hydrological attributes [soil texture, depth to the C-horizon, saturated conductivity, bulk density, porosity, and the field capacities at 33kpa (~ field capacity) and 1500kpa (~ wilting point) tensions]. In order to test the performance of the method the topographical adjusted soils and standard SSURGO soil (available at 1:20,000 scale) were overlaid on soil pedon pit data in the Grasslands Soil and Water Research Lab in Resiel, TX. The topographically adjusted soils exhibited significant correlations with measurements from the soil pits, while the SSURGO soil data showed almost no correlation to measured data. We also applied the method to the Grasslands Soil and Water Research watershed using the Soil and Water Assessment Tool (SWAT) model to 15 separate fields as a proxy to propagate changes in soil properties into field scale hydrological responses. Results of this test showed that the topographically adjusted soils resulted better model predictions of field runoff in 50% of the field, with the SSURGO soils preforming better in the remainder of the fields. However, the topographically adjusted soils generally predicted baseflow response more accurately, reflecting the influence of these soil properties on non-storm responses. These results indicate that adjusting soil properties based on topography can result in more accurate soil characterization and, in some cases improve model performance.

  7. Enhanced water vapor in Asian dust layer: Entrainment processes and implication for aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Yoon, Soon-Chang; Kim, Sang-Woo; Kim, Jiyoung; Sohn, Byung-Ju; Jefferson, Anne; Choi, Suk-Jin; Cha, Dong-Hyun; Lee, Dong-Kyou; Anderson, Theodore L.; Doherty, Sarah J.; Weber, Rodney J.

    The entrainment process of water vapor into the dust layer during Asian dust events and the effect of water vapor associated with the Asian dust layer (ADL) on aerosol hygroscopic properties are investigated. The entrainment processes of water vapor into the ADL is examined by using a PSU/NCAR MM5 together with the backward trajectory model, radiosonde data, and remotely sensed aerosol vertical distribution data. Two dust events in the spring of 1998 and 2001 are examined in detail. The results reveal that the water vapor mixing ratio (WVMR) derived by the MM5 fits in well with the WVMR observed by radiosonde, and is well coincident with the aerosol extinction coefficient ( σep) measured by the micro-pulse lidar. The temporal evolution of the vertical distributions of WVMR and σep exhibited similar features. On the basis of a well simulation of the enhanced water vapor within the dust layer by the MM5, we trace the dust storms to examine the entrainment mechanism. The enhancement of WVMR within the ADL was initiated over the mountainous areas. The relatively moist air mass in the well-developed mixing layer over the mountainous areas is advected upward from the boundary layer by an ascending motion. However, a large portion of the water vapor within the ADL is enhanced over the edge of a highland and the plains in China. This is well supported by the simulated WVMR and the wind vectors. Aircraft-based in situ measurements of the chemical and optical properties of aerosol enable a quantitative estimation of the effect of the enhanced WVMR on the aerosol hygroscopic properties. The submicron aerosol accompanied by the dust storm caused an increase of aerosol scattering through water uptakes during the transport. This increase could be explained by the chemical fact that water-soluble submicron pollution aerosols are enriched in the ADL.

  8. Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process-Structure-Property Relations

    DOE PAGES

    Ihlefeld, Jon F.; Harris, David T.; Keech, Ryan; ...

    2016-07-05

    Ferroelectric materials are well-suited for a variety of applications because they can offer a combination of high performance and scaled integration. Examples of note include piezoelectrics to transform between electrical and mechanical energies, capacitors used to store charge, electro-optic devices, and non-volatile memory storage. Accordingly, they are widely used as sensors, actuators, energy storage, and memory components, ultrasonic devices, and in consumer electronics products. Because these functional properties arise from a non-centrosymmetric crystal structure with spontaneous strain and a permanent electric dipole, the properties depend upon physical and electrical boundary conditions, and consequently, physical dimension. The change of properties withmore » decreasing physical dimension is commonly referred to as a size effect. In thin films, size effects are widely observed, while in bulk ceramics, changes in properties from the values of large-grained specimens is most notable in samples with grain sizes below several microns. It is important to note that ferroelectricity typically persists to length scales of about 10 nm, but below this point is often absent. Despite the stability of ferroelectricity for dimensions greater than ~10 nm, the dielectric and piezoelectric coefficients of scaled ferroelectrics are suppressed relative to their bulk counterparts, in some cases by changes up to 80%. The loss of extrinsic contributions (domain and phase boundary motion) to the electromechanical response accounts for much of this suppression. In this article the current understanding of the underlying mechanisms for this behavior in perovskite ferroelectrics are reviewed. We focus on the intrinsic limits of ferroelectric response, the roles of electrical and mechanical boundary conditions, grain size and thickness effects, and extraneous effects related to processing. Ultimately, in many cases, multiple mechanisms combine to produce the observed scaling

  9. Scaling Effects in Perovskite Ferroelectrics: Fundamental Limits and Process-Structure-Property Relations

    SciTech Connect

    Ihlefeld, Jon F.; Harris, David T.; Keech, Ryan; Jones, Jacob L.; Maria, Jon-Paul; Trolier-McKinstry, Susan

    2016-07-05

    Ferroelectric materials are well-suited for a variety of applications because they can offer a combination of high performance and scaled integration. Examples of note include piezoelectrics to transform between electrical and mechanical energies, capacitors used to store charge, electro-optic devices, and non-volatile memory storage. Accordingly, they are widely used as sensors, actuators, energy storage, and memory components, ultrasonic devices, and in consumer electronics products. Because these functional properties arise from a non-centrosymmetric crystal structure with spontaneous strain and a permanent electric dipole, the properties depend upon physical and electrical boundary conditions, and consequently, physical dimension. The change of properties with decreasing physical dimension is commonly referred to as a size effect. In thin films, size effects are widely observed, while in bulk ceramics, changes in properties from the values of large-grained specimens is most notable in samples with grain sizes below several microns. It is important to note that ferroelectricity typically persists to length scales of about 10 nm, but below this point is often absent. Despite the stability of ferroelectricity for dimensions greater than ~10 nm, the dielectric and piezoelectric coefficients of scaled ferroelectrics are suppressed relative to their bulk counterparts, in some cases by changes up to 80%. The loss of extrinsic contributions (domain and phase boundary motion) to the electromechanical response accounts for much of this suppression. In this article the current understanding of the underlying mechanisms for this behavior in perovskite ferroelectrics are reviewed. We focus on the intrinsic limits of ferroelectric response, the roles of electrical and mechanical boundary conditions, grain size and thickness effects, and extraneous effects related to processing. Ultimately, in many cases, multiple mechanisms combine to produce the observed scaling effects.

  10. Issues in nanocomposite ceramic engineering: focus on processing and properties of alumina-based composites.

    PubMed

    Palmero, Paola; Kern, Frank; Sommer, Frank; Lombardi, Mariangela; Gadow, Rainer; Montanaro, Laura

    2014-12-30

    Ceramic nanocomposites, containing at least one phase in the nanometric dimension, have received special interest in recent years. They have, in fact, demonstrated increased performance, reliability and lifetime with respect to monolithic ceramics. However, a successful approach to the production of tailored composite nanostructures requires the development of innovative concepts at each step of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering.This review aims to deepen understanding of some of the critical issues associated with the manufacturing of nanocomposite ceramics, focusing on alumina-based composite systems. Two case studies are presented and briefly discussed. The former illustrates the benefits, in terms of sintered microstructure and related mechanical properties, resulting from the application of an engineering approach to a laboratory-scale protocol for the elaboration of nanocomposites in the system alumina-ZrO2-YAG (yttrium aluminium garnet). The latter illustrates the manufacturing of alumina-based composites for large-scale applications such as cutting tools, carried out by an injection molding process. The need for an engineering approach to be applied in all processing steps is demonstrated also in this second case study, where a tailored manufacturing process is required to obtain the desired results.

  11. Mineral Properties and Dietary Value of Raw and Processed Stinging Nettle (Urtica dioica L.)

    PubMed Central

    Xu, Yixiang; Ramirez, Elizabeth

    2013-01-01

    Stinging nettle (Urtica dioica L.) has a long history of usage and is currently receiving attention as a source of fiber and alternative medicine. In many cultures, nettle is also eaten as a leafy vegetable. In this study, we focused on nettle yield (edible portion) and processing effects on nutritive and dietary properties. Actively growing shoots were harvested from field plots and leaves separated from stems. Leaf portions (200 g) were washed and processed by blanching (1 min at 96–98°C) or cooking (7 min at 98-99°C) with or without salt (5 g·L−1). Samples were cooled immediately after cooking and kept in frozen storage before analysis. Proximate composition, mineral, amino acid, and vitamin contents were determined, and nutritive value was estimated based on 100 g serving portions in a 2000 calorie diet. Results show that processed nettle can supply 90%–100% of vitamin A (including vitamin A as β-carotene) and is a good source of dietary calcium, iron, and protein. We recommend fresh or processed nettle as a high-protein, low-calorie source of essential nutrients, minerals, and vitamins particularly in vegetarian, diabetic, or other specialized diets. PMID:26904610

  12. Experimental analysis of tablet properties for discrete element modeling of an active coating process.

    PubMed

    Just, Sarah; Toschkoff, Gregor; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes; Knop, Klaus; Kleinebudde, Peter

    2013-03-01

    Coating of solid dosage forms is an important unit operation in the pharmaceutical industry. In recent years, numerical simulations of drug manufacturing processes have been gaining interest as process analytical technology tools. The discrete element method (DEM) in particular is suitable to model tablet-coating processes. For the development of accurate simulations, information on the material properties of the tablets is required. In this study, the mechanical parameters Young's modulus, coefficient of restitution (CoR), and coefficients of friction (CoF) of gastrointestinal therapeutic systems (GITS) and of active-coated GITS were measured experimentally. The dynamic angle of repose of these tablets in a drum coater was investigated to revise the CoF. The resulting values were used as input data in DEM simulations to compare simulation and experiment. A mean value of Young's modulus of 31.9 MPa was determined by the uniaxial compression test. The CoR was found to be 0.78. For both tablet-steel and tablet-tablet friction, active-coated GITS showed a higher CoF compared with GITS. According to the values of the dynamic angle of repose, the CoF was adjusted to obtain consistent tablet motion in the simulation and in the experiment. On the basis of this experimental characterization, mechanical parameters are integrated into DEM simulation programs to perform numerical analysis of coating processes.

  13. Influence of Processing and Heat Treatment on Corrosion Resistance and Properties of High Alloyed Steel Coatings

    NASA Astrophysics Data System (ADS)

    Hill, Horst; Weber, Sebastian; Raab, Ulrich; Theisen, Werner; Wagner, Lothar

    2012-09-01

    Corrosion and abrasive wear are two important aspects to be considered in numerous engineering applications. Looking at steels, high-chromium high-carbon tool steels are proper and cost-efficient materials. They can either be put into service as bulk materials or used as comparatively thin coatings to protect lower alloyed construction or heat treatable steels from wear and corrosion. In this study, two different corrosion resistant tool steels were used for the production of coatings and bulk material. They were processed by thermal spraying and super solidus liquid phase sintering as both processes can generally be applied to produce coatings on low alloyed substrates. Thermally sprayed (high velocity oxygen fuel) coatings were investigated in the as-processed state, which is the most commonly used condition for technical applications, and after a quenching and tempering treatment. In comparison, sintered steels were analyzed in the quenched and tempered condition only. Significant influence of alloy chemistry, processing route, and heat treatment on tribological properties was found. Experimental investigations were supported by computational thermodynamics aiming at an improvement of tribological and corrosive resistance.

  14. Effect of trisodium citrate concentration and cooking time on the physicochemical properties of pasteurized process cheese.

    PubMed

    Shirashoji, N; Jaeggi, J J; Lucey, J A

    2006-01-01

    The effects of the concentration of trisodium citrate (TSC) emulsifying salt (0.25 to 2.75%) and holding time (0 to 20 min) on the textural, rheological, and microstructural properties of pasteurized process Cheddar cheese were studied using a central composite rotatable design. The loss tangent parameter (from small amplitude oscillatory rheology), extent of flow (derived from the University of Wisconsin Meltprofiler), and melt area (from the Schreiber test) all indicated that the meltability of process cheese decreased with increased concentration of TSC and that holding time led to a slight reduction in meltability. Hardness increased as the concentration of TSC increased. Fluorescence micrographs indicated that the size of fat droplets decreased with an increase in the concentration of TSC and with longer holding times. Acid-base titration curves indicated that the buffering peak at pH 4.8, which is due to residual colloidal calcium phosphate, decreased as the concentration of TSC increased. The soluble phosphate content increased as concentration of TSC increased. However, the insoluble Ca decreased with increasing concentration of TSC. The results of this study suggest that TSC chelated Ca from colloidal calcium phosphate and dispersed casein; the citrate-Ca complex remained trapped within the process cheese matrix. Increasing the concentration of TSC helped to improve fat emulsification and casein dispersion during cooking, both of which probably helped to reinforce the structure of process cheese.

  15. Mineral Properties and Dietary Value of Raw and Processed Stinging Nettle (Urtica dioica L.).

    PubMed

    Rutto, Laban K; Xu, Yixiang; Ramirez, Elizabeth; Brandt, Michael

    2013-01-01

    Stinging nettle (Urtica dioica L.) has a long history of usage and is currently receiving attention as a source of fiber and alternative medicine. In many cultures, nettle is also eaten as a leafy vegetable. In this study, we focused on nettle yield (edible portion) and processing effects on nutritive and dietary properties. Actively growing shoots were harvested from field plots and leaves separated from stems. Leaf portions (200 g) were washed and processed by blanching (1 min at 96-98°C) or cooking (7 min at 98-99°C) with or without salt (5 g·L(-1)). Samples were cooled immediately after cooking and kept in frozen storage before analysis. Proximate composition, mineral, amino acid, and vitamin contents were determined, and nutritive value was estimated based on 100 g serving portions in a 2000 calorie diet. Results show that processed nettle can supply 90%-100% of vitamin A (including vitamin A as β-carotene) and is a good source of dietary calcium, iron, and protein. We recommend fresh or processed nettle as a high-protein, low-calorie source of essential nutrients, minerals, and vitamins particularly in vegetarian, diabetic, or other specialized diets.

  16. Alumina/silicon carbide nanocomposites by hybrid polymer/powder processing: Microstructures and mechanical properties

    SciTech Connect

    Sternitzke, M.; Derby, B.; Brook, R.J.

    1998-01-01

    Nanocomposites with fine, coarse, and bimodal silicon carbide (SiC) particle-size distributions were hot pressed and examined by transmission electron microscopy, scanning electron microscopy, and optical microscopy, as well as by four-point-bend and indentation tests. The finer SiC nanophase was introduced homogeneously by coating a silicon-containing polymer onto the alumina (Al{sub 2}O{sub 3}) powder, followed by a pyrolysis procedure; for the coarser SiC, nanophase conventional powder processing was used. Powder- and polymer-processed nanocomposites both had their maximum strengths at 5 vol% of SiC. High-strength nanocomposites that contained a higher volume fraction of SiC could be fabricated when the two methods were combined in a hybrid processing route. The SiC phase in the resulting hybrid materials originated from both the polymer and the SiC powder. The mechanical properties of these materials could be correlated with the fabrication route. Processing-flaw populations and calculated Griffith-flaw sizes were not only smaller, but they were also significantly different in the nanocomposites, in comparison to those in Al{sub 2}O{sub 3} ceramics; this may explain the strength increase in Al{sub 2}O{sub 3}/SiC nanocomposite materials.

  17. Evaluation of the Mechanical Properties of AA 6063 Processed by Severe Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Jafarlou, Davoud Mashhadi; Zalnezhad, Erfan; Hamouda, Abdelmagid Salem; Faraji, Ghader; Mardi, Noor Azizi Bin; Hassan Mohamed, Mohsen Abdelnaeim

    2015-05-01

    In this study, the mechanical properties, including surface hardness, tensile strength, fatigue, and fretting fatigue behavior of AA 6063 processed by equal channel angular pressing as the most efficient severe shear plastic deformation (SPD) technique, were investigated. Following the SPD process, samples were subjected to heat treatment (HT), hard anodizing (HA), and a combination of HT and HA. Rotating-bending fretting fatigue tests were performed to explore the samples' response to the fretting condition. From the experimental fatigue and fretting fatigue tests, it was apparent that the SPD treatment had a positive effect on enhancing the fatigue and fretting fatigue lives of the samples at low and high-cyclic loads compared with the HT technique by 78 and 67 pct, and 131 and 154 pct respectively. The results also indicate that the SPD + HT technique significantly increased the fatigue and fretting fatigue lives of the samples at high and low cycles by 15.56 and 8.33 pct, and 14.4 and 5.1 pct respectively, compared with the SPD method. HA of AA6063 increased the fatigue and fretting fatigue lives of SPD + HT-processed samples at low cycle by 15.5 and 18.4 pct respectively; however, at high cycle, HA had reverse effects, whereby the fatigue and fretting fatigue lives of SPD + HT-processed samples decreased by 16.7 and 30 pct, respectively.

  18. Home-Processed Red Beetroot (Beta vulgaris L.) Products: Changes in Antioxidant Properties and Bioaccessibility

    PubMed Central

    Guldiken, Burcu; Toydemir, Gamze; Nur Memis, Kubra; Okur, Sena; Boyacioglu, Dilek; Capanoglu, Esra

    2016-01-01

    In this study, the effects of home-processing on the antioxidant properties and in vitro bioaccessibility of red beetroot bioactives were investigated. For this purpose, fresh red beetroot and six different home-processed red beetroot products—including boiled, oven-dried, pickled, pureed, juice-processed, and jam-processed—were analyzed and compared for their total phenolic (TP) and total flavonoid (TF) contents, total antioxidant capacities (TAC), and individual anthocyanin contents. In addition, bioaccessibility of red beetroot antioxidants was determined using an in vitro simulated gastrointestinal digestion method. Dried, pureed, and fresh red beetroot samples had the highest TP, TF, and TAC values, which were 347 ± 23 mg gallic acid equivalent (GAE)/100 g, 289 ± 53 mg rutin equivalent (RE)/100 g, 3889 ± 982 mg trolox equivalent antioxidant capacity (TEAC)/100 g, respectively. The in vitro digestion method revealed the highest recovery for TP (16%) and TAC (1.3%) in jam. This study provides comparative data to evaluate the effects of various home-processing techniques on antioxidant potential of red beetroot products. PMID:27258265

  19. Annual Report: Property Improvement in CZT via Modeling and Processing Innovations

    SciTech Connect

    Henager, Charles H.; Setyawan, Wahyu; Gao, Fei; Hu, Shenyang Y.; Bliss, Mary; Riley, Brian J.; Alvine, Kyle J.; Stave, Jean A.

    2013-09-01

    The objective of this project is to develop growth models of CZT crystals from the melt using vertical gradient freeze (VGF) or vertical Bridgman growth as a typical process. Further, the project will perform critical experiments including single crystal growth to validate the growth models and to provide detailed data for modeling and simulation. Ideally, the project will develop growth models that will provide, for the first time, choices for optimal CZT single crystal growth from the melt based on model input. The overarching goal that guides this research proposal is to produce large, single crystals of CZT with good yield and reproducible properties. In our view this depends on 1) understanding crystal growth processes, including annealing and cool-down processing, and 2) understanding the role of defects on detector response since it is not possible, yet, to produce defect-free materials. Models of defect structure and formation are addressed. Validated models and experiments on reducing defects in melt-grown crystals are used to guide our understanding of growth processes and in-furnace annealing plus cool-down.

  20. [Performance optimization of property-improved biodiesel manufacturing process coupled with butanol extractive fermentation].

    PubMed

    Zhang, Longyun; Yang, Ying; Shi, Zhongping

    2008-11-01

    The products concentrations in traditional acetone-butanol (AB) fermentation are too low that large amount of energy has to be consumed in the distillation and product recovery process. Aiming at direct utilization of the fermentation products, in this study, optimization of property-improved biodiesel manufacturing process coupled with AB extractive fermentation was conducted, under the condition of using the biodiesel originated from waste cooking oil as the extractant and high concentrated corn flour medium. The effect of biodiesel/broth volume ratio, waste supernatant recycle ratio, and electronic carrier addition on the major process performance index was carefully investigated. Under the optimized condition, the biodiesel quality was improved with the cetane value increased from 51.4 to 54.4; "actual butanol yield" reached to a level of 18%, and waste supernatant recycle ratio exceeded 50%. In this way, elimination of energy-consuming product recovery process and realization of "energy-saving & waste minimization" industrial production target advocated by the state government, could be potentially expected.

  1. Effects of processing variables on the Y2BaCuO5 size and magnetic properties of melt-processed YBa2Cu3Ox

    NASA Astrophysics Data System (ADS)

    Yang, H. F.; Varanasi, C.; Ginn, P. J. M. C.

    1995-12-01

    Samples of YBa2Cu3Ox (123) with excess Y2BaCuO5 (211) in the molar ratio of 5:1 ( 123/211) were processed using the “solid liquid melt growth” (SLMG) technique. The effect of hold time above the peritectic on the magnetic properties was examined. Extended hold times above the peritectic during processing degrade the magnetic properties of SLMG processed 123. In SLMG 123, the very fine (>100 nm) 211 particles produced by this processing route are the primarymagnetic flux pinners. Extended hold periods reduce the number and/or coarsen the average size of these fine precipitates, resulting in a reduced magnetization. These results were compared to undoped Y123 processed by the more traditional melt texture growth (MTG). In MTG processing, extended hold times above the peritectic are found to result in improved magnetic behavior because of increased defect densities.

  2. Influence of process parameters on properties of Nanostructured Lipid Carriers (NLC) formulation.

    PubMed

    Lasoń, Elwira; Sikora, Elżbieta; Ogonowski, Jan

    2013-01-01

    Nanostructured lipid carriers (NLC) are stable colloidal formulations with notable advantages for drug delivery systems. Thanks to their physicochemical stability, biocompatibility, biodegradability and controlled drug release, they have received increasing attention for the last several years. The aim of the study was to prepare and characterize nanostructured lipid carriers (NLC). Both, the effect of the process parameters and the effect of the preemulsion composition on the NLC properties were investigated. In the work, different type of surfactants (i.e. decyl glucoside, Poloxamer188, Tween 80, sodium cholate) and their combinations were used to stabilize NLC dispersions. Moreover, several kinds of solid lipids (modified beeswax, gliceryl behenate, cetyl palmitate and berry wax) and liquid lipids (caprilic/capric triglyceride and decyl oleate) were applied. An ultrasonication method using a probe type sonicator was used to obtain NLC, and the time and energy of the process were modified throuhout. The physicochemical properties of the formulations, such as particle size, size distribution, polidispersity index were studied using the dynamic light scattering (DLS) method. The electrophoretic mobility of obtained particles was also measured, using the Zetasizer Nano ZS Malvern Instrument based on the Laser Doppler Velocimetry (LDV) technique. Knowing the value of electrophoretic mobility of particles for given conditions, the zeta potential was determined. The obtained results showed that the process parameters and the composition of the preemulsion had significant impact on the nanoparticles structure. The optimal formulations size ranged between 60 and 80 nm, and the value of their zeta potential was up to -30mV. The stability of these systems was further confirmed by macroscopic observation.

  3. Demonstrating the Effects of Processing on the Structure and Physical Properties of Plastic Using Disposable PETE Cups

    ERIC Educational Resources Information Center

    Erk, Kendra A.; Rhein, Morgan; Krafcik, Matthew J.; Ydstie, Sophie

    2015-01-01

    An educational activity is described in which the structure and physical properties of disposable plastic cups were directly related to the method of processing. The mechanical properties of specimens cut from the walls of poly(ethylene terephthalate) (PETE) cups, oriented parallel and perpendicular to the thermoforming direction, were measured in…

  4. Processing-microstructure-properties relationships in small-particle plasma-sprayed ceramic coatings

    NASA Astrophysics Data System (ADS)

    Mawdsley, Jennifer Renee

    The objective of this study was to determine processing-microstructure-properties relationships for small-particle plasma-sprayed (SPPS) ceramic coatings. Plasma-sprayed yttria partially-stabilized zirconia (YSZ) coatings, which are used to protect superalloys from heat and the environment in turbine engines, and plasma-sprayed alumina coatings, which are being investigated as a potential replacement for chrome in corrosion protection applications, were fabricated using SPPS technology and their microstructure and pertinent properties were examined. The properties of plasma-sprayed YSZ and alumina coatings were investigated with designed experiments. The parameters varied include power, spray distance, total plasma gas flow, percent hydrogen in the plasma gas, injector angle, injector offset and carrier gas flow. The variations in thermal diffusivity, thermal conductivity, elastic modulus, and hardness for the YSZ SPPS coatings were found to correlate to the variations in density, which were related to the processing variables. It was found that surface roughness was related to the amount of splashing and debris associated with the single splats. In four-point bending strain tolerance and fatigue tests, the SPPS YSZ coatings showed very little acoustic emission activity, except in the case of tensile fatigue of a coating without network cracks. Small angle X-ray scattering experiments revealed that SPPS YSZ coatings have significantly less submicron intersplat porosity than conventional plasma-sprayed coatings, and that the pore and microcrack scattering area decreases with heat treatment due to the sintering of microcracks and small pores. The SPPS alumina coatings were optimized to produce a coating with excellent corrosion protection capabilities. It was found that the hardest SPPS alumina coatings did not provide the best corrosion protection due to unique porosity defect structures associated with surface bumps in the coatings. The surface bumps were

  5. Processing and properties of a solid energy fuel from municipal solid waste (MSW) and recycled plastics.

    PubMed

    Gug, JeongIn; Cacciola, David; Sobkowicz, Margaret J

    2015-01-01

    Diversion of waste streams such as plastics, woods, papers and other solid trash from municipal landfills and extraction of useful materials from landfills is an area of increasing interest especially in densely populated areas. One promising technology for recycling municipal solid waste (MSW) is to burn the high-energy-content components in standard coal power plant. This research aims to reform wastes into briquettes that are compatible with typical coal combustion processes. In order to comply with the standards of coal-fired power plants, the feedstock must be mechanically robust, free of hazardous contaminants, and moisture resistant, while retaining high fuel value. This study aims to investigate the effects of processing conditions and added recyclable plastics on the properties of MSW solid fuels. A well-sorted waste stream high in paper and fiber content was combined with controlled levels of recyclable plastics PE, PP, PET and PS and formed into briquettes using a compression molding technique. The effect of added plastics and moisture content on binding attraction and energy efficiency were investigated. The stability of the briquettes to moisture exposure, the fuel composition by proximate analysis, briquette mechanical strength, and burning efficiency were evaluated. It was found that high processing temperature ensures better properties of the product addition of milled mixed plastic waste leads to better encapsulation as well as to greater calorific value. Also some moisture removal (but not complete) improves the compacting process and results in higher heating value. Analysis of the post-processing water uptake and compressive strength showed a correlation between density and stability to both mechanical stress and humid environment. Proximate analysis indicated heating values comparable to coal. The results showed that mechanical and moisture uptake stability were improved when the moisture and air contents were optimized. Moreover, the briquette

  6. Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

    NASA Astrophysics Data System (ADS)

    Sreeram, Arvind

    Conjugated polymers have found several applications in recent years, in energy conversion and storage devices such as organic light emitting diodes, solar cells, batteries, and super capacitors. Thin films of polymers used for these applications need to be mechanically and thermally stable to withstand the harsh operating conditions. Although there is significant information on the optoelectronic properties of many of these polymers, there are only few studies on their mechanical properties. There is little information in the literature on how processing of these films influence mechanical properties. In the first part of this study, poly(p-phenylene vinylene) (PPV) films were prepared by thermolytic conversion of poly[p -phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures and the kinetics of reaction was investigated using thermogravimetry and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties of the films, studied using nanoindentation, showed a dependence on the extent of conversion and chemical composition of the films. The presence of chemical defects (e.g., carbonyl groups, detected using FTIR spectroscopy), was also found to have a noticeable effect on the modulus and hardness of the films. The storage modulus, E', and plasticity decreased with an increase in conversion, whereas the loss modulus, E", showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower E" than E', consistent with the glassy nature of the polymers at room temperature. In the second part of the study, polyacetylene films were synthesized by acid-catalyzed dehydration reaction of poly(vinyl alcohol) (PVA) precursor films. The kinetics of this reaction was monitored by thermogravimetry. The chemical structure of the conjugated polymer films was characterized by Raman and IR spectroscopy. Polyacetylene films incorporated with 1-propyl-3-methylimidazolium ionic liquid

  7. "Processing and Mechanical Properties of NiTi-Nb Porous Structures with Microchannels"

    NASA Astrophysics Data System (ADS)

    Bewerse, Catherine Nicole

    Nickel-Titanium alloys are able to recover high amounts of strain (~5-8%) through a reversible phase transformation. This shape recovery, and its accompanying toughness and high yield strength, make the material attractive for biomedical, actuation, and energy absorption applications. Porous structures made out of NiTi are particularly interesting, as the mechanical properties can be tailored close to that of bone. While various methods exist to create NiTi porous structures, many are limited by pore interconnectivity, pore geometry and spatial arrangement, or undesirable formation of intermetallics. In this dissertation, we present three different processing methods to fabricate NiTi(Nb) porous structures with 3D fully interconnected microchannels. These structures have controllable volume fraction, orientation, and spatial distribution of the microchannels. In addition, we characterize the NiTi-Nb eutectic material used to bond the porous structures and investigate the strain field and stress concentrations around a model pore though Digital Image Correlation (DIC) and FEM. We first present a method using hot isostatic pressing (HIPing) with a steel wire scaffold to create a structure with a 60% volume fraction of a regular 3D network of orthogonally interconnected microchannels. This structure exhibited an effective stiffness similar to cortical bone, but exhibited brittle fracture at a relatively low strength, implying poor NiTi powder bonding. This prompted the use of liquid phase sintering instead of HIPing in our second method, where a quasi-binary NiTi-Nb eutectic was used to bond the NiTi powders. The resulting structure contained 34% channel porosity with 16% matrix porosity due to void consolidation and a clearly defined 3D network of interconnected microchannels with circular cross sections. In an effort to simplify the processing of these NiTi-Nb structures and enable scalability, the final method presented employs slip casting with and without

  8. Physical Properties Models for Simulation of Processes to Treat INEEL Tank Farm Waste: Thermodynamic Equilibrium

    SciTech Connect

    Nichols, T.T.; Taylor, D.D.

