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Sample records for reinforced aluminium metal

  1. Ageing characteristics of aluminium alloy aluminosilicate discontinuous fiber reinforced composites

    SciTech Connect

    Nath, D.; Singh, V.

    1999-03-05

    Development of continuous fiber reinforced metal matrix composites is aimed at providing high specific strength and stiffness needed for aerospace and some critical high temperature structural applications. Considerable efforts have been made, during the last decade, to improve the strength of age-hardening aluminium alloy matrix composites by suitable heat treatment. It has also been well established that age-hardenable aluminium alloy composites show accelerated ageing behavior because of enhanced dislocation density at the fiber/matrix interface resulting from thermal expansion mismatch between ceramic fiber and the metal matrix. The accelerated ageing of aluminium alloy composites either from dislocation density or the residual stress, as a result of thermal expansion mismatch is dependent on the size of whisker and particulate. Investigations have also been made on the effect of volume fraction of particulate on the ageing behavior of aluminium alloys. The present investigation is concerned with characterization of age-hardening behavior of an Al-Si-Cu-Mg(AA 336) alloy alumino-silicate discontinuous fiber-reinforced composites (referred to as aluminium MMCs in the present text) being developed for automotive pistons. An effort is made to study the effect of volume fraction of the reinforcement on age-hardening behavior of this composite.

  2. Aluminium contamination from fluoride assisted dissolution of metallic aluminium.

    PubMed

    Tennakone, K; Wickramanayake, S; Fernando, C A

    1988-01-01

    Trace amounts (microg g(-1) quantities) of fluoride ion are found to catalyse the dissolution of metallic aluminium in very slightly acidic or alkaline aqueous media. Possibly hazardous levels of aluminium could get leached from cooking utensils if fluoridated water or fluoride rich foodstuffs are used. The fluoride assisted corrosion of aluminium is most dramatic in oxalic, tartaric acids or sodium bicarbonate. Carbon dioxide also corrodes aluminium in the presence of the fluoride ion, generating colloidal hydrated aluminium oxide which is readily soluble in dilute organic and mineral acids. PMID:15092668

  3. Compressive strength of the mineral reinforced aluminium alloy composite

    NASA Astrophysics Data System (ADS)

    Arora, Rama; Sharma, Anju; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

    2016-05-01

    This paper presents the results of quasi-static compressive strength of aluminium alloy reinforced with different concentration of rutile mineral particles. The reinforced material shows increase in compressive strength with 5wt% rutile concentration as compared to the base alloy. This increase in compressive strength of composite is attributed to direct strengthening due to transfer of load from lower stiffness matrix (LM13 alloy) to higher stiffness reinforcement (rutile particles). Indirect strengthening mechanisms like increase in dislocation density at the matrix-reinforcement interface, grain size refinement of the matrix and dispersion strengthening are also the contributing factors. The decrease in compressive strength of composite with the increased concentration of rutile concentration beyond 5 wt.% can be attributed to the increase in dislocation density due to the void formation at the matrix-reinforcement interface.

  4. Laser Surface Pre-treatment of Aluminium for Hybrid Joints with Glass Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Heckert, André; Zaeh, Michael F.

    Lightweight construction is a major trend in the automotive industry. Theconnection of fibre reinforced plastics with aluminium is consequently seen as promising prospect. In this regard, thermal joining can be applied for bonding of such hybrid joints. But in order to create a load bearing metal plastic joint, the surface of the metal has to be pre-treated. Recent research has shown that with laser surface pre-treatment high joint strengths are obtained. Yet there are a variety of laser sources and manufacturable surface topographies with structure sizes ranging from macroscopic to nanoscopic profiles. Within this work,macroscopic, microscopic and nanoscopic laser processed structures are created on aluminium and consequently joined to glass fibre reinforced thermoplastics of different fibre length and fibre content. High shear tensile strengths of up to 42 N/mm2 were obtained depending on the allocated material and the surface pre-treatment.

  5. Synthesis and Characterization of TiB2 Reinforced Aluminium Matrix Composites: A Review

    NASA Astrophysics Data System (ADS)

    Kumar, Narendra; Gautam, Gaurav; Gautam, Rakesh Kumar; Mohan, Anita; Mohan, Sunil

    2015-09-01

    Aluminium-matrix composites (AMCs) are developed to meet the demands of light weight high performance materials in aerospace, automotive, marine and other applications. The properties of AMCs can be tailored suitably by combinations of matrix, reinforcement and processing route. AMCs are one of the most attractive alternatives for the manufacturing of light weight and high strength parts due to their low density and high specific strength. There are various techniques for preparing the AMCs with different reinforcement particles. In AMCs, the reinforcements are usually in the form of metal oxides, carbides, borides, nitrides and their combination. Among the various reinforcements titanium di-boride (TiB2) is of much interest due to its excellent stiffness, hardness, and wear resistance. This paper attempts to provide an overview to explore the possibilities of synthesizing titanium di-boride reinforced AMCs with different techniques. The mechanical and tribological properties of these composites have been emphasized to project these as tribo-materials.

  6. Mechanical Properties of Particulate Reinforced Aluminium Alloy Matrix Composite

    SciTech Connect

    Sayuti, M.; Sulaiman, S.; Baharudin, B. T. H. T.; Arifin, M. K. A.; Suraya, S.; Vijayaram, T. R.

    2011-01-17

    This paper discusses the mechanical properties of Titanium Carbide (TiC) particulate reinforced aluminium-silicon alloy matrix composite. TiC particulate reinforced LM6 alloy matrix composites were fabricated by carbon dioxide sand molding process with different particulate weight fraction. Tensile strength, hardness and microstructure studies were conducted to determine the maximum load, tensile strength, modulus of elasticity and fracture surface analysis have been performed to characterize the morphological aspects of the test samples after tensile testing. Hardness values are measured for the TiC reinforced LM6 alloy composites and it has been found that it gradually increases with increased addition of the reinforcement phase. The tensile strength of the composites increased with the increase percentage of TiC particulate.

  7. Laminates and reinforced metals

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1980-01-01

    A selective review is presented of the state of the art of metallic laminates and fiber reinforced metals called metallic matrix laminates (MMLs). Design and analysis procedures that are used for, and typical structural components that have been made from MMLs are emphasized. Selected MMLs, constituent materials, typical material properties and fabrication procedures are briefly described, including hybrids and superhybrids. Advantages, disadvantages, and special considerations required during design, analysis, and fabrication of MMLs are examined. Tabular and graphical data are included to illustrate key aspects of MMLs. Appropriate references are cited to provide a selective bibliography of a rapidly expanding and very promising research and development field.

  8. The fracture of boron fibre-reinforced 6061 aluminium alloy

    NASA Technical Reports Server (NTRS)

    Wright, M. A.; Welch, D.; Jollay, J.

    1979-01-01

    The fracture of 6061 aluminium alloy reinforced with unidirectional and cross-plied 0/90 deg, 0/90/+ or - 45 deg boron fibres has been investigated. The results have been described in terms of a critical stress intensity, K(Q). Critical stress intensity factors were obtained by substituting the failure stress and the initial crack length into the appropriate expression for K(Q). Values were obtained that depended on the dimensions of the specimens. It was therefore concluded that, for the size of specimen tested, the values of K(Q) did not reflect any basic materials property.

  9. Production of aluminium metal matrix composites by liquid processing methods

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Kumar, R.; Tharmaraj, R.; Velu, P. Shenbaga

    2016-05-01

    Owing to high strength to low weight ratio, Aluminium matrix composites are widely used in diverse applications of many industries. This lucrative property is achieved by reinforcing the brittle ceramic particles in the aluminium matrix. Aluminium matrix composites are produced by liquid processing methods and solid processing methods. Nevertheless, liquidprocessing techniques stand out because of its simplicity and its suitability for mass production. In this review article, the production of aluminium matrix composites by different liquid processing technique is discussed and a comparative study is carried out.

  10. Aluminium Sheet Metal Forming at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Schneider, R.; Heine, B.; Grant, R. J.; Zouaoui, Z.

    2015-02-01

    Low-temperature forming technology offers a new potential for forming operations of aluminium wrought alloys which show a limited formability at ambient temperatures. This paper indicates the mechanical behaviour of the commercial aluminium alloys EN AW-5182 and EN AW-6016 at low temperatures. Stress-strain relationships at different temperatures were investigated through tensile testing experiments. Flow curves were extrapolated using an adapted mathematical constitutive relationship of flow stress and strain. A device which allows cupping tests at sub-zero temperatures was specially designed and a limiting dome height was determined.

  11. Aspects regarding wearing behaviour in case of aluminium composite materials reinforced with carbon fibers

    NASA Astrophysics Data System (ADS)

    Caliman, R.

    2016-08-01

    This paper presents a study regarding wear comportment of sintered composite materials obtained by mixture of aluminium with short carbon fibers. The necessity to satisfying more and more the specific functions during design of high performance structures leads to perform multi-materials such as reinforced composite parts. The wear tests were made on three different orientations of fibers on a standard machine of tribology, pin disk type. Counter-disk was made of cast iron with a superficial hardness of 92 HB. The wear rate and friction coefficient decreased exponentially with time of friction and reached a stationary value. This behaviour was attributed to the development of a lubricating film on the friction surface. To conduct this work was performed measurements on samples from the Al matrix composites and carbon fiber 43%, wear mechanism was investigated by scanning electron microscopy. In addition to fiber orientation, the tribological behaviour of metal matrix composites reinforced with fiber is influenced by the interfacial reaction of fiber-matrix. The characteristics and the dimensions of the interface depend on the cycle of temperature and time at which the material has been subjected during the manufacturing process and thereafter.

  12. A Study on 3-Body Abrasive Wear Behaviour of Aluminium 8011 / Graphite Metal Matrix Composite

    NASA Astrophysics Data System (ADS)

    Latha Shankar, B.; Anil, K. C.; Patil, Rahul

    2016-09-01

    Metals and alloys have found their vital role in many applications like structural, corrosive, tribological, etc., in engineering environment. The alloys/composites having high strength to low weight ratio have gained attention of many researchers recently. In this work, graphite reinforced Aluminium 8011 metal matrix composite was prepared by conventional stir casting route, by varying the weight % of reinforcement. Uniform distribution of Graphite in matrix alloy was confirmed by optical micrographs. Prepared composite specimens were subjected to 3-body abrasive testing by varying applied load and time, the silica particles of 400 grit size were used as abrasive particles. It was observed that with the increase of weight% of Graphite the wear resistance of composite was also increasing and on comparison it was found that reinforced composite gives good wear resistance than base alloy.

  13. Quench Crucibles Reinforced with Metal

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Carrasquillo, Edgar; O'Dell, J. Scott; McKehnie, N.

    2008-01-01

    Improved crucibles consisting mainly of metal-reinforced ceramic ampules have been developed for use in experiments in which material specimens are heated in the crucibles to various high temperatures, then quenched by, for example, plunging the crucibles into water at room temperature. In a traditional quench crucible, the gap between the ampule and the metal cartridge impedes the transfer of heat to such a degree that the quench rate (the rate of cooling of the specimen) can be too low to produce the desired effect in the specimen. One can increase the quench rate by eliminating the metal cartridge to enable direct quenching of the ampule, but then the thermal shock of direct quenching causes cracking of the ampule. In a quench crucible of the present improved type, there is no gap and no metal cartridge in the traditional sense. Instead, there is an overlay of metal in direct contact with the ampule, as shown on the right side of the figure. Because there is no gap between the metal overlay and the ampule, the heat-transfer rate can be much greater than it is in a traditional quench crucible. The metal overlay also reinforces the ampule against cracking.

  14. Dry Sliding Wear behaviour of Aluminium-Red mud- Tungsten Carbide Hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Devi Chinta, Neelima; Selvaraj, N.; Mahesh, V.

    2016-09-01

    Red mud is an industrial waste obtained during the processing of alumina by Bayer's process. An attempt has been made to utilize the solid waste by using it as the reinforcement material in metal matrix composites. Red mud received from NALCO has been subjected for sieve analysis and milled to 42 nanometers using high energy ball mill. Red mud is used as a reinforcement material in Pure Aluminium matrix composite at 2%, 4%, and 6% weight at 100 microns level as well as 42 nano meters along with 4%Tungsten carbide by weight. Micro and Nano structured red mud powders, Tungsten carbide powder and Aluminium is mixed in a V-Blender, compacted at a pressure of 40 bar and samples are prepared by conventional sintering with vacuum as medium. In this current work, dry sliding wear characteristics at normal and heat treatment conditions are investigated with optimal combination of Aluminium, Tungsten carbide and different weight fractions of micro and nano structured red mud powder.

  15. Investigation of Selectively-Reinforced Metallic Lugs

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Abada, Christopher H.

    2007-01-01

    An investigation of the effects of material and geometric variables on the response of U-shaped band-reinforced metallic lugs was performed. Variables studied were reinforcement, adhesive and metallic lug mechanical properties, hole diameter, reinforcement and adhesive thickness, and the distance from the hole s center to the end of the lug. Generally, U-shaped band reinforced lugs exhibited superior performance than non-reinforced lugs, that is higher load at the conventional lug design criteria of four percent hole elongation. Depending upon the reinforcement configuration the increase in load may be negligible to 15 or 20 percent. U-shaped band reinforcement increases lug load carrying capability primarily through two mechanisms; increasing the slope of the response curve after the initial knee and restraining overall deformation of the metallic portion of the lug facilitating increased yielding of metallic material between the hole and the edge of the metallic portion of the lug.

  16. The effective thermal conductivity of insulation materials reinforced with aluminium foil at low temperatures

    NASA Astrophysics Data System (ADS)

    Yüksel, N.; Avcı, A.; Kılıç, M.

    2012-09-01

    The effective thermal conductivity (ETC) of multilayer thermal insulation materials was experimentally investigated as a function of temperature (0-25 °C). The materials consisted of binary/ternary glass wools or ternary expanded polystyrene foams reinforced with aluminium foil. The experimental measurements were performed using a guarded hot plate with temperature differences of 5, 10 and 15 °C. The results indicated that significant correlations exist between ETC and the characteristics of the materials with decreasing temperature. The ETC decreases with reinforcement with aluminium foil at the same temperature or with temperature differences of 5 and 15 °C. In addition, it was clearly observed that the ETC decreases sharply with decreased temperature. Consequently, reflective materials may reduce the ETC at low temperatures.

  17. Corrosion of aluminium metal in OPC- and CAC-based cement matrices

    SciTech Connect

    Kinoshita, Hajime; Swift, Paul; Utton, Claire; Carro-Mateo, Beatriz; Collier, Nick; Milestone, Neil

    2013-08-15

    Corrosion of aluminium metal in ordinary Portland cement (OPC) based pastes produces hydrogen gas and expansive reaction products causing problems for the encapsulation of aluminium containing nuclear wastes. Although corrosion of aluminium in cements has been long known, the extent of aluminium corrosion in the cement matrices and effects of such reaction on the cement phases are not well established. The present study investigates the corrosion reaction of aluminium in OPC, OPC-blast furnace slag (BFS) and calcium aluminate cement (CAC) based systems. The total amount of aluminium able to corrode in an OPC and 4:1 BFS:OPC system was determined, and the correlation between the amount of calcium hydroxide in the system and the reaction of aluminium obtained. It was also shown that a CAC-based system could offer a potential matrix to incorporate aluminium metal with a further reduction of pH by introduction of phosphate, producing a calcium phosphate cement.

  18. Wear Behavior of Aluminium Metal Matrix Composite Prepared from Industrial Waste.

    PubMed

    Xavier, L Francis; Suresh, Paramasivam

    2016-01-01

    With an increase in the population and industrialization, a lot of valuable natural resources are depleted to prepare and manufacture products. However industrialization on the other hand has waste disposal issues, causing dust and environmental pollution. In this work, Aluminium Metal Matrix Composite is prepared by reinforcing 10 wt% and 20 wt% of wet grinder stone dust particles an industrial waste obtained during processing of quarry rocks which are available in nature. In the composite materials design wear is a very important criterion requiring consideration which ensures the materials reliability in applications where they come in contact with the environment and other surfaces. Dry sliding wear test was carried out using pin-on-disc apparatus on the prepared composites. The results reveal that increasing the reinforcement content from 10 wt% to 20 wt% increases the resistance to wear rate. PMID:26989764

  19. Wear Behavior of Aluminium Metal Matrix Composite Prepared from Industrial Waste

    PubMed Central

    Xavier, L. Francis; Suresh, Paramasivam

    2016-01-01

    With an increase in the population and industrialization, a lot of valuable natural resources are depleted to prepare and manufacture products. However industrialization on the other hand has waste disposal issues, causing dust and environmental pollution. In this work, Aluminium Metal Matrix Composite is prepared by reinforcing 10 wt% and 20 wt% of wet grinder stone dust particles an industrial waste obtained during processing of quarry rocks which are available in nature. In the composite materials design wear is a very important criterion requiring consideration which ensures the materials reliability in applications where they come in contact with the environment and other surfaces. Dry sliding wear test was carried out using pin-on-disc apparatus on the prepared composites. The results reveal that increasing the reinforcement content from 10 wt% to 20 wt% increases the resistance to wear rate. PMID:26989764

  20. Aluminium plasmonics

    SciTech Connect

    Gerard, Davy; Gray, Stephen K.

    2014-12-15

    In this study, we present an overview of 'aluminium plasmonics', i.e. the study of both fundamental and practical aspects of surface plasmon excitations in aluminium structures, in particular thin films and metal nanoparticles. After a brief introduction noting both some recent and historical contributions to aluminium plasmonics, we discuss the optical properties of aluminium and aluminium nanostructures and highlight a few selected studies in a host of areas ranging from fluorescence to data storage.

  1. Reinforcement for Stretch Formed Sheet Metal

    NASA Technical Reports Server (NTRS)

    Lea, J. B.; Baxter, C. R.

    1983-01-01

    Tearing of aluminum sheet metal durinng stretch forming prevented by flame spraying layer of aluminum on edges held in stretch-forming machine. Technique improves grip of machine on metal and reinforced sheet better able to with stand concentration of force in vicinity of grips.

  2. Effect of Weight Percentage and Cutting Parameter on Surface Finish of SiC Reinforced Aluminium Composite

    NASA Astrophysics Data System (ADS)

    Kadadevaramath, R. S.; Kotresh, M. C.; Srinivasan, D.

    2016-09-01

    In the present work, aluminium alloy of series 1100 is selected as a matrix material and SiC of 45 microns as reinforcement. The composites are synthesized by 2 stage stir casting route, by varying a weight % of reinforcement from 6 % and 10%. The surface roughness of prepared composite were examined after plain turning operation. The machining parameters like speed, feed, DOC, SiC Wt. % are varied at 3 different levels. In order to minimize the time, cost and material a taguchi L9 orthogonal array was used for experiment. From the studies it was observed that the roughness value will increase with the increasing in reinforcement percentage.

  3. Acoustic emission from composite-reinforced metals

    NASA Technical Reports Server (NTRS)

    Henneke, E. G., II; Herakovich, C. T.; Jones, G. L.; Renieri, M. P.

    1975-01-01

    Acoustic-emission (AE) count rates are presented for tensile loading of unidirectional boron-epoxy and for aluminum sheets reinforced with unidirectional boron-epoxy. It is shown that different prepreg materials have different characteristic AE patterns. Results from composite-reinforced metal specimens show that early failures are accompanied by a sharp increase in AE count rate at the knee of the bilinear stress-strain diagram. It is further shown that the count rates are a function of specimen fabrication and that higher total counts do not necessarily correspond to early failures.