    2002-07-18

    A status is presented of the development during FY2002 of a database for physical properties models for the simulation of the treatment of Sodium-Bearing Waste (SBW) at the Idaho National Engineering and Environmental Laboratory. An activity coefficient model is needed for concentrated, aqueous, multi-electrolyte solutions that can be used by process design practitioners. Reasonable first-order estimates of activity coefficients in the relevant media are needed rather than an incremental improvement in theoretical approaches which are not usable by practitioners. A comparison of the Electrolyte Non-Random Two-Liquid (ENRTL) and Pitzer ion-interaction models for the thermodynamic representation of SBW is presented. It is concluded that Pitzer's model is superior to ENRTL in modeling treatment processes for SBW. The applicability of the Pitzer treatment to high concentrations of pertinent species and to the determination of solubilities and chemical equilibria is addressed. Alternate values of Pitzer parameters for HCl, H2SO4, and HNO3 are proposed, applicable up to 16m, and 12m, respectively. Partial validation of the implementation of Pitzer's treatment within the commercial process simulator ASPEN Plus was performed.

  9. Processing, microstructure, and electric properties of buried resistors in low-temperature co-fired ceramics

    SciTech Connect

    Yang, Pin; Rodriguez, Mark A.; Kotula, Paul; Miera, Brandon K.; Dimos, Duane

    2001-04-01

    The electrical properties of ruthenium oxide based devitrifiable resistors embedded within low-temperature co-fired ceramics were investigated from -100{sup o}C to 100{sup o}C. Special attention was given to the processing conditions and their effects on resistance and temperature coefficient of resistance (TCR). Results indicate that within this temperature range the conductance for these buried resistors is limited by tunneling of charge carriers through the thin glass layer between ruthenium oxide particles. A modified version of the tunneling barrier model is proposed to account for the microstructure ripening observed during thermal processing. The model parameters determined from curve fitting show that charging energy (i.e., the energy required for a charge carrier to tunnel through the glass barrier) is strongly dependent on particle size and particle--particle separation between ruthenium oxide grains. Initial coarsening of ruthenium oxide grains was found to reduce the charging energy and lower the resistance. However, when extended ripening occurs, the increase in particle--particle separation increases the charging energy, reduces the tunneling probability and gives rise to a higher resistance. The tradeoff between these two effects results in an optimum microstructure with a minimum resistance and TCR. Furthermore, the TCR of these buried resistors has been shown to be governed by the magnitude of the charging energy. Model parameters determined by our analysis appear to provide quantitative physical interpretations to the microstructural changes in the resistor, which in turn, are controlled by the processing conditions.

  10. Processing, Microstructure and Electric Properties of Buried Resistors in Low Temperature Co-Fired Ceramics

    SciTech Connect

    Dimos, D.B.; Kotula, P.G.; Miera, B.K.; Rodriguez, M.A.; Yang, Pin

    1999-09-17

    The electrical properties were investigated for ruthenium oxide based devitrifiable resistors embedded within low temperature co-fired ceramics. Special attention was given to the processing conditions and their affects on resistance and temperature coefficient of resistance (TCR). Results indicate that the conductance for these buried resistors is limited by tunneling of charge carriers through the thin glass layer between ruthenium oxide particles. A modified version of the tunneling barrier model is proposed to more accurately account for the microstructure ripening observed during thermal processing. The model parameters determined from curve fitting show that charging energy (i.e., the energy required for a charge carrier to tunnel through the glass barrier) is strongly dependent on particle size and particle-particle separation between ruthenium oxide grains. Initial coarsening of ruthenium oxide grains was found to reduce the charging energy and lower the resistance. However, when extended ripening occurs, the increase in particle-particle separation increases the charging energy, reduces the tunneling probability and gives rise to a higher resistance. The trade-off between these two effects results an optimum microstructure with a minimum resistance and TCR. Furthermore, the TCR of these resistors has been shown to be governed by the magnitude of the charging energy. Model parameters determined by our analysis appear to provide quantitative physical interpretations to the microstructural change in the resistor, which in turn, are controlled by the processing conditions.

  11. Modifying Mechanical, Optical Properties and Thermal Processability of Iridescent Cellulose Nanocrystal Films Using Ionic Liquid.

    PubMed

    Liu, Ping; Guo, Xin; Nan, Fuchun; Duan, Yongxin; Zhang, Jianming

    2017-01-25

    Iridescent films formed from the self-assembly of cellulose nanocrystals (CNCs) are brittle and difficult to handle or integrate within an industrial process. Here we present a simple approach to prepare iridescent CNC films with tunable pliability and coloration through the addition of ionic liquids (ILs) of 1-allyl-3-methylimidazolium chloride (AmimCl) as plasticizers. By using the undried CNC film as a filter membrane and ILs solution as a leaching liquid, it was found that the filtration process made ILs uniformly interpenetrate into CNC film due to the strong ionic interaction between CNC and AmimCl. Unexpectedly, the filtration process also gave rise to partial desulfurization of CNC film, which is conducive to the improvement of thermal stability. Benefiting from the improved thermal stability and the dissolving capacity of AmimCl for cellulose at high temperature, the incorporated ILs enable the cholesteric CNC film to be further toughened via a hot-pressing treatment. This study demonstrates that ionic liquids have great potential to modify the mechanical, optical properties as well as the thermal stability of iridescent CNC films.

  12. Properties of WZ21 (%wt) alloy processed by a powder metallurgy route.

    PubMed

    Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

    2015-06-01

    Microstructure, mechanical properties and corrosion behaviour of WZ21 (%wt) alloy prepared by a powder metallurgy route from rapidly solidified powders have been studied. Results were compared to those of the same alloy prepared through a conventional route of casting and extrusion. The microstructure of the extruded ingot consisted of α-Mg grains and Mg3Zn3Y2 (W-phase) and LPSO-phase particles located at grain boundaries. Moreover, stacking faults were also observed within α-Mg grains. The alloy processed by the powder metallurgy route exhibited a more homogeneous and finer microstructure, with a grain size of 2 μm. In this case W-phase and Mg24Y5 phase were identified, but not the LPSO-phase. The microstructural refinement induced by the use of rapidly solidified powders strengthened the alloy at room temperature and promoted superplasticity at higher strain rates. Corrosion behaviour in PBS medium evidenced certain physical barrier effect of the almost continuous arrangements of second phases aligned along the extrusion direction in conventionally processed WZ21 alloy, with a stable tendency around 7 mm/year. On the other hand, powder metallurgy processing promoted significant pitting corrosion, inducing accelerated corrosion rate during prolonged immersion times.

  13. Effect of cyclic freeze-thawing process on the structure and properties of collagen.

    PubMed

    Ding, Cuicui; Zhang, Min; Li, Guoying

    2015-09-01

    The influence of freeze-thawing cycles (named 'N') on the rheological and thermal properties of bovine skin collagen solution was investigated using a rheometer and differential scanning calorimetry (DSC). The results of dynamic frequency sweep tests showed that the elasticity of collagen increased as N increased to 3, 5 and 7. Especially, after the freeze-thawing cycles of N=7, the recovery capacity of collagen remarkably increased (from 17.76% to 74.98%) and the hysteresis loop areas of collagen also became larger (from 95.53 to 218.24 Pa/s). Moreover, DSC and non-isothermal kinetic analysis revealed that although the freeze-thawing process had little impact on the thermal denaturation temperature, the endothermic enthalpy was increased by 73% when N=7, as estimated from the area under the endothermic peak and from the Friedman isoconversional method. In addition, as observed by atomic force microscopy (AFM), the fibers of collagen became thicker after the process of freeze-thawing cycles, indicating that the aggregation of collagen molecules was enhanced in the process of freeze-thawing. Meanwhile, the morphology of freeze-thawed collagen sponge examined by scanning electron microscopy (SEM) exhibited a porous network structure, and the pores became more regular with increasing N.

  14. Functional magnetic resonance imaging adaptation reveals the cortical networks for processing grasp-relevant object properties.

    PubMed

    Monaco, Simona; Chen, Ying; Medendorp, W P; Crawford, J D; Fiehler, Katja; Henriques, Denise Y P

    2014-06-01

    Grasping behaviors require the selection of grasp-relevant object dimensions, independent of overall object size. Previous neuroimaging studies found that the intraparietal cortex processes object size, but it is unknown whether the graspable dimension (i.e., grasp axis between selected points on the object) or the overall size of objects triggers activation in that region. We used functional magnetic resonance imaging adaptation to investigate human brain areas involved in processing the grasp-relevant dimension of real 3-dimensional objects in grasping and viewing tasks. Trials consisted of 2 sequential stimuli in which the object's grasp-relevant dimension, its global size, or both were novel or repeated. We found that calcarine and extrastriate visual areas adapted to object size regardless of the grasp-relevant dimension during viewing tasks. In contrast, the superior parietal occipital cortex (SPOC) and lateral occipital complex of the left hemisphere adapted to the grasp-relevant dimension regardless of object size and task. Finally, the dorsal premotor cortex adapted to the grasp-relevant dimension in grasping, but not in viewing, tasks, suggesting that motor processing was complete at this stage. Taken together, our results provide a complete cortical circuit for progressive transformation of general object properties into grasp-related responses.

  15. Physical Properties Models for Simulation of Processes to Treat INEEL Tank Farm Waste: Thermodynamic Equilibrium

    SciTech Connect

    Nichols, Todd Travis; Taylor, Dean Dalton

    2002-07-01

    A status is presented of the development during FY2002 of a database for physical properties models for the simulation of the treatment of Sodium-Bearing Waste (SBW) at the Idaho National Engineering and Environmental Laboratory. An activity coefficient model is needed for concentrated, aqueous, multi-electrolyte solutions that can be used by process design practitioners. Reasonable first-order estimates of activity coefficients in the relevant media are needed rather than an incremental improvement in theoretical approaches which are not usable by practitioners. A comparison of the Electrolyte Non-Random Two-Liquid (ENRTL) and Pitzer ion-interaction models for the thermodynamic representation of SBW is presented. It is concluded that Pitzer's model is superior to ENRTL in modeling treatment processes for SBW. The applicability of the Pitzer treatment to high concentrations of pertinent species and to the determination of solubilities and chemical equilibria is addressed. Alternate values of Pitzer parameters for HCl, H2SO4, and HNO3 are proposed, applicable up to 16m, and 12m, respectively. Partial validation of the implementation of Pitzer's treatment within the commercial process simulator ASPEN Plus was performed.

  16. An overview on fermentation, downstream processing and properties of microbial alkaline proteases.

    PubMed

    Gupta, R; Beg, Q K; Khan, S; Chauhan, B

    2002-12-01

    Microbial alkaline proteases dominate the worldwide enzyme market, accounting for a two-thirds share of the detergent industry. Although protease production is an inherent property of all organisms, only those microbes that produce a substantial amount of extracellular protease have been exploited commercially. Of these, strains of Bacillus sp. dominate the industrial sector. To develop an efficient enzyme-based process for the industry, prior knowledge of various fermentation parameters, purification strategies and properties of the biocatalyst is of utmost importance. Besides these, the method of measurement of proteolytic potential, the selection of the substrate and the assay protocol depends upon the ultimate industrial application. A large array of assay protocols are available in the literature; however, with the predominance of molecular approaches for the generation of better biocatalysts, the search for newer substrates and assay protocols that can be conducted at micro/nano-scale are becoming important. Fermentation of proteases is regulated by varying the C/N ratio and can be scaled-up using fed-batch, continuous or chemostat approaches by prolonging the stationary phase of the culture. The conventional purification strategy employed, involving e.g., concentration, chromatographic steps, or aqueous two-phase systems, depends on the properties of the protease in question. Alkaline proteases useful for detergent applications are mostly active in the pH range 8-12 and at temperatures between 50 and 70 degrees C, with a few exceptions of extreme pH optima up to pH 13 and activity at temperatures up to 80-90 degrees C. Alkaline proteases mostly have their isoelectric points near to their pH optimum in the range of 8-11. Several industrially important proteases have been subjected to crystallization to extensively study their molecular homology and three-dimensional structures.

  17. Corrosion Properties of Polydopamine Coatings Formed in One-Step Immersion Process on Magnesium.

    PubMed

    Singer, Ferdinand; Schlesak, Magdalena; Mebert, Caroline; Höhn, Sarah; Virtanen, Sannakaisa

    2015-12-09

    Polydopamine layers were polymerized directly from Tris(hydroxymethyl)aminomethane-buffered solution in a one-step immersion process onto magnesium surface. Scanning electron microscopy showed successful formation of a ∼1 μm thick layer. ASTM D3359-09 "Tape test" revealed excellent adhesion of the layer. X-ray induced photoelectron spectroscopy and Fourier transform infrared spectroscopy verified the presence of polydopamine on the surface. Corrosion measurements were performed in 0.1 M NaCl solution investigating the influence of coating parameters: dopamine concentration, immersion time, solution pH, and immersion angle. Tafel analysis revealed strong improvement of corrosion behavior compared to bare magnesium. Polydopamine layers prepared with optimized coating procedure showed promising corrosion properties in Dulbecco's modified Eagle medium. In summary, polydopamine coatings offer a simple treatment for magnesium to improve the corrosion behavior and could further act as intermediate layer for further surface functionalization.

  18. Transfer of pesticides to the brew during mate drinking process and their relationship with physicochemical properties.

    PubMed

    Pérez-Parada, Andrés; González, Joaquín; Pareja, Lucía; Geis-Asteggiante, Lucía; Colazzo, Marcos; Niell, Silvina; Besil, Natalia; González, Gabriel; Cesio, Verónica; Heinzen, Horacio

    2010-11-01

    In order to evaluate the extraction of pesticide residues that are transferred to the brew during mate drinking process of P.U.1 yerba mate leaves (Ilex paraguariensis), a special device to simulate the way in which mate is drunk in Uruguay was developed. The transfer to the brew of 12 organophosphates, 5 synthethic pyrethroids and one organochlorine pesticide from spiked samples was studied. The relationship between the transfer data thus obtained and physicochemical properties like water solubility (Ws), octanol-water coefficient (Kow) and Henry's constant (H) was evaluated. The extractability of the pesticide residues from yerba mate can be correlated with log Ws and log Kow. These transfer values allowed the calculation of ARLs (acceptable residue level) for the pesticides following Food and Agriculture Organization (FAO), World Health Organizaion (WHO) guidelines. These results can help the future establishment of maximum residue levels (MRLs).

  19. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites.

    PubMed

    Liu, Tian; Wood, Weston; Zhong, Wei-Hong

    2011-12-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  20. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites

    PubMed Central

    2011-01-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials. PMID:27502631

  1. Preparation and properties of the magnetic absorbent polymer via the chemical transformation process

    NASA Astrophysics Data System (ADS)

    Liu, Shengyu; Zhang, Suhong; Guo, Jianying; Wen, Jing; Qiao, Yan

    2017-01-01

    Magnetic polyacrylic acid sodium polymer (MPAAS) was prepared by chemical transformation method. Key parameters were investigated in the synthesis process of the magnetic polymer and an optimum preparation condition was gained. The structure of the magnetic polymer was characterized by X-ray diffraction (XRD), Fourier transform infrared spectrosocopy (FTIR) and scanning electron microscope (SEM). Magnetic property of the magnetic polymer was measured by the magnet and superconducting quantum interference device (SQUID). Both the swelling ratio and kinetics and the water retention ratio and kinetics were investigated. Based on the results, it can be gained that both swelling rate and equilibrium swelling rate were lowered after magnetization while the water retention ability of the magnetic polymer is stronger than that of the polymer.

  2. Chemical properties of hydroxyapatite deposited through electrophoretic process on different sandblasted samples

    NASA Astrophysics Data System (ADS)

    Gradinariu, Irina; Stirbu, Ioan; Gheorghe, Cristina Angela; Cimpoesu, Nicanor; Agop, Maricel; Cimpoesu, Ramona; Popa, Cristina

    2014-12-01

    An implantable material based on titanium (Ti6Al4V) was sandblasted in order to be deposited with a thin film of hydroxyapatite. Two samples of the alloy, in a shape of a bar with 10 mm diameter and 20 mm length, were subjected to mechanical treatment. After deposition of the hydroxyapatite through electrophoresis process, the samples were analyzed by scanning electron microscopy. The nature and chemical properties of thin films formed on Ti-based substrate were investigated with electrochemical impedance spectroscopy based on the extremely high polarization resistance of the material. The results revealed the formation of a homogeneous layer on the surface of the metallic substrate. The layer composed of TiO2 and hydroxyapatite provided a high corrosion protection.

  3. Evolution of Microstructure and Mechanical Properties of Thermomechanically Processed Ultrahigh-Strength Steel

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, P. S.; Ghosh, S. K.; Kundu, S.; Chatterjee, S.

    2011-09-01

    In the present study, low carbon microalloyed ultrahigh-strength steel was manufactured on a pilot scale. Transformation of the aforesaid steel during continuous cooling was assessed. The steel sample was thermomechanically processed followed by air cooling and water quenching. Variation in microstructure and mechanical properties at different finish rolling temperatures (FRTs) was studied. A mixture of granular bainite and bainitic ferrite along with interlath and intralath precipitation of (Ti, Nb)CN particles is the characteristic microstructural feature of air-cooled steel. On the other hand, lath martensitic structure along with a similar type of microalloying precipitates of air-cooled steels is obtained in the case of water-quenched steel also. The best combination of strength (1440 to 1538 MPa) and ductility (11 to 16 pct) was achieved for the selected range of FRTs of water-quenched steel.

  4. WSi2 in Si(1-x)Ge(x) Composites: Processing and Thermoelectric Properties

    NASA Technical Reports Server (NTRS)

    Mackey, Jonathan A.; Sehirlioglu, Alp; Dynys, Fred

    2015-01-01

    Traditional SiGe thermoelectrics have potential for enhanced figure of merit (ZT) via nano-structuring with a silicide phase, such as WSi2. A second phase of nano-sized silicides can theoretically reduce the lattice component of thermal conductivity without significantly reducing the electrical conductivity. However, experimentally achieving such improvements in line with the theory is complicated by factors such as control of silicide size during sintering, dopant segregation, matrix homogeneity, and sintering kinetics. Samples were prepared using powder metallurgy techniques; including mechano-chemical alloying, via ball milling, and spark plasma sintering for densification. Processing, micro-structural development, and thermoelectric properties will be discussed. Additionally, couple and device level characterization will be introduced.

  5. Functional properties of raw and heat processed cashew nut (Anacardium occidentale, L.) kernel protein isolates.

    PubMed

    Neto, V Q; Narain, N; Silva, J B; Bora, P S

    2001-08-01

    The functional properties viz. solubility, water and oil absorption, emulsifying and foaming capacities of the protein isolates prepared from raw and heat processed cashew nut kernels were evaluated. Protein solubility vs. pH profile showed the isoelectric point at pH 5 for both isolates. The isolate prepared from raw cashew nuts showed superior solubility at and above isoelectric point pH. The water and oil absorption capacities of the proteins were slightly improved by heat treatment of cashew nut kernels. The emulsifying capacity of the isolates showed solubility dependent behavior and was better for raw cashew nut protein isolate at pH 5 and above. However, heat treated cashew nut protein isolate presented better foaming capacity at pH 7 and 8 but both isolates showed extremely low foam stability as compared to that of egg albumin.

  6. Size-controlled synthesis and optical properties of doped nanoparticles prepared by soft solution processing.

    PubMed

    Ullah, M H; Ha, Chang-Sik

    2005-09-01

    In this review, we outline the synthesis and luminescence properties of metal-ion-incorporated doped nanoparticles and surface-passivated doped nanoparticles. The synthetic routes we describe are limited to those involving soft solution processing. The doping effects are discussed in this review on the semiconductor nanoparticles confining the size range near to the 'quantum dot size.' The effects on luminescence with respect to ionic valance of dopants and the luminescence phenomena on mismatching of ionic radii between the host-guest are also provided. In addition, we discuss the role of passivated organic surfactants and the necessity of surface passivation of doped or undoped nanoparticles with other semiconductor materials that possess larger band gaps. Biocompatible semiconductor nanoparticles and some of their applications are also mentioned briefly.

  7. Processing and properties of chromate-free conversion coatings on aluminum

    SciTech Connect

    Buchheit, R.G.; Drewien, C.A.; Martinez, M.A.; Stoner, G.E.

    1994-12-31

    A conversion coating method has been developed based on precipitation of Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O from alkaline lithium salt solutions. The process is procedurally similar to chromate conversion coating but does not use or produce hazardous chemicals. The coating that forms is polycrystalline, continuous and conformal. The coating meets the MIL-C-5541E corrosion resistance, electrical contact resistance and paint adhesion requirements for certain aluminum alloys, but does not match the levels of performance exhibited by chromate conversion coatings. In this paper, methods for producing the coating are described. Corrosion resistance has been characterized using electrochemical impedance spectroscopy and salt spray exposure. The structural, compositional and property changes attending post-coating thermal exposure are discussed. Performance in standardized corrosion, electrical and paint adhesion tests is also presented.

  8. Improvement of shelf stability and processing properties of meat products by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Byun, Myung-Woo; Lee, Ju-Woon; Yook, Hong-Sun; Lee, Kyong-Haeng; Kim, Hee-Yun

    2002-03-01

    To evaluate the effects of gamma irradiation on the processing properties of meat products, emulsion-type sausage, beef patties and pork loin ham were manufactured. Most contaminated bacteria were killed by 3 kGy-irradiation to raw ground beef, and sausage can be manufactured with desirable flavor, a reduction of NaCl and phosphate, and extension of shelf life using gamma irradiation on the raw meat. The beef patties were manufactured with the addition of antioxidants (200 ppm), BHA, ascorbyl palmitate, α-tocopherol, or β-carotene, and gamma-irradiation. Retardation of lipid oxidation appeared at the patties with an antioxidant. A dose of 5 kGy was observed to be as effective as the use of 200 ppm NaNO 2 to provide and maintain the desired color of the product during storage. After curing, irradiation, heating and smoking could extensively prolong the shelf life of the hams.

  9. Consequences of Continuity: The Hunt for Intrinsic Properties within Parameters of Dynamics in Psychological Processes.

    PubMed

    Boker, Steven M

    2002-07-01

    A little over three hundred years ago Sir Isaac Newton wrote of a simple set of relations that could be used to predict the motions of objects relative to one another. The main advantage of this insight was that the relationship between the movements of the planets and stars could be predicted much more simply than with the accurate, but cumbersome Ptolemaic calculations. But perhaps the most important consequence of the acceptance of Newton's insight was that intrinsic properties such as mass could be distinguished from measurements such as weight. The success of Newtonian mechanics led directly to the widespread use of parameters such as force, relative speed, and momentum as a way of understanding the dynamics of moving objects. A similar revolution in thinking appears to be underway in the behavioral sciences. It is likely that intensive longitudinal measurement coupled with dynamical systems analyses will lead to simplified but powerful models of the evolution of psychological processes. In this case, it is reasonable to expect that a set of intrinsic psychological properties may be able to be extracted from the parameters of successful dynamical systems models. The purpose of this article is to issue an invitation to the hunt, to provide a tentative map as to where the game might likely be found, and blow a call on the hunting horn.

  10. Unique membrane properties and enhanced signal processing in human neocortical neurons.

    PubMed

    Eyal, Guy; Verhoog, Matthijs B; Testa-Silva, Guilherme; Deitcher, Yair; Lodder, Johannes C; Benavides-Piccione, Ruth; Morales, Juan; DeFelipe, Javier; de Kock, Christiaan Pj; Mansvelder, Huibert D; Segev, Idan

    2016-10-06

    The advanced cognitive capabilities of the human brain are often attributed to our recently evolved neocortex. However, it is not known whether the basic building blocks of the human neocortex, the pyramidal neurons, possess unique biophysical properties that might impact on cortical computations. Here we show that layer 2/3 pyramidal neurons from human temporal cortex (HL2/3 PCs) have a specific membrane capacitance (Cm) of ~0.5 µF/cm(2), half of the commonly accepted 'universal' value (~1 µF/cm(2)) for biological membranes. This finding was predicted by fitting in vitro voltage transients to theoretical transients then validated by direct measurement of Cm in nucleated patch experiments. Models of 3D reconstructed HL2/3 PCs demonstrated that such low Cm value significantly enhances both synaptic charge-transfer from dendrites to soma and spike propagation along the axon. This is the first demonstration that human cortical neurons have distinctive membrane properties, suggesting important implications for signal processing in human neocortex.

  11. Influence of processing conditions on the thermal and mechanical properties of SU8 negative photoresist coatings

    NASA Astrophysics Data System (ADS)

    Feng, Ru; Farris, Richard J.

    2003-01-01

    The thermal and mechanical properties of a new negative photoresist, SU8, were characterized. The influence of curing conditions, such as baking temperature, baking time and UV dosage, on the thermal and mechanical properties of the resultant coatings was studied in detail. It was found that the glass-transition temperature (Tg) of the coatings was coincident with the baking temperature over the temperature range of 25 °C-220 °C for coatings being baked for just 20 min. However, the Tg reached a limiting value (about 240 °C) once the cross-linking reaction was complete, and would not increase further with the baking temperature. The peak temperature of the dimension versus temperature plots, where heat shrinkage occurred, was about a factor of 1.16 times higher than the baking temperature for the temperature range studied. Both the Tg and the shrinkage temperature were affected by the baking time. The thermal expansion coefficients (TEC), including the volumetric TEC (alphav), the in-plane TEC (alpha1) and the out-of-plane TEC (alpha2), were measured by a pressure-volume-temperature (PVT) apparatus and thermal-mechanical analyzer (TMA). Great residual stress could be generated during the process, and the change in residual stress with the environmental humidity was investigated using vibrational holographic interferometry.