  4. The role of TiB2 in strengthening TiB2 reinforced aluminium casting composites

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Kang, H.; Zhao, Y.; Zheng, Y.; Wang, T.

    2016-03-01

    With an aim of developing high quality in situ TiB2 reinforced aluminium foundry alloy based composites, the conventional direct synthesis method was modified into a two-step route. In step one we optimized the halide salt route to fabricate in situ TiB2 particulate reinforced aluminium matrix composites and in step two we investigated the effects of the Al-5wt.% TiB2 composite, as a “master composite”, on strengthening the practical foundry alloys. The in situ formed TiB2 particles play two roles while strengthening the composites: (1) The grain refinement effect that improves the quality of the alloy matrix; and (2) The interactions between the hard particulates and the matrix add extra increment to the material strength. In different alloy systems, TiB2 may play distinct roles in these two aspects (figure 1). Further analysis of the strengthening mechanisms shows that particle agglomeration behaviour during solidification is responsible for the latter one. The present work details the role of TiB2 in strengthening TiB2 reinforced aluminium casting composites.

  5. Fatigue of continuous fiber reinforced metallic materials

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.; Mirdamadi, M.; Bakuckas, J. G., Jr.

    1993-01-01

    The complex damage mechanisms that occur in fiber reinforced advanced metallic materials are discussed. As examples, results for several layups of SCS-6/Ti-15-3 composites are presented. Fatigue tests were conducted and analyzed for both notched and unnotched specimens at room and elevated temperatures. Test conditions included isothermal, non-isothermal, and simulated mission profile thermomechanical fatigue. Test results indicated that the stress in the 0 degree fibers is the controlling factor for fatigue life for a given test condition. An effective strain approach is presented for predicting crack initiation at notches. Fiber bridging models were applied to crack growth behavior.

  6. Effect of aluminium metal on glutathione (GSH) level in plasma and cytosolic fraction of human blood.

    PubMed

    Khan, Haroon; Khan, M Farid; Jan, Syed Umer; Ullah, Naseem

    2011-01-01

    Aluminium is being used in the medicines in the form of antacids. The Aluminium metal can be leached from our utensils and can harm the body for its side effects, if become available to the systemic circulation. So it is important to check the effect of Aluminum on the Glutathione in vivo condition. Ellman method was used to determine the effect of Aluminum on GSH level in whole blood spectrophotometerically. 5,5-Dithiobis, 2-Nitrobenzoic Acid, Glutathione, Aluminium sulphate, phosphate buffer, HCl (Hydrochloric acid) and other laboratory instruments were used to conduct the research work. Time dependent effect of Aluminum on Glutathione level in whole blood was also checked and decrease was observed. This study also shows the effect of Aluminum as helping agent for the Glutathione to enhance the antioxidant system of the body or a cause for depletion of reduced Glutathione.

  7. Carbide-reinforced metal matrix composite by direct metal deposition

    NASA Astrophysics Data System (ADS)

    Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

    Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

  8. Preparation of SiC based Aluminium metal matrix nano composites by high intensity ultrasonic cavitation process and evaluation of mechanical and tribological properties

    NASA Astrophysics Data System (ADS)

    Murthy, N. V.; Prasad Reddy, A.; Selvaraj, N.; Rao, C. S. P.

    2016-09-01

    Request augments on a worldwide scale for the new materials. The metal matrix nano composites can be used in numerous applications of helicopter structural parts, gas turbine exit guide vane's, space shuttle, and other structural applications. The key mailman to ameliorate performance of composite matrix in aluminium alloy metal reinforces nano particles in the matrix of alloy uniformly, which ameliorates composite properties without affecting limit of ductility. The ultrasonic assisted stir casting helped agitation was successfully used to fabricate Al 2219 metal matrix of alloy reinforced with (0.5, 1, 1.5 and 2) wt.% of nano silicon carbide (SiC) particles of different sizes 50nm and 150nm. The micrographs of scanning electron microscopy of nano composite were investigated it reveals that the uniform dispersion of nano particles silicon carbide in aluminium alloy 2219 matrix and with the low porosity. How the specific wear rate was vary with increasing weight percentage of nano particles at constant load and speed as shown in results and discussions. And the mechanical properties showed that the ultimate tensile strength and hardness of metal matrix nano composite AA 2219 / nano SiC of 50nm and 150nm lean to augment with increase weight percentage of silicon carbide content in the matrix alloy.

  9. In situ study of the initiation of hydrogen bubbles at the aluminium metal/oxide interface.

    PubMed

    Xie, De-Gang; Wang, Zhang-Jie; Sun, Jun; Li, Ju; Ma, Evan; Shan, Zhi-Wei

    2015-09-01

    The presence of excess hydrogen at the interface between a metal substrate and a protective oxide can cause blistering and spallation of the scale. However, it remains unclear how nanoscale bubbles manage to reach the critical size in the first place. Here, we perform in situ environmental transmission electron microscopy experiments of the aluminium metal/oxide interface under hydrogen exposure. It is found that once the interface is weakened by hydrogen segregation, surface diffusion of Al atoms initiates the formation of faceted cavities on the metal side, driven by Wulff reconstruction. The morphology and growth rate of these cavities are highly sensitive to the crystallographic orientation of the aluminium substrate. Once the cavities grow to a critical size, the internal gas pressure can become great enough to blister the oxide layer. Our findings have implications for understanding hydrogen damage of interfaces.

  10. In situ study of the initiation of hydrogen bubbles at the aluminium metal/oxide interface

    NASA Astrophysics Data System (ADS)

    Xie, De-Gang; Wang, Zhang-Jie; Sun, Jun; Li, Ju; Ma, Evan; Shan, Zhi-Wei

    2015-09-01

    The presence of excess hydrogen at the interface between a metal substrate and a protective oxide can cause blistering and spallation of the scale. However, it remains unclear how nanoscale bubbles manage to reach the critical size in the first place. Here, we perform in situ environmental transmission electron microscopy experiments of the aluminium metal/oxide interface under hydrogen exposure. It is found that once the interface is weakened by hydrogen segregation, surface diffusion of Al atoms initiates the formation of faceted cavities on the metal side, driven by Wulff reconstruction. The morphology and growth rate of these cavities are highly sensitive to the crystallographic orientation of the aluminium substrate. Once the cavities grow to a critical size, the internal gas pressure can become great enough to blister the oxide layer. Our findings have implications for understanding hydrogen damage of interfaces.

  11. Metallized graphite as an improved cathode material for aluminium/air batteries

    NASA Astrophysics Data System (ADS)

    Mukherjee, Ambick; N. Basumallick, Indra

    1993-06-01

    This paper reports the fabrication of metallized (Pt, Ni, Cu, Fe, Co) graphite cathodes by an electrodeposition method from an appropriate electrolytic bath, together with the performance characteristics of specially-designed aluminium/air cells that utilize these cathodes. In these cells, the aluminium electrodes were separated by a glass-jacket separator. The latter prevents mixing of hydrogen gas evolved due to the corrosion of the aluminium electrode. While the open-circuit voltage of the cells is virtually invariant, the short-circuit current and discharge behaviour are markedly dependent upon the choice of catalytic metal. The discharge profiles are improved markedly for cells with a Pt-, Ni- or Cu-coated graphite air cathode, but the reverse is found for Fe- and Co-coated cathodes. The behaviour is explained in terms of chemisorption and the better catalytic activity of Pt, Ni and Cu. These results suggest that Ni- and Cu-coated graphite air cathodes are promising low-cost and efficiennt electrodes for aluminium/air batteries.

  12. Comparison of nickel silicide and aluminium ohmic contact metallizations for low-temperature quantum transport measurements

    PubMed Central

    2011-01-01

    We examine nickel silicide as a viable ohmic contact metallization for low-temperature, low-magnetic-field transport measurements of atomic-scale devices in silicon. In particular, we compare a nickel silicide metallization with aluminium, a common ohmic contact for silicon devices. Nickel silicide can be formed at the low temperatures (<400°C) required for maintaining atomic precision placement in donor-based devices, and it avoids the complications found with aluminium contacts which become superconducting at cryogenic measurement temperatures. Importantly, we show that the use of nickel silicide as an ohmic contact at low temperatures does not affect the thermal equilibration of carriers nor contribute to hysteresis in a magnetic field. PMID:21968083

  13. Aging effects of diamond reinforced aluminium alloys submitted to deep space real conditions. Structural, chemical and electrical degradation

    NASA Astrophysics Data System (ADS)

    Korneli, Grigorov; Bouzekova-Penkova, Anna; Datcheva, Maria; Avdeev, George; Grushin, Valerii; Klimov, Stanislav

    2016-07-01

    An aluminium alloy (Al-Cu-Zn-Mg) reinforced with ultra-dispersed diamond powder and tungsten (W), has been prepared in form of 7 cm bars and 4 mm diameter. One part of them stayed 2 years on satellite exposed to outer space, where the Sun activity and the background radiation were monitored. After satellite return both batches has been studied. Structural test, mainly micro-hardness together with detailed X-rays analyses was performed. The satellite makes a tour around the Earth each two hours, the temperature difference being circa 300oC. The micro-hardness being measured with Agilent G200 nano-indentor shows a significant drop of 25%. The XRD patterns are consistent with the previous results, states defects incorporation, and crystalline cells deterioration.

  14. Designing concrete EDS maglev guideways: Power losses in metallic reinforcement

    SciTech Connect

    Beto, D.; Plotkin, D.

    1997-05-01

    Conventional reinforced concrete designs will have to be altered when designing a guideway for a maglev using an electrodynamically suspended (EDS) propulsion system. This type of propulsion system generates large magnetic fields that will develop magnetically induced, circulating eddy currents in any conventional steel reinforcement in close proximity to the magnets. These eddy currents, if large enough, may produce significant power losses that could adversely effect operation of the system. This paper presents a method and explanation for civil engineers to use for estimating the power losses due to the presence of metallic reinforcement. This procedure may be used to help guide future designs in the selection and placement of reinforcing material.

  15. Iron and aluminium oxides containing industrial wastes as adsorbents of heavy metals: Application possibilities and limitations.

    PubMed

    Jacukowicz-Sobala, Irena; Ociński, Daniel; Kociołek-Balawejder, Elżbieta

    2015-07-01

    Industrial wastes with a high iron or aluminium oxide content are produced in huge quantities as by-products of water treatment (water treatment residuals), bauxite processing (red mud) and hard and brown coal burning in power plants (fly ash). Although they vary in their composition, the wastes have one thing in common--a high content of amorphous iron and/or aluminium oxides with a large specific surface area, whereby this group of wastes shows very good adsorbability towards heavy metals, arsenates, selenates, etc. But their physical form makes their utilisation quite difficult, since it is not easy to separate the spent sorbent from the solution and high bed hydraulic resistances occur in dynamic regime processes. Nevertheless, because of the potential benefits of utilising the wastes in industrial effluent treatment, this issue attracts much attention today. This study describes in detail the waste generation processes, the chemical structure of the wastes, their physicochemical properties, and the mechanisms of fixing heavy metals and semimetals on the surface of iron and aluminium oxides. Typical compositions of wastes generated in selected industrial plants are given. A detailed survey of the literature on the adsorption applications of the wastes, including methods of their thermal and chemical activation, as well as regeneration of the spent sorbents, is presented. The existing and potential ways of modifying the physical form of the discussed group of wastes, making it possible to overcome the basic limitation on their practical use, are discussed.

  16. Iron and aluminium oxides containing industrial wastes as adsorbents of heavy metals: Application possibilities and limitations.

    PubMed

    Jacukowicz-Sobala, Irena; Ociński, Daniel; Kociołek-Balawejder, Elżbieta

    2015-07-01

    Industrial wastes with a high iron or aluminium oxide content are produced in huge quantities as by-products of water treatment (water treatment residuals), bauxite processing (red mud) and hard and brown coal burning in power plants (fly ash). Although they vary in their composition, the wastes have one thing in common--a high content of amorphous iron and/or aluminium oxides with a large specific surface area, whereby this group of wastes shows very good adsorbability towards heavy metals, arsenates, selenates, etc. But their physical form makes their utilisation quite difficult, since it is not easy to separate the spent sorbent from the solution and high bed hydraulic resistances occur in dynamic regime processes. Nevertheless, because of the potential benefits of utilising the wastes in industrial effluent treatment, this issue attracts much attention today. This study describes in detail the waste generation processes, the chemical structure of the wastes, their physicochemical properties, and the mechanisms of fixing heavy metals and semimetals on the surface of iron and aluminium oxides. Typical compositions of wastes generated in selected industrial plants are given. A detailed survey of the literature on the adsorption applications of the wastes, including methods of their thermal and chemical activation, as well as regeneration of the spent sorbents, is presented. The existing and potential ways of modifying the physical form of the discussed group of wastes, making it possible to overcome the basic limitation on their practical use, are discussed. PMID:26060197

  17. Reinforcement of a mandibular complete denture with internal metal framework.

    PubMed

    Balch, J Heath; Smith, Pamela D; Marin, Mark A; Cagna, David R

    2013-03-01

    Metal framework reinforcement is used in complete dentures to improve the fracture resistance, dimensional stability, accuracy, weight, and retention of a definitive prosthesis. A novel technique for suspending a metal framework within the denture base of mandibular complete dentures is described.

  18. Macronutrients, aluminium from drinking water and foods, and other metals in cognitive decline and dementia.

    PubMed

    Solfrizzi, Vincenzo; Colacicco, Anna Maria; D'Introno, Alessia; Capurso, Cristiano; Parigi, Angelo Del; Capurso, Sabrina A; Torres, Francesco; Capurso, Antonio; Panza, Francesco

    2006-11-01

    A possible role of the macronutrients and the basic elements of carbohydrates (glucose administration or depletion), proteins (amino acids such as tryptophan and tyrosine), and fat (unsaturated fatty acids) was recently proposed for age-related changes of cognitive function, and the cognitive decline of degenerative (AD) or vascular origin. The availability and utilization of glucose has been implicated in cognitive function not only as a result of nutritional and systemic metabolic conditions, but also, although speculatively, as a crucial phase of the mechanism of action of molecules used as cognitive-enhancers. Furthermore, many lines of evidence have focused on the importance of oxidative stress mechanisms and free radical damage in AD pathogenesis. In addition, epidemiological studies have recently reported an association between alcohol and the incidence of AD and predementia syndromes. Foods with large amounts of aluminium-containing additives or aluminium from drinking water may affect the risk of developing AD, aluminium more likely acting as a cofactor somewhere in the cascade of events leading to the demented brain. A role for other metals in dementia have been speculated, given the encouraging results reported from studies on peripheral zinc concentrations, zinc supplementation, serum copper, either bound with ceruloplasmin or not, and iron metabolism in AD. Nonetheless, more data are needed to support a possible role of these metals in dementing diseases. Healthy diets, antioxidant supplements, and the prevention of nutritional deficiencies or exposure to foods and water with high content of metals could be considered the first line of defence against the development and progression of cognitive decline.

  19. Macronutrients, aluminium from drinking water and foods, and other metals in cognitive decline and dementia.

    PubMed

    Solfrizzi, Vincenzo; Colacicco, Anna Maria; D'Introno, Alessia; Capurso, Cristiano; Parigi, Angelo Del; Capurso, Sabrina A; Torres, Francesco; Capurso, Antonio; Panza, Francesco

    2006-11-01

    A possible role of the macronutrients and the basic elements of carbohydrates (glucose administration or depletion), proteins (amino acids such as tryptophan and tyrosine), and fat (unsaturated fatty acids) was recently proposed for age-related changes of cognitive function, and the cognitive decline of degenerative (AD) or vascular origin. The availability and utilization of glucose has been implicated in cognitive function not only as a result of nutritional and systemic metabolic conditions, but also, although speculatively, as a crucial phase of the mechanism of action of molecules used as cognitive-enhancers. Furthermore, many lines of evidence have focused on the importance of oxidative stress mechanisms and free radical damage in AD pathogenesis. In addition, epidemiological studies have recently reported an association between alcohol and the incidence of AD and predementia syndromes. Foods with large amounts of aluminium-containing additives or aluminium from drinking water may affect the risk of developing AD, aluminium more likely acting as a cofactor somewhere in the cascade of events leading to the demented brain. A role for other metals in dementia have been speculated, given the encouraging results reported from studies on peripheral zinc concentrations, zinc supplementation, serum copper, either bound with ceruloplasmin or not, and iron metabolism in AD. Nonetheless, more data are needed to support a possible role of these metals in dementing diseases. Healthy diets, antioxidant supplements, and the prevention of nutritional deficiencies or exposure to foods and water with high content of metals could be considered the first line of defence against the development and progression of cognitive decline. PMID:17119295

  20. The Potential of Aluminium Metal Powder as a Fuel for Space Propulsion Systems

    NASA Astrophysics Data System (ADS)

    Ismail, A. M.; Osborne, B.; Welch, C. S.

    Metal powder propulsion systems have been addressed intermittently since the Second World War, initially in the field of underwater propulsion where research in the application of propelling torpedoes continues until this day. During the post war era, researchers attempted to utilise metal powders as a fuel for ram jet applications in missiles. The 1960's and 1970's saw additional interest in the use of `pure powder' propellants, i.e. fluidised metal fuel and oxidiser, both in solid particulate form. Again the application was for employment in space-constrained missiles where the idea was to maximise the performance of high energy density powder propellants in order to enhance the missile's flight duration. Metal powder as possible fuel was investigated for in-situ resource utilisation propulsion systems post-1980's where the emphasis was on the use of gaseous oxygen or liquid oxygen combined with aluminium metal powder for use as a ``lunar soil propellant'' or carbon dioxide and magnesium metal powder as a ``Martian propellant''.Albeit aluminium metal powder propellants are lower in performance than cryogenic and Earth storable propellants, the former does have an advantage inasmuch that the propulsion system is generic, i.e. it can be powered with chemicals mined and processed on Earth, the Moon and Mars. Thus, due to the potential refuelling capability, the lower performing aluminium metal powder propellant would effectively possess a much higher change in velocity (V) for multiple missions than the cryogenic or Earth storable propellant which is only suitable for one planet or one mission scenario, respectively.One of the principal limitations of long duration human spaceflight beyond cis-lunar orbit is the lack of refuelling capabilities on distant planets resulting in the reliance on con- ventional non-cryogenic, propellants produced on Earth. If one could develop a reliable propulsion system operating on pro- pellants derived entirely of ingredients found on

  1. [Experimental evaluation of combined effects caused by stress and metals (cadmium and aluminium) in reproductivity of male rats].

    PubMed

    Makutina, V A; Balezin, S L; Slyshkina, T V; Pashnina, I A; Likhacheva, E I

    2014-01-01

    To investigate combined effects of stress and metal (aluminium, cadmium) on reproductivity, male rats twice per week received intraperitoneal injections of aluminium (3.8 mg Al3+ per kg of body weight) or cadmium (0.3 mg Cd2+ per kg of body weight) and were subjected to stress via short-term immobilization during spermatogenic cycle (54 +/- 3 days). Findings are cumulation of both cadmium and aluminium in genitals and brain, increasing under stress. When acting separately to the laboratory animals, the three factors (aluminium/cadmium/stress) increase serum corticosterone level, change testosterone level, increase number of aberrant mitoses of spermatogenic epithelium cells, increased sperm count with fragmented DNA, lower percentage of the impregnated females. If the exposure combined with stress, spermatogenesis disorders are more marked, and preimplantation death rate of intact females' offspirngs becomes statistically significant.

  2. Fatigue evaluation of composite-reinforced, integrally stiffened metal panels

    NASA Technical Reports Server (NTRS)

    Dumesnil, C. E.

    1973-01-01

    The fatigue behavior of composite-reinforced, integrally stiffened metal panels was investigated in combined metal and composite materials subjected to fatigue loading. The systems investigated were aluminum-graphite/epoxy, and aluminum-S glass/epoxy. It was found that the composite material would support the total load at limit stress after the metal had completely failed, and the weight of the composite-metal system would be equal to that of an all metal system which would carry the same total load at limit stress.

  3. Microbial interactions with aluminium.

    PubMed

    Piña, R G; Cervantes, C

    1996-07-01

    Although aluminium is the most abundant metal in the Earth's crust, it lacks biological functions and shows a low bioavailability. Acid rain, however, solubilizes aluminium to toxic levels. Most research on the biological effects of aluminium has been centred on the analysis of aluminium-tolerant plants as well as its possible relationship with neurological disorders in humans. Also, several studies have been reported concerning aluminium effects on microorganisms, with more interest directed to cyanobacteria, soil bacteria and mycorrhizal fungi. Competition with iron and magnesium, and binding to DNA, membranes or cell walls are considered the main toxic effects of aluminium in microbes.

  4. Scanning and transmission electron microscopy study of the microstructural changes occurring in aluminium matrix composites reinforced with SiC particles during casting and welding: interface reactions

    PubMed

    Urena; Gomez De Salazar JM; Gil; Escalera; Baldonedo

    1999-11-01

    Processing of aluminium matrix composites (AMCs), especially those constituted by a reactive system such as Al-SiC, presents great difficulties which limit their potential applications. The interface reactivity between SiC and molten Al generates an aluminium carbide which degrades the composite properties. Scanning and transmission electron microscopes equipped with energy-dispersive X-ray spectroscopes are essential tools for determining the structure and chemistry of the Al-SiC interfaces in AMCs and changes occurring during casting and arc welding. In the present work, an aluminium-copper alloy (AA2014) reinforced with three different percentages of SiC particles was subjected to controlled remelting tests, at temperatures in the range 750-900 degrees C for 10 and 30 min. Arc welding tests using a tungsten intert gas with power inputs in the range 850-2000 W were also carried out. The results of these studies showed that during remelting there is preferential SiC particle consumption with formation of Al4C3 by interface reaction between the solid SiC particle and the molten aluminium matrix. The formation of Al4C3 by the same mechanism has also been detected in molten pools of arc welded composites. However, in this case there was formation of an almost continuous layer of Al4C3, which protects the particle against further consumption, and formation of aciculate aluminium carbide on the top weld. Both are formed by fusion and dissolution of the SiC in molten aluminium followed by reaction and precipitation of the Al4C3 during cooling.

  5. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, Suri A.; Pemsler, J. Paul; Cooke, Richard A.; Litchfield, John K.; Smith, Mark B.

    1996-01-01

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates.

  6. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, S.A.; Pemsler, J.P.; Cooke, R.A.; Litchfield, J.K.; Smith, M.B.

    1996-03-05

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates. 2 figs.

  7. Fracture criteria for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.; Goree, J. G.; Albritton, J.; Ratnarparkhi, P.

    1988-01-01

    The effect of sample configuration on the details of initial crack propagation in discontinuously whisker reinforced aluminum metal matrix composites was investigated. Care was taken to allow direct comparison of fracture toughness values utilizing differing sample configurations and orientations, holding all materials variables constant, e.g., extrusion ration, heat treatment, and chemistry.

  8. Fracture criteria for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.; Goree, J. G.; Albritton, J.; Ratnaparkhi, P.

    1988-01-01

    Summarized is the progress achieved during the period September 16, 1987 to August 15, l988 on NASA Grant NAG1-724, Fracture Criteria for Discontinuously Reinforced Metal Matrix Composites. Appended are copies of three manuscripts prepared under NASA funding during the performance period.

  9. Design Guide for glass fiber reinforced metal pressure vessel

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1973-01-01

    Design Guide has been prepared for pressure vessel engineers concerned with specific glass fiber reinforced metal tank design or general tank tradeoff study. Design philosophy, general equations, and curves are provided for safelife design of tanks operating under anticipated space shuttle service conditions.

  10. Development and characterization of fatigue resistant Aramid reinforced aluminium laminates (ARALL) for fatigue Critical aircraft components

    NASA Astrophysics Data System (ADS)

    Qaiser, M. H.; Umar, S.; Nauman, S.

    2014-06-01

    The structural weight of an aircraft has always been a controlling parameter that governs its fuel efficiency and transport capacity. In pursuit of achieving light-weight aircraft structures, high design stress levels have to be adopted and materials with high specific strength such as Aluminum etc. are to be deployed. However, an extensive spectrum of fatigue load exists at the aircraft wings and other aerodynamic components that may cause initiation and propagation of fatigue cracks and concludes in a catastrophic rupture. Fatigue is therefore the limiting design parameter in such cases and materials with high fatigue resistance are then required. A major improvement in the fatigue behavior was observed by laminating Kevlar fibers with Aluminum using epoxy. ARALL (Aramid Reinforced ALuminum Laminates) is a fatigue resistant hybrid composite that consists of layers of thin high strength aluminum alloy sheets surface bonded with aramid fibers. The intact aramid fibers tie up the fatigue cracks, thus reducing the stress intensity factor at the crack tip as a result of which the fatigue properties of can be enhanced with orders of magnitude as compared to monolithic high strength Aluminum alloy sheets. Significant amount of weight savings can be achieved in fatigue critical components in comparison with the traditional materials used in aircraft.

  11. The assessment of metal fiber reinforced polymeric composites

    NASA Technical Reports Server (NTRS)

    Chung, Wenchiang R.

    1990-01-01

    Because of their low cost, excellent electrical conductivity, high specific strength (strength/density), and high specific modulus (modulus/density) short metal fiber reinforced composites have enjoyed a widespread use in many critical applications such as automotive industry, aircraft manufacturing, national defense, and space technology. However, little data has been found in the study of short metal fibrous composites. Optimum fiber concentration in a resin matrix and fiber aspect ratio (length-to-diameter ratio) are often not available to a user. Stress concentration at short fiber ends is the other concern when the composite is applied to a load-bearing application. Fracture in such composites where the damage will be initiated or accumulated is usually difficult to be determined. An experimental investigation is therefore carefully designed and undertaken to systematically evaluate the mechanical properties as well as electrical properties. Inconel 601 (nickel based) metal fiber with a diameter of eight microns is used to reinforce commercially available thermoset polyester resin. Mechanical testing such as tensile, impact, and flexure tests along with electrical conductivity measurements is conducted to study the feasibility of using such composites. The advantages and limitations of applying chopped metal fiber reinforced polymeric composites are also discussed.

  12. Molecular promoting of aluminium metal-organic framework topology MIL-101 by N,N - dimethylformamide

    PubMed Central

    Goesten, Maarten G.; Magusin, Pieter C.M.M; Pidko, Evgeny A.; Mezari, Brahim; Hensen, Emiel J.M.; Kapteijn, Freek; Gascon, Jorge

    2014-01-01

    In-situ NMR and DFT modelling demonstrate that N,N-dimethylformamide (DMF) promotes the formation of metal-organic framework NH2-MIL-101(Al). In-situ NMR studies show that upon dissociation of an aluminium-coordinated aqua ligand in NH2-MOF-235(Al), DMF forms an HCl-DMF complex during synthesis. This reaction induces a transformation from the MOF-235 topology into the MIL-101 topology. Electronic Structure Density Functional Theory (DFT) calculations show that the use of DMF instead of water as synthesis solvent decreases the energy gap between the kinetically favored MIL-101 and the thermodynamically favored MIL-53 products. DMF therefore promotes the MIL-101 topology both kinetically and thermodynamically. PMID:24405155

  13. The effect of exposure to aluminium on concentrations of essential metals in serum of foundry workers.

    PubMed Central

    Röllin, H B; Theodorou, P; Kilroe-Smith, T A

    1991-01-01

    The concentrations of aluminium (Al) in serum and urine of 33 volunteers exposed to inhalation of Al2O3 dust at a concentration in the air of less than 1 mg Al/m3 were measured. These were compared with results from 20 normal subjects not exposed. The concentrations of copper (Cu), zinc (Zn), and total iron (Fe) in serum were also measured. The Al concentration in serum was significantly raised in the subjects exposed to dust, but Al concentrations in urine showed no significant difference from controls. This suggests a possible change in distribution of metals in the body tissues due to the presence of Al, with incomplete excretion of Al in the urine. This redistribution was selective, as the serum concentrations of Cu were conclusively decreased whereas the serum concentrations of Zn were conclusively increased. The serum concentration of Fe did not change significantly. PMID:2025590

  14. Bone response to a titanium aluminium nitride coating on metallic implants.

    PubMed

    Freeman, C O; Brook, I M

    2006-05-01

    The design, surface characteristics and strength of metallic implants are dependant on their intended use and clinical application. Surface modifications of materials may enable reduction of the time taken for osseointegration and improve the biological response of bio-mechanically favourable metals and alloys. The influence of a titanium aluminium nitride (TAN) coating on the response of bone to commercially pure titanium and austenitic 18/8 stainless steel wire is reported. TAN coated and plain rods of stainless steel and commercially pure titanium were implanted into the mid-shaft of the femur of Wistar rats. The femurs were harvested at four weeks and processed for scanning electron and light microscopy. All implants exhibited a favourable response in bone with no evidence of fibrous encapsulation. There was no significant difference in the amount of new bone formed around the different rods (osseoconduction), however, there was a greater degree of shrinkage separation of bone from the coated rods than from the plain rods (p = 0.017 stainless steel and p = 0.0085 titanium). TAN coating may result in reduced osseointegration between bone and implant.

  15. Performance Enhancement Using Selective Reinforcement for Metallic Single- and Multi-Pin Loaded Holes

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Seshadri, Banavara R.

    2005-01-01

    An analysis based investigation of aluminum with metal matrix composite selectively reinforced single- and multi-hole specimens was performed and their results compared with results from geometrically comparable non-reinforced specimens. All reinforced specimens exhibited a significant increase in performance. Performance increase of up to 170 percent was achieved. Specimen failure modes were consistent with results from reinforced polymeric matrix composite specimens. Localized reinforcement application (circular) proved as effective as a broader area (strip) reinforcement. Also, selective reinforcement is an excellent method of increasing the performance of multi-hole specimens.

  16. Processing and mechanical properties of aluminium-silicon carbide metal matrix composites

    NASA Astrophysics Data System (ADS)

    Nuruzzaman, D. M.; Kamaruzaman, F. F. B.

    2016-02-01

    In this study, aluminium-silicon carbide (Al-SiC) metal matrix composites (MMCs) of different compositions were prepared under different compaction loads. Three different types Al-SiC composite specimens having 10%, 20% and 30% volume fractions of silicon carbide were fabricated using conventional powder metallurgy (PM) route. The specimens of different compositions were prepared under different compaction loads 10 ton and 15 ton. The effect of volume fraction of SiC particulates and compaction load on the properties of Al/SiC composites were investigated. The obtained results show that density and hardness of the composites are greatly influenced by volume fraction of silicon carbide particulates. Results also show that density, hardness and microstructure of Al-SiC composites are significantly influenced depending on the compaction load. The increase in the volume fraction of SiC enhances the density and hardness of the Al/SiC composites. For 15 ton compaction load, the composites show increased density and hardness as well as improved microstructure than the composites prepared under 10 ton compaction load. Furthermore, optical micrographs reveal that SiC particulates are uniformly distributed in the Al matrix.

  17. Aluminium fumarate metal-organic framework: A super adsorbent for fluoride from water.

    PubMed

    Karmakar, Sankha; Dechnik, Janina; Janiak, Christoph; De, Sirshendu

    2016-02-13

    Potential of aluminium fumarate metal organic framework (MOF) for fluoride removal from groundwater has been explored in this work. The laboratory produced MOF exhibited characteristics similar to the commercial version. MOF was found to be micro-porous with surface area of 1156 m(2)/g and average pore size 17Å. Scanning electron micrograph of the AlFu MOF showed minute pores and texture was completely different from either of the parent materials. Change in the composition of AlFu MOF after fluoride adsorption was evident from powder X-ray diffraction analysis. Thermal stability of the AlFu MOF up to 700K was established by thermo-gravimetric analysis. Incorporation of fluoride phase after adsorption was confirmed by X-ray fluorescence analysis. As observed from FTIR study, hydroxyl ions in AlFu MOF were substituted by fluoride. 0.75 g/l AlFu MOF was good enough for complete removal of 30 mg/l fluoride concentration in feed solution. The maximum adsorption capacity for fluoride was 600, 550, 504 and 431 mg/g, respectively, at 293, 303, 313 and 333K. PMID:26513559

  18. Effect of Reinforcement Architecture on Fracture of Selectively Reinforced Metallic Compact Tension Specimens

    NASA Technical Reports Server (NTRS)

    Abada, Christopher H.; Farley, Gary L.; Hyer, Michael W.

    2006-01-01

    A computer-based parametric study of the effect of reinforcement architectures on fracture response of aluminum compact-tension (CT) specimens is performed. Eleven different reinforcement architectures consisting of rectangular and triangular cross-section reinforcements were evaluated. Reinforced specimens produced between 13 and 28 percent higher fracture load than achieved with the non-reinforced case. Reinforcements with blunt leading edges (rectangular reinforcements) exhibited superior performance relative to the triangular reinforcements with sharp leading edges. Relative to the rectangular reinforcements, the most important architectural feature was reinforcement thickness. At failure, the reinforcements carried between 58 and 85 percent of the load applied to the specimen, suggesting that there is considerable load transfer between the base material and the reinforcement.

  19. Glass Fiber Reinforced Metal Pressure Vessel Design Guide

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1972-01-01

    The Engineering Guide presents curves and general equations for safelife design of lightweight glass fiber reinforced (GFR) metal pressure vessels operating under anticipated Space Shuttle service conditions. The high composite vessel weight efficiency is shown to be relatively insensitive to shape, providing increased flexibility to designers establishing spacecraft configurations. Spheres, oblate speroids, and cylinders constructed of GFR Inconel X-750, 2219-T62 aluminum, and cryoformed 301 stainless steel are covered; design parameters and performance efficiencies for each configuration are compared at ambient and cryogenic temperature for an operating pressure range of 690 to 2760 N/sq cm (1000 to 4000 psi). Design variables are presented as a function of metal shell operating to sizing (proof) stress ratios for use with fracture mechanics data generated under a separate task of this program.

  20. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, T. L.

    1989-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared on a strength to density basis. The effect of fiber orientation on the creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  1. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni L.

    1992-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  2. Decrements in cognitive performance in metal inert gas welders exposed to aluminium

    PubMed Central

    Akila, R.; Stollery, B. T.; Riihimaki, V.

    1999-01-01

    OBJECTIVES: Often little has been discovered of the cognitive functions affected by occupational toxins because many functions cooperate to produce the single performance scores typically reported from neuropsychological tests. To facilitate the interpretation of neuropsychological scores, the issue of occupational exposure to aluminium was examined with an approach intended to increase understanding of those cognitive processes that may be affected. METHODS: The investigation was a cross sectional study of asymptomatic aluminium welders and a reference group of mild steel welders. Based on urinary aluminium concentrations, welders were classified into a reference (n = 28), low (n = 27), and high (n = 24) exposure group. The mean urinary aluminium concentrations were 0.46, 2.25, and 9.98 mumol/l, respectively. A comprehensive neuropsychological examination was undertaken to assess psychomotor function, simple visual reaction time, attention related tasks, verbal and visual or visuospatial abilities as well as verbal and visual learning and memory. RESULTS: Aluminium welders showed no impairment on the finger tapping, Santa Ana dexterity, simple visual reaction times, any of the verbal memory tasks, the similarities subtest of Wechsler adult intelligence scale, or the Stroop task. However, the low exposed group performed poorer on the memory for designs and on more difficult block design items demanding preliminary visuospatial analysis. The time limited synonym task, embedded figures, digit symbol speed, and the backward counting component of the divided attention task showed exposure-response relations. CONCLUSIONS: The impairments found were circumscribed. When the neuropsychological tasks were scored to show some of the underlying theoretical cognitive structures, the results indicated that performance difficulties were mainly detected in tasks requiring working memory, particularly that relating to processing of visuospatial information. There was also evidence

  3. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    PubMed

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  4. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    PubMed

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  5. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    PubMed Central

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  6. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-04-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  7. Turning aluminium into a noble-metal-like catalyst for low-temperature activation of molecular hydrogen.

    PubMed

    Chopra, Irinder S; Chaudhuri, Santanu; Veyan, Jean François; Chabal, Yves J

    2011-11-01

    Activation of molecular hydrogen is the first step in producing many important industrial chemicals that have so far required expensive noble-metal catalysts and thermal activation. We demonstrate here that aluminium doped with very small amounts of titanium can activate molecular hydrogen at temperatures as low as 90 K. Using an approach that uses CO as a probe molecule, we identify the atomistic arrangement of the catalytically active sites containing Ti on Al(111) surfaces, combining infrared reflection-absorption spectroscopy and first-principles modelling. CO molecules, selectively adsorbed on catalytically active sites, form a complex with activated hydrogen that is removed at remarkably low temperatures (115 K; possibly as a molecule). These results provide the first direct evidence that Ti-doped Al can carry out the essential first step of molecular hydrogen activation under nearly barrierless conditions, thereby challenging the monopoly of noble metals in hydrogen activation. PMID:21946610

  8. The toxicity of aluminium in humans.

    PubMed

    Exley, C

    2016-06-01

    We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored. PMID:26922890

  9. The toxicity of aluminium in humans.

    PubMed

    Exley, C

    2016-06-01

    We are living in the 'aluminium age'. Human exposure to aluminium is inevitable and, perhaps, inestimable. Aluminium's free metal cation, Alaq(3+), is highly biologically reactive and biologically available aluminium is non-essential and essentially toxic. Biologically reactive aluminium is present throughout the human body and while, rarely, it can be acutely toxic, much less is understood about chronic aluminium intoxication. Herein the question is asked as to how to diagnose aluminium toxicity in an individual. While there are as yet, no unequivocal answers to this problem, there are procedures to follow to ascertain the nature of human exposure to aluminium. It is also important to recognise critical factors in exposure regimes and specifically that not all forms of aluminium are toxicologically equivalent and not all routes of exposure are equivalent in their delivery of aluminium to target sites. To ascertain if Alzheimer's disease is a symptom of chronic aluminium intoxication over decades or breast cancer is aggravated by the topical application of an aluminium salt or if autism could result from an immune cascade initiated by an aluminium adjuvant requires that each of these is considered independently and in the light of the most up to date scientific evidence. The aluminium age has taught us that there are no inevitabilities where chronic aluminium toxicity is concerned though there are clear possibilities and these require proving or discounting but not simply ignored.

  10. Cytoskeletal alterations in interphase cells of the green alga Spirogyra decimina in response to heavy metals exposure: II. The effect of aluminium, nickel and copper.