  12. Correlation between substrate bias, growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon films

    NASA Astrophysics Data System (ADS)

    Liu, Aiping; Zhu, Jiaqi; Han, Jiecai; Wu, Huaping; Jia, Zechun

    2007-09-01

    We investigate the growth process and structural properties of phosphorus incorporated tetrahedral amorphous carbon (ta-C:P) films which are deposited at different substrate biases by filtered cathodic vacuum arc technique with PH 3 as the dopant source. The films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, Raman spectroscopy, residual stress measurement, UV/VIS/NIR absorption spectroscopy and temperature-dependent conductivity measurement. The atomic fraction of phosphorus in the films as a function of substrate bias is obtained by XPS analysis. The optimum bias for phosphorus incorporation is about -80 V. Raman spectra show that the amorphous structures of all samples with atomic-scaled smooth surface are not remarkably changed when PH 3 is implanted, but some small graphitic crystallites are formed. Moreover, phosphorus impurities and higher-energetic impinging ions are favorable for the clustering of sp 2 sites dispersed in sp 3 skeleton and increase the level of structural ordering for ta-C:P films, which further releases the compressive stress and enhances the conductivity of the films. Our analysis establishes an interrelationship between microstructure, stress state, electrical properties, and substrate bias, which helps to understand the deposition mechanism of ta-C:P films.

  13. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  14. Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

    SciTech Connect

    Song, Meng; Xu, Peng; Wang, Xu; Wu, Huizhen; Wang, Miao E-mail: miaowang@css.zju.edu.cn; Song, Yenan; Li, Zhenhua; Zhao, Pei E-mail: miaowang@css.zju.edu.cn; Shang, Xuefu

    2015-09-15

    Integrating carbon nanotubes (CNTs) and graphene into hybrid structures provides a novel approach to three dimensional (3D) materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm{sup 2}, and field enhancement factor of ∼1.3 × 10{sup 4}. The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport.

  15. Joining of Silver Nanomaterials at Low Temperatures: Processes, Properties, and Applications.

    PubMed

    Peng, Peng; Hu, Anming; Gerlich, Adrian P; Zou, Guisheng; Liu, Lei; Zhou, Y Norman

    2015-06-17

    A review is provided, which first considers low-temperature diffusion bonding with silver nanomaterials as filler materials via thermal sintering for microelectronic applications, and then other recent innovations in low-temperature joining are discussed. The theoretical background and transition of applications from micro to nanoparticle (NP) pastes based on joining using silver filler materials and nanojoining mechanisms are elucidated. The mechanical and electrical properties of sintered silver nanomaterial joints at low temperatures are discussed in terms of the key influencing factors, such as porosity and coverage of substrates, parameters for the sintering processes, and the size and shape of nanomaterials. Further, the use of sintered silver nanomaterials for printable electronics and as robust surface-enhanced Raman spectroscopy substrates by exploiting their optical properties is also considered. Other low-temperature nanojoining strategies such as optical welding of silver nanowires (NWs) through a plasmonic heating effect by visible light irradiation, ultrafast laser nanojoining, and ion-activated joining of silver NPs using ionic solvents are also summarized. In addition, pressure-driven joining of silver NWs with large plastic deformation and self-joining of gold or silver NWs via oriented attachment of clean and activated surfaces are summarized. Finally, at the end of this review, the future outlook for joining applications with silver nanomaterials is explored.

  16. Structural control of weathering processes within exhumed granitoids: Compartmentalisation of geophysical properties by faults and fractures

    NASA Astrophysics Data System (ADS)

    Place, J.; Géraud, Y.; Diraison, M.; Herquel, G.; Edel, J.-B.; Bano, M.; Le Garzic, E.; Walter, B.

    2016-03-01

    In the latter stages of exhumation processes, rocks undergo weathering. Weathering halos have been described in the vicinity of structures such as faults, veins or dykes, with a lateral size gradually narrowing with depth, symmetrically around the structures. In this paper, we describe the geophysical characterisation of such alteration patterns on two granitoid outcrops of the Catalan Coastal Ranges (Spain), each of which is affected by one major fault, as well as minor faults and fractures. Seismic, electric and ground penetrating radar surveys were carried out to map the spatial distribution of P-wave velocity, electrical resistivity and to identify reflectors of electromagnetic waves. The analysis of this multi-method and complementary dataset revealed that, at shallow depth, geophysical properties of the materials are compartmentalised and asymmetric with respect to major and subsidiary faults affecting the rock mass. This compartmentalisation and asymmetry both tend to attenuate with depth, whereas the effect of weathering is more symmetric with respect to the major structure of the outcrops. We interpret such compartmentalisation as resulting from the role of hydraulic and mechanical boundaries played by subsidiary faults, which tend to govern both the chemical and physical alterations involved in weathering. Thus, the smoothly narrowing halo model is not always accurate, as weathering halos can be strongly asymmetrical and present highly irregular contours delimiting sharp contrasts of geophysical properties. These results should be considered when investigating and modelling fluid storage and transfer in top crystalline rock settings for groundwater applications, hydrocarbon or geothermal reservoirs, as well as mineral deposits.

  17. Thermodynamic and rheological properties of solid-liquid systems in coal processing

    SciTech Connect

    Kabadi, V.N.

    1995-06-30

    The objective of this project is to develop a model for solid-liquid equilibria and a model for viscosities of the products of coal liquefaction processes. The same characterization procedure and representation by continuous distributions as used in previous work on vapor-liquid equilibria and excess enthalpies of coal liquids will be used. Models when fully developed win give the solid-liquid phase equilibrium properties and viscosities as factors of temperature and pressure for known molecular weight distribution and structural characterization of the coal liquid. To accomplish this well, the project requires three tasks: (1) Solid-Liquid phase equilibrium model development; (2) Experimental Viscosity Measurements; and (3) Viscosity Model Development. A model for viscosity computation of coal model compound liquids and coal derived liquids has been developed. Literature review for this work included compilation of a number of data sets, critical investigation of data measurement techniques available in the literature, and investigation of models for liquid and solid phase thermodynamic computations. During the preliminary stages it was discovered that for development of a liquid or solid state equation of state, accurate predictive models for a number of saturation properties, such as, liquid and solid vapor pressures, saturated liquid and solid volumes, heat capacities of liquids and solids at saturation, etc. Most of the remaining time on this task was spent in developing predictive correlations for vapor pressures and saturated liquid volumes of organic liquids in general and coal model liquids in particular.

  18. Pitfalls and Limitations in the Interpretation of Geophysical Images for Hydrologic Properties and Processes

    NASA Astrophysics Data System (ADS)

    Day-Lewis, F. D.

    2014-12-01

    Geophysical imaging (e.g., electrical, radar, seismic) can provide valuable information for the characterization of hydrologic properties and monitoring of hydrologic processes, as evidenced in the rapid growth of literature on the subject. Geophysical imaging has been used for monitoring tracer migration and infiltration, mapping zones of focused groundwater/surface-water exchange, and verifying emplacement of amendments for bioremediation. Despite the enormous potential for extraction of hydrologic information from geophysical images, there also is potential for misinterpretation and over-interpretation. These concerns are particularly relevant when geophysical results are used within quantitative frameworks, e.g., conversion to hydrologic properties through petrophysical relations, geostatistical estimation and simulation conditioned to geophysical inversions, and joint inversion. We review pitfalls to interpretation associated with limited image resolution, spatially variable image resolution, incorrect data weighting, errors in the timing of measurements, temporal smearing resulting from changes during data acquisition, support-volume/scale effects, and incorrect assumptions or approximations involved in modeling geophysical or other jointly inverted data. A series of numerical and field-based examples illustrate these potential problems. Our goal in this talk is to raise awareness of common pitfalls and present strategies for recognizing and avoiding them.

  19. Influence of processing on the microstructure and mechanical properties of 14YWT

    SciTech Connect

    Hoelzer, D. T.; Unocic, K. A.; Sokolov, Mikhail A.; Byun, Thak Sang

    2016-04-25

    The investigation of the mechanical alloying (MA) conditions for producing the advanced oxide dispersion strengthened (ODS) 14YWT ferritic alloy led to significant improvements in balancing the strength, ductility and fracture toughness properties while still maintaining the salient microstructural features consisting of ultra-fine grains and high concentration of Y-, Ti- and O-enriched nanoclusters. The implemented changes to the processing conditions included reducing the contamination of the powder during ball milling, applying a pre-extrusion annealing treatment on the ball milled powder and exploring different extrusion temperatures at 850 C (SM170 heat), 1000 C (SM185) and 1150 C (SM200). The microstructural studies of the three 14YWT heats showed similarities in the dispersion of nanoclusters and sub-micron size grains, indicating the microstructure was insensitive to the different extrusion conditions. Compared to past 14YWT heats, the three new heats showed lower strength, but higher ductility levels between 25 and 800 C and significantly higher fracture toughness values between 25 C and 700 C. The lower contamination levels of O, C and N achieved with improved ball milling conditions plus the slightly larger grain size were identified as important factors for improving the balance in mechanical properties of the three heats of 14YWT.

  20. Short Term Preservation of Hide Using Vacuum: Influence on Properties of Hide and of Processed Leather

    PubMed Central

    Gudro, Ilze; Valeika, Virgilijus; Sirvaitytė, Justa

    2014-01-01

    The objective of this work was to investigate vacuum influence on hide preservation time and how it affects hide structure. It was established that vacuum prolongs the storage time without hide tissue putrefaction up to 21 days when the storage temperature is 4°C. The microorganisms act for all storage times, but the action is weak and has no observable influence on the quality of hide during the time period mentioned. The hide shrinkage temperature decrease is negligible, which shows that breaking of intermolecular bonds does not occur. Optical microscopy, infrared spectroscopy and differential scanning calorimetry also did not show any structural changes which can influence the quality of leather produced from such hide. The qualitative indexes of wet blue processed under laboratory conditions and of leather produced during industrial trials are presented. Indexes such as chromium compounds exhaustion, content of chromium in leather, content of soluble matter in dichloromethane, strength properties, and shrinkage temperature were determined. Properties of the leather produced from vacuumed hide under industrial conditions conformed to the requirements of shoe upper leather. PMID:25393637

  1. Microstructure, Precipitation, and Mechanical Properties of V-N-Alloyed Steel After Different Cooling Processes

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Wang, Fu-Ming; Yang, Zhan-Bing; Li, Chang-Rong

    2016-12-01

    Three cooling processes (direct air cooling, water cooling to 1023 K and 873 K (750 °C and 600 °C) followed by air cooling) after hot rolling are designed to develop V-N-alloyed 600 MPa grade high-strength steel for architectural construction. Microstructural characteristics, precipitation behavior, and mechanical properties were investigated. Experimental results indicate that all microstructures are composed of polygonal ferrite and pearlite. Compared to the microstructure obtained from traditional direct air cooling, the grain size of ferrite is refined from 6.5 to 4.6 μm and the interlamellar spacing of pearlite decreases from 136 to 45 nm, respectively, by the application of accelerated cooling and lower finish cooling temperature. The number fraction of high misorientation angle boundaries increases from 44 to 51 pct. Moreover, the sheet spacing of interphase precipitates decreases from (23 to 26 nm) to (14 to 17 nm) and the size of V(C,N) particles reduces from (5 to 8 nm) to (2 to 5 nm). Furthermore, the optimal mechanical properties are obtained in the steel water cooled to 873 K (600 °C), of which the yield strength, tensile strength, total elongation, uniform elongation, and impact energy at room temperature are 753 MPa, 922 MPa, 22 pct, 11 pct, and 36 J, respectively. Besides, the high yield strength is primarily attributed to the refined grains and precipitation hardening from interphase and random precipitation of nano-scale V(C,N) particles.

  2. Effect of composition on the processing and properties of sintered reaction-bonded silicon nitride

    SciTech Connect

    Tiegs, T.N.; Kiggans, J.O.; Montgomery, F.C.; Lin, H.T.; Barker, D.L.; Snodgrass, J.D.; Sabolsky, E.M.; Coffey, D.W.

    1996-04-01

    The type of silicon powder and sintering additive were found to influence the processing and final mechanical properties of sintered reaction bonded silicon nitride. High purity silicon powders produced low {alpha}-Si{sub 3}N{sub 4} content during nitridation. The Si powder type had no apparent effect on densification. More complete nitridation and higher room temperature mechanical properties were observed for the Si powders with higher Fe contents. However, the higher Fe contents resulted in greater high temperature strength degradation and so there was better high temperature strength retention with the higher purity Si. High {alpha}-Si{sub 3}N{sub 4} contents were found after nitridation with {alpha}-Si{sub 3}N{sub 4} seeded materials and with MgO-Y{sub 2}O{sub 3} as the sintering additive. Densification was inhibited by refractory additives, such as Y{sub 2}O{sub 3}-SiO{sub 2}. The highest room temperature strength and fracture toughness values correlated to high nitrided {alpha}-Si{sub 3}N{sub 4} contents. The high temperature strength behavior was similar for all additive types.

  3. Unique membrane properties and enhanced signal processing in human neocortical neurons

    PubMed Central

    Eyal, Guy; Verhoog, Matthijs B; Testa-Silva, Guilherme; Deitcher, Yair; Lodder, Johannes C; Benavides-Piccione, Ruth; Morales, Juan; DeFelipe, Javier; de Kock, Christiaan PJ; Mansvelder, Huibert D; Segev, Idan

    2016-01-01

    The advanced cognitive capabilities of the human brain are often attributed to our recently evolved neocortex. However, it is not known whether the basic building blocks of the human neocortex, the pyramidal neurons, possess unique biophysical properties that might impact on cortical computations. Here we show that layer 2/3 pyramidal neurons from human temporal cortex (HL2/3 PCs) have a specific membrane capacitance (Cm) of ~0.5 µF/cm2, half of the commonly accepted 'universal' value (~1 µF/cm2) for biological membranes. This finding was predicted by fitting in vitro voltage transients to theoretical transients then validated by direct measurement of Cm in nucleated patch experiments. Models of 3D reconstructed HL2/3 PCs demonstrated that such low Cm value significantly enhances both synaptic charge-transfer from dendrites to soma and spike propagation along the axon. This is the first demonstration that human cortical neurons have distinctive membrane properties, suggesting important implications for signal processing in human neocortex. DOI: http://dx.doi.org/10.7554/eLife.16553.001 PMID:27710767

  4. Influence of processing on the microstructure and mechanical properties of 14YWT

    SciTech Connect

    Hoelzer, David T.; Unocic, Kinga A.; Sokolov, Mikhail A.; Byun, Thak Sang

    2015-12-15

    In this study, the investigation of the mechanical alloying (MA) conditions for producing the advanced oxide dispersion strengthened (ODS) 14YWT ferritic alloy led to significant improvements in balancing the strength, ductility and fracture toughness properties while still maintaining the salient microstructural features consisting of ultra-fine grains and high concentration of Y-, Ti- and O-enriched nanoclusters. The implemented changes to the processing conditions included reducing the contamination of the powder during ball milling, applying a pre-extrusion annealing treatment on the ball milled powder and exploring different extrusion temperatures at 850 °C (SM170 heat), 1000 °C (SM185) and 1150 °C (SM200). The microstructural studies of the three 14YWT heats showed similarities in the dispersion of nanoclusters and sub-micron size grains, indicating the microstructure was insensitive to the different extrusion conditions. Compared to past 14YWT heats, the three new heats showed lower strength, but higher ductility levels between 25 and 800 °C and significantly higher fracture toughness values between 25 °C and 700 °C. The lower contamination levels of O, C and N achieved with improved ball milling conditions plus the slightly larger grain size were identified as important factors for improving the balance in mechanical properties of the three heats of 14YWT.

  5. Influence of processing on the microstructure and mechanical properties of 14YWT

    DOE PAGES

    Hoelzer, David T.; Unocic, Kinga A.; Sokolov, Mikhail A.; ...

    2015-12-15

    In this study, the investigation of the mechanical alloying (MA) conditions for producing the advanced oxide dispersion strengthened (ODS) 14YWT ferritic alloy led to significant improvements in balancing the strength, ductility and fracture toughness properties while still maintaining the salient microstructural features consisting of ultra-fine grains and high concentration of Y-, Ti- and O-enriched nanoclusters. The implemented changes to the processing conditions included reducing the contamination of the powder during ball milling, applying a pre-extrusion annealing treatment on the ball milled powder and exploring different extrusion temperatures at 850 °C (SM170 heat), 1000 °C (SM185) and 1150 °C (SM200). Themore » microstructural studies of the three 14YWT heats showed similarities in the dispersion of nanoclusters and sub-micron size grains, indicating the microstructure was insensitive to the different extrusion conditions. Compared to past 14YWT heats, the three new heats showed lower strength, but higher ductility levels between 25 and 800 °C and significantly higher fracture toughness values between 25 °C and 700 °C. The lower contamination levels of O, C and N achieved with improved ball milling conditions plus the slightly larger grain size were identified as important factors for improving the balance in mechanical properties of the three heats of 14YWT.« less

  6. Influence of the Ageing Process on the Resistive and Reactive Properties of the Respiratory System

    PubMed Central

    e Tramont, Caio Vinicius Villalón; Faria, Alvaro Camilo Dias; Lopes, Agnaldo José; Jansen, José Manoel; de Melo, Pedro Lopes

    2009-01-01

    INTRODUCTION In an increasingly old society, the study of the respiratory system changes and new techniques dedicated to older patients are of interest in physiologic studies as well as in the diagnosis of respiratory diseases. OBJECTIVES (1) To investigate the impact of ageing on the resistive and reactive properties of the respiratory system, and (2) to compare the easiness of accomplishment of spirometry and forced oscillation for assessing lung function. METHODS We conducted a cross-sectional study in which forced oscillation was used to investigate respiratory system resistive and reactive properties, while spirometry was used as a reference test to evaluate 80 normal subjects aged between 20 and 86 years. A questionnaire was used to evaluate the easiness of accomplishment of spirometry and forced oscillation. RESULTS There was a significant increase in the respiratory system resonance frequency (p<0.003) and a reduction in the mean reactance (p<0.004) with increasing age. Respiratory system resistance and dynamic compliance were not related to the ageing process. The easiness of accomplishment of forced oscillation measurements was greater than that of spirometry. This result was particularly relevant in subjects over 70 years old (p<0.05). CONCLUSIONS Respiratory system resistance and dynamic compliance are not modified with ageing. On the other hand, respiratory system homogeneity decreases during the ageing process. Forced oscillation is easy to perform and provides information complementary to spirometry. This technique may be a promising alternative and/or complement to other conventional exams used to evaluate older people who are unable to adequately perform spirometric tests. PMID:19936180

  7. Thalamic Kv7 channels: pharmacological properties and activity control during noxious signal processing

    PubMed Central

    Cerina, Manuela; Szkudlarek, Hanna J; Coulon, Philippe; Meuth, Patrick; Kanyshkova, Tatyana; Nguyen, Xuan Vinh; Göbel, Kerstin; Seidenbecher, Thomas; Meuth, Sven G; Pape, Hans-Christian; Budde, Thomas

    2015-01-01

    Background and Purpose The existence of functional Kv7 channels in thalamocortical (TC) relay neurons and the effects of the K+-current termed M-current (IM) on thalamic signal processing have long been debated. Immunocytochemical evidence suggests their presence in this brain region. Therefore, we aimed to verify their existence, pharmacological properties and function in regulating activity in neurons of the ventrobasal thalamus (VB). Experimental Approach Characterization of Kv7 channels was performed by combining in vitro, in vivo and in silico techniques with a pharmacological approach. Retigabine (30 μM) and XE991 (20 μM), a specific Kv7 channel enhancer and blocker, respectively, were applied in acute brain slices during electrophysiological recordings. The effects of intrathalamic injection of retigabine (3 mM, 300 nL) and/or XE991 (2 mM, 300 nL) were investigated in freely moving animals during hot-plate tests by recording behaviour and neuronal activity. Key Results Kv7.2 and Kv7.3 subunits were found to be abundantly expressed in TC neurons of mouse VB. A slow K+-current with properties of IM was activated by retigabine and inhibited by XE991. Kv7 channel activation evoked membrane hyperpolarization, a reduction in tonic action potential firing, and increased burst firing in vitro and in computational models. Single-unit recordings and pharmacological intervention demonstrated a specific burst-firing increase upon IM activation in vivo. A Kv7 channel-mediated increase in pain threshold was associated with fewer VB units responding to noxious stimuli, and increased burst firing in responsive neurons. Conclusions and Implications Kv7 channel enhancement alters somatosensory activity and may reflect an anti-nociceptive mechanism during acute pain processing. PMID:25684311

  8. Characterization and antibacterial properties of stable silver substituted hydroxyapatite nanoparticles synthesized through surfactant assisted microwave process

    SciTech Connect

    Iqbal, Nida; Abdul Kadir, Mohammed Rafiq; Nik Malek, Nik Ahmad Nazim; Mahmood, Nasrul Humaimi Bin; Murali, Malliga Raman; Kamarul, T.

    2013-09-01

    Highlights: • Stable nano sized silver substitute hydroxyapatite is prepared under surfactant assisted microwave process at 600 W power for 7 min. • The nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. • Increase in silver concentration resulted in better dielectric properties. • Good antibacterial activity and silver release. - Abstract: The present study reports a relatively simple method for the synthesis of stable silver substituted hydroxyapatite nanoparticles with controlled morphology and particle size. In order to achieve this, CTAB is included as a surfactant in the microwave refluxing process (600 W for 7 min). The nanoparticles produced with different silver ion concentrations (0.05, 0.1 and 0.2 wt%) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX) and Brunauer–Emmett–Teller (BET) analysis. XRD and FTIR analyses reveal that the Ag-HA nanoparticles were phase pure at 1000 °C. FESEM images showed that the produced nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. The dielectric properties suggest that the increase in dielectric constant (ε′) and dissipation factor (D) values with increasing Ag concentrations. Antibacterial performance of the Ag-HA samples elucidated using disk diffusion technique (DDT) and minimum inhibitory concentration (MIC) demonstrates anti-bacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. This effect was dose dependent and was more pronounced against Gram-negative bacteria than Gram-positive organisms.

  9. Biological processes, properties and molecular wiring diagrams of candidate low-penetrance breast cancer susceptibility genes

    PubMed Central

    Bonifaci, Núria; Berenguer, Antoni; Díez, Javier; Reina, Oscar; Medina, Ignacio; Dopazo, Joaquín; Moreno, Víctor; Pujana, Miguel Angel

    2008-01-01

    Background Recent advances in whole-genome association studies (WGASs) for human cancer risk are beginning to provide the part lists of low-penetrance susceptibility genes. However, statistical analysis in these studies is complicated by the vast number of genetic variants examined and the weak effects observed, as a result of which constraints must be incorporated into the study design and analytical approach. In this scenario, biological attributes beyond the adjusted statistics generally receive little attention and, more importantly, the fundamental biological characteristics of low-penetrance susceptibility genes have yet to be determined. Methods We applied an integrative approach for identifying candidate low-penetrance breast cancer susceptibility genes, their characteristics and molecular networks through the analysis of diverse sources of biological evidence. Results First, examination of the distribution of Gene Ontology terms in ordered WGAS results identified asymmetrical distribution of Cell Communication and Cell Death processes linked to risk. Second, analysis of 11 different types of molecular or functional relationships in genomic and proteomic data sets defined the "omic" properties of candidate genes: i/ differential expression in tumors relative to normal tissue; ii/ somatic genomic copy number changes correlating with gene expression levels; iii/ differentially expressed across age at diagnosis; and iv/ expression changes after BRCA1 perturbation. Finally, network modeling of the effects of variants on germline gene expression showed higher connectivity than expected by chance between novel candidates and with known susceptibility genes, which supports functional relationships and provides mechanistic hypotheses of risk. Conclusion This study proposes that cell communication and cell death are major biological processes perturbed in risk of breast cancer conferred by low-penetrance variants, and defines the common omic properties, molecular

  10. Spectral band selection for vegetation properties retrieval using Gaussian processes regression

    NASA Astrophysics Data System (ADS)

    Verrelst, Jochem; Rivera, Juan Pablo; Gitelson, Anatoly; Delegido, Jesus; Moreno, José; Camps-Valls, Gustau

    2016-10-01

    With current and upcoming imaging spectrometers, automated band analysis techniques are needed to enable efficient identification of most informative bands to facilitate optimized processing of spectral data into estimates of biophysical variables. This paper introduces an automated spectral band analysis tool (BAT) based on Gaussian processes regression (GPR) for the spectral analysis of vegetation properties. The GPR-BAT procedure sequentially backwards removes the least contributing band in the regression model for a given variable until only one band is kept. GPR-BAT is implemented within the framework of the free ARTMO's MLRA (machine learning regression algorithms) toolbox, which is dedicated to the transforming of optical remote sensing images into biophysical products. GPR-BAT allows (1) to identify the most informative bands in relating spectral data to a biophysical variable, and (2) to find the least number of bands that preserve optimized accurate predictions. To illustrate its utility, two hyperspectral datasets were analyzed for most informative bands: (1) a field hyperspectral dataset (400-1100 nm at 2 nm resolution: 301 bands) with leaf chlorophyll content (LCC) and green leaf area index (gLAI) collected for maize and soybean (Nebraska, US); and (2) an airborne HyMap dataset (430-2490 nm: 125 bands) with LAI and canopy water content (CWC) collected for a variety of crops (Barrax, Spain). For each of these biophysical variables, optimized retrieval accuracies can be achieved with just 4 to 9 well-identified bands, and performance was largely improved over using all bands. A PROSAIL global sensitivity analysis was run to interpret the validity of these bands. Cross-validated RCV2 (NRMSECV) accuracies for optimized GPR models were 0.79 (12.9%) for LCC, 0.94 (7.2%) for gLAI, 0.95 (6.5%) for LAI and 0.95 (7.2%) for CWC. This study concludes that a wise band selection of hyperspectral data is strictly required for optimal vegetation properties mapping.

  11. Lycopene in tomatoes: chemical and physical properties affected by food processing.

    PubMed

    Shi, J; Le Maguer, M

    2000-01-01

    Lycopene is the pigment principally responsible for the characteristic deep-red color of ripe tomato fruits and tomato products. It has attracted attention due to its biological and physicochemical properties, especially related to its effects as a natural antioxidant. Although it has no provitamin A activity, lycopene does exhibit a physical quenching rate constant with singlet oxygen almost twice as high as that of beta-carotene. This makes its presence in the diet of considerable interest. Increasing clinical evidence supports the role of lycopene as a micronutrient with important health benefits, because it appears to provide protection against a broad range of epithelial cancers. Tomatoes and related tomato products are the major source of lycopene compounds, and are also considered an important source of carotenoids in the human diet. Undesirable degradation of lycopene not only affects the sensory quality of the final products, but also the health benefit of tomato-based foods for the human body. Lycopene in fresh tomato fruits occurs essentially in the all-trans configuration. The main causes of tomato lycopene degradation during processing are isomerization and oxidation. Isomerization converts all-trans isomers to cis-isomers due to additional energy input and results in an unstable, energy-rich station. Determination of the degree of lycopene isomerization during processing would provide a measure of the potential health benefits of tomato-based foods. Thermal processing (bleaching, retorting, and freezing processes) generally cause some loss of lycopene in tomato-based foods. Heat induces isomerization of the all-trans to cis forms. The cis-isomers increase with temperature and processing time. In general, dehydrated and powdered tomatoes have poor lycopene stability unless carefully processed and promptly placed in a hermetically sealed and inert atmosphere for storage. A significant increase in the cis-isomers with a simultaneous decrease in the all

  12. On the processing, structure and properties of aluminum oxide-magnesium aluminate nanocomposites

    NASA Astrophysics Data System (ADS)

    McEnerney, Bryan William

    Improvement in the mechanical properties of ceramic materials is required to better integrate them into new technological applications, such as ballistic armor. While considerable attention has been given to advanced power preparation and powder processing techniques, there has been comparatively little investigation of the nanostructure of the materials. No systematic study has been performed to correlate very fine grain sizes with dynamic mechanical properties of ceramic materials. The purpose of this study is to investigate the high-strain-rate behavior of nanocomposite ceramic materials fabricated by a cost-effective, scalable processing. The starting powders chosen were Baikowski RC-SPT DBM Al 2O3 and Malakoff S30CR MgAl2O4, both being high-purity sub-1 mum powders. The test compositions studied were Al2O3---20 vol. % MgAl2O4, Al2O3---40 vol. % MgAl2O4, and Al2O3---60 vol. % MgAl2O4. The powders were consolidated by spray drying and then melting in a direct current (DC) arc plasma and, subsequently, quenched in water. The metastable powders were comminuted, cold pressed, and densified using hot isostatic pressing. The Vickers hardness of the materials was measured as a function of indentation load, and the strength was measured using a Split-Hopkinson Pressure Bar. The hardness of all three compositions was found to be unexpectedly high. This high hardness was attributed to the unique nanostructure of the materials. This nanostructure developed during decomposition of the metastable, plasma melted powder to the thermodynamically stable phases by solid state diffusion during hot isostatic pressing. With decreasing processing temperatures, the hardness of the samples improved significantly for the Al2O 3---40 vol. % MgAl2O4 and Al2O 3---60 vol. % MgAl2O4 compositions. It was further found that, within the standard deviation, there was minimal deviation between the hardness behaviors of these compositions, which was contrary to the behavior of the control samples

  13. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Several court cases involving acquisition, use, and disposal of property by institutions of higher education are briefly summarized in this chapter. Cases discussed touch on such topics as municipal annexation of university property; repurchase of properties temporarily allocated to faculty members; implications of zoning laws and zoning board…

  14. Formation Mechanisms, Structure, and Properties of HVOF-Sprayed WC-CoCr Coatings: An Approach Toward Process Maps

    NASA Astrophysics Data System (ADS)

    Varis, T.; Suhonen, T.; Ghabchi, A.; Valarezo, A.; Sampath, S.; Liu, X.; Hannula, S.-P.