    PubMed

    Pribyl, Pavel; Cepák, Vladislav; Zachleder, Vilém

    2008-08-01

    The effect of the toxic metal ions, aluminium (Al3+), nickel (Ni2+), and copper (Cu2+), on both the actin and tubulin cytoskeleton of the green alga Spirogyra decimina was studied. Batch cultured cells were grown for different time intervals at concentrations of 10, 15, 40 and 100 microM of aluminium as AlCl3, nickel as NiCl2 and copper as CuSO(4).5H2O. The impact of copper on the morphology of both MTs and AFs was much more prominent than the other two metals. A rapid irreversible depolymerization of cytoskeletal structures occurred, whereas in the presence of aluminium or nickel, changes in the cytoskeleton were slight and reversible to some extent. Nickel changed the orientation of cortical MTs, which turned from a transverse to a skewed or longitudinal direction. Aluminium caused slight depolymerization of the cytoskeleton, which reverted spontaneously to the normal cytoskeletal state (in AlCl3 free nutrient solution). Copper exerted a strong effect on both the MT and AF cytoskeleton, which fragmented and disorganized rapidly. The extent of cytoskeletal damage by copper was dosage and time dependent and AFs were slightly more sensitive than MTs. PMID:18440197

  11. Cytoskeletal alterations in interphase cells of the green alga Spirogyra decimina in response to heavy metals exposure: II. The effect of aluminium, nickel and copper.

    PubMed

    Pribyl, Pavel; Cepák, Vladislav; Zachleder, Vilém

    2008-08-01

    The effect of the toxic metal ions, aluminium (Al3+), nickel (Ni2+), and copper (Cu2+), on both the actin and tubulin cytoskeleton of the green alga Spirogyra decimina was studied. Batch cultured cells were grown for different time intervals at concentrations of 10, 15, 40 and 100 microM of aluminium as AlCl3, nickel as NiCl2 and copper as CuSO(4).5H2O. The impact of copper on the morphology of both MTs and AFs was much more prominent than the other two metals. A rapid irreversible depolymerization of cytoskeletal structures occurred, whereas in the presence of aluminium or nickel, changes in the cytoskeleton were slight and reversible to some extent. Nickel changed the orientation of cortical MTs, which turned from a transverse to a skewed or longitudinal direction. Aluminium caused slight depolymerization of the cytoskeleton, which reverted spontaneously to the normal cytoskeletal state (in AlCl3 free nutrient solution). Copper exerted a strong effect on both the MT and AF cytoskeleton, which fragmented and disorganized rapidly. The extent of cytoskeletal damage by copper was dosage and time dependent and AFs were slightly more sensitive than MTs.

  12. Selective Reinforcement to Enhance the Structural Performance of Metallic Compression Panels

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    2004-01-01

    An experimental and analytical investigation of the influence of selective reinforcement on metallic panels with cutouts was conducted. Selective reinforcement was shown to be a weight effective concept for increasing structural performance of panels with cutouts designed to carry loads into the post-buckled regime. For instance, a selectively reinforced aluminum panel under shear load exhibited a 68 percent increase in specific-buckling load as compared to a geometrically comparable unreinforced aluminum panel. In comparison, a quasi-isotropic carbon-fiber-reinforced-polymer composite panel only produced a 45 percent higher specific-buckling load than the same unreinforced aluminum panel. Selective reinforcement offers the potential to tailor structural response through local strengthening and stiffening the structure for a broad range of structural application.

  13. Fracture Analysis of Particulate Reinforced Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Min, James B.; Cornie, James A.

    2013-01-01

    A fracture analysis of highly loaded particulate reinforced composites was performed using laser moire interferometry to measure the displacements within the plastic zone at the tip of an advancing crack. Ten castings were made of five different particulate reinforcement-aluminum alloy combinations. Each casting included net-shape specimens which were used for the evaluation of fracture toughness, tensile properties, and flexure properties resulting in an extensive materials properties data. Measured fracture toughness range from 14.1 MPa for an alumina reinforced 356 aluminum alloy to 23.9 MPa for a silicon carbide reinforced 2214 aluminum alloy. For the combination of these K(sub Ic) values and the measured tensile strengths, the compact tension specimens were too thin to yield true plane strain K(sub Ic) values. All materials exhibited brittle behavior characterized by very small tensile ductility suggesting that successful application of these materials requires that the design stresses be below the elastic limit. Probabilistic design principles similar to those used with ceramics are recommended when using these materials. Such principles would include the use of experimentally determined design allowables. In the absence of thorough testing, a design allowable stress of 60 percent of the measured ultimate tensile stress is recommended.

  14. Al-based metal matrix composites reinforced with nanocrystalline Al-Ti-Ni particles

    NASA Astrophysics Data System (ADS)

    Scudino, S.; Ali, F.; Surreddi, K. B.; Prashanth, K. G.; Sakaliyska, M.; Eckert, J.

    2010-07-01

    Al-based metal matrix composites containing different volume fractions of nanocrystalline Al70Ti20Ni10 reinforcing particles have been produced by powder metallurgy and the effect of the volume fraction of reinforcement on the mechanical properties of the composites has been studied. Room temperature compression tests reveal a considerable improvement of the mechanical properties as compared to pure Aluminum. The compressive strength increases from 155 MPa for pure Al to about 200 and 240 MPa for the samples with 20 and 40 vol.% of reinforcement, respectively, while retaining appreciable plastic deformation with a fracture strain ranging between 43 and 28 %.

  15. Method of making metal matrix composites reinforced with ceramic particulates

    DOEpatents

    Cornie, James A.; Kattamis, Theodoulos; Chambers, Brent V.; Bond, Bruce E.; Varela, Raul H.

    1989-01-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

  16. Method of making metal matrix composites reinforced with ceramic particulates

    DOEpatents

    Cornie, J.A.; Kattamis, T.; Chambers, B.V.; Bond, B.E.; Varela, R.H.

    1989-08-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys. 2 figs.

  17. Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

    NASA Technical Reports Server (NTRS)

    Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

    1990-01-01

    A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

  18. Microgravity processing of particulate reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Morel, Donald E.; Stefanescu, Doru M.; Curreri, Peter A.

    1989-01-01

    The elimination of such gravity-related effects as buoyancy-driven sedimentation can yield more homogeneous microstructures in composite materials whose individual constituents have widely differing densities. A comparison of composite samples consisting of particulate ceramics in a nickel aluminide matrix solidified under gravity levels ranging from 0.01 to 1.8 G indicates that the G force normal to the growth direction plays a fundamental role in determining the distribution of the reinforcement in the matrix. Composites with extremely uniform microstructures can be produced by these methods.

  19. Assessment of the biological effects of welding fumes emitted from metal inert gas welding processes of aluminium and zinc-plated materials in humans.

    PubMed

    Hartmann, L; Bauer, M; Bertram, J; Gube, M; Lenz, K; Reisgen, U; Schettgen, T; Kraus, T; Brand, P

    2014-03-01

    The aim of this study was to investigate biological effects and potential health risks due to two different metal-inert-gas (MIG) welding fumes (MIG welding of aluminium and MIG soldering of zinc coated steel) in healthy humans. In a threefold cross-over design study 12 male subjects were exposed to three different exposure scenarios. Exposures were performed under controlled conditions in the Aachener Workplace Simulation Laboratory (AWSL). On three different days the subjects were either exposed to filtered ambient air, to welding fumes from MIG welding of aluminium, or to fumes from MIG soldering of zinc coated materials. Exposure was performed for 6 h and the average fume concentration was 2.5 mg m(-3). Before, directly after, 1 day after, and 7 days after exposure spirometric and impulse oscillometric measurements were performed, exhaled breath condensate (EBC) was collected and blood samples were taken and analyzed for inflammatory markers. During MIG welding of aluminium high ozone concentrations (up to 250 μg m(-3)) were observed, whereas ozone was negligible for MIG soldering. For MIG soldering, concentrations of high-sensitivity CRP (hsCRP) and factor VIII were significantly increased but remained mostly within the normal range. The concentration of neutrophils increased in tendency. For MIG welding of aluminium, the lung function showed significant decreases in Peak Expiratory Flow (PEF) and Mean Expiratory Flow at 75% vital capacity (MEF 75) 7 days after exposure. The concentration of ristocetin cofactor was increased. The observed increase of hsCRP during MIG-soldering can be understood as an indicator for asymptomatic systemic inflammation probably due to zinc (zinc concentration 1.5 mg m(-3)). The change in lung function observed after MIG welding of aluminium may be attributed to ozone inhalation, although the late response (7 days after exposure) is surprising.

  20. Occupational asthma caused by aluminium welding.

    PubMed

    Vandenplas, O; Delwiche, J P; Vanbilsen, M L; Joly, J; Roosels, D

    1998-05-01

    Work-related asthma has been documented in workers employed in the primary aluminium industry and in the production of aluminium salts. The role of aluminium in the development of occupational asthma has, however, never been convincingly substantiated. We investigated a subject who experienced asthmatic reactions related to manual metal arc welding on aluminium. Challenge exposure to aluminium welding with flux-coated electrodes, as well as with electrodes without flux, elicited marked asthmatic reactions. Manual metal arc welding on mild steel did not cause significant bronchial response. The results of inhalation challenges combined with exposure assessments provided evidence that aluminium can cause asthmatic reactions in the absence of fluorides. Awareness of this possibility may be relevant to the investigation of asthma in workers exposed to aluminium. PMID:9648975

  1. Stabilising metal(loid)s in soil with iron and aluminium-based products: microbial, biochemical and plant growth impact.

    PubMed

    Garau, Giovanni; Silvetti, Margherita; Castaldi, Paola; Mele, Elena; Deiana, Pietrino; Deiana, Salvatore

    2014-06-15

    Four iron and aluminium-based products, including red mud (RM), hematite (Fe2O3), an iron-rich water treatment residual (Fe-WTR) and amorphous Al hydroxide (Al-OH), were evaluated for their effectiveness at stabilising As and heavy metals (i.e. Cd, Cu, Pb, Zn) in a circumneutral contaminated soil [As (2105 mg kg(-1)), Cd (18 mg kg(-1)), Cu (264 mg kg(-1)), Pb (710 mg kg(-1)), Zn (522 mg kg(-1))]. Treatment impacts on soil microbial and biochemical features (i.e. microbial biomass-C, microbial counts, 16S rRNA PCR-TTGE of culturable bacteria, dehydrogenase, urease and β-glucosidase activity, Biolog derived parameters-AWCD and richness) as well as bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth were also assessed. After 6 months equilibration, all the amendments (application rate 3% w/w) but RM reduced labile As while only Al-OH reduced the concentration of water-soluble heavy metals. Despite the highest bioavailability of contaminants, most of the soil microbial and biochemical features monitored (i.e. microbial biomass-C, total bacterial counts, dehydrogenase activity and AWCD) were significantly higher in the RM-soil. Bean germination was completely inhibited in RM-soil while wheat growth was similar to that of the control. The Al-OH treatment was best overall, promoting microbial abundance, diversity and activity while increasing bean and wheat growth and reducing As accumulated in plant shoots. Results suggest that Al-OH is a suitable candidate for field evaluations while the use of RM in the remediation of circumneutral or subalkaline contaminated soils should be reconsidered. PMID:24685456

  2. Management of a Large Internal Resorption Lesion with Metal Reinforced Glass Ionomer Cement

    PubMed Central

    Bhuyan, Atool Chandra; Arora, Suraj; Sethi, Kunal; Kalra, Tarun

    2014-01-01

    Mineral trioxide aggregate is the mainstay of treatment of large internal resorption defects. But its cost may be a deterrent to its use in some patients. The present case report describes the successful endodontic management of an extensive internal resorptive lesion in a mandibular molar with metal reinforced glass ionomer cement. PMID:25436156

  3. An In Vitro Comparative Evaluation of Fracture Resistance of Custom Made, Metal, Glass Fiber Reinforced and Carbon Reinforced Posts in Endodontically Treated Teeth

    PubMed Central

    Sonkesriya, Subhash; Olekar, Santosh T; Saravanan, V; Somasunderam, P; Chauhan, Rashmi Singh; Chaurasia, Vishwajit Rampratap

    2015-01-01

    Background: Posts are used to enhance crown buildup in pulpless teeth with destructed crown portion. Different types of post are used in endodontically treated teeth. The aim of the present in vitro study was to evaluate fracture resistance of custom made, metal, glass fiber reinforced and carbon reinforced posts in endodontically treated teeth. Materials and Methods: An in vitro study was carried out on extracted 40 human maxillary central incisor teeth, which was divided into four groups with 10 samples in each group with custom made, metal post, glass fiber reinforced, and carbon reinforced posts. The samples were decoronated at cemento-enamel junction and endodontically treated. Post space was prepared and selected posts were cemented. The composite cores were prepared at the height of 5 mm and samples mounted on acrylic blocks. Later fracture resistance to the compressive force of samples was measured using Universal Testing Machine. Results: The maximum resistance to the compressive force was observed in carbon reinforced and glass fiber reinforced posts compared others which is statistically significant (P > 0.001) and least was seen in custom fabricated post. Conclusion: It is concluded that carbon reinforced fiber post and glass fiber posts showed good fracture resistance compared to custom made and metal posts. PMID:26028904

  4. Usinage des composites a matrice d'alliage d'aluminium GrA-Ni(Reg)

    NASA Astrophysics Data System (ADS)

    Songmene, Victor

    2001-07-01

    Aluminium Metal Matrix Composites (MMC) reinforced with ceramic particles have been increasingly developed during the last decade. Ceramic particles used as reinforcement that improve the wear resistance of composites also cause high abrasive wear on cutting tools. This thesis investigates the machinability of graphitic MMC consisting of an aluminium alloy matrix reinforced with both soft nickel-coated graphite particles and hard (SiC or Al2O 3) particles. These composites were developed seven years ago, but the lack of optimised machining data to machine GrA-NIRTM composites cost effectively have been slowing down their use in engineering applications. Turning, milling and drilling tests were performed to evaluate the machinability of different GrA-NIRTM and to establish cutting conditions. It was found that: (1) The machinability of GrA-NiRTM composites depends on the nature and the percentage of the reinforcing particles. GrA-NiRTM containing alumina and graphite are easier to machine than those reinforced with silicon carbide and graphite. (2) Polycrystalline (PCD) and diamond-coated carbide (DCC) are the tool material of choice for machining GrA-NiRTM. DCC tools are most cost effective while PCD tools produce better part finishes. (3) The cutting force required to machine the GrA-NIRTM composites is similar to that used for aluminium alloys such as Al 380.

  5. Toxic Aluminium and Heavy Metals in Groundwater of Middle Russia: Health Risk Assessment

    PubMed Central

    Momot, Olga; Synzynys, Boris

    2005-01-01

    Two approaches are distinguished in modern ecological monitoring. The first one is physicochemical analysis of environmental objects with respect to maximum allowable concentrations (MACs) of chemical substances, which is performed by standards methods in accordance with state regulations. The second approach (biological monitoring) is based on the methodology of biotesting and bio indication. The task of this work is to create biotests for estimation of Al and other metals toxicity in ground water and to compare these results with physicochemical analysis dates. Risk assessment for heavy metals contaminated groundwater was also performed. Risk assessment was performed accordingly EPA US recommendation and gave results about 90 per 100000 citizens for Al and 402 per 100000 for mixture of different heavy metals. For comparison: risk for earth background radiation for Middle Russia is (Individual dose 1 millisivert per year) consist 5 per 100000 people. It was shown that groundwater consist HCO3− ions (360 mg/l), sometimes Al compounds 0.21–0.65 mg/l (MAC for Al is 0.5 mg/l for Russia). Other groundwater contain Hg – 0.004 mg/l (MAC – 0.0005 mg/l); Cr – 0.072 mg/l (MAC – 0.05 mg/l); As – less than 0.03 mg/l (MAC – 0.05 mg/l). We developed plant biotest for estimation of groundwater quality with barley roots, tradescatia and others. Some biotests parameters correlate with HCO3−, Cl−, SO42− and metal ions content positively, for another biotest this correlation is strongly negative. The quality of groundwater near Obninsk and in Kaluga Region is very different but hasn’t been changed since the year 1998. PMID:16705820

  6. Tribological properties of metal-matrix composite materials reinforced by superelastic hard carbon particles

    NASA Astrophysics Data System (ADS)

    Ushakova, I. N.; Drozdova, E. I.; Chernogorova, O. P.; Blinov, V. M.; Ekimov, E. A.

    2016-05-01

    Metal-matrix composite materials (CMs) are synthesized from a mixture of a metal powder (Ti, Fe, Co, Ni, Cu, Al-based alloy) and fullerenes (10 wt %). The thermobaric synthesis conditions (700-1000°C, 5-8 GPa) ensure the collapse of fullerene molecules and their transformation into superelastic carbon phase particles with an indentation hardness H IT = 10-37 GPa, an elastic modulus E IT = 60-260 GPa, and an elastic recovery of >80% upon indentation. After reinforcing by superelastic hard carbon, the friction coefficient of CM decreases by a factor of 2-4 as compared to the friction coefficient of the matrix metal, and the abrasive wear resistance increases by a factor of 4-200. Superelastic hard carbon particles are a unique reinforcing material for an increase in the wear resistance and a simultaneous decrease in the friction coefficient of CM.

  7. Application of composites to the selective reinforcement of metallic aerospace structures. [application of structural design criteria for weight reduction

    NASA Technical Reports Server (NTRS)

    Brooks, W. A., Jr.; Mathauser, E. E.; Pride, R. A.

    1972-01-01

    The use of composite materials to selectively reinforce metallic structures provides a low-cost way to reduce weight and a means of minimizing the risks usually associated with the introduction of new materials. An overview is presented of the NASA Langley Research Center programs to identify the advantages and to develop the potential of the selective reinforcement approach to the use of composites. These programs have shown that selective reinforcement provides excellent strength and stiffness improvements to metallic structures. Significant weight savings can be obtained in a cost effective manner. Flight service programs which have been initiated to validate further the merits of selective reinforcement are described.

  8. Design synthesis of a boron/epoxy reinforced metal shear web.

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.

    1972-01-01

    An advanced composite shear web design concept has been developed for the Space Shuttle Orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad, boron/epoxy plate with vertical boron/epoxy reinforced stiffeners. Baseline composite and titanium shear resistant designs are compared; the composite concept is 28% lighter than the titanium web. Element test results show the metal cladding effectively reinforces critical composite load transfer and fastener hole areas making the composite web concept practical for other shear structure applications.-

  9. Reinforcement of metal with liquid-exfoliated inorganic nano-platelets

    NASA Astrophysics Data System (ADS)

    May, Peter; Khan, Umar; Coleman, Jonathan N.

    2013-10-01

    We have prepared metal matrix composites of a pewter alloy filled with liquid-exfoliated Molybdenum Telluride (MoTe2) nano-platelets. The combination of MoTe2 and pewter was chosen due to their near-identical densities, thus reducing the scope for buoyancy-induced separation during melt mixing. The addition of nanofiller results in a doubling of the Young's modulus, Y, for a volume fraction, Vf, of <1% MoTe2, corresponding to a reinforcement of dY/dVf = 110 GPa. We find that this degree of reinforcement to be reasonably consistent with that predicted by a simplified version of Halpin-Tsai theory.

  10. Biopharmaceutical characterisation of ciprofloxacin-metallic ion interactions: comparative study into the effect of aluminium, calcium, zinc and iron on drug solubility and dissolution.

    PubMed

    Stojković, Aleksandra; Tajber, Lidia; Paluch, Krzysztof J; Djurić, Zorica; Parojčić, Jelena; Corrigan, Owen I

    2014-03-01

    Ciprofloxacin bioavailability may be reduced when ciprofloxacin is co-administered with metallic ion containing preparations. In our previous study, physicochemical interaction between ciprofloxacin and ferrous sulphate was successfully simulated in vitro. In the present work, comparative in vitro ciprofloxacin solubility and dissolution studies were performed in the reactive media containing aluminium hydroxide, calcium carbonate or zinc sulphate. Solid phases collected from the dissolution vessel with aluminium hydroxide, calcium carbonate and zinc sulphate were investigated for their properties. The results obtained indicate that different types of adducts may form and retard ciprofloxacin solubility and dissolution. In the case of aluminium, no phase changes were observed. The solid phase generated in the presence of calcium carbonate was identified as hydrated ciprofloxacin base. Similarly to iron, a new complex consistent with Zn(SO4)2(Cl)2(ciprofloxacin)2 × nH2O stoichiometry was generated in the presence of relatively high concentrations of ciprofloxacin hydrochloride and zinc sulphate, indicating that small volume dissolution experiments can be useful for biorelevant dissolution tests.

  11. Dynamic Effects in Elastothermodynamic Damping of Hollow Particle Reinforced Metal-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Srivastava, Sunil Kumar; Mishra, Bhanu Kumar

    2016-06-01

    The Metal-Matrix Composites (MMCs) containing hollow spherical reinforcements are under active development for the applications such as space structures, submarine hulls etc. where weight is of critical importance. When these materials are subjected to a time varying strain field, energy is dissipated because of the thermoelastic effect (Elastothermodynamic Damping or ETD). The quasi-static ETD analysis for the MMCs containing hollow spherical particles has been reported in literature. The entropic approach, which is better suited for composite materials with perfect or imperfect interfaces, is used for the analysis. In the present work, the effect of inertia forces is carried out on ETD of hollow particle-reinforced MMCs. For given particle volume fractions (V p ), the inertia forces are found to be more significant at higher value of thermal parameter (Ω T1) (alternatively, frequency of vibration if reinforcement radius is fixed), large cavity volume fraction (V h ) and low value of the parameter B1.

  12. Tensile and fatigue behaviour of self-piercing rivets of CFRP to aluminium for automotive application

    NASA Astrophysics Data System (ADS)

    Kang, J.; Rao, H.; Zhang, R.; Avery, K.; Su, X.

    2016-07-01

    In this study, the tensile and fatigue behaviour of self-piercing rivets (SPRs) in carbon fibre reinforced plastic (CFRP) to aluminium 6111 T82 alloys were evaluated. An average maximum lap-shear tensile load capacity of 3858 N was achieved, which is comparable to metal-to-metal SPR lap-shear joints. The CFRP-Al SPRs failed in lap-shear tension due to pull-out of the rivet head from the CFRP upper sheet. The CFRP-Al SPR lap- shear specimens exhibited superior fatigue life compared to previously studied aluminium-to- aluminium SPR lap-shear joints. The SPR lap-shear joints under fatigue loads failed predominantly due to kinked crack growth along the width of the bottom aluminium sheet. The fatigue cracks initiated in the plastically deformed region of the aluminium sheet close to the rivet shank in the rivet-sheet interlock region. Scatter in fatigue life and failure modes was observed in SPR lap-shear specimens tested close to maximum tensile load.

  13. Residual thermal stress control in composite reinforced metal structures. [by mechanical loading of metal component prior to bonding

    NASA Technical Reports Server (NTRS)

    Kelly, J. B.; June, R. R.

    1972-01-01

    Advanced composite materials, composed of boron or graphite fibers and a supporting matrix, make significant structural efficiency improvements available to aircraft and aerospace designers. Residual stress induced during bonding of composite reinforcement to metal structural elements can be reduced or eliminated through suitable modification to the manufacturing processes. The most successful method employed during this program used a steel tool capable of mechanically loading the metal component in compression prior to the adhesive bonding cycle. Compression loading combined with heating to 350 F during the bond cycle can result in creep deformation in aluminum components. The magnitude of the deformation increases with increasing stress level during exposure to 350 F.

  14. Aluminium, antiperspirants and breast cancer.

    PubMed

    Darbre, P D

    2005-09-01

    Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer. PMID:16045991

  15. Aluminium, antiperspirants and breast cancer.

    PubMed

    Darbre, P D

    2005-09-01

    Aluminium salts are used as the active antiperspirant agent in underarm cosmetics, but the effects of widespread, long term and increasing use remain unknown, especially in relation to the breast, which is a local area of application. Clinical studies showing a disproportionately high incidence of breast cancer in the upper outer quadrant of the breast together with reports of genomic instability in outer quadrants of the breast provide supporting evidence for a role for locally applied cosmetic chemicals in the development of breast cancer. Aluminium is known to have a genotoxic profile, capable of causing both DNA alterations and epigenetic effects, and this would be consistent with a potential role in breast cancer if such effects occurred in breast cells. Oestrogen is a well established influence in breast cancer and its action, dependent on intracellular receptors which function as ligand-activated zinc finger transcription factors, suggests one possible point of interference from aluminium. Results reported here demonstrate that aluminium in the form of aluminium chloride or aluminium chlorhydrate can interfere with the function of oestrogen receptors of MCF7 human breast cancer cells both in terms of ligand binding and in terms of oestrogen-regulated reporter gene expression. This adds aluminium to the increasing list of metals capable of interfering with oestrogen action and termed metalloestrogens. Further studies are now needed to identify the molecular basis of this action, the longer term effects of aluminium exposure and whether aluminium can cause aberrations to other signalling pathways in breast cells. Given the wide exposure of the human population to antiperspirants, it will be important to establish dermal absorption in the local area of the breast and whether long term low level absorption could play a role in the increasing incidence of breast cancer.

  16. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

    NASA Technical Reports Server (NTRS)

    Bryson, L. L.; Mccarty, J. E.

    1973-01-01

    Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria.

  17. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 1: Concept development and feasibility

    NASA Technical Reports Server (NTRS)

    Oken, S.; June, R. R.

    1971-01-01

    The analytical and experimental investigations are described in the first phase of a program to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites. The interactions resulting from combining the two types of materials into single assemblies as well as their ability to function structurally were studied. The combinations studied were boron-epoxy reinforced aluminum, boron-epoxy reinforced titanium, and boron-polyimide reinforced titanium. The concepts used unidirectional composites as reinforcement in the primary loading direction and metal for carrying the transverse loads as well as its portion of the primary load. The program established that several realistic concepts could be fabricated, that these concepts could perform to a level that would result in significant weight savings, and that there are means for predicting their capability within a reasonable degree of accuracy. This program also encountered problems related to the application of polyimide systems that resulted in their relatively poor and variable performance.

  18. Additive Manufacturing and Characterization of Polylactic Acid (PLA) Composites Containing Metal Reinforcements

    NASA Technical Reports Server (NTRS)

    Kuentz, Lily; Salem, Anton; Singh, M.; Halbig, M. C.; Salem, J. A.

    2016-01-01

    Additive manufacturing of polymeric systems using 3D printing has become quite popular recently due to rapid growth and availability of low cost and open source 3D printers. Two widely used 3D printing filaments are based on polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) systems. PLA is much more environmentally friendly in comparison to ABS since it is made from renewable resources such as corn, sugarcane, and other starches as precursors. Recently, polylactic acid-based metal powder containing composite filaments have emerged which could be utilized for multifunctional applications. The composite filaments have higher density than pure PLA, and the majority of the materials volume is made up of polylactic acid. In order to utilize functionalities of composite filaments, printing behavior and properties of 3-D printed composites need to be characterized and compared with the pure PLA materials. In this study, pure PLA and composite specimens with different metallic reinforcements (Copper, Bronze, Tungsten, Iron, etc) were 3D printed at various layer heights and resulting microstructures and properties were characterized. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) behavior of filaments with different reinforcements were studied. The microscopy results show an increase in porosity between 3-D printed regular PLA and the metal composite PLA samples, which could produce weaker mechanical properties in the metal composite materials. Tensile strength and fracture toughness behavior of specimens as a function of print layer height will be presented.

  19. Process for the manufacture of seamless metal-clad fiber-reinforced organic matrix composite structures

    NASA Technical Reports Server (NTRS)

    Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

    1991-01-01

    A process for producing seamless metal-clad composite structures includes providing a hollow, metallic inner member and an outer sleeve to surround the inner member and define an inner space therebetween. A plurality of continuous reinforcing fibers is attached to the distal end of the outside diameter of the inner member, and the inner member is then introduced, distal end first, into one end of the outer sleeve. The inner member is then moved, distal end first, into the outer sleeve until the inner member is completely enveloped by the outer sleeve. A liquid matrix material is then injected into the space containing the reinforcing fibers between the inner member and the outer sleeve. Next a pressurized heat transfer medium is passed through the inner member to cure the liquid matrix material. Finally, the wall thickness of both the inner member and the outer sleeve are reduced to desired dimensions by chemical etching, which adjusts the thermal expansion coefficient of the metal-clad composite structure to a desired value.

  20. Optimized process parameters for fabricating metal particles reinforced 5083 Al composite by friction stir processing

    PubMed Central

    Bauri, Ranjit; Yadav, Devinder; Shyam Kumar, C.N.; Janaki Ram, G.D.

    2015-01-01

    Metal matrix composites (MMCs) exhibit improved strength but suffer from low ductility. Metal particles reinforcement can be an alternative to retain the ductility in MMCs (Bauri and Yadav, 2010; Thakur and Gupta, 2007) [1,2]. However, processing such composites by conventional routes is difficult. The data presented here relates to friction stir processing (FSP) that was used to process metal particles reinforced aluminum matrix composites. The data is the processing parameters, rotation and traverse speeds, which were optimized to incorporate Ni particles. A wide range of parameters covering tool rotation speeds from 1000 rpm to 1800 rpm and a range of traverse speeds from 6 mm/min to 24 mm/min were explored in order to get a defect free stir zone and uniform distribution of particles. The right combination of rotation and traverse speed was found from these experiments. Both as-received coarse particles (70 μm) and ball-milled finer particles (10 μm) were incorporated in the Al matrix using the optimized parameters. PMID:26566541

  1. Aluminium neurotoxicity: neurobehavioural and oxidative aspects.

    PubMed

    Kumar, Vijay; Gill, Kiran Dip

    2009-11-01

    Aluminium is the most widely distributed metal in the environment and is extensively used in daily life that provides easy exposure to human beings. The exposure to this toxic metal occurs through air, food and water. However, there is no known physiological role for aluminium within the body and hence this metal may produce adverse physiological effects. Chronic exposure of animals to aluminium is associated with behavioural, neuropathological and neurochemical changes. Among them, deficits of learning and behavioural functions are most evident. Some epidemiological studies have shown poor performance in cognitive tests and a higher abundance of neurological symptoms for workers occupationally exposed to aluminium. However, in contrast to well established neurotoxic effects, neurobehavioural studies of aluminium in rodents have generally not produced consistent results. Current researches show that any impairment in mitochondrial functions may play a major role in many human disorders including neurodegenerative disorders. Being involved in the production of reactive oxygen species, aluminium may cause impairments in mitochondrial bioenergetics and may lead to the generation of oxidative stress which may lead to a gradual accumulation of oxidatively modified cellular proteins. In this review, the neuropathologies associated with aluminium exposure in terms of neurobehavioural changes have been discussed. In addition, the impact of aluminium on the mitochondrial functions has also been highlighted.

  2. Dry sliding wear of heat treated hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Naveed, Mohammed; Khan, A. R. Anwar

    2016-09-01

    In recent years, there has been an ever-increasing demand for enhancing mechanical properties of Aluminum Matrix Composites (AMCs), which are finding wide applications in the field of aerospace, automobile, defence etc,. Among all available aluminium alloys, Al6061 is extensively used owing to its excellent wear resistance and ease of processing. Newer techniques of improving the hardness and wear resistance of Al6061 by dispersing an appropriate mixture of hard ceramic powder and whiskers in the aluminium alloy are gaining popularity. The conventional aluminium based composites possess only one type of reinforcements. Addition of hard reinforcements such as silicon carbide, alumina, titanium carbide, improves hardness, strength and wear resistance of the composites. However, these composites possessing hard reinforcement do posses several problems during their machining operation. AMCs reinforced with particles of Gr have been reported to be possessing better wear characteristics owing to the reduced wear because of formation of a thin layer of Gr particles, which prevents metal to metal contact of the sliding surfaces. Further, heat treatment has a profound influence on mechanical properties of heat treatable aluminium alloys and its composites. For a solutionising temperature of 5500C, solutionising duration of 1hr, ageing temperature of 1750C, quenching media and ageing duration significantly alters mechanical properties of both aluminium alloy and its composites. In the light of the above, the present paper aims at developing aluminium based hybrid metal matrix composites containing both silicon carbide and graphite and characterize their mechanical properties by subjecting it to heat treatment. Results indicate that increase of graphite content increases wear resistance of hybrid composites reinforced with constant SiC reinforcement. Further heat treatment has a profound influence on the wear resistance of the matrix alloy as well as its hybrid composites

  3. Residual stress alleviation of aircraft metal structures reinforced with filamentary composites

    NASA Technical Reports Server (NTRS)

    Kelly, J. B.; June, R. R.

    1973-01-01

    Methods to eliminate or reduce residual stresses in aircraft metal structures reinforced by filamentary composites are discussed. Residual stress level reductions were achieved by modifying the manufacturing procedures used during adhesive bonding. The residual stress alleviation techniques involved various forms of mechanical constraint which were applied to the components during bonding. Nine methods were evaluated, covering a wide range in complexity. All methods investigated during the program affected the residual stress level. In general, residual stresses were reduced by 70 percent or more from the stress level produced by conventional adhesive bonding procedures.

  4. Metal-reinforced single implant mandibular overdenture retained by an attachment: a clinical report.

    PubMed

    Grageda, Edgar; Rieck, Bastian

    2014-01-01

    Results of studies have shown that a single implant mandibular overdenture significantly increases the satisfaction and quality of life of patients with edentulism. The single implant-retained overdenture has the additional advantage of being less expensive and invasive than a 2-implant supported overdenture but has a high incidence of fracture of the acrylic resin base at the point of the implant. The treatment, design, and fabrication of a metal-reinforced single-implant mandibular overdenture with the Locator attachment as a retention device is described.

  5. Effect of reinforcement type and porosity on strength of metal matrix composite

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. G.; Lal, Achchhe; Menghani, J. V.

    2016-05-01

    In the present work, experimental investigation and the numerical analysis are carried out for strength analysis of A356 alloy matrix composites reinforced with alumina, fly ash and hybrid particle composites. The combined strengthening effect of load bearing, Hall-Petch, Orowan, coefficient of thermal expansion mismatch and elastic modulus mismatch is studied for predicting accurate uniaxial stress-strain behavior of A356 based alloy matrix composite. The unit cell micromechanical approach and nine noded isoparametric finite element analysis (FEA) is used to investigate the yield failure load by considering material defect of porosity as fabrication errors in particulate composite. The Ramberg-Osgood approach is considered for the linear and nonlinear relationship between stress and strain of A356 based metal matrix composites containing different amounts of fly ash and alumina reinforcing particles. A numerical analysis of material porosity on the stress strain behavior of the composite is performed. The literature and experimental results exhibit the validity of this model and confirm the importance of the fly ash as the cheapest and low density reinforcement obtained as a waste by product in thermal power plants.

  6. Influence of thermal residual stress on behaviour of metal matrix composites reinforced with particles

    NASA Astrophysics Data System (ADS)

    Guzmán, R. E.; Hernández Arroyo, E.

    2016-02-01

    The properties of a metallic matrix composites materials (MMC's) reinforced with particles can be affected by different events occurring within the material in a manufacturing process. The existence of residual stresses resulting from the manufacturing process of these materials (MMC's) can markedly differentiate the curves obtained in tensile tests obtained from compression tests. One of the themes developed in this work is the influence of residual stresses on the mechanical behaviour of these materials. The objective of this research work presented is numerically estimate the thermal residual stresses using a unit cell model for the Mg ZC71 alloy reinforced with SiC particles with volume fraction of 12% (hot-forging technology). The MMC's microstructure is represented as a three dimensional prismatic cube-shaped with a cylindrical reinforcing particle located in the centre of the prism. These cell models are widely used in predicting stress/strain behaviour of MMC's materials, in this analysis the uniaxial stress/strain response of the composite can be obtained through the calculation using the commercial finite-element code.

  7. Deformation behavior of FRP-metal composites locally reinforced with carbon fibers

    NASA Astrophysics Data System (ADS)

    Scholze, M.; Kolonko, A.; Lindner, T.; Lampke, T.; Helbig, F.

    2016-03-01

    This study investigates variations of hybrid laminates, consisting of one aluminum sheet and a unidirectional glass fiber (GF) reinforced polyamide 6 (PA6) basic structure with partial carbon fiber (CF) reinforcement. To create these heterogeneous FRP laminates, it is necessary to design and produce semi-finished textile-based products. Moreover, a warp knitting machine in conjunction with a warp thread offset unit was used to generate bionic inspired compounds. By the variation of stacking prior to the consolidation process of the hybrid laminate, an oriented CF reinforcement at the top and middle layer of the FRP is realized. In both cases the GFRP layer prevents contact between the aluminum and carbon fibers. In so doing, the high strength of carbon fibers can be transferred to the hybrid laminate in load directions with an active prevention of contact corrosion. The interface strength between thermoplastic and metal component was improved by a thermal spray coating on the aluminum sheet. Because of the high surface roughness and porosity, mechanical interlock was used to provide high interface strength without bonding agents between both components. The resulting mechanical properties of the hybrid laminates are evaluated by three point bending tests in different load directions. The effect of local fiber orientation and layer positioning on failure and deformation mechanism is additionally investigated by digital image correlation (DIC).

  8. Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

    SciTech Connect

    D. Schwam: J.F. Wallace: Y. Zhu: J.W. Ki

    2004-10-01

    The utilization of aluminum die casting as enclosures where internal equipment is rotating inside of the casting and could fracture requires a strong housing to restrain the fractured parts. A typical example would be a supercharger. In case of a failure, unless adequately contained, fractured parts could injure people operating the equipment. A number of potential reinforcement materials were investigated. The initial work was conducted in sand molds to create experimental conditions that promote prolonged contact of the reinforcing material with molten aluminum. Bonding of Aluminum bronze, Cast iron, and Ni-resist inserts with various electroplated coatings and surface treatments were analyzed. Also toughening of A354 aluminum cast alloy by steel and stainless steel wire mesh with various conditions was analyzed. A practical approach to reinforcement of die cast aluminum components is to use a reinforcing steel preform. Such performs can be fabricated from steel wire mesh or perforated metal sheet by stamping or deep drawing. A hemispherical, dome shaped casting was selected in this investigation. A deep drawing die was used to fabricate the reinforcing performs. The tendency of aluminum cast enclosures to fracture could be significantly reduced by installing a wire mesh of austenitic stainless steel or a punched austenitic stainless steel sheet within the casting. The use of reinforcements made of austenitic stainless steel wire mesh or punched austenitic stainless steel sheet provided marked improvement in reducing the fragmentation of the casting. The best strengthening was obtained with austenitic stainless steel wire and with a punched stainless steel sheet without annealing this material. Somewhat lower results were obtained with the annealed punched stainless steel sheet. When the annealed 1020 steel wire mesh was used, the results were only slightly improved because of the lower mechanical properties of this unalloyed steel. The lowest results were

  9. Fabrication and fracture behavior of metallic fiber reinforced NiAl matrix composites

    SciTech Connect

    Chang, S.Y.; Lin, S.J.