    2014-08-01

    Our study focuses on understanding the damage tolerance and performance reliability of WC-CoCr coatings. In this paper, the formation of HVOF-sprayed tungsten carbide-based cermet coatings is studied through an integrated strategy: First-order process maps are created by using online-diagnostics to assess particle states in relation to process conditions. Coating properties such as hardness, wear resistance, elastic modulus, residual stress, and fracture toughness are discussed with a goal to establish a linkage between properties and particle characteristics via second-order process maps. A strong influence of particle state on the mechanical properties, wear resistance, and residual stress stage of the coating was observed. Within the used processing window (particle temperature ranged from 1687 to 1831 °C and particle velocity from 577 to 621 m/s), the coating hardness varied from 1021 to 1507 HV and modulus from 257 to 322 GPa. The variation in coating mechanical state is suggested to relate to the microstructural changes arising from carbide dissolution, which affects the properties of the matrix and, on the other hand, cohesive properties of the lamella. The complete tracking of the coating particle state and its linking to mechanical properties and residual stresses enables coating design with desired properties.

  15. The role of silver in the processing and properties of Bi-2212

    NASA Technical Reports Server (NTRS)

    Lang, TH.; Heeb, B.; Buhl, D.; Gauckler, L. J.

    1995-01-01

    The influence of the silver content and the oxygen partial pressure on the solidus temperature and the weight loss during melting of Bi2Sr2Ca1Cu2O(x) has been examined by means of DTA and TGA. By decreasing the oxygen partial pressure the solidus is lowered (e.g. del T = 59 C by decreasing pO2 from 1 atm to 0.001 atm) and the weight loss is increased. The addition of silver causes two effects: (1) the solidus is further decreased (e.g. 2 wt% Ag lower T (solidus) by up to 25 C, depending on the oxygen partial pressure); and (2) the weight loss during melting is reduced. Thick films (10-20 micron in thickness) with 0 and 5 wt% silver and bulk samples with) and 2.7 wt% silver were melt processed in flowing oxygen on a silver substrate in the DTA, allowing the observation of the melting process and a good temperature control. The critical current densities are vigorously dependent on the maximum processing temperature. The highest j(sub c) in thick films (8000 A/sq cm at 77 K, O T) was reached by melting 7 C above the solidus temperature. The silver addition shows no significant effect on the processing parameters or the superconducting properties. The highest j(sub c) for bulk samples (1 mm in thickness) was obtained by partial melting at 900 C or 880 C, depending on the silver content of the powder (0 or 2.7 wt%). The j(sub c) of the samples is slightly enhanced from 1800 A/sq cm (at 77 K, O T) to 2000 A/sq cm by the silver addition. To be able to reach at least 80% of the maximum critical current density, the temperature has to be controlled in a window of 5 C for thick films and 17 C for bulk samples.

  16. Evolution of microstructure and mechanical properties during Q&P processing of medium-carbon steels with different silicon levels

    NASA Astrophysics Data System (ADS)

    Jenicek, S.; Vorel, I.; Kana, J.; Opatova, K.; Rubesova, K.; Kotesovec, V.; Masek, B.

    2017-03-01

    Evolution of microstructure during heat treatment plays a fundamental role in the resulting mechanical properties of steel. Today, mechanical properties in conjunction with technological properties, such as weldability, formability, and machinability, and their optimum combinations, are widely discussed in a number of mechanical engineering disciplines. In this manner, requirements arise for developing steels which could offer high strength and good formability, and which could be used for making parts with high resistance to failure and with a long life. One present-day example of such steels involves Q&P-processed martensitic steels. Their properties are dictated by their treatment, as well as their alloying, particularly by the silicon content. Silicon fundamentally affects microstructure evolution during Q&P processing and, as a result, mechanical properties. With this way it is possible to receive microstructures consinsting of martensite and retained austenite with an ultimate tensile stress of more than 1600 MPa and a uniform elongation of more than 12 %.

  17. Engineering processes in meat products and how they influence their biophysical properties.

    PubMed

    Tornberg, E

    2013-12-01

    Food engineering aspects of cooking of meat products in relation to their biophysical properties, such as water- and fat-holding, have been reviewed. Moreover, some of the new emerging, mild cooking technologies, such as high pressure and electro-based heating (radio frequency cooking and ohmic heating) have been discussed in relation to the biophysical properties of the meat products treated. The holding of the bulk water (about 70% of the muscle weight) was discussed, arguing capillary forces to be one of the dominating mechanisms for this holding, whereas the losses of water and fat (the flow) within the meat are governed by Darcy's law. If we compare the fat-holding in beef burgers and emulsion sausages (frankfurter type) beef burgers lose much larger part of the fat than the emulsion sausages and for the former the fat losses increase with fat content. For emulsion sausages, however, fat losses are independent of fat content and the properties of the fat and the protein matrix are more interrelated. It has been shown experimentally during double sided pan frying of beef burgers that the pressure driven water loss (up to 80% of the water loss) is a substantially more important mechanism governing the water loss than the evaporation losses occurring at the surface crust. Fat losses increased significantly with fat content and were not influenced to any large extent by the cooking temperature and were in the form of drip. By using processing technologies such as high pressure and/or electro-based heating (radio frequency cooking and ohmic heating) a more homogenous heating can be achieved, the reason being volumetric heating. In comparison with conventional heating shorter cooking times were obtained and with smaller temperature gradients lower water- and fat-losses occurred and the yield can be substantially improved. High pressure processing (100-1000MPa) is a preservation technology that allows the reduction of the microbial load at low or moderate temperature

  18. Investigations of the processing-structure-property relationships of selected semicrystalline polymers

    NASA Astrophysics Data System (ADS)

    Johnson, Matthew Brian

    2000-10-01

    investigation was conducted of the optical properties of blown and cast films made from conventional Ziegler-Natta catalyzed linear low density polyethylene (LLDPE) as well as metallocene-catalyzed LLDPE resins. From this work, it was determined that in PE blown and cast films made using conventional processing conditions, the optical haze properties are adversely affected due to enhanced surface roughness caused by the formation of spherulitic-like superstructures in polymer melts that possess fast relaxing and low melt elasticity rheological characteristics. This optical property study was also published in J. Appl. Polym. Sci., 77(13), 2845, (2000).

  19. Processing, Microstructure, and Mechanical Properties of Interpenetrating Biomorphic Graphite/Copper Composites

    NASA Astrophysics Data System (ADS)

    Childers, Amanda Esther Sall

    Composite properties can surpass those of the individual phases, allowing for the development of advanced, high-performance materials. Bio-inspired and naturally-derived materials have garnered attention as composite constituents due to their inherently efficient and complex structures. Wood-derived ceramics, produced by converting a wood precursor into a ceramic scaffold, can exhibit a wide range of microstructures depending on the wood species, including porosity, pore size and distribution, and connectivity. The focus of this work was to investigate the processing, microstructure, and properties of graphite/copper composites produced using wood-derived graphite scaffolds. Graphite/copper composites combine low specific gravity, high thermal conductivity, and tailorable thermal expansion properties, and due to the non-wetting behavior of copper to graphite, offer a unique system in which mechanically bonded interfaces in composites can be studied. Graphite scaffolds were produced from red oak, beech, and pine precursors using a catalytic pyrolyzation method, resulting in varying types of pore networks. Two infiltration methods were investigated to overcome challenges associated with non-wetting systems: copper electrodeposition and pressure-assisted melt infiltration. The phase distributions, constituent properties, interfacial characteristics, mechanical behavior, and load partitioning of these biomorphic graphite/copper composites were investigated, and were correlated to the wood species. The multi-domain feature sizes in the graphite scaffolds resulted in composites with copper relegated not only to the large, connected channels produced from the transport features in the wood, but also within the smaller, lower aspect ratio fibrous regions of the scaffold. Both features contributed to the mechanical behavior of the composites to varying degrees depending on the wood species. A multi-component predictive model also was developed and used to guide the additive

  20. Processing and properties of a solid energy fuel from municipal solid waste (MSW) and recycled plastics

    SciTech Connect

    Gug, JeongIn Cacciola, David Sobkowicz, Margaret J.

    2015-01-15

    Highlights: • Briquetting was used to produce solid fuels from municipal solid waste and recycled plastics. • Optimal drying, processing temperature and pressure were found to produce stable briquettes. • Addition of waste plastics yielded heating values comparable with typical coal feedstocks. • This processing method improves utilization of paper and plastic diverted from landfills. - Abstract: Diversion of waste streams such as plastics, woods, papers and other solid trash from municipal landfills and extraction of useful materials from landfills is an area of increasing interest especially in densely populated areas. One promising technology for recycling municipal solid waste (MSW) is to burn the high-energy-content components in standard coal power plant. This research aims to reform wastes into briquettes that are compatible with typical coal combustion processes. In order to comply with the standards of coal-fired power plants, the feedstock must be mechanically robust, free of hazardous contaminants, and moisture resistant, while retaining high fuel value. This study aims to investigate the effects of processing conditions and added recyclable plastics on the properties of MSW solid fuels. A well-sorted waste stream high in paper and fiber content was combined with controlled levels of recyclable plastics PE, PP, PET and PS and formed into briquettes using a compression molding technique. The effect of added plastics and moisture content on binding attraction and energy efficiency were investigated. The stability of the briquettes to moisture exposure, the fuel composition by proximate analysis, briquette mechanical strength, and burning efficiency were evaluated. It was found that high processing temperature ensures better properties of the product addition of milled mixed plastic waste leads to better encapsulation as well as to greater calorific value. Also some moisture removal (but not complete) improves the compacting process and results in

  1. Processing-property relationships in epoxy resin/titanium dioxide nanocomposites

    SciTech Connect

    Polyzos, Georgios; Tuncer, Enis; Sauers, Isidor; More, Karren Leslie

    2010-01-01

    In situ precipitated titanium dioxide nanoparticles improve the physical properties of polymer composites. Since the pioneering work at Toyota Research Center on exfoliated montmorillonite nanoparticles in a nylon matrix, extensive studies have been performed on polymer nanocomposites in an effort to better integrate organic and inorganic phases. Inorganic fillers, such as silicon and titanium oxides, are widely used because of their remarkable enhancement of the mechanical, electrical, barrier, and flame-retardancy properties of organic polymers. The dispersion and size of the fillers determine the performance of nanocomposites and, despite numerous methods and processing conditions reported in the literature, a universally simple method to scale up the distribution of nanofillers remains a challenge. A significant part of our research involves formulation of novel nanodielectrics that can withstand high electric fields and exhibit superior mechanical performance. Focusing on nanocomposites operating at cryogenic temperatures, our group developed an in situ method for nucleating titanium dioxide (TiO{sub 2}) nanoparticles in polyvinyl alcohol. We also applied this method to a variety of polymer matrices. Here, we present our recent work on a cryogenic resin filled with TiO{sub 2} nanoparticles. Using a particle-precursor solution from which TiO{sub 2} precipitates, we nucleated nanoparticles within the cryogenic epoxy resin Araldite 5808 (Huntsman Advanced Materials Inc., USA). We fabricated nanocomposite films at low weight percentages ({approx}2.5%) to avoid formation of large aggregates and interfaces. The morphology and dispersion of the in situ synthesized nanoparticles are shown by low- and high-magnification transmission-electron-microscopy (TEM) images. The TiO{sub 2} particles ({le}5nm in diameter) are uniformly nucleated and form evenly distributed nanometer-sized clusters in the polymer matrix. This morphology differs significantly from nanocomposites

  2. Processing of novel elevated amylose wheats: functional properties and starch digestibility of extruded products.

    PubMed

    Chanvrier, Hélène; Appelqvist, Ingrid A M; Bird, Anthony R; Gilbert, Elliot; Htoon, Aung; Li, Zhongyi; Lillford, Peter J; Lopez-Rubio, Amparo; Morell, Matthew K; Topping, David L

    2007-12-12

    Different types of novel wheat lines with different starch contents and amylose/amylopectin ratios, relating to defined alterations in the number and activity of starch synthase IIa genes, were processed by pilot-plant extrusion. Two types of products were produced: pure wholemeal products and breakfast cereals made from wholemeal/maize blends. Lower apparent shear viscosity was obtained in the extruder with lower starch content and higher amylose/amylopectin ratio flours (SSIIa-deficient line). The bulk density of the products decreased with increasing extrusion temperature and was always higher for the triple-null line. The bulk density was not completely explained by the melt shear viscosity, suggesting the importance of the fillers (fibers, brans) in the process of expansion and structure acquisition. The different mechanical properties were explained by the density and by the material constituting the cell walls. Enzyme-resistant starch (RS) content and hydrolysis index (HI) were not correlated to the extrusion temperature, but RS was higher in pure wholemeal products and in the SSIIa-deficient line. These results are discussed in terms of starch molecular architecture and product microstructure.

  3. Effect of processing parameters and glycerin addition on the properties of Al foams

    NASA Astrophysics Data System (ADS)

    Gilani, Hossein; Jafari, Sajjad; Gholami, Roozbeh; Habibolahzadeh, Ali; Mirshahi, Mohammad

    2012-04-01

    Aluminum foam has been produced by sintering and dissolution processes using NaCl powders as a space holder. In this research, glycerin is used as a novel lubricant along with acetone. The effects of the processing parameters including compacting pressure, sintering temperatures (620, 640 and 650 °C), size, and volume fraction of the space holder, on the physical and mechanical properties of the produced foams have been investigated. Due to segregation of the Al and NaCl powders at high compaction pressures, spalling of Al foams was observed. Meanwhile, adding small amounts of acetone and glycerin to the mixture ensures homogeneity and prevents segregation of dissimilar powders at varying pressure. Moreover, the addition of glycerin provides an improved homogenous stress distribution within the produced foams during mechanical testing, which in turn halts crack propagation. Meanwhile, an alternative technique to remove NaCl particles during the dissolution stage has been proposed. The results showed that high quality foams were successfully produced under a compaction pressure range of 250-265 MPa and sintering temperature of 650 °C.

  4. Study of Microstructure and Mechanical Properties Effects on Workpiece Quality in Sheet Metal Extrusion Process.

    PubMed

    Suriyapha, Chatkaew; Bubphachot, Bopit; Rittidech, Sampan

    2015-01-01

    Sheet metal extrusion is a metal forming process in which the movement of a punch penetrates a sheet metal surface and it flows through a die orifice; the extruded parts can be deflected to have an extrusion cavity and protrusion on the opposite side. Therefore, this process results in a narrow region of highly localized plastic deformation due to the formation and microstructure effect on the work piece. This research investigated the characteristics of the material-flow behavior during the formation and its effect on the microstructure of the extruded sheet metal using the finite element method (FEM). The actual parts and FEM simulation model were developed using a blank material made from AISI-1045 steel with a thickness of 5 mm; the material's behavior was determined subject to the punch penetration depths of 20%, 40%, 60%, and 80% of the sheet thickness. The results indicated the formation and microstructure effects on the sheet metal extrusion parts and defects. Namely, when increasing penetration, narrowing the die orifice the material flows through, the material was formed by extruding, and defects were visibility, and the microstructure of the material's grains' size was flat and very fine. Extrusion defects were not found in the control material flow. The region of highly localized plastic deformation affected the material gain and mechanical properties. The FEM simulation results agreed with the experimental results. Moreover, FEM could be investigated as a tool to decrease the cost and time in trial and error procedures.

  5. The effect of extrusion processing on the physiochemical properties of extruded orange pomace.

    PubMed

    Huang, Ya-Ling; Ma, Ya-Sheng

    2016-02-01

    Soluble dietary fibre (SDF) is considered the most effective fraction of dietary fibre (DF) for human health. In this study, extrusion technology was applied to enhance the SDF obtained from orange pomace, a byproduct of juice extraction containing a high level of DF. The pomace was processed in a single-screw extruder at various barrel temperatures (X1; 115-135 °C), feed moistures (X2; 10-18 g/100g), and screw speeds (X3; 230-350 rpm). Based on response surface methodology, the optimum extrusion conditions, which produced a maximum SDF value of 30.36%, were as follows: barrel temperature, 129 °C; feed moisture, 15%; and screw speed, 299 rpm. Compared with unextruded pomace, SDF fraction in extrudate had a higher level of uronic acid. Furthermore, the extrusion process improved the physicochemical properties of extrudate, increasing the water-holding capacity, swelling, water solubility index, and cation-exchange capacity and decreasing the oil-holding capacity.

  6. Forced torsional properties of PMR composites with varying nadic ester concentrations and processing histories

    NASA Technical Reports Server (NTRS)

    Hurwitz, F. I.

    1982-01-01

    PMR polyimide resin was prepared from 4,4'-methylenedianiline, the dimethyl ester of 3,3',4,4'-benzophenonetetracarboxylic acid and the monomethyl ester of 5-norbornene-2,3-dicarboxylic acid (NE). The NE group serves as a chain terminator and crosslinking site. PMR/Celion 6000 composites were fabricated from resins having varying NE concentrations using two molding processes, and the laminates characterized in forced torsion. Glass transition temperatures (T(g)) of 360-390 C were observed in the crosslinked resins, as compared with the literature value of 284 C reported for the uncrosslinked system. T(g) did not decrease with decreasing NE concentrations over the range from 2.0 to 1.25 moles. Stoichiometry, within the range studied, showed little influence on shear properties; however, a 25% variation in matrix shear modulus with processing was observed. The G(12) values determined in forced torsion were in excellent agreement with those reported from tensile tests of + or - 45 deg laminates. A branching and possible secondary crosslink mechanism is proposed based on dynamic mechanical behavior and infrared spectra of the composites.

  7. Ultrasonic Spot and Torsion Welding of Aluminum to Titanium Alloys: Process, Properties and Interfacial Microstructure

    NASA Astrophysics Data System (ADS)

    Balle, Frank; Magin, Jens

    Hybrid lightweight structures shape the development of future vehicles in traffic engineering and the aerospace industry. For multi-material concepts made out of aluminum and titanium alloys, the ultrasonic welding technique is an alternative effective joining technology. The overlapped structures can be welded in the solid state, even without gas shielding. In this paper the conventional ultrasonic spot welding with longitudinal oscillation mode is compared to the recent ultrasonic torsion welding with a torsional mode at 20 kHz working frequency. For each technique the process parameters welding force, welding energy and oscillation amplitude were optimized for the hybrid joints using design of experiments. Relationships between the process parameters, mechanical properties and related welding zone should be understood. Central aspects of the research project are microscopic studies of the joining zone in cross section and extensive fracture surface analysis. Detailed electron microscopy and spectroscopy of the hybrid interface help to understand the interfacial formation during ultrasonic welding as well as to transfer the gained knowledge for further multi-metal joints.

  8. Mechanical Properties Studies of Components Formulation for Mixing Process Contain of Polypropylene, Polyethylene, and Aluminium Powder

    NASA Astrophysics Data System (ADS)

    Hamsi, A.; Dinzi, R.

    2017-03-01

    Certain powder and others components can induce toxic reactions if not properly handled in the mixing stage. During handling, the small particles can become airborne and be trapped in the lungs, another concern is inhomogeneities in the mixing process. Uniform quantities of the particles of the components are needed in all portions of the mixture. This paper reports the results of mechanical properties studies of mixing three components formulation for mixing process. Contain of Polyethylene (PE), Polyprophylene (PP) and Aluminium Powder. Powder mixer, Autodesk mold flow and computer based on excell method was carried out to study the influence of each formulation component on the flow %, PE 20% and Aluminium powder 2%. Macroscopic optic and macro photo was carried out to identify the homogenity of mixing, tensile test for identify the strength of component after mixing. Finally the optimal tensile test with composition PP 785,PE 20% and Aluminium powder 2% at speed 52 rpm, temperature 1500C, the tensile strength 20,92 N/mm2. At temperature 1600C, speed 100 rpm the optimum tensile strength 17,91 N/mm2. The result of simulation autodesk mold flow adviser the filling time 6 seconds. Otherwise on manual hot hidraulic press the time of filling 10 seconds.

  9. The fabrication and properties of Nb{sub 3}Sn superconductors by the internal tin process

    SciTech Connect

    Jakob, B.; Pasztor, G.; Cerri, A.; Vanini, F.

    1996-07-01

    This paper describes recent progress in the development of Nb{sub 3}Sn wires in Switzerland using the internal tin method. The work was carried out in close collaboration between the Fusion Technology Division of CRPP and Swissmetal, with the emphasis on conductors suitable for fusion magnets. The manufacturing process is based on the tubular extrusion of a niobium-copper composite, followed by the cold working of the composite containing a tin core. 19 Nb-Cu-Sn subelements were assembled inside a tantalum diffusion barrier and a copper can and subsequently reduced to wire size by swaging and drawing. The intention was to obtain nonreacted filament sizes of typically 3{micro}m in 0.8--1 mm wires. The evolution of the design and the manufacturing process are discussed. Experience gained with model conductors has been used to guide the design. The strands have been evaluated with respect to electrical and mechanical properties. In particular, critical current densities in the non-copper area exceeding 750 A/mm{sup 2} at 12T and 4.2K have been achieved.

  10. Processing and properties of magnesium containing a dense uniform dispersion of nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Lian-Yi; Xu, Jia-Quan; Choi, Hongseok; Pozuelo, Marta; Ma, Xiaolong; Bhowmick, Sanjit; Yang, Jenn-Ming; Mathaudhu, Suveen; Li, Xiao-Chun

    2015-12-01

    Magnesium is a light metal, with a density two-thirds that of aluminium, is abundant on Earth and is biocompatible; it thus has the potential to improve energy efficiency and system performance in aerospace, automobile, defence, mobile electronics and biomedical applications. However, conventional synthesis and processing methods (alloying and thermomechanical processing) have reached certain limits in further improving the properties of magnesium and other metals. Ceramic particles have been introduced into metal matrices to improve the strength of the metals, but unfortunately, ceramic microparticles severely degrade the plasticity and machinability of metals, and nanoparticles, although they have the potential to improve strength while maintaining or even improving the plasticity of metals, are difficult to disperse uniformly in metal matrices. Here we show that a dense uniform dispersion of silicon carbide nanoparticles (14 per cent by volume) in magnesium can be achieved through a nanoparticle self-stabilization mechanism in molten metal. An enhancement of strength, stiffness, plasticity and high-temperature stability is simultaneously achieved, delivering a higher specific yield strength and higher specific modulus than almost all structural metals.

  11. Processing and properties of magnesium containing a dense uniform dispersion of nanoparticles.

    PubMed

    Chen, Lian-Yi; Xu, Jia-Quan; Choi, Hongseok; Pozuelo, Marta; Ma, Xiaolong; Bhowmick, Sanjit; Yang, Jenn-Ming; Mathaudhu, Suveen; Li, Xiao-Chun

    2015-12-24

    Magnesium is a light metal, with a density two-thirds that of aluminium, is abundant on Earth and is biocompatible; it thus has the potential to improve energy efficiency and system performance in aerospace, automobile, defence, mobile electronics and biomedical applications. However, conventional synthesis and processing methods (alloying and thermomechanical processing) have reached certain limits in further improving the properties of magnesium and other metals. Ceramic particles have been introduced into metal matrices to improve the strength of the metals, but unfortunately, ceramic microparticles severely degrade the plasticity and machinability of metals, and nanoparticles, although they have the potential to improve strength while maintaining or even improving the plasticity of metals, are difficult to disperse uniformly in metal matrices. Here we show that a dense uniform dispersion of silicon carbide nanoparticles (14 per cent by volume) in magnesium can be achieved through a nanoparticle self-stabilization mechanism in molten metal. An enhancement of strength, stiffness, plasticity and high-temperature stability is simultaneously achieved, delivering a higher specific yield strength and higher specific modulus than almost all structural metals.

  12. Influence of emulsification process on the properties of Pickering emulsions stabilized by layered double hydroxide particles.

    PubMed

    Zhang, Nana; Zhang, Li; Sun, Dejun

    2015-04-28

    This paper reports the influence of emulsification process on the packing of layered double hydroxide (LDH) particles at the aqueous/oil phase interface and the properties of the resulting Pickering emulsions. Emulsions prepared by ultrasonication display superior long-term stability and gel-like characteristics at the dispersed phase volume fraction well below the random close packing limit, whereas emulsions with same compositions prepared by vortex mixing show some extent of sedimentation and liquid-like behaviors. Rheological measurements demonstrate that the zero-shear elastic modulus and yield stress of gel-like emulsions exhibit power-law dependences on particle concentration and independence on aqueous/oil phase ratio. The microstructural origin of this behavior is investigated by optical microscopy, revealing the droplets become strongly adhesive and a heterogeneous percolating network is formed among neighboring droplets. Fluorescent confocal microscopy measurements further confirm that the droplet adhesion is due to particle layers bridging opposite interfaces. In contrast, homogeneous, isolated, and densely packed droplets are present in emulsions prepared by vortex mixing, which results in these systems being dominantly viscous like the suspending fluid. This study shows that the emulsification process can be used as a trigger to modify long-term stability and rheology of solid-stabilized multiphase mixtures, which greatly expands their potential technological applications.

  13. The effect of preheat on the material properties of copper and steel in a lens process

    NASA Astrophysics Data System (ADS)

    Styrcula, Matt

    Working with pure copper powder deposited on a steel substrate is difficult in a laser additive manufacturing process due to the relatively high thermal conductivity and reflectivity of copper. In addition to these properties, the difference in thermal conductivity between the copper and steel presents an environment where cracking and porosity is present in the copper-steel transition. One application is the creation of steel-copper die casts for improved thermal management. Removing cracks and limiting porosity is of the utmost importance to this application. Through recent research at NIU, it has been observed that adding preheat while depositing copper and steel in a LAM process all but eliminates this transitional zone along with the cracking and porosity associated with it. This thesis will explore the effects of preheat, laser power, powder feed rate, and laser travel speed on the size of the transitional layer, the presence of cracks, porosity within the deposit, hardness, and all of the parameters effects on the bead and heat affected zone geometry.

  14. Process-structure-property correlations in pulsed dc reactive magnetron sputtered vanadium oxide thin films

    SciTech Connect

    Venkatasubramanian, Chandrasekaran; Cabarcos, Orlando M.; Drawl, William R.; Allara, David L.; Ashok, S.; Horn, Mark W.; Bharadwaja, S. S. N.

    2011-11-15

    Cathode hysteresis in the reactive pulsed dc sputtering of a vanadium metal target was investigated to correlate the structural and electrical properties of the resultant vanadium oxide thin films within the framework of Berg's model [Berg et al., J. Vac. Sci. Technol. A 5, 202 (1987)]. The process hysteresis during reactive pulsed dc sputtering of a vanadium metal target was monitored by measuring the cathode (target) current under different total gas flow rates and oxygen-to-argon ratios for a power density of {approx}6.6.W/cm{sup 2}. Approximately 20%-25% hysteretic change in the cathode current was noticed between the metallic and oxidized states of the V-metal target. The extent of the hysteresis varied with changes in the mass flow of oxygen as predicted by Berg's model. The corresponding microstructure of the films changed from columnar to equiaxed grain structure with increased oxygen flow rates. Micro-Raman spectroscopy indicates subtle changes in the film structure as a function of processing conditions. The resistivity, temperature coefficient of resistance, and charge transport mechanism, obeying the Meyer-Neldel relation [Meyer and Neldel, Z. Tech. Phys. (Leipzig) 12, 588 (1937)], were correlated with the cathode current hysteric behavior.