    1997-07-01

    NiAl intermetallic is recently of considerable interest as the high temperature structure material because of its high melting point, high specific stiffness, better oxidation and creep resistance. However, the low-temperature brittleness of the NiAl intermetallic remained a main reason for its unpopularity for industrial applications. Composite ductile phase toughening approaches have been utilized by many researchers to improve the fracture toughness of intermetallics. In liquid metallurgy, pressure casting or infiltration of molten nickel aluminide into a preform is the usual method for the fabrication of nickel aluminide intermetallic composites. But generally, it is not useful for metallic reinforcements because of the drastic reactions between the molten nickel aluminide and the metallic preform, and the difficulty in sustaining the performance of the metallic preform at a high temperature. In solid metallurgy, this process is based on reactive powder metallurgy and hot pressing, hot extrusion and hot isostatic pressing (HIP). High processing temperature and pressure, generally at a temperature of at least 1,200 C, are necessary conditions for hot pressing, hot extrusion and HIP. Hence the processes require sophisticated manufacturing equipment and considerable energy and render the application of nickel aluminide intermetallic composites unpopular. Work on reactive hot pressing(RHP) at a low temperature near the melting point of aluminum is reconsidered again. Efforts indicated that by combining the spontaneous reaction of the electrically coated nickel film and the aluminum foils, and hot pressing at a temperature about 500 C lower than previously accomplished by HIP, would overcome the fabrication problem of NiAl intermetallic composites reinforced with the uniformly distributed metallic fibers.

  10. The meaning of aluminium exposure on human health and aluminium-related diseases.

    PubMed

    Crisponi, Guido; Fanni, Daniela; Gerosa, Clara; Nemolato, Sonia; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Faa, Gavino

    2013-02-01

    The aim of this review is to attempt to answer extremely important questions related to aluminium-related diseases. Starting from an overview on the main sources of aluminium exposure in everyday life, the principal aspects of aluminium metabolism in humans have been taken into consideration in an attempt to enlighten the main metabolic pathways utilised by trivalent metal ions in different organs. The second part of this review is focused on the available evidence concerning the pathogenetic consequences of aluminium overload in human health, with particular attention to its putative role in bone and neurodegenerative human diseases.

  11. Aluminium in human sweat.

    PubMed

    Minshall, Clare; Nadal, Jodie; Exley, Christopher

    2014-01-01

    It is of burgeoning importance that the human body burden of aluminium is understood and is measured. There are surprisingly few data to describe human excretion of systemic aluminium and almost no reliable data which relate to aluminium in sweat. We have measured the aluminium content of sweat in 20 healthy volunteers following mild exercise. The concentration of aluminium ranged from 329 to 5329μg/L. These data equate to a daily excretion of between 234 and 7192μg aluminium and they strongly suggest that perspiration is the major route of excretion of systemic aluminium in humans.

  12. Evidence of aluminium accumulation in aluminium welders.

    PubMed Central

    Elinder, C G; Ahrengart, L; Lidums, V; Pettersson, E; Sjögren, B

    1991-01-01

    Using atomic absorption spectrometry the aluminium concentrations in blood and urine and in two iliac bone biopsies obtained from welders with long term exposure to fumes containing aluminium were measured. The urinary excretion of two workers who had welded for 20 and 21 years varied between 107 and 351 micrograms Al/l, more than 10 times the concentration found in persons without occupational exposure. Urinary aluminium excretion remained high many years after stopping exposure. Blood and bone aluminium concentrations (4-53 micrograms Al/l and 18-29 micrograms Al/g respectively) were also raised but not to the same extent as urine excretion. It is concluded that long term exposure to aluminium by inhalation gives rise to accumulation of aluminium in the body and skeleton of health persons, and that the elimination of retained aluminium is very slow, in the order of several years. PMID:1954151

  13. Feet sunk in molten aluminium: The burn and its prevention.

    PubMed

    Alonso-Peña, David; Arnáiz-García, María Elena; Valero-Gasalla, Javier Luis; Arnáiz-García, Ana María; Campillo-Campaña, Ramón; Alonso-Peña, Javier; González-Santos, Jose María; Fernández-Díaz, Alaska Leonor; Arnáiz, Javier

    2015-08-01

    Nowadays, despite improvements in safety rules and inspections in the metal industry, foundry workers are not free from burn accidents. Injuries caused by molten metals include burns secondary to molten iron, aluminium, zinc, copper, brass, bronze, manganese, lead and steel. Molten aluminium is one of the most common causative agents of burns (60%); however, only a few publications exist concerning injuries from molten aluminium. The main mechanisms of lesion from molten aluminium include direct contact of the molten metal with the skin or through safety apparel, or when the metal splash burns through the pants and rolls downward along the leg. Herein, we report three cases of deep dermal burns after 'soaking' the foot in liquid aluminium and its evolutive features. This paper aims to show our experience in the management of burns due to molten aluminium. We describe the current management principles and the key features of injury prevention.

  14. Ceramics reinforced metal base composite coatings produced by CO II laser cladding

    NASA Astrophysics Data System (ADS)

    Yang, Xichen; Wang, Yu; Yang, Nan

    2008-03-01

    Due to the excellent performance in high strength, anti-temperature and anti-wear, ceramics reinforced metal base composite material was used in some important fields of aircraft, aerospace, automobile and defense. The traditional bulk metal base composite materials are the expensive cost, which is limited in its industrial application. Development of laser coating of ceramics reinforced metal base composite is very interesting in economy. This paper is focused on three laser cladding ceramics coatings of SiC particle /Al matrix , Al IIO 3 powder/ Al matrix and WC + Co/mild steel matrix. Powder particle sizes are of 10-60μm. Chemical contents of aluminum matrix are of 3.8-4.0% Cu, 1.2-1.8% Mg, 0.3-0.99% Mn and balance Al. 5KW CO II laser, 5 axes CNC table, JKF-6 type powder feeder and co-axis feeder nozzle are used in laser cladding. Microstructure and performance of laser composite coatings have been respectively examined with OM,SEM and X-ray diffraction. Its results are as follows : Microstructures of 3C-,6H- and 5H- SiC particles + Al + Al 4SiC 4 + Si in SiC/Al composite, hexagonal α-Al IIO 3 + cubic γ-Al IIO 3 + f.c.c Al in Al IIO 3 powder/ Al composite and original WC particles + separated WC particles + eutectic WC + γ-Co solid solution + W IIC particles in WC + Co/steel coatings are respectively recognized. New microstructures of 5H-SiC in SiC/Al composite, cubic γ-Al IIO 3 in Al IIO 3 composite and W IIC in WC + Co/ steel composite by laser cladding have been respectively observed.

  15. The role of rapid solidification processing in the fabrication of fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Locci, Ivan E.; Noebe, Ronald D.

    1989-01-01

    Advanced composite processing techniques for fiber reinforced metal matrix composites require the flexibility to meet several widespread objectives. The development of uniquely desired matrix microstructures and uniformly arrayed fiber spacing with sufficient bonding between fiber and matrix to transmit load between them without degradation to the fiber or matrix are the minimum requirements necessary of any fabrication process. For most applications these criteria can be met by fabricating composite monotapes which are then consolidated into composite panels or more complicated components such as fiber reinforced turbine blades. Regardless of the end component, composite monotapes are the building blocks from which near net shape composite structures can be formed. The most common methods for forming composite monotapes are the powder cloth, foil/fiber, plasma spray, and arc spray processes. These practices, however, employ rapid solidification techniques in processing of the composite matrix phase. Consequently, rapid solidification processes play a vital and yet generally overlooked role in composite fabrication. The future potential of rapid solidification processing is discussed.

  16. Microstructures and properties of ceramic particle-reinforced metal matrix composite layers produced by laser cladding

    NASA Astrophysics Data System (ADS)

    Zhang, Qingmao; He, Jingjiang; Liu, Wenjin; Zhong, Minlin

    2005-01-01

    Different weight ratio of titanium, zirconium, WC and Fe-based alloy powders were mixed, and cladded onto a medium carbon steel substrate using a 3kW continuous wave CO2 laser, aiming at producing Ceramic particles- reinforced metal matrix composites (MMCs) layers. The microstructures of the layers are typical hypoeutectic, and the major phases are Ni3Si2, TiSi2, Fe3C, FeNi, MC, Fe7Mo3, Fe3B, γ(residual austenite) and M(martensite). The microstructure morphologies of MMCs layers are dendrites/cells. The MC-type reinforcements are in situ synthesis Carbides which main compositions consist of transition elements Zr, Ti, W. The MC-type particles distributed within dendrite and interdendritic regions with different volume fractions for single and overlapping clad layers. The MMCs layers are dense and free of cracks with a good metallurgical bonding between the layer and substrate. The addition ratio of WC in the mixtures has the remarkable effect on the microhardness of clad layers.

  17. Effects of weld metal profile on the fatigue life of integrally reinforced weld-on fittings

    SciTech Connect

    Woods, G.E. ); Rodabaugh, E.C. , Dublin, OH )

    1994-06-01

    The cyclic fatigue life of fabricated tee intersections, including integrally reinforced weld-on fittings, has been a topic of discussion in the recent past. The discussion has centered around questions concerning the accuracy of the ASME B31.3 Code equations in calculating the stress intensification factors, (SIFs), for these types of intersection geometries. The SIF of an intersection is an indicator of the fatigue life of the intersection when it is subjected to bending moments caused by thermal, flow, or mechanically induced cyclical displacements. Schneider, Rodabaugh, and Woods concur that inaccuracies in the Code SIF equations do exist and that these equations should be revised. This report presents new Markl type SIF data on the B.W.Pipet (BWP), an integrally reinforced weld-on branch fitting, manufactured by WFI International, Inc., in Houston, Texas. The scope of this research project was to determine the influence of the installation weld metal profile of the Pipet to the run pipe on the SIF. The SIF data were then compared to calculated SIF values using equations from the American Society of Mechanical engineers (ASME) B31.1, ASME B31.3, and ASME Section 3, Subsection NC, for the purpose of determining which Code equation may be the most appropriate for calculating the SIF for these particular fittings.

  18. Lactobacillus plantarum CCFM639 alleviates aluminium toxicity.

    PubMed

    Yu, Leilei; Zhai, Qixiao; Liu, Xiaoming; Wang, Gang; Zhang, Qiuxiang; Zhao, Jianxin; Narbad, Arjan; Zhang, Hao; Tian, Fengwei; Chen, Wei

    2016-02-01

    Aluminium (Al) is the most abundant metal in the earth's crust. Al exposure can cause a variety of adverse physiological effects in humans and animals. Our aim was to demonstrate that specific probiotic bacteria can play a special physiologically functional role in protection against Al toxicity in mice. Thirty strains of lactic acid bacteria (LAB) were tested for their aluminium-binding ability, aluminium tolerance, their antioxidative capacity, and their ability to survive the exposure to artificial gastrointestinal (GI) juices. Lactobacillus plantarum CCFM639 was selected for animal experiments because of its excellent performance in vitro. Forty mice were divided into four groups: control, Al only, Al plus CCFM639, and Al plus deferiprone (DFP). CCFM639 was administered at 10(9) CFU once daily for 10 days, followed by a single oral dose of aluminium chloride hexahydrate at 5.14 mg aluminium (LD50) for each mouse. The results showed that CCFM639 treatment led to a significant reduction in the mortality rates with corresponding decrease in intestinal aluminium absorption and in accumulation of aluminium in the tissues and amelioration of hepatic histopathological damage. This probiotic treatment also resulted in alleviation of hepatic, renal, and cerebral oxidative stress. The treatment of L. plantarum CCFM639 has potential as a therapeutic dietary strategy against acute aluminium toxicity.

  19. Evolution of In-Situ Generated Reinforcement Precipitates in Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Sen, S.; Kar, S. K.; Catalina, A. V.; Stefanescu, D. M.; Dhindaw, B. K.

    2004-01-01

    Due to certain inherent advantages, in-situ production of Metal Matrix Composites (MMCs) have received considerable attention in the recent past. ln-situ techniques typically involve a chemical reaction that results in precipitation of a ceramic reinforcement phase. The size and spatial distribution of these precipitates ultimately determine the mechanical properties of these MMCs. In this paper we will investigate the validity of using classical growth laws and analytical expressions to describe the interaction between a precipitate and a solid-liquid interface (SLI) to predict the size and spatial evolution of the in-situ generated precipitates. Measurements made on size and distribution of Tic precipitates in a Ni&I matrix will be presented to test the validity of such an approach.

  20. Evaluation of non-metallic fiber reinforced concrete in new full depth pcc pavements. Final report

    SciTech Connect

    Ramakrishnan, V.; Tolmare, N.S.

    1998-12-30

    This final report presents the construction and performance evaluation of a new full depth pavement, constructed with a new type non-metallic fiber reinforced concrete (NMFRC). The mixture proportions used, the quality control tests conducted for the evaluation of the fresh and hardened concrete properties, the procedure used for mixing, transporting, placing, consolidating, finishing, and curing of the concrete are described. Periodic inspection of the full depth pavement was done and this report includes the results of these inspections. The feasibility of using this NMFRC in the construction of highway structures has been discussed. The new NMFRC with enhanced fatigue, impact resistance, modulus of rupture, ductility and toughness properties is suitable for the construction of full depth pavements. However, a life-cycle cost analysis shows that NMFRC is not a favorable choice, because of it`s high initial cost.

  1. Aluminium in Alzheimer's disease: are we still at a crossroad?

    PubMed

    Gupta, Veer Bala; Anitha, S; Hegde, M L; Zecca, L; Garruto, R M; Ravid, R; Shankar, S K; Stein, R; Shanmugavelu, P; Jagannatha Rao, K S

    2005-01-01

    Aluminium, an environmentally abundant non-redox trivalent cation has long been implicated in the pathogenesis of Alzheimer's disease (AD). However, the definite mechanism of aluminium toxicity in AD is not known. Evidence suggests that trace metal homeostasis plays a crucial role in the normal functioning of the brain, and any disturbance in it can exacerbate events associated with AD. The present paper reviews the scientific literature linking aluminium with AD. The focus is on aluminium levels in brain, region-specific and subcellular distribution, its relation to neurofibrillary tangles, amyloid beta, and other metals. A detailed mechanism of the role of aluminium in oxidative stress and cell death is highlighted. The importance of complex speciation chemistry of aluminium in relation to biology has been emphasized. The debatable role of aluminium in AD and the cross-talk between aluminium and genetic susceptibility are also discussed. Finally, it is concluded based on extensive literature that the neurotoxic effects of aluminium are beyond any doubt, and aluminium as a factor in AD cannot be discarded. However, whether aluminium is a sole factor in AD and whether it is a factor in all AD cases still needs to be understood.

  2. Aluminium in Biological Environments: A Computational Approach

    PubMed Central

    Mujika, Jon I; Rezabal, Elixabete; Mercero, Jose M; Ruipérez, Fernando; Costa, Dominique; Ugalde, Jesus M; Lopez, Xabier

    2014-01-01

    The increased availability of aluminium in biological environments, due to human intervention in the last century, raises concerns on the effects that this so far “excluded from biology” metal might have on living organisms. Consequently, the bioinorganic chemistry of aluminium has emerged as a very active field of research. This review will focus on our contributions to this field, based on computational studies that can yield an understanding of the aluminum biochemistry at a molecular level. Aluminium can interact and be stabilized in biological environments by complexing with both low molecular mass chelants and high molecular mass peptides. The speciation of the metal is, nonetheless, dictated by the hydrolytic species dominant in each case and which vary according to the pH condition of the medium. In blood, citrate and serum transferrin are identified as the main low molecular mass and high molecular mass molecules interacting with aluminium. The complexation of aluminium to citrate and the subsequent changes exerted on the deprotonation pathways of its tritable groups will be discussed along with the mechanisms for the intake and release of aluminium in serum transferrin at two pH conditions, physiological neutral and endosomatic acidic. Aluminium can substitute other metals, in particular magnesium, in protein buried sites and trigger conformational disorder and alteration of the protonation states of the protein's sidechains. A detailed account of the interaction of aluminium with proteic sidechains will be given. Finally, it will be described how alumnium can exert oxidative stress by stabilizing superoxide radicals either as mononuclear aluminium or clustered in boehmite. The possibility of promotion of Fenton reaction, and production of hydroxyl radicals will also be discussed. PMID:24757505

  3. Human exposure to aluminium.

    PubMed

    Exley, Christopher

    2013-10-01

    Human activities have circumvented the efficient geochemical cycling of aluminium within the lithosphere and therewith opened a door, which was previously only ajar, onto the biotic cycle to instigate and promote the accumulation of aluminium in biota and especially humans. Neither these relatively recent activities nor the entry of aluminium into the living cycle are showing any signs of abating and it is thus now imperative that we understand as fully as possible how humans are exposed to aluminium and the future consequences of a burgeoning exposure and body burden. The aluminium age is upon us and there is now an urgent need to understand how to live safely and effectively with aluminium.

  4. Simulator trials to determine the wear of the combination aluminium oxide ceramic-carbon fibre reinforced plastic (CFRP) used as an insert in a hip socket.

    PubMed

    Scheller, G; Schwarz, M; Früh, H J; Jani, L

    1999-01-01

    Hip simulator trials were conducted to determine the initial wear between alumina femoral heads and carbon fibre reinforced plastic (CFRP, CAPROMAN) insert in a titanium socket. A force of 2500 N and a frequency of 0.857 H were applied. Using surface and sphericity measurement techniques, the amount of wear was determined. After 500,000 cycles, the centre of the head had moved by 10 microm into the insert, and the average radius increased by 2 microm. After 1 million cycles, the additional changes were less than 1 microm. Based on an examination of retrieved implants (wear rate: 6.1 microm/year) and based on the simulator results, the combination alumina-CFRP inserts could be approved for total hip replacement.

  5. The removal of iron from molten aluminium

    SciTech Connect

    Donk, H.M. van der; Nijhof, G.H.; Castelijns, C.A.M.

    1995-12-31

    In this work an overview is given about the techniques available for the removal of metallic impurities from molten aluminium. The overview is focused on the removal of iron. Also, some experimental results are given about the creation of iron-rich intermetallic compounds in an aluminium system, which are subsequently removed by gravity segregation and filtration techniques. This work is part of an ongoing research project of three major European aluminium companies who are co-operating on the subject of recycling of aluminium packaging materials recovered from household waste by means of Eddy-Current techniques. Using this technique the pick-up of some contaminating metals, particularly iron, is almost unavoidable.

  6. Accumulation of polycyclic aromatic hydrocarbons and heavy metals in the tree foliage of Eucalyptus rostrata, Pinus radiata and Populus hybridus in the vicinity of a large aluminium smelter in Argentina

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. H.; Wannaz, E. D.; Salazar, M. J.; Pignata, M. L.; Fangmeier, A.; Franzaring, J.

    2012-08-01

    A pollution gradient of polycyclic aromatic hydrocarbons (PAHs) was observed in tree foliage sampled in the vicinity of a large aluminium production facility in Patagonia (Argentina). Leaves of Eucalyptus rostrata, Populus hybridus and one-year-old needles of Pinus radiata were collected, and concentrations of 12 PAHs including the so-called EPA priority pollutants as well as heavy metals (Cd, Cu, Fe, Mn, Ni and Zn) were analysed. The PAH concentrations indicated a steep pollution gradient in the study area associated with the Al-industry, while the heavy metal content was unrelated to this activity. The present study confirms that aluminium smelting results in the deposition of PAH in the study area, and therefore further studies should be carried out taking into account the potentially adverse effects of these compounds on human and ecosystem health.

  7. Fatigue testing and damage development in continuous fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1988-01-01

    A general overview of the fatigue behavior of metal matrix composites (MMC) is presented. The first objective is to present experimental procedures and techniques for conducting a meaningful fatigue test to detect and quantify fatigue damage in MMC. These techniques include interpretation of stress-strain responses, acid etching of the matrix, edge replicas of the specimen under load, radiography, and micrographs of the failure surfaces. In addition, the paper will show how stiffness loss in continuous fiber reinforced metal matrix composites can be a useful parameter for detecting fatigue damage initiation and accumulation. Second, numerous examples of how fatigue damage can initiate and grow in various MMC are given. Depending on the relative fatigue behavior of the fiber and matrix, and the interface properties, the failure modes of MMC can be grouped into four categories: (1) matrix dominated, (2) fiber dominated, (3) self-similar damage growth, and (4) fiber/matrix interfacial failures. These four types of damage will be discussed and illustrated by examples with the emphasis on the fatigue of unnotched laminates.

  8. Fatigue testing and damage development in continuous fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1989-01-01

    A general overview of the fatigue behavior of metal matrix composites (MMC) is presented. The first objective is to present experimental procedures and techniques for conducting a meaningful fatigue test to detect and quantify fatigue damage in MMC. These techniques include interpretation of stress-strain responses, acid etching of the matrix, edge replicas of the specimen under load, radiography, and micrographs of the failure surfaces. In addition, the paper will show how stiffness loss in continuous fiber reinforced metal matrix composites can be a useful parameter for detecting fatigue damage initiation and accumulation. Second, numerous examples of how fatigue damage can initiate and grow in various MMC are given. Depending on the relative fatigue behavior of the fiber and matrix, and the interface properties, the failure modes of MMC can be grouped into four categories: (1) matrix dominated, (2) fiber dominated, (3) self-similar damage growth, and (4) fiber/matrix interfacial failures. These four types of damage will be discussed and illustrated by examples with the emphasis on the fatigue of unnotched laminates.

  9. Selective Reinforcement to Improve Fracture Toughness and Fatigue Crack Growth Resistance in Metallic Structures

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Newman, John A.; James, Mark A.

    2004-01-01

    Experimental and analytical investigations of the fatigue crack growth and fracture response of aluminum selectively reinforced compact tension specimens were performed. It was shown that selective reinforcement significantly improved these responses primarily through load sharing by the reinforcement. With the appropriate combination of reinforcement architecture and mechanical properties, as well as reinforcement to base aluminum interface properties, fatigue cracks can be arrested using selective reinforcement. Maximum load associated with fracture increased up to 20 percent for the cases investigated and crack growth at maximum load increased as much as 150 percent. For both fatigue crack growth and fracture, the three most influential properties identified within the bounds of this investigation that influence this response are reinforcement width, reinforcement stiffness and interface stiffness. Considerable coupling occurs between the different fiber architecture and material properties and how they influence fatigue crack growth and fracture responses.

  10. A Study on Effect of Graphite Particles on Tensile, Hardness and Machinability of Aluminium 8011 Matrix Material

    NASA Astrophysics Data System (ADS)

    Latha Shankar, B.; Anil, K. C.; Karabasappagol, Prasann J.

    2016-09-01

    Industrial application point of view, metal matrix composites in general and Aluminium alloy matrix composites in particular are ideal candidates because of their favourable engineering properties. Being lightweight Aluminium matrix composites are widely used in aircraft, defence and automotive industries. In this work Aluminium 8011 metal matrix was reinforced with fine Graphite particles of 50 μm. developed by two-step Stir casting method. Graphite weight %was varied in the range 2, 4, 6 and 8%. Uniform dispersion of graphite particle is examined under optical microscope. Tensile test coupons were prepared as per standard to determine % of elongation and tensile strength for various % of graphite particle. Hardness of developed composite for various % of graphite particle and Machinability parameters were also studied for effect on surface finish. It was observed that with increase of weight percentage of Graphite particles up to 8% in Aluminium 8011 alloy matrix there was increase in tensile strength, decrease in % of elongation with increase in hardness. Machinability study revealed that, there was decrease in surface roughness with increase in Graphite content.

  11. Alveolar proteinosis associated with aluminium dust inhalation.

    PubMed

    Chew, R; Nigam, S; Sivakumaran, P

    2016-08-01

    Secondary alveolar proteinosis is a rare lung disease which may be triggered by a variety of inhaled particles. The diagnosis is made by detection of anti-granulocyte-macrophage colony-stimulating factor antibodies in bronchoalveolar lavage fluid, which appears milky white and contains lamellar bodies. Aluminium has been suggested as a possible cause, but there is little evidence in the literature to support this assertion. We report the case of a 46-year-old former boilermaker and boat builder who developed secondary alveolar proteinosis following sustained heavy aluminium exposure. The presence of aluminium was confirmed both by histological examination and metallurgical analysis of a mediastinal lymph node. Despite cessation of exposure to aluminium and treatment with whole-lung lavage which normally results in improvements in both symptoms and lung function, the outcome was poor and novel therapies are now being used for this patient. It may be that the natural history in aluminium-related alveolar proteinosis is different, with the metal playing a mediating role in the disease process. Our case further supports the link between aluminium and secondary alveolar proteinosis and highlights the need for measures to prevent excessive aluminium inhalation in relevant industries. PMID:27099254

  12. Specimen Preparation for Metal Matrix Composites with a High Volume Fraction of Reinforcing Particles for EBSD Analysis

    NASA Astrophysics Data System (ADS)

    Smirnov, A. S.; Belozerov, G. A.; Smirnova, E. O.; Konovalov, A. V.; Shveikin, V. P.; Muizemnek, O. Yu.

    2016-07-01

    The paper deals with a procedure of preparing a specimen surface for the EBSD analysis of a metal matrix composite (MMC) with a high volume fraction of reinforcing particles. Unlike standard procedures of preparing a specimen surface for the EBSD analysis, the proposed procedure is iterative with consecutive application of mechanical and electrochemical polishing. This procedure significantly improves the results of an indexed MMC matrix in comparison with the standard procedure of specimen preparation. The procedure was verified on a MMC with pure aluminum (99.8% Al) as the matrix, SiC particles being used as reinforcing elements. The average size of the SiC particles is 14 μm, and their volume fraction amounts to 50% of the total volume of the composite. It has been experimentally found that, for making the EBSD analysis of a material matrix near reinforcing particles, the difference in height between the particles and the matrix should not exceed 2 µm.

  13. The potential role of aluminium in Alzheimer's disease.

    PubMed

    Campbell, Arezoo

    2002-01-01

    Aluminium is a trivalent cation that does not undergo redox changes. It has, nonetheless, been implicated in a variety of neurological disorders that have been associated with an increase in the formation of reactive oxygen species (ROS). The exact mechanism of aluminium toxicity is not known. However, accumulating evidence suggests that the metal can potentiate oxidative and inflammatory events, leading to tissue damage. A review of the epidemiological and clinical evidence linking aluminium to Alzheimer's disease (AD) is presented. The article discusses the role of aluminium in two mechanisms that have been linked to neurodegenerative disorders, including AD. Studies are summarized that describe how aluminium can potentiate iron-induced oxidative events. Involvement of aluminium in inflammatory responses, mediated by interleukins and other inflammatory cytokines, is also discussed. Although a direct relationship between aluminium and AD has not been clearly demonstrated, a detailed mechanistic basis for the hypothesis that aluminium may exacerbate events associated with AD is clearly emerging. The results discussed here have broad implications for the role played by aluminium and other metals in neurodegenerative diseases, and suggest that long-term exposure to supra-physiological amounts these metals should be avoided.

  14. Effect of Size, Content and Shape of Reinforcements on the Behavior of Metal Matrix Composites (MMCs) Under Tension

    NASA Astrophysics Data System (ADS)

    Paknia, A.; Pramanik, A.; Dixit, A. R.; Chattopadhyaya, S.

    2016-08-01

    The objective of this research was to investigate the mechanical behavior of metal matrix composites (MMCs) 6061 aluminum, reinforced with silicon carbide particles, under unidirectional tensile loading by finite element analysis. The effects of particle's shape, size and content on the tensile properties of the composites were studied and compared with each other. In addition, stress and strain distributions and possible particle fracture or debonding were investigated. It was found that, among different shapes, a certain shape of reinforcement particle provided better tensile properties for MMCs and, within each shape category, composites with smaller particle size and higher particle content (20%) also showed better properties. It was also found that when the reinforcement content was 10%, the effects of shape and size of the particles were negligible. Not only interfacial length between the reinforcement and matrix materials, but also state of matrix material, due to the presence of the reinforcement particles, affected the stiffness of the MMCs. In almost all of the cases, except for MMCs with triangular particles, when the stress increased, with the increase in the applied positive displacement, the stress distributions remained unchanged.

  15. Effect of Size, Content and Shape of Reinforcements on the Behavior of Metal Matrix Composites (MMCs) Under Tension

    NASA Astrophysics Data System (ADS)

    Paknia, A.; Pramanik, A.; Dixit, A. R.; Chattopadhyaya, S.

    2016-10-01

    The objective of this research was to investigate the mechanical behavior of metal matrix composites (MMCs) 6061 aluminum, reinforced with silicon carbide particles, under unidirectional tensile loading by finite element analysis. The effects of particle's shape, size and content on the tensile properties of the composites were studied and compared with each other. In addition, stress and strain distributions and possible particle fracture or debonding were investigated. It was found that, among different shapes, a certain shape of reinforcement particle provided better tensile properties for MMCs and, within each shape category, composites with smaller particle size and higher particle content (20%) also showed better properties. It was also found that when the reinforcement content was 10%, the effects of shape and size of the particles were negligible. Not only interfacial length between the reinforcement and matrix materials, but also state of matrix material, due to the presence of the reinforcement particles, affected the stiffness of the MMCs. In almost all of the cases, except for MMCs with triangular particles, when the stress increased, with the increase in the applied positive displacement, the stress distributions remained unchanged.

  16. Control of Porosity and Pore Size of Metal Reinforced Carbon Nanotube Membranes

    PubMed Central

    Dumee, Ludovic; Velleman, Leonora; Sears, Kallista; Hill, Matthew; Schutz, Jurg; Finn, Niall; Duke, Mikel; Gray, Stephen

    2011-01-01

    Membranes are crucial in modern industry and both new technologies and materials need to be designed to achieve higher selectivity and performance. Exotic materials such as nanoparticles offer promising perspectives, and combining both their very high specific surface area and the possibility to incorporate them into macrostructures have already shown to substantially increase the membrane performance. In this paper we report on the fabrication and engineering of metal-reinforced carbon nanotube (CNT) Bucky-Paper (BP) composites with tuneable porosity and surface pore size. A BP is an entangled mesh non-woven like structure of nanotubes. Pure CNT BPs present both very high porosity (>90%) and specific surface area (>400 m2/g). Furthermore, their pore size is generally between 20–50 nm making them promising candidates for various membrane and separation applications. Both electro-plating and electroless plating techniques were used to plate different series of BPs and offered various degrees of success. Here we will report mainly on electroless plated gold/CNT composites. The benefit of this method resides in the versatility of the plating and the opportunity to tune both average pore size and porosity of the structure with a high degree of reproducibility. The CNT BPs were first oxidized by short UV/O3 treatment, followed by successive immersion in different plating solutions. The morphology and properties of these samples has been investigated and their performance in air permeation and gas adsorption will be reported. PMID:24957493

  17. Filament-reinforced metal composite pressure vessel evaluation and performance demonstration

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1976-01-01

    Two different Kevlar-49 filament-reinforced metal sphere designs were developed, and six vessels of each type were fabricated and subjected to fatigue cycling, sustained loading, and hydrostatic burst. The 61 cm (24 inch) diameter Kevlar-49/cryoformed 301 stainless steel pressure vessels demonstrated the required pressure cycle capability, burst factor of safety, and a maximum pressure times volume divided by weight (pV/W) performance of 210 J/g (834 000 in-lb/lbm) at burst; this represented a 25 to 30% weight saving over the lightest weight comparable, 6A1-4V Ti, homogeneous pressure vessel. Both the Kevlar/stainless steel design and the 97 cm (38 inch) diameter Kevlar-49/2219-T62 aluminum sphere design demonstrated nonfragmentation and controlled failure mode features when pressure cycled to failure at operating pressure. When failure occurred during pressure cycling, the mode was localized leakage and not catastrophic. Kevlar/stainless steel vessels utilized a unique conical boss design, and Kevlar/aluminum vessels incorporated a tie-rod to carry port loads; both styles of polar fittings performed as designed during operational testing of the vessels.

  18. Micromechanical and macroscopic models of ductile fracture in particle reinforced metallic materials

    NASA Astrophysics Data System (ADS)

    Hu, Chao; Bai, Jie; Ghosh, Somnath

    2007-06-01

    This paper is aimed at developing two modules contributing to the overall framework of multi-scale modelling of ductile fracture of particle reinforced metallic materials. The first module is for detailed micromechanical analysis of particle fragmentation and matrix cracking of heterogeneous microstructures. The Voronoi cell FEM for particle fragmentation is extended in this paper to incorporate ductile failure through matrix cracking in the form of void growth and coalescence using a non-local Gurson-Tvergaard-Needleman (GTN) model. In the resulting enriched Voronoi cell finite element model (VCFEM) or E-VCFEM, the assumed stress-based hybrid VCFEM formulation is overlaid with narrow bands of displacement based elements to accommodate strain softening in the constitutive behaviour. The second module develops an anisotropic plasticity-damage model in the form of the GTN model for macroscopic analysis in the multi-scale material model. Parameters in this model are calibrated from results of homogenization of microstructural variables obtained by E-VCFEM analysis of microstructural representative volume element. Numerical examples conducted yield satisfactory results.

  19. Micromechanical Modeling the Plastic Deformation of Particle-Reinforced Bulk Metallic Glass Composites

    NASA Astrophysics Data System (ADS)

    Jiang, Yunpeng; Shi, Xueping; Qiu, Kun

    2015-08-01

    A micromechanics model was employed to investigate the mechanical performance of particle-reinforced bulk metallic glass (BMG) composites. The roles of shear banding in the tensile deformation are accounted for in characterizing the strength and ductility of ductile particle-filled BMGs. For the sake of simplicity and convenience, shear band was considered to be a micro-crack in the present model. The strain-based Weibull probability distribution function and percolation theory were applied to describe the equivalent micro-crack evolution, which results in the progressive failure of BMG composites. Based on the developed model, the influences of shear bands on the plastic deformation were discussed for various microstructures. The predictions were in fairly good agreement with the experimental data from the literatures, which confirms that the developed analytical model is able to successfully describe the mechanical properties, such as yield strength, strain hardening, and stress softening elongation of composites. The present results will shed some light on optimizing the microstructures in effectively improving the tensile ductility of BMG composites.

  20. Fatigue behavior of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites

    SciTech Connect

    Liaw, P.K.; Diaz, E.S.; Chiang, K.T.; Loh, D.H.

    1995-05-15

    Flexure fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-poly, continuous silicon carbide (SiC) fibers. The Ti/SCS-6 composites had an 8-ply, (0{degree}, 90{degree}, +45{degree}, {minus}45{degree}), symmetric lay-up. During fatigue testing, four stages of flexure deflection behavior were observed. The deflection at stage 1 increased slightly with fatigue cycling, while that at stage 2 increased significantly with cycling. Interestingly, the deflection at stage 3 again increased negligibly with fatigue cycling. Stage 4 was associated with final failure, and the deflection increased abruptly. In the stage 1 region of the deflection behavior, no cracks were observed, the Ti/SiC interface debonding could be present, and the deflection changed slightly with cycling. When the stage 2 region commenced, cracks began to initiate. As stage 2 progressed, both crack density and crack length increased. The increased crack density and crack length contributed to the great increase in the deflection during stage 2. In stage 3, significant crack deflection and branching, and fiber bridging occurred, and crack density remained relatively constant. Crack deflection and branching, and fiber bridging slowed down crack driving force, and little crack extension was observed, which resulted in an insignificant amount of increase in the stage 3 deflection. The breakage of fibers in stage 4 significantly increased deflection.

  1. Steady-state creep of bent reinforced metal-composite plates with consideration of their reduced resistance to transverse shear. 1. Deformation model

    NASA Astrophysics Data System (ADS)

    Yankovskii, A. P.

    2014-05-01

    The problem of deformation of reinforced metal-composite plates is formulated in rectangular Cartesian coordinates using the second version of Timoshenko theory and taking into account the reduced transverse shear resistance of the plates under steady-state creep conditions. A similar model problem of axisymmetric bending of reinforced plates is considered in polar coordinates.

  2. Microstructure, mechanical characteristics and cell compatibility of β-tricalcium phosphate reinforced with biodegradable Fe-Mg metal phase.

    PubMed

    Swain, Sanjaya K; Gotman, Irena; Unger, Ronald; Kirkpatrick, C James; Gutmanas, Elazar Y

    2016-01-01

    The use of beta-tricalcium phosphate (β-TCP) ceramic as a bioresorbable bone substitute is limited to non-load-bearing sites by the material׳s brittleness and low bending strength. In the present work, new biocompatible β-TCP-based composites with improved mechanical properties were developed via reinforcing the ceramic matrix with 30 vol% of a biodegradable iron-magnesium metallic phase. β-TCP-15Fe15Mg and β-TCP-24Fe6Mg (vol%) composites were fabricated using a combination of high energy attrition milling, cold sintering/high pressure consolidation of powders at room temperature and annealing at 400 °C. The materials synthesized had a hierarchical nanocomposite structure with a nanocrystalline β-TCP matrix toughened by a finely dispersed nanoscale metallic phase (largely Mg) alongside micron-scale metallic reinforcements (largely Fe). Both compositions exhibited high strength characteristics; in bending, they were about 3-fold stronger than β-TCP reinforced with 30 vol% PLA polymer. Immersion in Ringer׳s solution for 4 weeks resulted in formation of corrosion products on the specimens׳ surface, a few percent weight loss and about 50% decrease in bending strength. In vitro studies of β-TCP-15Fe15Mg composite with human osteoblast monocultures and human osteoblast-endothelial cell co-cultures indicated that the composition was biocompatible for the growth and survival of both cell types and cells exhibited tissue-specific markers for bone formation and angiogenesis, respectively. PMID:26409234

  3. Effects of aluminium salts on bone marrow chromosomes in rats in vivo.

    PubMed

    Roy, A K; Sharma, A; Talukder, G

    1991-01-01

    Oral administration of aluminium sulphate to laboratory bred Rattus norvegicus for prolonged period induced dose dependent inhibition of dividing cells and an increase in chromosomal aberrations. The effect was not influenced by the duration of exposure. The toxicity of the two salts, aluminium sulphate and potassium aluminium sulphate, did not differ significantly at doses in which the metal contents were kept constant. PMID:1868749

  4. A comparative study on low cycle fatigue behaviour of nano and micro Al2O3 reinforced AA2014 particulate hybrid composites

    NASA Astrophysics Data System (ADS)

    Senthilkumar, R.; Arunkumar, N.; Manzoor Hussian, M.

    Aluminium based metal matrix composites have drawn more attraction due to their improved properties in structural applications for the past two decades. The fatigue behaviour of composite materials needs to be studied for their structural applications. In this work, powder metallurgy based aluminium (AA2014) alloy reinforced with micro and nano-sized alumina particles were fabricated and consolidated with the hot extrusion process. The evaluation of mechanical properties in the extruded composite was carried out. This composite was subjected to low cycle fatigue test with a constant strain rate. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) images were used to evaluate the fatigue behaviour of aluminium-nano composite samples. Enhanced mechanical properties were exhibited by the nano alumina reinforced aluminium composites, when compared to the micron sized alumina reinforced composites. The failure cycle is observed to be higher for the nano alumina reinforced composites when compared with micron sized alumina composites due to a lower order of induced plastic strain.