  15. Effect of processing parameters on tensile properties of thermoplastic natural rubber (TPNR) blend with polyaniline

    NASA Astrophysics Data System (ADS)

    Zailan, Farrah Diyana; Ahmad, Sahrim; Chen, Ruey Shan; Shahdan, Dalila

    2016-11-01

    This study was aimed to determine the optimum processing parameter for the fabrication of thermoplastic natural rubber (TPNR), polyaniline (PANI) incorporated with liquid natural rubber (LNR) as a compatibilizer. The TPNR matrix, which comprised of linear low-density polyethylene (LLDPE), natural rubber (NR), and LNR in the ratio of 50:40:10, and TPNR/PANI (90 wt % /10 wt %) blend were prepared via melt blending method using Haake Rheomix internal mixer with various mixing parameter condition. The independent effects of mixing temperature (120 - 150°C), mixing speed of rotation (20-50 rpm) and time of mixing (13, 14, 15 minutes) on the tensile properties were investigated. Tensile results showed that the optimum processing parameter TPNR/PANI blend obtained at 130°C, 30 rpm, and 13 minutes. Compared to TPNR, the presence of PANI in TPNR improved the tensile strength and Young Modulus as compared to the neat TPNR acted as a control sample. The morphology characterization of TPNR and TPNR/PANI was examined by using Scanning Electron Microscopy (SEM) for further confirmation of good PANI dispersion within TPNR matrix.

  16. The magnetic properties and microstructure of Co-Pt thin films using wet etching process.

    PubMed

    Lee, Chang-Hyoung; Cho, Young-Lae; Lee, Won-Pyo; Suh, Su-Jeong

    2014-11-01

    Perpendicular magnetic recording (PMR) is a promising candidate for high density magnetic recording and has already been applied to hard disk drive (HDD) systems. However, media noise still limits the recording density. To reduce the media noise and achieve a high signal-to-noise ratio (SNR) in hard disk media, the grains of the magnetic layer must be magnetically isolated from each other. This study examined whether sputter-deposited Co-Pt thin films can have adjacent grains that are physically isolated. To accomplish this, the effects of the sputtering conditions and wet etching process on magnetic properties and the microstructure of the films were investigated. The film structure was Co-Pt (30 nm)/Ru (30 nm)/NiFe (10 nm)/Ta (5 nm). The composition of the Co-Pt thin films was Co-30.7 at.% Pt. The Co-Pt thin films were deposited in Ar gas at 5, 10, 12.5, and 15 mTorr. Wet etching process was performed using 7% nitric acid solution at room temperature. These films had high out-of-plane coercivity of up to 7032 Oe, which is twice that of the as-deposited film. These results suggest that wet etched Co-Pt thin films have weaker exchange coupling and enhanced out-of-plane coercivity, which would reduce the medium noise.

  17. Microstructure and tensile properties after thermohydrogen processing of Ti-6 Al-4V.

    PubMed

    Guitar, A; Vigna, G; Luppo, M I

    2009-04-01

    Thermohydrogen processing (THP), a technique in which hydrogen is used as a temporary alloying element, can refine the microstructure and improve the final mechanical properties of the Ti-6 Al-4V alloy. THP allows microstructural modification of titanium alloys near net shape such as biomaterial components obtained by powder metallurgy and castings, since it does not require mechanical working. Two THP, called THP-A and THP-B, have been evaluated in samples of Ti-6Al-4V with a coarse and lamellar microstructure typical of castings and powder metallurgy. The THP-A is based in the eutectoid decomposition of the beta(H) phase to alpha phase and hydride phase. The THP-B is based in the isothermal decomposition of alpha('') martensite phase, obtained by quenching of hydrogenated samples. The refinement of the microstructure due to THP has been evaluated by means of optical and electron microscopy. Tensile tests showed that while both processes were able to increase the strength of the alloy as compared with the starting material, the ductility in samples subjected to THP-B was severely reduced.

  18. Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 2, Appendices

    SciTech Connect

    Butner, R.S.; Elliott, D.C.; Sealock, L.J., Jr.; Pyne, J.W.

    1988-12-01

    This report presents an exploration of the relationships between biomass feedstocks and the conversion processes that utilize them. Specifically, it discusses the effect of the physical and chemical structure of biomass on conversion yields, rates, and efficiencies in a wide variety of available or experimental conversion processes. A greater understanding of the complex relationships between these conversion systems and the production of biomass for energy uses is required to help optimize the complex network of biomass production, collection, transportation, and conversion to useful energy products. The review of the literature confirmed the scarcity of research aimed specifically at identifying the effect of feedstock properties on conversion. In most cases, any mention of feedstock-related effects was limited to a few brief remarks (usually in qualitative terms) in the conclusions, or as a topic for further research. Attempts to determine the importance of feedstock parameters from published data were further hampered by the lack of consistent feedstock characterization and the difficulty of comparing results between different experimental systems. Further research will be required to establish quantitative relationships between feedstocks and performance criteria in conversion. 127 refs., 4 figs., 7 tabs.

  19. The influence of thermal processing on emulsion properties of defatted hazelnut flour.

    PubMed

    Turan, Deniz; Altay, Filiz; Capanoğlu Güven, Esra

    2015-01-15

    In this study, the influences of roasting and the amount of hazelnut flour on the formation and stabilization of emulsions containing different amounts of oil were investigated. After hazelnuts were roasted in an oven at 140°C for 40 min, the oil content was removed. The emulsions with defatted hazelnut flour containing corn oil at 3%, 10% and 50% were prepared. Roasting process significantly decreased the interfacial tension values of samples down to 1.9 mN/m due to protein denaturation. There was no significant difference between the particle sizes of oil droplets in emulsions with roasted and raw hazelnut flour at the same concentration. However, diffusion coefficients of oil droplets increased for emulsions containing roasted defatted flour samples. The zeta (ζ) potential values of all emulsions increased when roasted hazelnut flour was used, indicating the stabilization of suspensions and the solution resistance against aggregation. Storage modulus (G'), loss modulus (G″) and complex viscosity (η(∗)) of emulsions were measured. G' value was found to be greater than the G″ value, which fits into weak gel model. The roasting process resulted with lower transition temperatures but with increased transition enthalpies of the flour samples based on differential scanning (DSC) measurements. Lower transition temperatures may be attributed to the partial gelatinization of starch in the flour and partial denaturation of proteins. These results may help to tailor the properties of defatted hazelnut flour when it is used in food products containing emulsions such as sauces, dressings and creams for stabilizing purposes.

  20. The properties of biomimetically processed calcium phosphate on bioactive ceramics and their response on bone cells.

    PubMed

    Vaahtio, M; Peltola, T; Hentunen, T; Ylänen, H; Areva, S; Wolke, J; Salonen, J I

    2006-11-01

    This study looks for grounds to alter the chemical composition (phosphate, calcium, silica and carbonate), dissolution properties, structure and nanotopography of the biomimetically processed surfaces on bioactive ceramics to optimize their shown ability to influence bone cell behaviour and production of new bone. In the bone environment desirable characteristic of these materials is their ability to be remodeled by natural osteoclastic resorption. Different silica and carbonate containing calcium phosphate layers were prepared on bioactive glasses 9 (S53P4) and 1-98 (S53P2) and sol-gel processed pure silica SiO2 in C- and R-SBF (conventional and revised simulated body fluid) for varying periods of time. It was shown that in R-SBF the CaP layer formed faster compared to C-SBF. The CaP layer in the R-SBF contained more carbonate (CO3(2-)) compared to that formed with the same immersion time in C-SBF. The CaP so formed in R-SBF with faster precipitation is more amorphous than the bonelike HCA formed in C-SBF. The results indicate that the most suitable surface for both osteoblasts and osteoclasts was found to be an amorphous CaP having mesoporous nanotopography and proper dissolution rate of calcium and silica.

  1. Processable fluoropolymers with low dielectric constants: Preparation and structure-property relationships of polyacrylates and polymethacrylates

    SciTech Connect

    Hu, H. S.W.; Griffith, J.R.

    1993-12-31

    The preparation of a series of processable heavily fluorinated acrylic and methacrylic homo- and co-polymers with low dielectric constants is carried out to elucidate the structure-property relationships. The monomers were prepared through the condensation of the respective alcohols with acryloyl and methacryloyl chloride. Unlike tetrafluoroethylene, these monomers are easy to process into transparent polymers under normal conditions due to their liquid or semisolid nature. All polymers exhibit dielectric constants around 2.06-2.41 with variation within 0.03 over a frequency region of 500 MHz to 18.5 GHz. These values are very close to the minimum known dielectric constants of 2.0-2.08 for Teflon and 1.89-1.93 for Teflon AF. The factors which affect the dielectric constant include the fluorine content, the polymer type and molecular features. Lower dielectric constants are obtained as fluorine contents from polymer backbone or sidechain increase, when acrylate is replaced by methacrylate, when ether linkages are present in the fluorocarbon and when aromatic structure is symmetrically meta-substituted.

  2. Removal properties of human enteric viruses in a pilot-scale membrane bioreactor (MBR) process.

    PubMed

    Miura, Takayuki; Okabe, Satoshi; Nakahara, Yoshihito; Sano, Daisuke

    2015-05-15

    In order to evaluate removal properties of human enteric viruses from wastewater by a membrane bioreactor (MBR), influent, anoxic and oxic mixed liquor, and membrane effluent samples were collected in a pilot-scale anoxic-oxic MBR process for 16 months, and concentrations of enteroviruses, norovirus GII, and sapoviruses were determined by real-time PCR using murine norovirus as a process control. Mixed liquor samples were separated into liquid and solid phases by centrifugation, and viruses in the bulk solution and those associated with mixed liquor suspended solids (MLSS) were quantified. Enteroviruses, norovirus GII, and sapoviruses were detected in the influent throughout the sampling period (geometrical mean, 4.0, 3.1, and 4.4 log copies/mL, respectively). Enterovirus concentrations in the solid phase of mixed liquor were generally lower than those in the liquid phase, and the mean log reduction value between influent and anoxic mixed liquor was 0.40 log units. In contrast, norovirus GII and sapovirus concentrations in the solid phase were equal to or higher than those in the liquid phase, and higher log reduction values (1.3 and 1.1 log units, respectively) were observed between influent and anoxic mixed liquor. This suggested that enteroviruses were less associated with MLSS than norovirus GII and sapoviruses, resulting in lower enterovirus removal in the activated sludge process. Enteroviruses and norovirus GII were detected in the MBR effluent but sapoviruses were not in any effluent samples. When MLSS concentration was reduced to 50-60% of a normal operation level, passages of enteroviruses and norovirus GII through a PVDF microfiltration membrane were observed. Since rejection of viruses by the membrane was not related to trans-membrane pressure which was monitored as a parameter of membrane fouling, the results indicated that adsorption to MLSS plays an important role in virus removal by an MBR, and removal properties vary by viruses reflecting different

  3. Development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements

    NASA Technical Reports Server (NTRS)

    Rey, Charles A.

    1991-01-01

    The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

  4. Effects of the Selective Laser Melting manufacturing process on the properties of CoCrMo single tracks

    NASA Astrophysics Data System (ADS)

    Monroy, Karla P.; Delgado, Jordi; Sereno, Lídia; Ciurana, Joaquim; Hendrichs, Nicolas J.

    2014-09-01

    Selective Laser Melting (SLM) is an additive technology that produces solid parts by selectively melting thin layers of metallic powder. SLM can produce significant differences in the final properties due to the melting-consolidation phenomena of the process, which can be controlled by the appropriate parameters. Therefore, the objective of this study was to create a link between the process conditions and the resulting properties by experimenting in an own-developed SLM machine using CoCrMo powder as material. The fabricated samples were characterized by density, hardness and microstructural properties. The experimental results proved the capability of the SLM technique to build high dense samples. The hardness results gave evidence of a superior outcome compared to conventional processes. Finally, it was found that grain size was defined by scanning speed. Based on the results, a better understanding of the processing principles given by the parameters was achieved and improved fabrication quality was promoted.

  5. Process for modifying the properties of a swelling coal, an installation for carrying out the process and a chamber for treatment of coal by fluidization and crushing

    SciTech Connect

    Delessard, S.L.; Kita, J.; Puff, R.M.

    1983-05-10

    The present invention relates to a process for modifying the properties of a swelling coal, to an installation for carrying out the process and to a chamber for treatment by fluidization and crushing. A percussion-type crusher is installed in a fluidization chamber at about 1 meter above the zone of connection between a duct for conveying coal by pneumatic transport and the chamber. A combustion chamber produces gases for transport and fluidization, having an oxygen content of at least 10%.

  6. Mechanical properties and biocompatibility of melt processed, self-reinforced ultrahigh molecular weight polyethylene.

    PubMed

    Huang, Yan-Fei; Xu, Jia-Zhuang; Li, Jian-Shu; He, Ben-Xiang; Xu, Ling; Li, Zhong-Ming

    2014-08-01

    The low efficiency of fabrication of ultrahigh molecular weight polyethylene (UHMWPE)-based artificial knee joint implants is a bottleneck problem because of its extremely high melt viscosity. We prepared melt processable UHMWPE (MP-UHMWPE) by addition of 9.8 wt% ultralow molecular weight polyethylene (ULMWPE) as a flow accelerator. More importantly, an intense shear flow was applied during injection molding of MP-UHMWPE, which on one hand, promoted the self-diffusion of UHMWPE chains, thus effectively reducing the structural defects; on the other hand, increased the overall crystallinity and induced the formation of self-reinforcing superstructure, i.e., interlocked shish-kebabs and oriented lamellae. Aside from the good biocompatibility, and the superior fatigue and wear resistance to the compression-molded UHMWPE, the injection-molded MP-UHMWPE exhibits a noteworthy enhancement in tensile properties and impact strength, where the yield strength increases to 46.3 ± 4.4 MPa with an increment of 128.0%, the ultimate tensile strength and Young's modulus rise remarkably up to 65.5 ± 5.0 MPa and 1248.7 ± 45.3 MPa, respectively, and the impact strength reaches 90.6 kJ/m(2). These results suggested such melt processed and self-reinforced UHMWPE parts hold a great application promise for use of knee joint implants, particularly for younger and more active patients. Our work sets up a new method to fabricate high-performance UHMWPE implants by tailoring the superstructure during thermoplastic processing.

  7. TC17 titanium alloy laser melting deposition repair process and properties

    NASA Astrophysics Data System (ADS)

    Liu, Qi; Wang, Yudai; Zheng, Hang; Tang, Kang; Li, Huaixue; Gong, Shuili

    2016-08-01

    Due to the high manufacturing cost of titanium compressor blisks, aero engine repairing process research has important engineering significance and economic value. TC17 titanium alloy is a rich β stable element dual α+β phase alloy whose nominal composition is Ti-5Al-2Sn-2Zr-4Mo-4Cr. It has high mechanical strength, good fracture toughness, high hardenability and a wide forging-temperature range. Through a surface response experiment with different laser powers, scanning speeds and powder feeding speeds, the coaxial powder feeding laser melting deposition repair process is studied for the surface circular groove defects. In this paper, the tensile properties, relative density, microhardness, elemental composition, internal defects and microstructure of the laser-repaired TC17 forging plate are analyzed. The results show that the laser melting deposition process could realize the form restoration of groove defect; tensile strength and elongation could reach 1100 MPa and 10%, which could reach 91-98% that of original TC17 wrought material; with the optimal parameters (1000 W-25 V-8 mm/s), the microhardness of the additive zone, the heat-affected zone and base material is evenly distributed at 370-390 HV500. The element content difference between the additive zone and base material is less than ±0.15%. Due to the existence of the pores 10 μm in diameter, the relative density could reach 99%, which is mainly inversely proportional to the powder feeding speed. The repaired zone is typically columnar and dendrite crystal, and the 0.5-1.5 mm-deep heat-affected zone in the groove interface is coarse equiaxial crystal.

  8. A review of corn masa processing residues: generation, properties, and potential utilization.

    PubMed

    Rosentrater, K A

    2006-01-01

    The production of corn masa-based products in the US has been increasing over the last several years, and as a result, so has the quantity of waste materials being generated from this industry. Although currently landfilled, these byproduct streams may have potential for value-added processing and utilization, which are options that simultaneously hold the promise of increased economic benefit for masa processors as well as decreased potential pollution for the environment. Fundamental to any byproduct development effort is knowledge of the characteristics of the residue stream, because physical and chemical properties are vital for the proper design of subsequent processing operations and applications. Data for masa byproduct materials are currently not readily available, however. Thus, the objective of this study was to fully investigate, review, and summarize the existing literature in order to develop a comprehensive knowledge base for these residue streams. The most substantial findings from this study were that masa residues currently are not being utilized as coproducts, but instead are being landfilled; they have a high fiber content, and thus much untapped potential exists for its extraction and value-added utilization vis-à-vis human and industrial applications, including phytosterol and ethanol production. It was also determined that masa byproducts, due to the high fiber content, may also be suitable for use as livestock feed additives, especially for ruminant animals that can digest these materials. Furthermore, due to substantial calcium content, masa byproducts could also potentially be used as a calcium resource. Under current processing practices, though, these residues have very high moisture contents. Before they can be effectively and economically utilized, they must be dehydrated in order to reduce transportation costs, decrease microbial activity, and increase shelf life.

  9. Incorporation of nisin in poly (ethylene-co-vinyl acetate) films by melt processing: a study on the antimicrobial properties.

    PubMed

    Scaffaro, Roberto; Botta, Luigi; Marineo, Sandra; Puglia, Anna Maria

    2011-07-01

    Both industry and academia have shown a growing interest in materials with antimicrobial properties suitable for food packaging applications. In this study, we prepared and characterized thin films of ethylene-co-vinyl acetate (EVA) copolymer with antimicrobial properties. The films were prepared with a film blowing process by incorporating a nisin preparation as an antimicrobial agent in the melt. Two grades of EVA containing 14 and 28% (wt/wt) vinyl acetate (EVA 14 and EVA 28, respectively) and two commercial formulations of nisin with different nominal activities were used. The effect of the nisin concentration also was evaluated. The films with the highest antimicrobial activity were those formulated with nisin at the highest activity and EVA with the highest content of vinyl acetate. The use of the commercial formulation of nisin with high activity in the EVA films allowed reduction in the amount of nisin needed to provide antimicrobial properties. Consequently, the mechanical properties of these films were only slightly inferior to those of the pure polymers. In contrast, films prepared by incorporating more of the nisin with lower activity had poor mechanical properties. The effect of different processing temperatures used in the preparation of the films on the antimicrobial properties of the films also was evaluated. The materials displayed antimicrobial properties even when they were prepared at temperatures as high as 160 °C, probably because of the very short processing time (60 to 90 s) required for preparation.

  10. Thermodynamic and rheological properties of solid-liquid systems in coal processing. Final technical report

    SciTech Connect

    Kabadi, V.N.

    1995-06-30

    The work on this project was initiated on September 1, 1991. The project consisted of two different tasks: (1) Development of a model to compute viscosities of coal derived liquids, and (2) Investigate new models for estimation of thermodynamic properties of solid and liquid compounds of the type that exist in coal, or are encountered during coal processing. As for task 1, a model for viscosity computation of coal model compound liquids and coal derived liquids has been developed. The detailed model is presented in this report. Two papers, the first describing the pure liquid model and the second one discussing the application to coal derived liquids, are expected to be published in Energy & Fuels shortly. Marginal progress is reported on task 2. Literature review for this work included compilation of a number of data sets, critical investigation of data measurement techniques available in the literature, investigation of models for liquid and solid phase thermodynamic computations. During the preliminary stages it was discovered that for development of a liquid or solid state equation of state, accurate predictive models for a number of saturation properties, such as, liquid and solid vapor pressures, saturated liquid and solid volumes, heat capacities of liquids and solids at saturation, etc. Most the remaining time on this task was spent in developing predictive correlations for vapor pressures and saturated liquid volumes of organic liquids in general and coal model liquids in particular. All these developments are discussed in this report. Some recommendations for future direction of research in this area are also listed.

  11. A Review on Biomass Torrefaction Process and Product Properties for Energy Applications

    SciTech Connect

    Jaya Shankar Tumuluru; Shahab Sokhansanj; J. Richard Hess; Christopher T. Wright; Richard D. Boardman

    2011-10-01

    Torrefaction of biomass can be described as a mild form of pyrolysis at temperatures typically ranging between 200 and 300 C in an inert and reduced environment. Common biomass reactions during torrefaction include devolatilization, depolymerization, and carbonization of hemicellulose, lignin and cellulose. Torrefaction process produces a brown to black solid uniform product and also condensable (water, organics, and lipids) and non condensable gases (CO2, CO, and CH4). Typically during torrefaction, 70% of the mass is retained as a solid product, containing 90% of the initial energy content, and 30% of the lost mass is converted into condensable and non-condensable products. The system's energy efficiency can be improved by reintroducing the material lost during torrefaction as a source of heat. Torrefaction of biomass improves its physical properties like grindability; particle shape, size, and distribution; pelletability; and proximate and ultimate composition like moisture, carbon and hydrogen content, and calorific value. Carbon and calorific value of torrefied biomass increases by 15-25%, and moisture content reduces to <3% (w.b.). Torrefaction reduces grinding energy by about 70%, and the ground torrefied biomass has improved sphericity, particle surface area, and particle size distribution. Pelletization of torrefied biomass at temperatures of 225 C reduces specific energy consumption by two times and increases the capacity of the mill by two times. The loss of the OH group during torrefaction makes the material hydrophobic (loses the ability to attract water molecules) and more stable against chemical oxidation and microbial degradation. These improved properties make torrefied biomass particularly suitable for cofiring in power plants and as an upgraded feedstock for gasification.

  12. Effect of cationic polyacrylamide on the processing and properties of nanocellulose films.

    PubMed

    Raj, Praveena; Varanasi, Swambabu; Batchelor, Warren; Garnier, Gil

    2015-06-01

    The use of high molecular weight cationic polyacrylamide (CPAM) was investigated to accelerate the drainage of nanocellulose (Microfibrillated Cellulose) suspensions into films. The mechanism was quantified and optimized by measuring the gel point, the lowest solids concentration at which a continuous network is formed. The flocculation of MFC was analysed as a function of the polyelectrolyte dosage, charge density and molecular weight as well as process parameters (drainage time) and material properties. The adsorption isotherms of CPAMs on nanocellulose and their zeta potential curves were also analysed as a function of CPAM charge and dosage. Measured CPAM adsorption capacities for the 50% and 10% charged 13MDa CPAM onto MFC were 5mg/g and 8mg/g, respectively, corresponding to adsorption coverage on cellulose of 0.14mg/m(2) and 0.22mg/m(2). The floc strength and drainability of MFC suspensions were quantified with the gel point as a function of CPAM properties. For all combinations of polyelectrolyte molecular weight and charge density, the gel point of a nanocellulose suspension goes through a minimum with increasing polymer dosage. The minimum gel point was independent of the polyelectrolyte charge density at constant molecular weight. However, it reduced with decreasing CPAM molecular weight, at a constant addition rate. The drainage time of a nanocellulose suspension into a film is reduced by 2/3 by halving the gel point from 0.2 to 0.1kg/m(3); this is due to the more flocculated suspension facilitating drainage between flocs. Nanocellulose films of increased porosity also result from reducing the gel point, signifying that the more open 3D structure of the flocculated cellulose suspension is retained upon drying the 2D film cellulose film structure.

  13. Sublimation process and physical properties of vapor grown γ-In2Se3 platelet crystals

    NASA Astrophysics Data System (ADS)

    Ajayakumar, C. J.; Kunjomana, A. G.

    2016-11-01

    Indium selenide (γ-In2Se3) crystals have been grown by the closed tube sublimation process in the absence of seed crystals and chemical transporting agents. The composition, structure and morphology of the samples grown under different vacuum conditions were examined by energy dispersive analysis, X-ray diffraction, and scanning electron microscope. Structural features of the crystals obtained in a vacuum of 10-3 mbar exhibited a few reflections not belonging to γ phase, whereas X-ray diffraction spectra of the crystals deposited under a vacuum of 10-6 mbar revealed evidence of sharp peaks with high intensities of γ-In2Se3 crystalline phase. When growth runs were performed for 72 h, voids were observed on the surface whereas for a duration of 120 h, platelet crystals were obtained. Optical properties of these samples were investigated using the FT-IR and photoluminescence spectroscopy. The average transmittance of the platelets in the visible and near infrared region of solar spectrum was found to be ∼81% and an optical band gap of ∼2.05 eV was computed from the transmission spectrum. Photoluminescence spectra of the grown In2Se3 crystals recorded at room temperature using an excitation laser of wavelength 355 nm showed a peak in the near band edge emission (NBE) corresponding to an energy of 2.01 eV. Under an illumination power of 12 mW/cm2, the photocurrent increased linearly with applied voltage and the dark current was found to be 2.5×10-9 A for 10 V. These results suggest that the as-grown γ-In2Se3 platelets crystallized from vapor deposition, possess superior optoelectronic properties than the other phases for solar cell applications.

  14. Effect of processing temperature on the properties of nanophase Fe-substituted Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Kathriarachchi, Vindu Wathsala

    The effect of processing temperature on the crystal structure properties of the Fe-substituted Hydroxyapatite (Fe-HAp) was studied by using the Rietveld refinement method of powder x-ray (XRD) and neutron diffraction (NPD) patterns. Superconducting QUantum Interference Device (SQUID) magnetometry, transmission electron microscopy (TEM) and x-ray fluorescence spectroscopy (XRF) were used to study the magnetic properties, particle morphology and chemical composition of the prepared samples. Two sets of samples of chemical formula Ca5- xFex(PO4)3OH were prepared with x = 0, 0.05, 0.1, 0.2 and 0.3 by using processing temperatures of 37°C and 80°C, following a two-step co-precipitation method. A single phase HAp was identified in samples with x = 0 and 0.05. Processing temperature affects the type and percentage of secondary phases: hematite was detected in samples prepared at 37°C with x ≥ 0.1, hematite and maghemite were detected in samples prepared at 80°C with x = 0.2 and 0.3. Rietveld refinements of NPD and XRD patterns showed that the a lattice constants are greater in Fe-substituted samples prepared at 37°C, whereas the c lattice constants are greater in the 80°C samples for x ≥ 0.05. Fe preferentially substitutes at the Ca2 site in the 80°C samples, whereas Ca1 is the preferred substitution site in the 37°C samples. Fe substitution results to a decrease of the lattice constants at both preparation temperatures. The ratios Fe/(Fe + Ca) of the refined atomic fractions of the samples prepared at 80°C are greater than those of the 37°C samples. Further, more secondary phases form in samples prepared at 37°C compared to 80°C samples. The magnetic measurements reveal that pure HAp is diamagnetic, whereas samples with x = 0.05 and 0.1 are paramagnetic. Samples with x = 0.3 showed superparamagnetic behavior based on ZFC and FC measurements. Similar hysteresis loops in samples x = 0.2 and 0.3 indicate that the samples with x = 0.2 may show

  15. Invariant Measures and Convergence Properties for Cellular Automaton 184 and Related Processes

    NASA Astrophysics Data System (ADS)

    Belitsky, Vladimir; Ferrari, Pablo A.

    2005-02-01

    Our results concern long time limit properties of a deterministic dynamics that is common for a wide class of processes that have been studied so far during at least last two decades. The most widely known process from this class is a cellular automaton that acquired number 184 in the classification of S. Wolfram. This CA 184 is being intensively used to model vehicular traffic. However, our results are mainly derived with help of another process that offers a helpful insight into the studied dynamics, it is a so-called Ballistic Annihilation Model (abbreviated by BA). BA is a model for chemical reaction A+B → inert. In BA, A and B-type particles move in opposite directions with velocities 1 and -1, respectively, and annihilate upon collisions. Certain results concerning BA and CA 184 are also formulated in terms of another process known as a Model of Surface Growth (SG, for short); the surface shape in this process behaves as the integrated profile of particle distribution in CA 184. Our results are as follows. First, we characterize the invariant measures of the dynamics in interest. The bulk of our effort is devoted to the characterization of those of them that are not translation invariant; we call them phase separating invariant measures. In the case of BA, such measures are concentrated on the configurations consisting of two converging infinite blocks of (not necessarily adjacent) particles. In the case of CA 184, a phase separating measure describes the transition from free traffic phase to jammed phase. We also analyze domains of attraction of invariant measures and rates of convergence to them. This analysis then allows us to express the long time limit of particle current in CA 184 as a function of certain characteristics of its initial distribution, when it is translation invariant. This expression has been used in a companion paper (V. Belitsky, J. Krug, E. J. Neves and G. Schütz, A cellular automaton model for two-lane traffic, J. Stat. phys.103

  16. The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 2. Constituent Properties and Macroscopic Performance: CMCs

    DTIC Science & Technology

    1993-04-01

    multiple matrix cracking (Zok). The tensile stress- strain behavior of composites containing such cracks is analogous to the behavior of unidirectional...developed (Suo). 2.2 Matrix Cracking Models of the plastic strain and modulus changes cati’ed by various modes of matrix cracking have been developed...displacement measurements to constituent properties (Table I). (ii) Stress/ strain curves and matrix crack evolution have been simulated for specific

  17. Processing and properties of ceramic matrix-polymer composites for dental applications

    NASA Astrophysics Data System (ADS)

    Huang, Hsuan Yao

    The basic composite structure of natural hard tissue was used to guide the design and processing of dental restorative materials. The design incorporates the methodology of using inorganic minerals as the main structural phase reinforced with a more ductile but tougher organic phase. Ceramic-polymer composites were prepared by slip casting a porous ceramic structure, heating and chemical treating the porous preform, infiltrating with monomer and then curing. The three factors that determined the mechanical properties of alumina-polymer composites were the type of polymer used, the method of silane treatments, and the type of bond between particles in the porous preforms. Without the use of silane coupling agents, the composites were measured to have a lower strength. The composite with a more "flexible" porous alumina network had a greater ability to plastically dissipate the energy of propagating cracks. However, the aggressive nature of the alumina particles on opposing enamel requires that these alumina-polymer composites have a wear compatible coating for practical application. A route to dense bioactive apatite wollastonite glass ceramics (AWGC)-polymer composites was developed. The problems associated with glass dissolution into the aqueous medium for slip casting were overcome with the use of silane. The role of heating rate and development of ceramic compact microstructure on composite properties was explored. In general, if isothermal heating was not applied, decreasing heating rate increased glass crystallinity and particle-particle fusion, but decreased pore volume. Also composite strength and fracture toughness decreased while modulus and hardness increased with decreasing heating rate. If isothermal heating was applied, glass crystallinity, pore content, and composite mechanical properties showed relatively little change regardless of the initial heating rate. The potential of AWGC-polymer composites for dental and implant applications was explored

  18. Hydrogeophysical characterization of subsurface processes and properties in the critical zone

    NASA Astrophysics Data System (ADS)

    Vereecken, H.; Huisman, J. A.; Altdorf, D.; von Hebel, C.; Gueting, N.; Klotzsche, A.; Van Der Kruk, J.

    2015-12-01

    Hydrogeophysical methods are ideally suited to characterize subsurface hydrologic structures and processes within the critical zone. Recent improvements in the acquisition and inversion of Ground Penetrating Radar (GPR) and ElectroMagnetic Induction (EMI) data now enable to characterize the subsurface in terms of spatially distributed information on soil and hydrologic properties, and to monitor hydrological processes using time-lapse measurements. We will illustrate these new developments by presenting three example cases. The first case illustrates the potential of using GPR full-waveform inversion techniques to obtain detailed information on subsurface porosity. For this purpose, we used cross-borehole GPR measurements along a series of longitudinal and transversal transects at the test site Krauthausen. The obtained information is key for modelling flow and solute transport because the high resolution of the GPR inversion results allows to study the effect of hydraulic connectivity on solute transport. In the following two cases, we illustrate the potential of multi-receiver electromagnetic induction (EMI) sensors that enable the imaging of the soil at different depths. The second case deals with the mapping of peat land properties at the field scale. We used multi-coil offset EMI measurements to provide spatial estimates of SOC content, bulk density, and SOC stock. Together with laser scanning elevation and soil core reference data, regression equations were built predicting SOC content, bulk density, and SOC stocks. EMI-derived explanatory variables were shown to strongly determine the prediction quality of the regression equations. In the last example, we investigated the origin of observed leaf area index (LAI) patterns that indicate crop performance. Using multi-coil offset EMI, we obtained a moderate to excellent spatial consistency of ECa and LAI patterns. It was concluded from these EMI measurements that improved crop performance was related to a higher

  19. The role of silver in the processing and properties of Bi-2212

    SciTech Connect

    Lang, T.; Heeb, B.; Buhl, D.

    1994-12-31

    The influence of the silver content and the oxygen partial pressure on the solidus temperature and the weight loss during melting of Bi{sub 2}Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub x} has been examined by means of DTA and TGA. By decreasing the oxygen partial pressure the solidus is lowered (e.g. {triangle}T=59{degrees}C by decreasing pO{sub 2} from 1 atm to 0.001 atm) and the weight loss is increased. The addition of silver causes two effects: (a) the solidus is further decreased (e.g. 2wt% Ag lower T{sub solidus} by up to 25{degrees}C, depending on the oxygen partial pressure), (b) the weight loss during melting is reduced. Thick films (10-20 {mu}m in thickness) with 0 and 5 wt% silver and bulk samples with 0 and 2.7 wt% silver were melt processed in flowing oxygen on a silver substrate in the DTA, allowing the observation of the melting process and a good temperature control. The critical current densities are vigorously dependent on the maximum processing temperature. The highest j{sub c} in thick films (8000 A/cm{sup 2} at 77 K, O T) was reached by melting 7{degrees}C above the solidus temperature. The silver addition shows no significant effect on the processing parameters or the superconducting properties. The highest j{sub c} for bulk samples (1 mm in thickness) was obtained by partial melting at 900{degrees}C or 880{degrees}C, depending on the silver content of the powder (0 or 2.7 wt%). The j{sub c} of the samples is slightly enhanced from 1800 A/cm{sup 2} (at 77 K, O T) to 2000 A/cm{sup 2} by the silver addition. To be able to reach at least 80% of the maximum critical current density, the temperature has to be controlled in a window of 5{degrees}C for thick films and 17{degrees}C for bulk samples.

  20. Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures

    SciTech Connect

    Simunovic, S

    2003-09-23

    The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of UltraLight Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. This report is organized into three main sections. The first section describes the results of the computational analysis of ULSAB crash simulations that were performed using advanced material modeling techniques. The effects of strain-rate sensitivity on a high strength steel (HSS) intensive vehicle were analyzed. Frontal and frontal offset crash scenarios were used in a finite element parametric study of the ULSAB body structure. Comparisons are made between the crash results using the piece-wise-linear isotropic plasticity strain-rate dependent material model, and the isotropic plasticity material model based on quasi-static properties. The simulation results show the importance of advanced material modeling techniques for vehicle crash simulations due to strain-rate sensitivity and rapid hardening characteristics of advanced high strength steels. Material substitution was investigated for the main frontal crush structure using the material of similar yield stress a significantly different strain-rate and hardening characteristics. The objective of the research presented in Section 2 was to assess the influence of stamping process on crash response of ULSAB vehicle. Considered forming effects included thickness variations and plastic strain hardening imparted in the part forming process. The as-formed thickness and plastic strain for front crash parts were used as input data for vehicle crash analysis. Differences in structural performance between crash models with and without forming data were analyzed in order to determine the effects and feasibility of

  1. Property.

    ERIC Educational Resources Information Center

    Goldblatt, Steven M.; Piele, Philip K.

    This chapter reviews 1982 cases related to school property. Cases involving citizen efforts to overturn school board decisions to close schools dominate the property chapter, and courts continue to uphold school board authority to close schools, transfer students, and sell or lease the buildings. Ten cases involving detachment and attachment of…

  2. Property.

    ERIC Educational Resources Information Center

    Bickel, Robert D.; Zeller, Trisha A.

    A number of cases related to property issues involving institutions of higher education are examined in this chapter. Cases discussed touch on such topics as funding for property and equipment acquisition; opposition to building construction or demolition; zoning issues; building construction and equipment contracts; and lease agreements. Current…

  3. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Johnson, Margaret M.

    This chapter deals with 1981 cases involving disputes over property. Cases involving the detachment and attachment of land continue to dominate the property chapter with 11 cases reported, the same number summarized in last year's chapter. One case involving school board referenda raised the interesting question of whether or not a state could…

  4. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Chapter 7 of a book on school law, this chapter deals with 1979 cases involving disputes over property. Cases involving taxpayer attempts to prevent the construction of school buildings dominate this year's property chapter, as they did last year's. Yet, paradoxically, there is also a significant increase in cases in which taxpayers tried to…

  5. Fault zone hydrogeologic properties and processes revealed by borehole temperature monitoring

    NASA Astrophysics Data System (ADS)

    Fulton, P. M.; Brodsky, E. E.

    2015-12-01

    High-resolution borehole temperature monitoring can provide valuable insight into the hydrogeologic structure of fault zones and transient processes that affect fault zone stability. Here we report on results from a subseafloor temperature observatory within the Japan Trench plate boundary fault. In our efforts to interpret this unusual dataset, we have developed several new methods for probing hydrogeologic properties and processes. We illustrate how spatial variations in the thermal recovery of the borehole after drilling and other spectral characteristics provide a measure of the subsurface permeability architecture. More permeable zones allow for greater infiltration of cool drilling fluids, are more greatly thermally disturbed, and take longer to recover. The results from the JFAST (Japan Trench Fast Drilling Project) observatory are consistent with geophysical logs, core data, and other hydrologic observations and suggest a permeable damage zone consisting of steeply dipping faults and fractures overlays a low-permeability clay-rich plate boundary fault. Using high-resolution time series data, we have also developed methods to map out when and where fluid advection occurs in the subsurface over time. In the JFAST data, these techniques reveal dozens of transient earthquake-driven fluid pulses that are spatially correlated and consistently located around inferred permeable areas of the fault damage zone. These observations are suspected to reflect transient fluid flow driven by pore pressure changes in response to dynamic and/or static stresses associated with nearby earthquakes. This newly recognized hydrologic phenomenon has implications for understanding subduction zone heat and chemical transport as well as the redistribution of pore fluid pressure which influences fault stability and can trigger other earthquakes.

  6. Processing effects on physicochemical properties of creams formulated with modified milk fat.

    PubMed

    Bolling, J C; Duncan, S E; Eigel, W N; Waterman, K M

    2005-04-01

    Type of thermal process [high temperature, short time pasteurization (HTST) or ultra-high temperature pasteurization (UHT)] and homogenization sequence (before or after pasteurization) were examined for influence on the physicochemical properties of natural cream (20% milk fat) and creams formulated with 20% low-melt, fractionated butteroil emulsified with skim milk, or buttermilk and butter-derived aqueous phase. Homogenization sequence influenced physicochemical makeup of the creams. Creams homogenized before pasteurization contained more milk fat surface material, higher phospholipid levels, and less protein at the milk fat interface than creams homogenized after pasteurization. Phosphodiesterase I activity was higher (relative to protein on lipid globule surface) when cream was homogenized before pasteurization. Creams formulated with skim milk and modified milk fat had relatively more phospholipid adsorbed at the milk fat interface. Ultra-high-temperature-pasteurized natural and reformulated creams were higher in viscosity at all shear rates investigated compared with HTST-pasteurized creams. High-temperature, short time-pasteurized natural cream was more viscous than HTST-pasteurized reformulated creams at most shear rates investigated. High-temperature, short time-pasteurized creams had better emulsion stability than UHT-pasteurized creams. Cream formulated with buttermilk had creaming stability most comparable to natural cream, and cream formulated with skim milk and modified butteroil was least stable to creaming. Most creams feathered in a pH range of 5.00 to 5.20, indicating that they were moderately stable to slightly unstable emulsions. All processing sequences yielded creams within sensory specifications with the exception of treatments homogenized before UHT pasteurization and skim milk formulations homogenized after UHT pasteurization.

  7. Modelling properties and understanding processes across different spatial scales within the critical zone through environmental correlation.

    NASA Astrophysics Data System (ADS)

    Wilford, J.; de Caritat, P.

    2015-12-01

    An environmental correlation approach establishes predictive relationships between the measured properties of the critical zone with a comprehensive suite of environmental covariates. The environmental covariates ideally cover or represent proxies for the factors that control soil/regolith formation. These factors include parent material, time, climate, biological and landscape processes. The corresponding proxies include lithology maps, satellite imagery (e.g. Landsat TM, MODIS), geophysical imagery (e.g. magnetics, radiometrics and gravity), terrain attributes (e.g. slope, wetness index) and climate surfaces (e.g. annual rainfall). Using this approach we model and spatially predict two important components of the critical zone including: depth of weathering and geochemistry. Predictive maps of these attributes are based on nested piecewise linear tree models. Models of critical zone thickness and geochemistry (including elements, element ratios and chemical indices) have been developed at the catchment scale and at the continental scale. Thickness and weathering intensity (determined through geochemical weathering indices) of the critical zone profoundly affects groundwater interactions, subsoil water movement, water storage and nutrient availability. In highly weathered Australian landscapes we commonly see geochemical convergence typified by the abundance of end-member weathering phases such as quartz, clays and oxyhydroxides. The modelling can be used to map elements of economic importance or those which are potentially hazardous to human health. Modelling and integration of environmental covariates helps to facilitate our understanding of the processes occurring within the lithosphere, hydrosphere, atmosphere and biosphere that control the nature and distribution of the weathered materials. It also provides an approach to integrate and model the vast amount of spatial information we have from ground, airborne and satellite remote sensing.

  8. Effects of the freezing and thawing process on biomechanical properties of the human skull.

    PubMed

    Torimitsu, Suguru; Nishida, Yoshifumi; Takano, Tachio; Koizumi, Yoshinori; Hayakawa, Mutsumi; Yajima, Daisuke; Inokuchi, Go; Makino, Yohsuke; Motomura, Ayumi; Chiba, Fumiko; Iwase, Hirotaro

    2014-03-01

    The aim of this study was to determine if biomechanical investigations of skull samples are reliable after skulls have been subjected to a freezing and thawing process. The skulls were obtained from 105 Japanese cadavers (66 males, 39 females) of known age that were autopsied in our department between October 2012 and June 2013. We obtained bone specimens from eight sites (four bilaterally symmetrical pairs) of each skull and measured the mass of each specimen. They were then classified into three groups (A, B, C) based on the duration of freezing of the experimental samples. The left-side samples were subjected to frozen storage (experimental group). The corresponding right-side samples were their controls. Bending tests were performed on the controls immediately after they were obtained. The experimental samples were preserved by refrigeration at -20 °C for 1 day (group A), 1 month (group B), or 3 months (group C). Following refrigeration, these samples were placed at 37 °C to thaw for 1 h and then were subjected to bending tests using a three-point-bending apparatus attached to a Handy force gauge. The device recorded the fracture load automatically when the specimen fractured. Statistical analyses revealed that there were no significant differences in sample fracture loads between the frozen preserved/thawed samples and the unfrozen controls for each of the cryopreservation intervals. We eliminated any possible sample mass bias by using controls from the same skull in each case. The results suggest that the freezing/thawing process has little effect on the mechanical properties of human skulls. Thus, frozen storage for up to 3 months is a good method for preserving human skulls.

  9. Irradiating of Bulk Soybeans: Influence on Their Functional and Sensory Properties for Soyfood Processing

    NASA Technical Reports Server (NTRS)

    Chia, Chiew-Ling; Wilson, Lester A.; Boylston, Terri; Perchonok, Michele; French, Stephen

    2006-01-01

    Soybeans were chosen for lunar and planetary missions, where soybeans will be supplied in bulk or grown locally, due to their nutritive value and ability to produce oil and protein for further food applications. However, soybeans must be processed into foods prior to consumption. Radiation that soybeans would be exposed to during bulk storage prior to and during a Mars mission may influence their germination and functional properties. The influence of radiation includes the affect of surface pasteurization to ensure the astronauts safety from food-borne illnesses (HACCP, CCP), and the affect of the amount of radiation the soybeans receive during a Mars mission. Decreases in the amount of natural antioxidants free radical formation, and oxidation-induced changes in the soybean will influence the nutritional value, texture, color, and aroma of soyfoods. The objective of this study was to determine the influence of pasteurization and sterilization surface radiation on whole soybeans using gamma and electron beam radiation. The influence of 0, 1, 5, 10, and 30kGy on microbial load, germination rate, ease of processing, and quality of soymilk and tofu were determined. Surface radiation of whole dry soybeans using electron beam or gamma rays from 1-30kGy did provide microbial safety for the astronauts. However, the lower dose levels had surviving yeasts and molds. These doses caused oxidative changes that resulted in soymilk and tofu with rancid aromas. GC-MS of the aroma compounds using SPME Headspace confirmed the presence of lipid oxidation compounds. Soybean germination ability was reduced as radiation dosage increased. While lower doses may reduce these problems, the ability to insure microbial safety of bulk soybeans will be lost. Counter measures could include vacuum packaging, nitrogen flushing, added antioxidants, and radiating under freezing conditions. Doses below 1kGy need to be investigated further to determine the influence of the radiation encountered

  10. Effects of Extrusion-Shear Process Conditions on the Microstructures and Mechanical Properties of AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Hu, H. J.; Li, Y. Y.; Wang, X.; Zhang, D. F.; Yang, M. B.

    2016-11-01

    In this paper, the effects of extrusion-shear (ES) on the microstructures and mechanical properties of AZ31 magnesium alloy has been studied, which has been achieved by conducting a lot of experiments and tests, including ES process, direct extrusion with different billet temperatures, microstructure analysis, hardness test, tensile & compression tests. The results show that the ES-processed rods has higher strengths (yield strength and tensile strength) than the direct extrusion ones with the same billet temperature, which contributed to their lower averaged grain size obtained from microstructure analysis according to Hall-Petch relation. Besides, the hardness of ES-processed AZ31 magnesium alloy decreases with the increasing of billet temperature. By comparing the two processes, it can be seen that the ES process could refine the microstructure and improve the mechanical properties of magnesium alloy.

  11. Effect of friction stir processing on the fatigue properties of a Zr-modified 2014 aluminium alloy

    SciTech Connect

    Cavaliere, P. . E-mail: pasquale.cavaliere@unile.it

    2006-08-15

    The fatigue properties of a Zr-modified 2014 aluminium alloy resulting from friction stir processing (FSP) were analysed in the present study. The sheets were processed parallel to the extrusion direction; the tensile mechanical properties were evaluated at room temperature in the longitudinal direction with respect to the processing one in order to observe the differences from the parent material as a function of the strong grain refinement due to the friction stir process. The fatigue endurance (S-N) curve of the FSP material was obtained by using a resonant electro-mechanical testing machine under constant loading control up to 250 Hz with sine wave loading. The cyclic fatigue tests were conducted in the axial total stress-amplitude control mode with R = {sigma} {sub min}/{sigma} {sub max} = 0.1. The microstructure resulting from the FSW process was studied by employing optical and scanning electron microscopy.

  12. Effect of the Metal Transport on the Mechanical Properties of Al-2Si Alloys Processed through Friction Stir Welding Processes

    NASA Astrophysics Data System (ADS)

    Shailesh Rao, A.; Naik, Yuvaraja

    2017-03-01

    In this study, Al-2Si alloys were joined using friction stir welding with various process parameters. The process parameters considered here were rotational speeds from 600 to 1200 rpm, feed rate from 50 to 150 mm/min with three equal increments. In this study, the mushy state metal movements during the processes are discussed. The experimental observation and results indicate that the flaw formations, surface roughness of the weld, and hardness value depend on the metal movement and are explained in this study. The microstructure of the weld zone was studied finally.

  13. PROCESSING, MICROSTRUCTURE AND MECHANICAL PROPERTY CORRELATION IN Al-B4C SURFACE COMPOSITE PRODUCED VIA FRICTION STIR PROCESSING

    SciTech Connect

    Komarasamy, Mageshwari; Mishra, Rajiv S.; Baumann, John A.; Grant, Glenn J.; Hovanski, Yuri

    2013-01-29

    Friction stir processing (FSP) was employed to prepare surface composites (SC) composed of B4C particles in 5024 Al matrix. The processing parameters, such as hole pattern and geometry,and the number of FSP passes, were optimized to obtain uniform powder distribution. The micrographs revealed a homogeneous distribution of the particles with good interfacial bonding. The hardness of the composite was uniform across the processed region which again indicates the uniformity of powder distribution. The modulus of the surface composite was measured using strain gage and showed a significant improvement. This improvement in modulus lies in the load sharing capability from the soft matrix to the hard particles.

  14. Effect of marination in gravy on the radio frequency and microwave processing properties of beef.

    PubMed

    Basaran-Akgul, Nese; Rasco, Barbara A

    2015-02-01

    Dielectric properties (the dielectric constant (ε') and the dielectric loss factor (ε″)) and the penetration depth of raw eye of round beef Semitendinosus muscle, raw beef marinated in gravy, raw beef cooked in gravy, and gravy alone were determined as a function of the temperature (20-130 °C) and frequency (27-1,800 MHz). Both ε' and ε″ values increased as the temperature increased at low frequencies (27 and 40 MHz). At high frequencies (915 and 1,800 MHz), ε' showed a 50 % decrease while ε″ increased nearly three fold with increasing temperature in the range from 20 to 130 °C. ε' increased gradually while ε″ increased five fold when the temperature increased from 20 to 130 °C. Both ε' and ε″ of all samples decreased with increase in frequency. Marinating the beef in gravy dramatically increased the ε″ values, particularly at the lower frequencies. Power penetration depth of all samples decreased with increase temperature and frequency. These results are expected to provide useful data for modeling dielectric heating processes of marinated muscle food.

  15. Effect of Thermomechanical Processing on the Microstructure and Properties of a Cu-Fe-P Alloy

    NASA Astrophysics Data System (ADS)

    Dong, Qiyi; Shen, Leinuo; Cao, Feng; Jia, Yanlin; Liao, Kaiju; Wang, Mingpu

    2015-04-01

    A Cu-0.7Fe-0.15P (wt.%) alloy was designed, and its comprehensive properties, especially electrical conductivity and temper-softening resistance of the designed alloy, were higher than those of traditional Cu-Fe-P alloys. The microstructure of this alloy was investigated with optical microscopy, scanning electron microscopy, and transmission electron microscopy. The particle of secondary phase was confirmed to be Fe2P with x-ray spectroscopy and digital diffractogram. By virtue of precipitation hardening and work hardening, the tensile strength and electrical conductivity of Cu-0.7Fe-0.15P alloy were 498 MPa and 62% IACS, respectively. The electrical conductivity of this alloy can be up to 92% IACS due to the complete precipitation of Fe2P. After repeating the cold rolling and aging process for three times, the tensile strength, elongation, and conductivity of this alloy were 467 MPa, 22%, and 78% IACS, respectively. Due to the low driving force of recrystallization and the pinning effect of fine dispersed Fe2P, the alloy with low deformation rate showed excellent softening resistance. The designed alloy can be used as a high-strength, high-electrical-conductivity lead-frame alloy.

  16. Investigation of the effect of contaminations and cleaning processes on the surface properties of brazing surfaces

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Wiesner, S.

    2017-03-01

    The quality of brazed joints is determined by different factors such as the atmosphere and the parameters during brazing as well as the condition of the brazing surfaces. Residues of lubricants used during machining of the components and the subsequent cleaning processes can contaminate the faying surfaces and can hence influence the flow ability of the molten filler metals. Besides their influence on the filler metal flow, the residues can result in the formation of carbonic phases in the joint leading to a possible reduction of the corrosion resistance and the mechanical properties. The first step of the current study with the aim of avoiding these defects is to identify the influence of critical contaminations and cleaning methods on the quality of the brazed joints. In a first step, contaminations on AISI304 and Inconel alloy 625 due to different cooling lubricants and the effect of several cleaning methods, in particular plasma cleaning, have been investigated. Information about the surface energy of contaminated and cleaned surfaces was gained by measuring contact angle of testing fluids. Additionally, the lubricants and the resulting contamination products have been analyzed considering the influence of a heat treatment.

  17. 3D printed glass: surface finish and bulk properties as a function of the printing process

    NASA Astrophysics Data System (ADS)

    Klein, Susanne; Avery, Michael P.; Richardson, Robert; Bartlett, Paul; Frei, Regina; Simske, Steven

    2015-03-01

    It is impossible to print glass directly from a melt, layer by layer. Glass is not only very sensitive to temperature gradients between different layers but also to the cooling process. To achieve a glass state the melt, has to be cooled rapidly to avoid crystallization of the material and then annealed to remove cooling induced stress. In 3D-printing of glass the objects are shaped at room temperature and then fired. The material properties of the final objects are crucially dependent on the frit size of the glass powder used during shaping, the chemical formula of the binder and the firing procedure. For frit sizes below 250 μm, we seem to find a constant volume of pores of less than 5%. Decreasing frit size leads to an increase in the number of pores which then leads to an increase of opacity. The two different binders, 2- hydroxyethyl cellulose and carboxymethylcellulose sodium salt, generate very different porosities. The porosity of samples with 2-hydroxyethyl cellulose is similar to frit-only samples, whereas carboxymethylcellulose sodium salt creates a glass foam. The surface finish is determined by the material the glass comes into contact with during firing.

  18. Processing and Properties of Fiber Reinforced Polymeric Matrix Composites. Part 2; Processing Robustness of IM7/PETI Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung

    1996-01-01

    The processability of a phenylethynyl terminated imide (PETI) resin matrix composite was investigated. Unidirectional prepregs were made by coating an N-methylpyrrolidone solution of the amide acid oligomer onto unsized IM7. Two batches of prepregs were used: one was made by NASA in-house, and the other was from an industrial source. The composite processing robustness was investigated with respect to the effect of B-staging conditions, the prepreg shelf life, and the optimal processing window. Rheological measurements indicated that PETI's processability was only slightly affected over a wide range of B-staging temperatures (from 250 C to 300 C). The open hole compression (OHC) strength values were statistically indistinguishable among specimens consolidated using various B-staging conditions. Prepreg rheology and OHC strengths were also found not to be affected by prolonged (i.e., up to 60 days) ambient storage. An optimal processing window was established using response surface methodology. It was found that IM7/PETI composite is more sensitive to the consolidation temperature than to the consolidation pressure. A good consolidation was achievable at 371 C/100 Psi, which yielded an OHC strength of 62 Ksi at room temperature. However, processability declined dramatically at temperatures below 350 C.

  19. Processing and mechanical properties of silicon nitride/silicon carbide ceramic nanocomposites derived from polymer precursors

    NASA Astrophysics Data System (ADS)

    Gasch, Matthew Jeremy

    Creep deformation of silicon nitride and silicon carbide ceramics is dominated by a solution-precipitation process through the glassy interface phase at grain boundary regions, which is formed by the reaction of oxide additives with the silicon oxide surface layer of the ceramic powder particles during liquid phase sintering. The ultimate approach to increase the creep resistance of these materials is to decrease the oxide content at the grain boundaries, rendering the solution-precipitation process non-effective. This research presents a new method of enhancing the creep properties of silicon nitride/silicon carbide composites by forming micro-nano and nano-nano microstructures during sintering. Starting from amorphous Si-C-N powders of micrometric size particles, powders were consolidated in three ways: (1) Consolidation of pyrolyzed powders without additives, (2) Electric Field Assisted Sintering (EFAS) of pyrolyzed powders with and without additives and (3) High pressure sintering. In all three cases, nanocomposites with varied grain size were achieved. High temperature mechanical creep testing was performed on the samples sintered by EFAS. Creep rates ranged from 1 x 10-8/s to 1 x 10-11/s depending on method in which powders were prepared and total oxide additive amount. For samples with high oxide contents the stress exponent was found to be n ˜ 2 with an activation energy of Q ˜ 600kJ/mol*K, indicating the typical solution precipitation process of deformation. But for the nano-nano composites sintered with little to none oxide additive, the stress exponent was found to be n ˜ 1 with and activation energy of Q ˜ 200kJ/mol*K, hinting at a diffusion controlled mechanism of creep deformation. For the nano-nano composites sintered without oxide additives, oxygen was found in the microstructure. However, oxygen contamination was found to distribute at grain boundary regions especially triple junctions. It is suggested that this highly dispersed distribution of

  20. Processing-structure-property relationships of carbon nanotube and nanoplatelet enabled piezoresistive sensors

    NASA Astrophysics Data System (ADS)

    Luo, Sida

    Individual carbon nanotubes (CNTs) possess excellent piezoresistive performance, which is manifested by the significant electrical resistance change when subject to mechanical deformation. In comparison to individual CNTs, the CNT thin films, formed by a random assembly of individual tubes or bundles, show much lower piezoresistive sensitivity. Given the progress made to date in developing CNT ensemble based-piezoresistive sensors, the related piezoresistive mechanism(s) are still not well understood. The crucial step to obtain a better understanding of this issue is to study the effects of CNT structure in the dispersion on the piezoresistivity of CNT ensemble based-piezoresistive sensors. To reach this goal, my Ph.D. research first focuses on establishing the processing-structure-property relationship of SWCNT thin film piezoresistive sensors. The key accomplishment contains: 1) developing the combined preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS) method to quantitatively characterized SWCNT particle size in dispersions under various sonication conditions; 2) designing combined ultrasonication and microfluidization processing protocol for high throughput and large-scale production of high quality SWCNT dispersions; 3) fabricating varied SWCNT thin film piezoresistive sensors through spray coating technique and immersion-drying post-treatment; and 4) investigating the effect of microstructures of SWCNTs on piezoresistivity of SWCNT thin film sensors. This experimental methodology for quantitative and systematic investigation of the processing-structure-property relationships provides a means for the performance optimization of CNT ensemble based piezoresistive sensors. As a start to understand the piezoresistive mechanism, the second focus of my Ph.D. research is studying charge transport behaviors in SWCNT thin films. It was found that the temperature-dependent sheet resistance of SWCNT thin films could be explained by a 3D variable

  1. Effect of thermal implying during ageing process of nanorods growth on the properties of zinc oxide nanorod arrays

    NASA Astrophysics Data System (ADS)

    Ismail, A. S.; Mamat, M. H.; Malek, M. F.; Abdullah, M. A. R.; Sin, M. D.; Rusop, M.

    2016-07-01

    Undoped and Sn-doped Zinc oxide (ZnO) nanostructures have been fabricated using a simple sol-gel immersion method at 95°C of growth temperature. Thermal sourced by hot plate stirrer was supplied to the solution during ageing process of nanorods growth. The results showed significant decrement in the quality of layer produced after the immersion process where the conductivity and porosity of the samples reduced significantly due to the thermal appliance. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM) electrical properties has been characterized using current voltage (I-V) measurement.

  2. Processing and properties of high-purity, fine-grain-size depleted-uranium, deep-drawn shapes

    SciTech Connect

    Jackson, R J; Lundberg, M R; Bruchey, W L

    1980-10-01

    Unalloyed uranium is a candidate material for shaped charge liners used in conventional ordinance applications. For test purposes, it was decided that a high-grade uranium material with good toughness should be used. This report describes a process for producing a high-purity (less than 500 ppM total impurities) wrought material consisting of a recrystallized, equiaxed grain structure with a 10 micron (ASTM-8) average grain size. The fabrication process is discussed in detail. In all, six material conditions having a wide range of mechanical and structural properties were investigated. The tensile, hardness, and microstructural properties of these six material conditions are reported in detail.

  3. Martian subsurface properties and crater formation processes inferred from fresh impact crater geometries

    NASA Astrophysics Data System (ADS)

    Stewart, Sarah T.; Valiant, Gregory J.

    2006-10-01

    The geometry of simple impact craters reflects the properties of the target materials, and the diverse range of fluidized morphologies observed in Martian ejecta blankets are controlled by the near-surface composition and the climate at the time of impact. Using the Mars Orbiter Laser Altimeter (MOLA) data set, quantitative information about the strength of the upper crust and the dynamics of Martian ejecta blankets may be derived from crater geometry measurements. Here, we present the results from geometrical measurements of fresh craters 3-50 km in rim diameter in selected highland (Lunae and Solis Plana) and lowland (Acidalia, Isidis, and Utopia Planitiae) terrains. We find large, resolved differences between the geometrical properties of the freshest highland and lowland craters. Simple lowland craters are 1.5-2.0 times deeper (≥5σo difference) with >50% larger cavities (≥2σo) compared to highland craters of the same diameter. Rim heights and the volume of material above the preimpact surface are slightly greater in the lowlands over most of the size range studied. The different shapes of simple highland and lowland craters indicate that the upper ˜6.5 km of the lowland study regions are significantly stronger than the upper crust of the highland plateaus. Lowland craters collapse to final volumes of 45-70% of their transient cavity volumes, while highland craters preserve only 25-50%. The effective yield strength of the upper crust in the lowland regions falls in the range of competent rock, approximately 9-12 MPa, and the highland plateaus may be weaker by a factor of 2 or more, consistent with heavily fractured Noachian layered deposits. The measured volumes of continuous ejecta blankets and uplifted surface materials exceed the predictions from standard crater scaling relationships and Maxwell's Z model of crater excavation by a factor of 3. The excess volume of fluidized ejecta blankets on Mars cannot be explained by concentration of ejecta through

  4. Processing and Properties of Metallic Foams for Solid-Oxide Fuel Cell Interconnects

    NASA Astrophysics Data System (ADS)

    Scott, Justin Aaron

    Metallic foams possess a unique array of mechanical, thermal, and acoustic properties that have led to an increasing portfolio of potential applications. One of the newest additions includes solid-oxide fuel cells (SOFCs), where commercialization hinges on the development of improved materials and designs that can withstand the severe operational requirements of high temperature (up to 850 °C) and long service lifetimes (>10,000 hours). These demands place strict design limitations on the interconnect, which serves as a current path and fluid barrier between fuel and oxidant gases in the SOFC stack. Materials with excellent oxidation and creep resistance are sought. Chromia-forming Iron and Nickel-based alloy families have shown the most promise in preliminary studies. While a wealth of knowledge is available on these alloys as dense interconnects, limited research has also explored the option of porous metallic interconnects that offer the potential for cheaper, lightweight, and more mechanically robust stacks. This thesis aims to provide a more thorough examination of porous metallic interconnect construction beginning with refinement of the place-holder replication techniques to create fully-interconnected, open porosity in a E-Brite (Fe-26Cr-1Mo, wt.%) and J5 (Ni-22.5Mo-12.5Cr-1Ti-0.5Mn-0.1Al-0.1Y, wt.%) alloy. Mechanical response of the E-Brite was examined at room temperature and found good agreement with existing, beam-based models for stiffness and yield strength. High temperature mechanical deformation was also recorded and a creep strengthening effect due to the formation of oxide was characterized. Electrochemical properties of porous E-Brite including the activation energy of oxide formation and area-specific resistance were also determined and found to be comparable to existing literature on bulk response. Finite element modeling (FEM) of the creep of unoxidized and oxidized E-Brite was also performed and successfully captured the qualitative behavior

  5. Processing, Microstructure, and Residual Stress Effects on Strength and Fatigue Crack Growth Properties in Friction Stir Welding: A Review

    NASA Astrophysics Data System (ADS)

    Biro, Andrew L.; Chenelle, Brendan F.; Lados, Diana A.

    2012-12-01

    The purpose of this review is to provide a comprehensive overview of friction stir welding (FSW), as well as to introduce current research and applications involving this relatively new process. FSW is a new, efficient way of joining metal alloys that are considered unsuitable for welding via conventional fusion joining methods, and is capable of welding dissimilar metals with ease. This process also has the benefit of being solid-state, which mitigates the need for liquid filler metals that are common with conventional fusion welding techniques. This review will examine different facets of the FSW process, exploring the resulting static and dynamic properties and factors that influence these properties including weld zone boundaries, grain refinement, residual stress, and addition of reinforcing particles. Highlights of current research in this area and applications of this process in various industries will also be presented and discussed.

  6. 41 CFR 102-36.125 - How do we process a Standard Form 122 (SF 122), Transfer Order Excess Personal Property, through...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false How do we process a Standard Form 122 (SF 122), Transfer Order Excess Personal Property, through GSA? 102-36.125 Section 102-36.125 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION...

  7. Properties of the Sodium Naproxen-Lactose-Tetrahydrate Co-Crystal upon Processing and Storage.

    PubMed

    Sovago, Ioana; Wang, Wenbo; Qiu, Danwen; Raijada, Dhara; Rantanen, Jukka; Grohganz, Holger; Rades, Thomas; Bond, Andrew D; Löbmann, Korbinian

    2016-04-19

    Co-crystals and co-amorphous systems are two strategies to improve the physical properties of an active pharmaceutical ingredient and, thus, have recently gained considerable interest both in academia and the pharmaceutical industry. In this study, the behavior of the recently identified sodium naproxen-lactose-tetrahydrate co-crystal and the co-amorphous mixture of sodium, naproxen, and lactose was investigated. The structure of the co-crystal is described using single-crystal X-ray diffraction. The structural analysis revealed a monoclinic lattice, space group P21, with the asymmetric unit containing one molecule of lactose, one of naproxen, sodium, and four water molecules. Upon heating, it was observed that the co-crystal transforms into a co-amorphous system due to the loss of its crystalline bound water. Dehydration and co-amorphization were studied using synchrotron X-ray radiation and thermogravimetric analysis (TGA). Subsequently, different processing techniques (ball milling, spray drying, and dehydration) were used to prepare the co-amorphous mixture of sodium, naproxen, and lactose. X-ray powder diffraction (XRPD) revealed the amorphous nature of the mixtures after preparation. Differential scanning calorimetry (DSC) analysis showed that the blends were single-phase co-amorphous systems as indicated by a single glass transition temperature. The samples were subsequently tested for physical stability under dry (silica gel at 25 and 40 °C) and humid conditions (25 °C/75% RH). The co-amorphous samples stored at 25 °C/75% RH quickly recrystallized into the co-crystalline state. On the other hand, the samples stored under dry conditions remained physically stable after five months of storage, except the ball milled sample stored at 40 °C which showed signs of recrystallization. Under these dry conditions, however, the ball-milled co-amorphous blend crystallized into the individual crystalline components.

  8. Effect of processing temperature on the properties of Fe-Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Kathriarachchi, Vindu; Leventouri, Theodora; Rondinone, Adam; Sorge, Korey

    2015-03-01

    Multi-substituted Hydroxyapatite (HAp), Ca5(PO4)3OH, is the main mineral phase in physiological apatite. Fe is a minor substitution element in bone and enamel substituting Ca in the HAp structure. Crystal structure, magnetic and microstructure properties of Ca5-xFex(PO4)3OH depend on processing parameters. We present results from our research on the Ca5-xFex(PO4)3OH system (x = 0.0, 0.05, 0.1, 0.2 and 0.3) prepared at 37° C, and 80° C. Hydroxyapatite single-phase was detected for x <0.1 in both sets of samples, while hematite and/or maghemite develops starting at x = 0.1. Rietveld refinements of XRD and NPD patterns show that the a and c lattice constants decrease with increasing Fe concentration for both sets of samples. Pure HAp is diamagnetic but as x increases, Fe-HAp transitions from paramagnetic to weak ferromagnetic behavior. TEM images show spherical particles in samples prepared at 37° C, and elongated particles in samples prepared at 80° C. XRF studies confirm the iron substitution and show that the Ca/P stoichiometric ratio of 1.67 decreases with increasing the Fe concentration. Further, the Fe/Ca +Fe atomic ratios of samples prepared at 37° C are greater than those prepared at 80° C. TEM and XRF data were collected at the Center for Nanophase Materials Sciences which is a DOE Office of Science User Facility. NPD data were collected at the SNS of the ORNL.

  9. Influence of DE-value on the physicochemical properties of maltodextrin for melt extrusion processes.

    PubMed

    Castro, Natalia; Durrieu, Vanessa; Raynaud, Christine; Rouilly, Antoine

    2016-06-25

    In this study, five different types of maltodextrins (DE-2, DE-6, DE-12, DE-17 and DE-19) were characterized for the physico-chemical properties. TGA, DVS and SEC analyses were carried out and additionally apparent melt-viscosity (in a micro-extruder) and the glass transition temperature (analyzed by DMA) of maltodextrin/plasticizer mixtures were also measured in order to evaluate both the effect of plasticizer nature and content and the effect of the DE-value. For this, three plasticizing agents were compared: water, d-sorbitol and glycerin. The adsorption isotherms showed that depending on the DE-value and the relative humidity they were exposed to, different behavior could be obtained. For example, for relative humidities below 60% RH maltodextrin DE-2 was the least hygroscopic. And on the contrary for relative humidities above 75% RH maltodextrin DE-2 was the most hygroscopic. The rheology measurements showed that the viscosity decreased with the increase of the DE-value and with the plasticizer content, as expected. On the contrary, no direct correlation could be established between the DE-value and the glass transition temperature. These results demonstrated that to predict maltodextrins behavior and to better adapt the process conditions, combined analyses are mandatory as the DE-value alone is not sufficient. The most compelling evidence was obtained by size exclusion chromatography, which pointed out that maltodextrins had a bimodal molecular weight distribution composed of high and low molecular weight oligo-saccharides. Indeed, maltodextrins are highly polydisperse materials (i.e. polydispersity index ranging from 5 to 12) and that should be the reason why such distinct behaviors were observed in some of the physico-chemical analyses that were preformed.

  10. Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins

    USGS Publications Warehouse

    O'Reilly, Andrew M.; Wanielista, Martin P.; Chang, Ni-Bin; Harris, Willie G.; Xuan, Zhemin

    2012-01-01

    Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L-1 and decreases in nitrate nitrogen (NO3-–N) from 2.7 mg L-1 to -1, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0–7.8 mg L-1), resulting in NO3-–N of 1.3 to 3.3 mg L-1 in shallow groundwater. Enrichment of d15N and d18O of NO3- combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO3- transport beneath the sandy basin. Soil-extractable NO3-–N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO3- impacts.

  11. Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins.

    PubMed

    O'Reilly, Andrew M; Wanielista, Martin P; Chang, Ni-Bin; Harris, Willie G; Xuan, Zhemin

    2012-01-01

    Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L and decreases in nitrate nitrogen (NO-N) from 2.7 mg L to <0.016 mg L, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0-7.8 mg L), resulting in NO-N of 1.3 to 3.3 mg L in shallow groundwater. Enrichment of δN and δO of NO combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO transport beneath the sandy basin. Soil-extractable NO-N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO impacts.

  12. Processing, properties, and ballistic performance of titanium-aluminum titanium metal-intermetallic laminate (MIL) composites

    NASA Astrophysics Data System (ADS)

    Harach, David John

    2000-10-01

    A systematic investigation into the processing of Ti-Al3Ti metal-intermetallic laminate (MIL) composites from elemental titanium and aluminum foils in open air by a novel one step technique, and subsequent characterization, physical, mechanical and ballistic testing was carried out. Al3Ti is the only intermetallic phase to form, and no oxides or other phases are formed. Composites with Ti volume fractions of ˜0, 14, 20, 35, and 57 percent can be processed consistently, with measured density agreeing well with calculated density. The intermetallic reaction occurs in two parts that are linear with respect to Al3Ti growth with time: oxide controlled diffusion of Al, and the order of magnitude faster chemical reaction that occurs after the oxide layer breaks down and transient liquid phases are formed. A reaction model based on the production of Al3Ti spheroids that are ejected from the Ti reaction surface has been developed, and is titled reactive foil sintering. Quasi-static and dynamic compression tests resulted in maximum yield stresses for the 20Ti composite, and end-confined quasi-static and dynamic compression tests, tension tests, and 3-point bend tests resulted in maximum yield stresses and bending loads for the 35Ti composite. Maximum yield stresses occurred in specimens tested with layers parallel to the load. Arrester orientation R-curve testing was completed for the 14Ti composite under large-scale bridging conditions, with initiation toughness values obtained for 20Ti and 35Ti which developed cracks in the intermetallic layer growing perpendicular to the load axis. Divider orientation R-curves were obtained, with the 20Ti and 35Ti curves closely approaching calculated steady-state toughness values. Ballistics testing of bonded Ti, bonded Ti-Al, 5Ti, 14Ti, 35Ti, 57Ti, and Al3Ti at projectile velocities of 500--700 m/s resulted in the 14Ti and 35Ti having the best ballistic performance based on mass efficiency. Ballistics testing of 14Ti, 20Ti, and 35Ti

  13. Effects of soil structural development on soil hydraulic properties and hydraulic processes in forested hillslopes

    NASA Astrophysics Data System (ADS)

    Hayashi, Y.; Kosugi, K.; Mizuyama, T.

    2010-12-01

    We evaluated the effects of the forest soil on flood and drought mitigation, and decrease of the danger of slope failures. Forest soils usually contain a primary textural pore system, which is determined by solid particle-size distribution and particle arrangements, accompanied by a secondary structural pore system formed by the effects of forest ecosystems. With this background, we investigated the effects of the pore structural development on the unsaturated hydraulic properties and rainwater dynamics on a forested hillslope. The undisturbed soil samples were collected from an entire forested hillslope. The undisturbed soils contain the primary and secondary pore systems, and were set to be as structural developed soils. The water retention curve and saturated hydraulic conductivity of each sample were measured. After that, each undisturbed soil was crushed to break up aggregate structure and packed into core sampler to prepare the structural undeveloped soil. We conducted same measurement of the structural undeveloped soils as those used for the structural developed soils. Generally, compared with the structural undeveloped soils, the structural developed soils had large median pore radius and width of pore size distribution, and large saturated hydraulic conductivity. We conducted 2-dimentional numerical simulations of hydraulic processes on a forested hillslope with the code programmed by Kosugi (2007), using the data sets of the structural developed and undeveloped soils. The peak flow of stream is formed by the direct discharge from the lower end of the slope, and the base flow is formed by the seepage into the bedrock (Kosugi, 2007). Furthermore, slope failure are caused by the positive pore water pressure in the soil layer. Therefore, for evaluating the effect of forest soil on hydraulic processes, we estimated the discharge rate of the lower end of the slope and the rate of the seepage into the bedrock from the soil layer, and the matric pressure head. As

  14. Solution processable semiconductor thin films: Correlation between morphological, structural, optical and charge transport properties

    NASA Astrophysics Data System (ADS)

    Isik, Dilek

    This Ph.D. thesis is a result of multidisciplinary research bringing together fundamental concepts in thin film engineering, materials science, materials processing and characterization, electrochemistry, microfabrication, and device physics. Experiments were conducted by tackling scientific problems in the field of thin films and interfaces, with the aim to correlate the morphology, crystalline structure, electronic structure of thin films with the functional properties of the films and the performances of electronic devices based thereon. Furthermore, novel strategies based on interfacial phenomena at electrolyte/thin film interfaces were explored and exploited to control the electrical conductivity of the thin films. Three main chemical systems were the object of the studies performed during this Ph.D., two types of organic semiconductors (azomethine-based oligomers and polymers and soluble pentacene derivatives) and one metal oxide semiconductor (tungsten trioxide, WO3). To explore the morphological properties of the thin films, atomic force microscopy was employed. The morphological properties were further investigated by hyperspectral fluorescence microscopy and tentatively correlated to the charge transport properties of the films. X-ray diffraction (Grazing incidence XRD, GIXRD) was used to investigate the crystallinity of the film and the effect of the heat treatment on such crystallinity, as well as to understand the molecular arrangement of the organic molecules in the thin film. The charge transport properties of the films were evaluated in thin film transistor configuration. For electrolyte gated thin film transistors, time dependent transient measurements were conducted, in parallel to more conventional transistor characterizations, to explore the specific effects played on the gating by the anion and cation constituting the electrolyte. The capacitances of the electrical double layers at the electrolyte/WO3 interface were obtained from

  15. Control of the Physical and Technical Properties of Water in Technological Processes

    NASA Astrophysics Data System (ADS)

    Klopotov, V. D.; Gorlenko, N. P.; Sarkisov, Yu S.; Kulchenko, A. K.; Klopotov, A. A.

    2016-08-01

    The physical and technical properties of water activated by the electrochemical treatment in a two-chamber electrolizer are investigated. The regularities of changes inthe values of acidity, redox potential, ionic composition, concentration of oxygen, structural organization of catholyte and anolyte are revealed. The possibility of controlling the properties of the liquid for more efficient extraction of polymetallic minerals by flotation is described.

  16. The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 5, Section 4: Processing: Matrices and Composites. Part 1

    DTIC Science & Technology

    1989-10-15

    PROCESSING: Matrices and Composites Partlof2 89 12 21 038 SUMMARY of TABLE OF CONTENTS EXECUTIVE SUMMARY SECTION 1: COATINGS AND INTERFACES Book 1...The first section in Book 1 is concerned with the properties and structure of bimaterial interfaces and the related problem of coating decohesion and...solidification products to provide a basis for microstructural development and alloy design in high temperature intermetallics in titanium and niobium base

  17. Thermomechanical Processing and Ambient Temperature Properties of a 6061 Aluminum 10 Volume Percent Alumina Metal Matrix Composite

    DTIC Science & Technology

    1990-03-01

    Submitted in partial fulfillment of the requirements for the degree of’ MASTER OF SCIENCE IN MECHANICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL March... Mechanical Properties................. 15 3. Effects of Processing on Particle Size...........................16 C. AGE HARDENING STUDY...modulus * density - elevated temperature strength - thermal and electrical conductivities - corrosion and abrasion resistance. Furthermore, mechanical

  18. Caramel as a Model System for Evaluating the Roles of Mechanical Properties and Oral Processing on Sensory Perception of Texture.

    PubMed

    Wagoner, Ty B; Luck, Paige J; Foegeding, E Allen

    2016-03-01

    Food formulation can have a significant impact on texture perception during oral processing. We hypothesized that slight modifications to caramel formulations would significantly alter mechanical and masticatory parameters, which can be used to explain differences in texture perception. A multidisciplinary approach was applied by evaluating relationships among mechanical properties, sensory texture, and oral processing. Caramels were utilized as a highly adhesive and cohesive model system and the formulation was adjusted to generate distinct differences in sensory hardness and adhesiveness. Descriptive analysis was used to determine sensory texture, and mechanical properties were evaluated by oscillatory rheology, creep recovery, and pressure sensitive tack measurements. Oral processing was measured by determining activity of anterior temporalis and masseter muscles via electromyography and tracking jaw movement during chewing. The substitution of agar or gelatin for corn syrup at 0.6% w/w of the total formulation resulted in increased sensory hardness and decreased adhesiveness. Creep recovery and pressure sensitive tack testing were more effective at differentiating among treatments than oscillatory rheology. Hardness correlated inversely with creep compliance, and both stickiness and tooth adhesiveness correlated with pressure sensitive adhesive force. Harder samples, despite being less adhesive, were associated with increased muscle activity and jaw movement during mastication. Tooth packing, not linked with any mechanical property, correlated with altered jaw movement. The combination of material properties and oral processing parameters were able to explain all sensory texture differences in a highly adhesive food.

  19. State-Space Modeling of Dynamic Psychological Processes via the Kalman Smoother Algorithm: Rationale, Finite Sample Properties, and Applications

    ERIC Educational Resources Information Center

    Song, Hairong; Ferrer, Emilio

    2009-01-01

    This article presents a state-space modeling (SSM) technique for fitting process factor analysis models directly to raw data. The Kalman smoother via the expectation-maximization algorithm to obtain maximum likelihood parameter estimates is used. To examine the finite sample properties of the estimates in SSM when common factors are involved, a…

  20. Effects of the preparation processes on structural, electronic, and optical properties of LaHoO{sub 3}

    SciTech Connect

    Siaï, Amira; Horchani-Naifer, Karima; Haro-González, Patricia

    2016-04-15

    Highlights: • The preparation of LaHoO{sub 3} by combustion and hydrothermal techniques was performed. • The crystal structure and characterization of the synthesized oxides were carried out. • The lattice distortions have effects on Raman, luminescence and optical band gap. • Electronic properties and band structure have been carried out by DFT method. • Sample prepared by hydrothermal process gives higher emission intensities. - ABSTRACT: Lanthanum holmium oxide (LaHoO{sub 3}) was synthesized using combustion and hydrothermal processes in order to compare the effects of preparation method on structural, electronic, and optical properties. For this purpose, the as-prepared samples were characterized with infrared spectroscopy, Raman scattering, X-ray diffraction, and scanning electronic microscopy. The Rietveld refinements structure of as-prepared samples show that lattice distortions and volume expansion were obtained for LaHoO{sub 3} synthesized with hydrothermal method compared to combustion process. The luminescence properties were investigated upon 488 and 750 nm laser excitations. The emission curves show the presence of characteristic Ho{sup 3+} transitions with a higher emission intensity for a sample prepared by hydrothermal method than the one obtained by combustion process. The structures properties effects on the band structure and the density of states were realized via generalized gradient approximation functional with Hubbard correction. The lattice distortions were found to have effects on Raman, luminescence and optical band gap.

  1. Strength-Ductility Property Maps of Powder Metallurgy (PM) Ti-6Al-4V Alloy: A Critical Review of Processing-Structure-Property Relationships

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Chandran, K. S. Ravi

    2017-02-01

    A comprehensive assessment of tensile properties of powder metallurgical (PM) processed Ti-6Al-4V alloy, through the mapping of strength-ductility property domains, is performed in this review. Tensile property data of PM Ti-6Al-4V alloys made from blended element (BE) and pre-alloyed powders including that additive manufactured (AM) from powders, as well as that made using titanium hydride powders, have been mapped in the form of strength-ductility domains. Based on this, porosity and microstructure have been identified as the dominant variables controlling both the strength and the tensile ductility of the final consolidated materials. The major finding is that tensile ductility of the PM titanium is most sensitive to the presence of pores. The significance of extreme-sized pores or defects in inducing large variations in ductility is emphasized. The tensile strength, however, has been found to depend only weakly on the porosity. The effect of microstructure on properties is masked by the variations in porosity and to some extent by the oxygen level. It is shown that any meaningful comparison of the microstructure can only be made under a constant porosity or density level. The beneficial effect of a refined microstructure is also brought out by logically organizing the data in terms of microstructure groups. The advantages of new processes, using titanium hydride powder to produce PM titanium alloys, in simultaneously increasing strength and ductility, are also highlighted. The tensile properties of AM Ti-6Al-4V alloys are also brought to light, in comparison with the other PM and wrought alloys, through the strength-ductility maps.

  2. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Numerous cases in this year's chapter dealt with the same topics of previous years--contracts and bids for building construction, and detachment and annexation of a portion of a school district. The courts continued to attribute board discretionary authority to school boards in school property matters. Intergovernmental disputes over ownership or…

  3. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Forsberg, James R.

    This chapter summarizes and analyze all state supreme court and federal court decisions as well as other significant court decisions involving school property. The cases discussed are generally limited to those decided during 1974 and reported in the General Digest on or before March 1, 1975. In their discussion, the authors attempt to integrate…

  4. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    A review of cases involving higher education property matters shows that many are concerned with building construction, equipment installation, or repair contracts. A number of other cases involve routine conflicts between colleges or universities and other governmental entities over matters such as requests for special exceptions to zoning…

  5. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Forsberg, James R.

    This chapter summarizes recent state supreme court and federal court decisions involving school property. The cases discussed are generally limited to those decided during 1975 and reported in the General Digest as of March 1976. In their discussion, the authors attempt to integrate related cases and to illuminate any unifying legal principles…

  6. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Reflecting widespread unhappiness with the growing tax burdens in this country, the most active area of litigation reported in the property chapter this year involves various attempts by taxpayers to prevent the construction or remodeling of public school facilities. While some taxpayers fought to keep schools from being built, others in New York…

  7. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    The author notes that controversies over construction bids and contracts continue to represent the largest number of property cases reported in this year's chapter. Most of these cases are routine disputes between colleges or universities and contractors over such issues as the return of bid bonds, recovery of additional costs for construction…

  8. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Johnson, Margaret M.

    While the number of cases dealing with school property issues was significantly lower than in previous years, a significant number of cases involving the detachment and attachment of land to school districts arose. Eight of the eleven cases dealing with land detachment come from Illinois. The cases concerned requests from parents that their…

  9. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Forsberg, James R.

    While the types of cases reported in this year's chapter are essentially the same as those reported in last year's, the number of certain types of cases have changed--in some instances significantly. For example, the number of cases raising constitutional issues in the areas of school construction, location, and property use have declined. On the…

  10. Processing-structure-property relationships of thermal barrier coatings deposited using the solution precursor plasma spray process

    NASA Astrophysics Data System (ADS)

    Xie, Liangde

    This research is intended to develop a novel process, solution-precursor plasma-spray (SPPS), for the deposition of highly durable thermal barrier coatings (TBCs). In the SPPS process a solution precursor feedstock, that results in ZrO2-7 wt% Y2O3 ceramic, is injected into the plasma jet and the coating is deposited on a metal substrate. The formed coating has the following novel microstructural features: (i) ultra-fine splats, (ii) through-thickness cracks, (iii) micrometer and nanometer porosity, and (iv) interpass boundaries. The deposition mechanisms of the solution precursor droplets injected into the different regions of the plasma jet were found to be different due to large temperature variation across the plasma jet. The solution precursor droplets injected into the core of the plasma jet are deposited on the substrate as ultra-fine splats that account for around 65 volume% of the coating. The other 35 volume% of the coating includes porosity and deposits formed from the solution precursor droplets injected into other regions of the plasma jet. The optimum processing condition for highly durable TBCs was determined using Taguchi design of experiments. Meanwhile, the relationship of the microstructural features and processing parameters was revealed. During thermal cycling, the unmelted particles in the coating were observed to pyloyze and/or sinter, while no sign of sintering was observed for the ultra-fine splats. The spacing of through-thickness cracks remains in the range of 160 to 190 mum throughout the thermal cycling test. Three stages of oxidation of the bond coat were observed. Failure of the SPPS TBC starts with the crack nucleation along the unmelted particles in the top coat and the Ni, Cr, Co-rich oxides of large thickness. These cracks propagate and coalesce with thermal cycling. The extensive cracking of the rapidly formed Ni, Cr, Co-rich oxides resulting from the depletion of aluminum in the bond coat leads to the development of large

  11. Effects of process variables on the properties of YBa2Cu3O(7-x) ceramics formed by investment casting

    NASA Technical Reports Server (NTRS)

    Hooker, M. W.; Taylor, T. D.; Leigh, H. D.; Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.

    1993-01-01

    An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.

  12. Microstructure and textural and viscoelastic properties of model processed cheese with different dry matter and fat in dry matter content.

    PubMed

    Černíková, Michaela; Nebesářová, Jana; Salek, Richardos Nikolaos; Řiháčková, Lada; Buňka, František

    2017-04-05

    The aim of this work was to examine the effect of a different dry matter (DM) contents (35 and 45% wt/wt) and fat in DM contents (40 and 50% wt/wt) on the textural and viscoelastic properties and microstructure of model processed cheeses made from real ingredients regularly used in the dairy industry. A constant DM content and constant fat in DM content were kept throughout the whole study. Apart from the basic chemical parameters, textural and viscoelastic properties of the model samples were measured and scanning electron microscopy was carried out. With increasing DM content, the rigidity of the products increased and the size of the fat globules in the model samples of the processed cheeses decreased. With increasing fat in DM content, the rigidity of the processed cheeses decreased and the size of the fat globules increased.

  13. Optical property measurements as a diagnostic tool for control of materials processing in space and on Earth

    NASA Technical Reports Server (NTRS)

    Krishnan, Shankar; Weber, J. K. Richard; Nordine, Paul C.; Schiffman, Robert A.

    1990-01-01

    A new method is described, including results, to measure, control, and follow containerless processing in ground based levitators. This technique enables instantaneous optical property measurements from a transient solid or liquid surface concurrent with true temperature measurement. This was used successfully as a diagnostic tool to follow processing of Al, Si, and Ti during electromagnetic levitation. Experiments on Al show the disappearance of the oxide (emittance 0.33) at ca. 1300 C leaving a liquid surface with an emittance of 0.06. Electromagnetic levitation of silicon shows a liquid with a constant emittance (0.2) but with a solid whose emittance decreases very rapidly with increasing temperature. Consequently, the processing of materials at high temperatures can be controlled quite well through the control of surface optical properties.

  14. Induction thermal plasma process modifies the physicochemical properties of materials used for carbon nanotube production, influencing their cytotoxicity.

    PubMed

    Alinejad, Yasaman; Faucheux, Nathalie; Soucy, Gervais

    2013-11-01

    The effect of radio frequency induction thermal plasma (RFITP) process on the cytotoxicity of materials used for single-walled carbon nanotube production remains unknown. In this study, the influence of RFITP process on physicochemical and cytotoxic properties of commercial Co, Ni, Y₂O₃, Mo catalysts and carbon black was investigated. The cytotoxic assays (MTS, LDH, neutral red, TUNEL) revealed the strongest effect of commercial Co on murine Swiss 3T3 fibroblasts affecting their viability in a dose-dependent manner within 24 h. The cells contained also less actin stress fibres. Although RFITP affects the properties of each catalyst (size, morphology, chemistry), only cytotoxicity of Ni catalyst was increased. The plasma-treated Ni induced apoptosis. Comparing Ni particles before and after RFITP process with commercial nanoparticles of Ni revealed that the particles with similar surface area have different cytotoxicities. Interestingly, the observed toxicity of the catalysts was not mainly due to the release of ions.

  15. Connecting Organic Aerosol Climate-Relevant Properties to Chemical Mechanisms of Sources and Processing

    SciTech Connect

    Thornton, Joel

    2015-01-26

    The research conducted on this project aimed to improve our understanding of secondary organic aerosol (SOA) formation in the atmosphere, and how the properties of the SOA impact climate through its size, phase state, and optical properties. The goal of this project was to demonstrate that the use of molecular composition information to mechanistically connect source apportionment and climate properties can improve the physical basis for simulation of SOA formation and properties in climate models. The research involved developing and improving methods to provide online measurements of the molecular composition of SOA under atmospherically relevant conditions and to apply this technology to controlled simulation chamber experiments and field measurements. The science we have completed with the methodology will impact the simulation of aerosol particles in climate models.

  16. Effect of zinc doping on magnetic and magnetoelastic properties of cobalt ferrite synthesized by autocombustion process

    NASA Astrophysics Data System (ADS)

    Reddy, M. Vinitha; Paul, J. Praveen; Das, Dibakar

    2013-06-01

    Zn-doped cobalt-ferrite, with nominal compositions Co1-xZnxFe2O4(0≤x≤0.3), were synthesized by a novel auto combustion technique. The structural properties of the Zn substituted ferrites have been characterized using x-ray diffraction (XRD). The as-synthesized powders were calcined at 800°C for 3 hrs and the powders were pressed into cylindrical pellets. Solid-state sintering at 1300°C for 12 hrs of the green pellets resulted in a single phase cubic-spinel structure, as observed and analyzed from the XRD spectra. Room temperature magnetic properties were studied using vibrating sample magnetometer (VSM) with field strengths up to ± 15 kOe. Magnetoelastic properties were measured using strain gauge method in a pulsed field magnetometer. Effect of zinc doping on its magnetic and magnetoelastic properties of cobalt ferrite is discussed in this paper.

  17. Tungsten Carbide-Cobalt with Nano-Crystalline Tungsten Carbide Platelets ---Synthesis, Processing, Sintering and Properties

    NASA Astrophysics Data System (ADS)

    Zhong, Yang

    Tungsten Carbide --- Cobalt (WC-Co) is one of the most important ceramic-metal composites, which has been used in variety areas of different industries. Future applications of WC-Co in more areas of industries require higher hardness and fracture toughness. Current technology of synthesis, processing and sintering of WC-Co barely enhances the hardness and fracture toughness of WC-Co simultaneously (including nanostructured WC-Co). Within this project, a new approach of effectively controlling the structure of WC to lead to the simultaneous enhancement of hardness and fracture toughness has been investigated. The nano-WC platelet is proposed to be promising for the simultaneous enhancement. Several different aspects related to the formation of nano-WC platelets are studied. A new and effective method to produce nanostructured WC-Co powder is established in this study. This method is a combination of high energy milling and carbothermic reduction of the mixture of tungsten oxide (WO 3) and cobalt oxide (Co3O4). The condition to remove the free carbon without decarburization of WC has been achieved by thermodynamic analysis and coupled experiments. By the utilization of density functional theory simulations and Wulff construction, the equilibrium shape of WC crystals inside WC-Co is predicted to be bulky structure instead of platelet structure. The growth mechanisms for the WC in commercial coarse grained WC-Co under different heating conditions are observed. It is found that the heating temperature is a critical factor affecting the structure of WC inside WC-Co. Higher temperature will lead to the layer-by-layer structure formation due to higher thermodynamic driving force. The in situ formation of nano-WC platelet is achieved using different W containing sources. The formation mechanism has been studied. Bulk WC-Co samples with nano-WC platelets are obtained through sintering of WC-Co nano-powder at relatively low sintering temperatures. The mechanical properties of

  18. Processing of doped yttrium barium cuprate melt textured bulk single crystals for enhanced superconducting properties

    NASA Astrophysics Data System (ADS)

    Sofie, Stephen Wayne

    2002-08-01

    YBa2Cu3O7-x (123) high temperature superconducting powders were synthesized by mixing Y2O3, CuO, and BaCO3 precursor powders and subsequently reacting them at 920°C in a rotary calciner. The effects of carbon on the critical temperature (Tc), critical current density (Jc), trapped field, as well as the growth of melt textured 123 single crystals were examined as a function of the extent of calcination. Increasing carbon content in the sample resulted in lower and broader transition temperatures, however, J c's were improved showing a high field "fishtail" effect at 77K. Highly porous microstructure were, however, formed with increasing carbon content, thus degrading the properties of the material. To further improve Jc density, non-volatile substitutional and secondary phase dopants were utilized. The addition of 1 wt% CeO 2 (secondary phase particulate) led to an approximate 35% increase in Jc by the formation of ˜1mum BaCeO3 inclusions. Liquid loss was consequently reduced from the CeO2 additions due to increased capillary forces in the semi-solid melt. Nd2O 3 (substitutional dopant) not only substitutes yttrium lattice sites, but also barium lattice sites which can effectively kill superconductivity in a local regions, creating very small flux pinning sites. Additions of less than 0.1mol% Nd2O3 have shown improved high field J c's, however, Nd2O3 additions beyond 1mol% are deleterious to crystal growth due to the formation of Nd123, a higher melting point perovskite, resulting in polycrystalline crystal growth. YBa2Cu3O7-x growth kinetics have been examined to determine factors that may effect particle pushing/entrapment. These factors, such as critical particle radius, critical interface growth velocity, and interfacial energy contributions, are essential for the processing of melt textured single crystals with homogeneous distributions of fine secondary phase dopants. Melt textured single crystals have been grown utilizing an off axis [100] seed which

  19. Effect of Heat Treatment Process on Mechanical Properties and Microstructure of a 9% Ni Steel for Large LNG Storage Tanks

    NASA Astrophysics Data System (ADS)

    Zhang, J. M.; Li, H.; Yang, F.; Chi, Q.; Ji, L. K.; Feng, Y. R.

    2013-12-01

    In this paper, two different heat treatment processes of a 9% Ni steel for large liquefied natural gas storage tanks were performed in an industrial heating furnace. The former was a special heat treatment process consisting of quenching and intercritical quenching and tempering (Q-IQ-T). The latter was a heat treatment process only consisting of quenching and tempering. Mechanical properties were measured by tensile testing and charpy impact testing, and the microstructure was analyzed by optical microscopy, transmission electron microscopy, and x-ray diffraction. The results showed that outstanding mechanical properties were obtained from the Q-IQ-T process in comparison with the Q-T process, and a cryogenic toughness with charpy impact energy value of 201 J was achieved at 77 K. Microstructure analysis revealed that samples of the Q-IQ-T process had about 9.8% of austenite in needle-like martensite, while samples of the Q-T process only had about 0.9% of austenite retained in tempered martensite.

  20. Processing, structure, property and performance relationships for the thermal spray of the internal surface of aluminum cylinders

    NASA Astrophysics Data System (ADS)

    Cook, David James

    The increased need for automotive weight reduction has necessitated the use of aluminum for engine blocks. Conventional aluminum alloys cannot survive the constant wear from a piston ring reciprocating on the surface. However, a wear resistant thermal spray coating can be applied on the internal surface of the cylinder bore, which has significant advantages over other available options. Thermal spray is a well-established process for depositing molten, semi-molten, or solid particles onto a substrate to form a protective coating. For this application, the two main challenges were obtaining good wear resistance, and achieving good adhesion. To design a system capable of producing a well-adhered, wear resistant coating for this high volume application it is necessary to identify the overall processing, structure, properties, and performance relationships. The results will demonstrate that very important relationships exist among particle characteristics, substrate conditions, and the properties of the final coating. However, it is the scientific studies to understand some of the process physics in these relationships that allow recognition of the critical processing conditions that need to be controlled to ensure a consistent, reliable thermal spray coating. In this investigation, it will be shown that the critical microstructural aspect of the coating that produced the required tribological properties was the presence of wuestite (FeO). It was found that by using a low carbon steel material with compressed air atomizing gas, it was possible to create an Fe/FeO structure that exhibited excellent tribological properties. This study will also show that traditional thermal spray surface preparation techniques were not ideal for this application, therefore a novel alternative approach was developed. The application of a flux to the aluminum surface prior to thermal spray promotes excellent bond strengths to non-roughened aluminum. Analysis will show that this flux strips

  1. Impact of thermal properties of the trees cultivated by processed waste water and sludge

    SciTech Connect

    Drakatos, P.A.; Kalavrouziotis, I.K.; Skuras, D.G.; Drakatos, S.P.; Fanariotou, I.

    1997-07-01

    Eucalyptus trees were planted and irrigated with wastewater from the wastewater treatment plan (WWTP) of the University of Patras in certain experimental design including treatment and control groups. Measurements of the thermal properties from treatment and control specimens (Eucalyptus sp.), showed significantly different values. Preliminary findings showed that the use of sludge and wastewater affect the thermal properties of wood. The implications of this finding on the future planning of wastewater reuse are discussed.

  2. A study on properties of PLA/PBAT from blown film process

    NASA Astrophysics Data System (ADS)

    Hongdilokkul, P.; Keeratipinit, K.; Chawthai, S.; Hararak, B.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    The aim of this work was to study the properties of films based on PLA/PBAT blend prepared by the reactive compounding. PLA/PBAT blends were prepared at the weight ratio of 80:20 together with peroxide as a reactive agent in a twin screw extruder with temperature profile of 160/170/180/210/220/190/175/150°C from feed to die zone. All blended samples, neat PLA, and neat PBAT were characterized for morphology, mechanical and rheological properties. SEM micrographs showed finely dispersed phases of PBAT in PLA in all cases. The particle sizes of PBAT were around 1 μm. The results indicated that the drawability and toughness properties of PLA were greatly improved when blended with 20%wt PBAT. The interface adhesion, and mechanical properties of PLA/PBAT blends were also improved when adding a very small quantity of peroxide. PLA/PBAT blends were then used to produce films. The film characteristics and mechanical properties were examined. Tensile strength of films was significantly improved in the machine direction in PLA/PBAT/peroxide blends whereas the good optical transparent property were remained the same compared with neat PLA.

  3. Effect of proteolysis and calcium equilibrium on functional properties of natural cheddar cheese during ripening and the resultant processed cheese.

    PubMed

    Wang, Fang; Zhang, Xiaoying; Luo, Jie; Guo, Huiyuan; Zeng, Steve S; Ren, Fazheng

    2011-04-01

    The changes in proteolysis, calcium (Ca) equilibrium, and functional properties of natural Cheddar cheeses during ripening and the resultant processed cheeses were investigated. For natural Cheddar cheeses, the majority of the changes in pH 4.6 soluble nitrogen as a percentage of total nitrogen (pH 4.6 SN/TN) and the soluble Ca content occurred in the first 90 d of ripening, and subsequently, the changes were slight. During ripening, functional properties of natural Cheddar cheeses changed, that is, hardness decreased, meltability was improved, storage modulus at 70 °C (G'T=70) decreased, and the maximum tan delta (TDmax) increased. Both pH 4.6 SN/TN and the soluble Ca were correlated with changes in functional properties of natural Cheddar cheeses during ripening. Kendall's partial correlation analysis indicated that pH 4.6 SN/TN was more significantly correlated with changes in hardness and TDmax. For processed cheeses manufactured from natural Cheddar cheeses with different ripening times, the soluble Ca content did not show significant difference, and the trends of changes in hardness, meltability, G'T=70, and TDmax were similar to those of natural Cheddar cheeses. Kendall's partial correlation analysis suggested that only pH 4.6 SN/TN was significantly correlated with the changes in functional properties of processed cheeses.

  4. Processing, wear, and mechanical properties of polyethylene composites prepared with pristine and organosilane-treated carbon nanofibers

    NASA Astrophysics Data System (ADS)

    Wood, Weston

    Polymers and nanocomposites have been increasingly used for tribological applications over the last few decades. In particular, ultrahigh molecular weight polyethylene (UHMWPE) is a high performance polymer with excellent strength, toughness, and wear resistance. Because of these properties, UHMWPE is an ideal material for a variety of applications including body armor, components of sporting goods such as skies and snowboards, and liners in total joint replacement. Though the toughness and wear resistance far exceed that of most other polymeric materials, there is a high demand for improving the tribological and mechanical properties of UHMWPE for many applications. The approach used in this work for improving such properties is through nanocomposite technology, specifically via the incorporation of carbon nanofibers. In order to obtain the full potential of nanocomposite technology, two critical issues need to be addressed: appropriate interactions between the filler and matrix and proper dispersion of the nano-reinforcement. These critical issues are particularly important for UHMWPE nanocomposites in that UHMWPE is an extremely viscous polymer and thus cannot be processed conventionally, typically resulting in dispersion issues far worse than that of other composite systems. Furthermore, UHMWPE is non-polar, so interactions between filler and matrix will be limited to Van der Waals forces for untreated nanofillers. Therefore, the research presented aims at solving these issues by using a paraffin-assisted processing method and applying appropriate surface treatment to the carbon nanofibers. Under optimized processing conditions, wear and mechanical properties of UHMWPE composites can be substantially improved.

  5. Mantle properties and the MOR process: a new and versatile model for mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Osmaston, Miles

    2014-05-01

    Introduction. First I summarize the reasons why a radical departure from the current MOR model is now essential. I then outline the new model and its apparent versatility, not only in providing the observed contrasting spreading-rate-dependent characteristics but also some of the other common features of the MOR system which warrant clearer explanation. Ophiolites have been thought to provide on-land guidance but turn out to be a non-mid-ocean variant, outside the scope of this presentation. Seismic anisotropy and mantle mobility. Ever since the 1969 discovery [1] of seismic anisotropy in the uppermost oceanic mantle, this has been attributed to the shearing of olivine in a convectively driven MOR-divergent flow beneath the flanks. This would imply a high degree of rheological mobility of this mantle, but new constraints on its rheological properties and dynamical behaviour have come from two directions and need to be taken into account in forming a model. 1. Contrary to the seismologists' rule-book, the oceanic seismological Low Velocity Zone (LVZ) is no longer to be thought of as mobile, because the presence of interstitial melt strips out the water-weakening of the mineral structure [2, 3]. So we require a substitute for the divergent-flow model for MORs which, we find, also has other, apparently unrecognized, dynamical inconsistencies. One of these [4] is that there are in the record many rapid changes of spreading rate and direction, and ridge jumps. This cannot happen with a process driven by slow-to-change body forces, such as thermal convection. 2. My work on the global dynamic pattern for the past 150Ma (I will show examples) has shown [4 - 7] that the tectospheres of cratons must extend to very close to the bottom of the upper mantle (660km). The metasomatism of kimberlite xenoliths from >180km depth suggests that the reason for this downwards extent of 'keels' is the same as [3]. Phase changes. Another geodynamically important property apparently

  6. The impact of local processes and the prohibition of multiple links in the topological properties of directed complex networks

    NASA Astrophysics Data System (ADS)

    Esquivel-Gómez, J.; Arjona-Villicaña, P. D.; Acosta-Elías, J.

    2015-05-01

    Local processes exert influence on the growth and evolution of complex networks, which in turn shape the topological and dynamic properties of these networks. Some local processes have been researched, for example: Addition of nodes and links, rewiring of links between nodes, accelerated growth, link removal, aging, copying and multiple links prohibition. These processes impact directly into the topological and dynamical properties of complex networks. This paper introduces a new model for growth of directed complex networks which incorporates the prohibition of multiple links, addition of nodes and links, and rewiring of links. This paper also reports on the impact that these processes have in the topological properties of the networks generated with the proposed model. Numerical simulation shows that, when the frequency of rewiring increases in the proposed model, the γ exponent of the in-degree distribution approaches a value of 1.1. When the frequency of adding new links increases, the γ exponent approaches 1. That is the proposed model is able to generate all exponent values documented in real-world networks which range 1.05 < γ < 8.94.

  7. Physicochemical properties and oral bioavailability of amorphous atorvastatin hemi-calcium using spray-drying and SAS process.

    PubMed

    Kim, Jeong-Soo; Kim, Min-Soo; Park, Hee Jun; Jin, Shun-Ji; Lee, Sibeum; Hwang, Sung-Joo

    2008-07-09

    The objective of the study was to prepare amorphous atorvastatin hemi-calcium using spray-drying and supercritical antisolvent (SAS) process and evaluate its physicochemical properties and oral bioavailability. Atorvastatin hemi-calcium trihydrate was transformed to anhydrous amorphous form by spray-drying and SAS process. With the SAS process, the mean particle size and the specific surface area of amorphous atorvastatin were drastically changed to 68.7+/-15.8nm, 120.35+/-1.40m2/g and 95.7+/-12.2nm, 79.78+/-0.93m2/g from an acetone solution and a tetrahydrofuran solution, respectively and appeared to be associated with better performance in apparent solubility, dissolution and pharmacokinetic studies, compared with unprocessed crystalline atorvastatin. Oral AUC0-8h values in SD rats for crystalline and amorphous atorvastatin were as follow: 1121.4+/-212.0ngh/mL for crystalline atorvastatin, 3249.5+/-406.4ngh/mL and 3016.1+/-200.3ngh/mL for amorphous atorvastatin from an acetone solution and a tetrahydrofuran solution with SAS process, 2227.8+/-274.5 and 2099.9+/-339.2ngh/mL for amorphous atorvastatin from acetone and tetrahydrofuran with spray-drying. The AUCs of all amorphous atorvastatin significantly increased (P<0.05) compared with crystalline atorvastatin, suggesting that the enhanced bioavailability was attributed to amorphous nature and particle size reduction. In addition, the SAS process exhibits better bioavailability than spray-drying because of particle size reduction with narrow particle size distribution. It was concluded that physicochemical properties and bioavailability of crystalline atorvastatin could be improved by physical modification such as particle size reduction and generation of amorphous state using spray-drying and SAS process. Further, SAS process was a powerful methodology for improving the physicochemical properties and bioavailability of atorvastatin.

  8. Bottom-up processing and low temperature transport properties of polycrystalline SnSe

    SciTech Connect

    Ge, Zhen-Hua; Wei, Kaya; Lewis, Hutton; Martin, Joshua; Nolas, George S.

    2015-05-15

    A hydrothermal approach was employed to efficiently synthesize SnSe nanorods. The nanorods were consolidated into polycrystalline SnSe by spark plasma sintering for low temperature electrical and thermal properties characterization. The low temperature transport properties indicate semiconducting behavior with a typical dielectric temperature dependence of the thermal conductivity. The transport properties are discussed in light of the recent interest in this material for thermoelectric applications. The nanorod growth mechanism is also discussed in detail. - Graphical abstract: SnSe nanorods were synthesized by a simple hydrothermal method through a bottom-up approach. Micron sized flower-like crystals changed to nanorods with increasing hydrothermal temperature. Low temperature transport properties of polycrystalline SnSe, after SPS densification, were reported for the first time. This bottom-up synthetic approach can be used to produce phase-pure dense polycrystalline materials for thermoelectrics applications. - Highlights: • SnSe nanorods were synthesized by a simple and efficient hydrothermal approach. • The role of temperature, time and NaOH content was investigated. • SPS densification allowed for low temperature transport properties measurements. • Transport measurements indicate semiconducting behavior.

  9. Processing and properties of multiscale cellular thermoplastic fiber reinforced composite (CellFRC)

    NASA Astrophysics Data System (ADS)

    Sorrentino, L.; Cafiero, L.; D'Auria, M.; Iannace, S.

    2015-12-01

    High performance fiber reinforced polymer composites are made by embedding high strength/modulus fibers in a polymeric matrix. They are a class of materials that owe its success to the impressive specific mechanical properties with respect to metals. In many weight-sensitive applications, where high mechanical properties and low mass are required, properties per unit of mass are more important than absolute properties and further weight reduction is desirable. A route to reach this goal could be the controlled induction of porosity into the polymeric matrix, while still ensuring load transfer to the reinforcing fibers and fiber protection from the environment. Cellular lightweight fiber reinforced composites (CellFRC) were prepared embedding gas bubbles of controlled size within a high performance thermoplastic matrix reinforced with continuous fibers. Pores were induced after the composite was first saturated with CO2 and then foamed by using an in situ foaming/shaping technology based on compression moulding with adjustable mould cavities. The presence of micro- or submicro-sized cells in the new CellFRC reduced the apparent density of the structure and led to significant improvements of its impact properties. Both structural and functional performances were further improved through the use of a platelet-like nanofiller (Expanded Graphite) dispersed into the matrix.

  10. Capturing extracellular matrix properties in vitro: Microengineering materials to decipher cell and tissue level processes

    PubMed Central

    Abdeen, Amr A; Lee, Junmin

    2016-01-01

    Rapid advances in biology have led to the establishment of new fields with tremendous translational potential including regenerative medicine and immunoengineering. One commonality to these fields is the need to extract cells for manipulation in vitro; however, results obtained in laboratory cell culture will often differ widely from observations made in vivo. To more closely emulate native cell biology in the laboratory, designer engineered environments have proved a successful methodology to decipher the properties of the extracellular matrix that govern cellular decision making. Here, we present an overview of matrix properties that affect cell behavior, strategies for recapitulating important parameters in vitro, and examples of how these properties can affect cell and tissue level processes, with emphasis on leveraging these tools for immunoengineering. PMID:27075930

  11. Processing and mechanical properties of silicon nitride formed by robocasting aqueous slurries

    SciTech Connect

    HE,GUOPING; HIRSCHFELD,DEIDRE A.; CESARANO III,JOSEPH

    2000-01-26

    Robocasting is a new freeform fabrication technique for dense ceramics. It uses robotics to control deposition of ceramic slurries through an orifice. The optimization of concentrated aqueous Si{sub 3}N{sub 4} slurry properties to achieve high green density robocast bodies and subsequent high sintered densities was investigated. The effects of pH, electrolyte, additives and solids loading on the dispersion and rheological properties of Si{sub 3}N{sub 4} slurries were determined. The mechanical behavior of sintered robocast bars was determined and compared to conventionally produced silicon nitride ceramics.

  12. High k dielectrics on silicon: Effects of processing on nanostructure and properties

    NASA Astrophysics Data System (ADS)

    Das, Anirban

    High permittivity hafnia, HfO2, and hafnium silicate, HfSiO 4, are the most promising candidates to replace oxide (SiOx) or oxynitride (SiOxNy) based gate dielectrics in future generation CMOS devices. In this thesis, the effects of processing (deposition techniques, post deposition annealing, nitridation) on nanostructure evolution (crystallization, phase segregation, interlayer growth), changes in nanochemistry (impurity content, interfacial reaction, interdiffusion, oxygen diffusion, paramagnetic charge centers) and properties (EOT, oxide charges) of atomic layer deposited (ALD) Hf-O/Hf-Si-O films on Si, with different interlayers (IL), were studied. A variety of analytical techniques including XRD, RBS, XPS, SIMS, AFM, HRTEM, STEM-EELS and EPR were used. In general, PEALD Hf-O films deposited using metal-organic precursors showed a higher C and H and lower Cl content compared to thermal ALD films using halide based precursors. Also, as-deposited ALD films (Hf-O/IL/Si) showed the formation of Hf-O-Si bonds at the Hf-O/IL interface, with increasing tendency in the presence of a chemical oxide interlayer and upon oxygen annealing. Upon post deposition annealing (PDA) of ALD Hf-O films up to 1000°C, m-HfO2 was the stable crystalline phase. It was observed that the chemical oxide interlayer grew significantly during PDA in oxygen, the rate of which was a f (t, T) due to oxygen diffusion. Additionally, an annealed Hf-O stack (i.e., target Hf-O thickness of 4.0 nm/1.2 nm nitrided chemical oxide interlayer/Si) showed a chemically diffused HfSiOx region (2 nm) in between pure HfO