  5. Aluminium salt slag characterization and utilization--a review.

    PubMed

    Tsakiridis, P E

    2012-05-30

    Aluminium salt slag (also known as aluminium salt cake), which is produced by the secondary aluminium industry, is formed during aluminium scrap/dross melting and contains 15-30% aluminium oxide, 30-55% sodium chloride, 15-30% potassium chloride, 5-7% metallic aluminium and impurities (carbides, nitrides, sulphides and phosphides). Depending on the raw mix the amount of salt slag produced per tonne of secondary aluminium ranges from 200 to 500 kg. As salt slag has been classified as toxic and hazardous waste, it should be managed in compliance with the current legislation. Its landfill disposal is forbidden in most of the European countries and it should be recycled and processed in a proper way by taking the environmental impact into consideration. This paper presents a review of the aluminium salt slag chemical and mineralogical characteristics, as well as various processes for metal recovery, recycling of sodium and potassium chlorides content back to the smelting process and preparation of value added products from the final non metallic residue.

  6. Hot tearing evaluation for aluminium alloys

    NASA Astrophysics Data System (ADS)

    Brůna, Marek

    2016-06-01

    Hot tearing during solidification of aluminium alloys castings can be a serious problem. This phenomenon is well known but still insufficiently investigated. Hot tearing occurs in form of irregular cracks in metal castings that develop during solidification and cooling. The cause of hot tearing is generally attributed to the development of thermally induced tensile stresses and strains in a casting as the molten metal contracts during solidification and solid state shrinkage. Submited paper consists of two parts. The first part introduces the reader to the phenomenon of hot tearing. The second part describes newly developed method for assessing hot tearing susceptibility of aluminium alloys, and also gives the results on hot tearing for various aluminium alloys.

  7. Aluminium Electroplating on Steel from a Fused Bromide Electrolyte

    SciTech Connect

    Prabhat Tripathy; Laura Wurth; Eric Dufek; Toni Y. Gutknecht; Natalie Gese; Paula Hahn; Steven Frank; Guy Fredrickson; J Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr-KBr-CsBr-AlBr3) was used to electro-coat aluminium on steel substrates. The electrolyte was prepared by the addition of AlBr3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminium coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminium coverage. Both salt immersion and open circuit potential measurement suggest that the coatings did display good corrosion-resistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminium coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminium coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  8. Accumulation and toxicity of aluminium-contaminated food in the freshwater crayfish, Pacifastacus leniusculus.

    PubMed

    Woodburn, Katie; Walton, Rachel; McCrohan, Catherine; White, Keith

    2011-10-01

    The accumulation and toxicity of aluminium in freshwater organisms have primarily been examined following aqueous exposure. This study investigated the uptake, excretion and toxicity of aluminium when presented as aluminium-contaminated food. Adult Pacifastacus leniusculus were fed control (3 μg aluminium/g) or aluminium-spiked pellets (420 μg aluminium/g) over 28 days. Half the crayfish in each group were then killed and the remainder fed control pellets for a further 10 days (clearance period). Concentrations of aluminium plus the essential metals calcium, copper, potassium and sodium were measured in the gill, hepatopancreas, flexor muscle, antennal gland (kidney) and haemolymph. Histopathological analysis of tissue damage and sub-cellular distribution of aluminium were examined in the hepatopancreas. Haemocyte number and protein concentration in the haemolymph were analysed as indicators of toxicity. The hepatopancreas of aluminium-fed crayfish contained significantly more aluminium than controls on days 28 and 38, and this amount was positively correlated with the amount ingested. More than 50% of the aluminium in the hepatopancreas of aluminium-fed crayfish was located in sub-cellular fractions thought to be involved in metal detoxification. Aluminium concentrations were also high in the antennal glands of aluminium-fed crayfish suggesting that some of the aluminium lost from the hepatopancreas is excreted. Aluminium exposure via contaminated food caused inflammation in the hepatopancreas but did not affect the number of circulating haemocytes, haemolymph ion concentrations or protein levels. In conclusion, crayfish accumulate, store and excrete aluminium from contaminated food with only localised toxicity.

  9. Investigation of metal and ceramic-matrix composites moduli: Experiment and theory

    SciTech Connect

    Liaw, P.K.; Miriyala, N.; Yu, N.; Hsu, D.K.; Saini, V.; Jeong, H.

    1996-05-01

    The elastic behavior of metal and ceramic-matrix composites were characterized by ultrasonic techniques. While an immersion ultrasonic technique was used to measure the stiffness moduli of silicon carbide (SiC) particulate reinforced aluminium metal-matrix composites, a dry-coupling method was used to determine the elastic constants of woven Nicalon{trademark} fiber reinforced SiC ceramic-matrix composites. A unified micromechanics model was developed to predict the elastic moduli of these composites from the knowledge of their constituent elastic constants. The model quantitatively predicted the effects of microstructural characteristics, such as the reinforcement content and porosity in the material, on the elastic moduli of the composite systems studied. The predicted moduli were in good agreement with the experimental results for both the particulate reinforced metal-matrix composites and woven fiber reinforced ceramic-matrix composites.

  10. Aluminium-aluminium nitride composites fabricated by melt infiltration under pressure

    PubMed

    Chedru; Vicens; Chermant; Mordike

    1999-11-01

    Aluminium-matrix composites containing approximately 55 vol.% AlN particles were fabricated by melt infiltration of aluminium into an AlN preform under a pressure of up to 130 MPa. Two different AlN powders (H.C. Starck, Goslar, Germany, and ESK, Elektroschmelzwerk, Kempten, Germany) and four types of aluminium alloy (2024, 1070, 6060 and 5754) were used. The initial AlN powders were characterized by scanning electron microscopy. The composites were studied by light microscopy, scanning and transmission electron microscopies and energy-dispersive X-ray spectroscopy. Particle-matrix interfaces were observed using high-resolution electron microscopy. As a result of the melt infiltration process, the composites are very dense and the microstructure shows a homogeneous distribution of the reinforcement. The interfaces are clean with very little porosity. Some Al2Cu precipitates were observed in the 2024 matrix.

  11. Effects of aluminium surface morphology and chemical modification on wettability

    NASA Astrophysics Data System (ADS)

    Rahimi, M.; Fojan, P.; Gurevich, L.; Afshari, A.

    2014-03-01

    Aluminium alloys are some of the predominant metals in industrial applications such as production of heat exchangers, heat pumps. They have high heat conductivity coupled with a low specific weight. In cold working conditions, there is a risk of frost formation on the surface of aluminium in the presence of water vapour, which can lead to the deterioration of equipment performance. This work addresses the methods of surface modification of aluminium and their effect of the underlying surface morphology and wettability, which are the important parameters for frost formation. Three groups of real-life aluminium surfaces of different morphology: unpolished aluminium, polished aluminium, and aluminium foil, were subjected to surface modification procedures which involved the formation of a layer of hydrophilic hyperbranched polyethyleneglycol via in situ polymerization, molecular vapour deposition of a monolayer of fluorinated silane, and a combination of those. The effect of these surface modification techniques on roughness and wettability of the aluminium surfaces was elucidated by ellipsometry, contact angle measurements and atomic force microscopy. We demonstrated that by employing different types of surface modifications the contact angle of water droplets on aluminium samples can be varied from 12° to more than 120°. A crossover from Cassie-Baxter to Wenzel regime upon changing the surface roughness was also observed.

  12. Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique — Optimization of process parameters

    SciTech Connect

    Ghosh, Subrata Kumar; Bandyopadhyay, Kaushik; Saha, Partha

    2014-07-01

    In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO{sub 2} and B{sub 4}C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB{sub 2} and Al{sub 2}O{sub 3} in the composite.

  13. Deformation behavior of metallic glass composites reinforced with shape memory nanowires studied via molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Şopu, D.; Stoica, M.; Eckert, J.

    2015-05-01

    Molecular dynamics simulations indicate that the deformation behavior and mechanism of Cu64Zr36 composite structures reinforced with B2 CuZr nanowires are strongly influenced by the martensitic phase transformation and distribution of these crystalline precipitates. When nanowires are distributed in the glassy matrix along the deformation direction, a two-steps stress-induced martensitic phase transformation is observed. Since the martensitic transformation is driven by the elastic energy release, the strain localization behavior in the glassy matrix is strongly affected. Therefore, the composite materials reinforced with a crystalline phase, which shows stress-induced martensitic transformation, represent a route for controlling the properties of glassy materials.

  14. Use of spray techniques to synthesize particulate-reinforced metal-matrix composites

    NASA Astrophysics Data System (ADS)

    Srivatsan, T. S.; Lavernia, E. J.

    1992-11-01

    Spray processing of particulate-reinforced MMCs combines microstructural refinement and compositional modifications with in situ processing and even near-net-shape manufacturing. Representative spray-processing methods encompass spray-atomization and -deposition, low-pressure plasma deposition, modified gas welding, and high velocity oxyfuel thermal spraying. Because they involve the mixing of matrix and reinforcement under nonequilibrium conditions, these processes allow the modification and enhancement of existing alloy systems' properties, as well as to develop novel alloy compositions; this approach precludes the extreme thermal excursions associated with conventional casting, and their concomitant macrosegregation.

  15. DENA: A finite element program for the non-linear stress analysis of two-dimensional, metallic and reinforced concrete, structures

    NASA Astrophysics Data System (ADS)

    Ranjbaran, A.; Phipps, M. E.

    1994-04-01

    A finite element program for the nonlinear stress analysis of two-dimensional problems is introduced. Both metallic and reinforced concrete structures are considered. In the case of metals plasticity is taken into account. For reinforced concrete structures cracking of concrete in tension, plasticity and crushing of concrete in compression, and plasticity of reinforcement is accounted for. A new and unified model for embedding reinforcement in concrete elements is proposed. The proposed model is quite general in the sense that it can be used both for two- and three-dimensional problems. The theoretical basis of the program is presented. The accuracy, efficiency and robustness of the program and its implementation is verified through the analysis of two-dimensional problems.

  16. On Porosity Formation in Metal Matrix Composites Made with Dual-Scale Fiber Reinforcements Using Pressure Infiltration Process

    NASA Astrophysics Data System (ADS)

    Etemadi, Reihaneh; Pillai, Krishna M.; Rohatgi, Pradeep K.; Hamidi, Sajad Ahmad

    2015-05-01

    This is the first such study on porosity formation phenomena observed in dual-scale fiber preforms during the synthesis of metal matrix composites (MMCs) using the gas pressure infiltration process. In this paper, different mechanisms of porosity formation during pressure infiltration of Al-Si alloys into Nextel™ 3D-woven ceramic fabric reinforcements (a dual-porosity or dual-scale porous medium) are studied. The effect of processing conditions on porosity content of the ceramic fabric infiltrated by the alloys through the gas PIP (PIP stands for "Pressure Infiltration Process" in which liquid metal is injected under pressure into a mold packed with reinforcing fibers.) is investigated. Relative density (RD), defined as the ratio of the actual MMC density and the density obtained at ideal 100 pct saturation of the preform, was used to quantify the overall porosity. Increasing the infiltration temperature led to an increase in RD due to reduced viscosity of liquid metal and enhanced wettability leading to improved feedability of the liquid metal. Similarly, increasing the infiltration pressure led to enhanced penetration of fiber tows and resulted in higher RD and reduced porosity. For the first time, the modified Capillary number ( Ca*), which is found to predict formation of porosity in polymer matrix composites quite well, is employed to study porosity in MMCs made using PIP. It is observed that in the high Ca* regime which is common in PIP, the overall porosity shows a strong downward trend with increasing Ca*. In addition, the effect of matrix shrinkage on porosity content of the samples is studied through using a zero-shrinkage Al-Si alloy as the matrix; usage of this alloy as the matrix led to a reduction in porosity content.

  17. Metallic Concepts for Repair of Reinforced Carbon-Carbon Space Shuttle Leading Edges

    NASA Technical Reports Server (NTRS)

    Ritzert, Frank; Nesbitt, James

    2007-01-01

    The Columbia accident has focused attention on the critical need for on-orbit repair concepts for wing leading edges in the event that potentially catastrophic damage is incurred during Space Shuttle Orbiter flight. The leading edge of the space shuttle wings consists of a series of eleven panels on each side of the orbiter. These panels are fabricated from reinforced carbon-carbon (RCC) which is a light weight composite with attractive strength at very high temperatures. The damage that was responsible for the loss of the Colombia space shuttle was deemed due to formation of a large hole in one these RCC leading edge panels produced by the impact of a large piece of foam. However, even small cracks in the RCC are considered as potentially catastrophic because of the high temperature re-entry environment. After the Columbia accident, NASA has explored various means to perform on-orbit repairs in the event that damage is sustained in future shuttle flights. Although large areas of damage, such as that which doomed Columbia, are not anticipated to re-occur due to various improvements to the shuttle, especially the foam attachment, NASA has also explored various options for both small and large area repair. This paper reports one large area repair concept referred to as the "metallic over-wrap." Environmental conditions during re-entry of the orbiter impose extreme requirements on the RCC leading edges as well as on any repair concepts. These requirements include temperatures up to 3000 F (1650 C) for up to 15 minutes in the presence of an extremely oxidizing plasma environment. Figure 1 shows the temperature profile across one panel (#9) which is subject to the highest temperatures during re-entry. Although the RCC possesses adequate mechanical strength at these temperatures, it lacks oxidation resistance. Oxidation protection is afforded by converting the outer layers of the RCC to SiC by chemical vapor deposition (CVD). At high temperatures in an oxidizing

  18. Volatilisation and oxidation of aluminium scraps fed into incineration furnaces

    SciTech Connect

    Biganzoli, Laura; Gorla, Leopoldo; Nessi, Simone; Grosso, Mario

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Aluminium packaging partitioning in MSW incineration residues is evaluated. Black-Right-Pointing-Pointer The amount of aluminium packaging recoverable from the bottom ashes is evaluated. Black-Right-Pointing-Pointer Aluminium packaging oxidation rate in the residues of MSW incineration is evaluated. Black-Right-Pointing-Pointer 80% of aluminium cans, 51% of trays and 27% of foils can be recovered from bottom ashes. - Abstract: Ferrous and non-ferrous metal scraps are increasingly recovered from municipal solid waste incineration bottom ash and used in the production of secondary steel and aluminium. However, during the incineration process, metal scraps contained in the waste undergo volatilisation and oxidation processes, which determine a loss of their recoverable mass. The present paper evaluates the behaviour of different types of aluminium packaging materials in a full-scale waste to energy plant during standard operation. Their partitioning and oxidation level in the residues of the incineration process are evaluated, together with the amount of potentially recoverable aluminium. About 80% of post-consumer cans, 51% of trays and 27% of foils can be recovered through an advanced treatment of bottom ash combined with a melting process in the saline furnace for the production of secondary aluminium. The residual amount of aluminium concentrates in the fly ash or in the fine fraction of the bottom ash and its recovery is virtually impossible using the current eddy current separation technology. The average oxidation levels of the aluminium in the residues of the incineration process is equal to 9.2% for cans, 17.4% for trays and 58.8% for foils. The differences between the tested packaging materials are related to their thickness, mechanical strength and to the alloy.

  19. Evaluation of metal landing gear door assembly selectively reinforced with filamentary composite for space shuttle application

    NASA Technical Reports Server (NTRS)

    Kong, S. J.; Freeman, V. L.

    1972-01-01

    The development and evaluation of a main landing gear door for space shuttle applications are discussed. The door is constructed on composite materials using a rib-stiffened titanium panel selectively reinforced with boron/epoxy composite. A weight comparison between the hybrid design and the all-titanium baseline design showed a weight saving of approximately fifteen percent. Detailed descriptions of the door structure and method of manufacture are presented.

  20. Acid-shock, aluminium, and presence of Sphagnum aurantiacum: effect on embryological development in the common frog, Rana temporaria and the moor frog, Rana arvalis

    SciTech Connect

    Olsson, M.; Hogstrand, C.; Dahlberg, A.; Berglind, S.A.

    1987-07-01

    During the last two decades, several effects of acidification have been shown, e.g., enhanced leaching of metals from sediments and soil. Furthermore, an increased growth of Sphagnum aurantiacum frequently occurs in acidified waters. The aim of the present study is to investigate some effects of acidification on the embryological development on two Anurans. The toxicity of aluminium is thought to vary with pH. The highest toxicity of aluminium in the hydroxyl form have been found at pH 5. In the present study a laboratory experiment was performed to investigate the toxicity of Al to frog embryos in water with pH 5.0. In acidified waters Sphagnum and especially S. aurantiacum, is competitive and quickly become established. It has been indicated that frog spawn deposited on Sphagnum show an unusually high mortality and questions have been raised if Sphagnum reinforces the detrimental effects of acidification on Anuran reproduction.

  1. Characterization of anisotropie elastic constants of silicon-carbide participate reinforced aluminum metal matrix composites: Part I. Experiment

    NASA Astrophysics Data System (ADS)

    Jeong, Hyunjo; Hsu, David K.; Shannon, Robert E.; Liaw, Peter K.

    1994-04-01

    The anisotropic elastic properties of silicon-carbide particulate (SiC p ) reinforced Al metal matrix composites were characterized using ultrasonic techniques and microstructural analysis. The composite materials, fabricated by a powder metallurgy extrusion process, included 2124, 6061, and 7091 Al alloys reinforced by 10 to 30 pct of α-SiC p by volume. Results were presented for the assumed orthotropic elastic constants obtained from ultrasonic velocities and for the microstructural data on particulate shape, aspect ratio, and orientation distribution. All of the composite samples exhibited a systematic anisotropy: the stiffness in the extrusion direction was the highest, and the stiffness in the out-of-plane direction was the lowest. Microstructural analysis suggested that the observed anisotropy could be attributed to the preferred orientation of SiC p . The ultrasonic velocity was found to be sensitive to internal defects such as porosity and intermetallic compounds. It has been observed that ultrasonics may be a useful, nondestructive technique for detecting small directional differences in the overall elastic constants of the composites since a good correlation has been noted between the velocity and microstructure and the mechanical test. By incorporating the observed microstructural characteristics, a theoretical model for predicting the anisotropic stiffnesses of the composites has been developed and is presented in a companion article (Part II).

  2. Mechanical characterization and modeling of non-linear deformation and fracture of a fiber reinforced metal matrix composite

    NASA Technical Reports Server (NTRS)

    Jansson, S.

    1991-01-01

    The nonlinear anisotropic mechanical behavior of an aluminum alloy metal matrix composite reinforced with continuous alumina fibers was determined experimentally. The mechanical behavior of the composite were modeled by assuming that the composite has a periodical microstructure. The resulting unit cell problem was solved with the finite element method. Excellent agreement was found between theoretically predicted and measured stress-strain responses for various tensile and shear loadings. The stress-strain responses for transverse and inplane shear were found to be identical and this will provide a simplification of the constitutive equations for the composite. The composite has a very low ductility in transverse tension and a limited ductility in transverse shear that was correlated to high hydrostatic stresses that develop in the matrix. The shape of the initial yield surface was calculated and good agreement was found between the calculated shape and the experimentally determined shape.

  3. Impact of Volume Fraction and Size of Reinforcement Particles on the Grain Size in Metal-Matrix Micro and Nanocomposites

    NASA Astrophysics Data System (ADS)

    Ferguson, J. B.; Lopez, Hugo F.; Rohatgi, Pradeep K.; Cho, Kyu; Kim, Chang-Soo

    2014-08-01

    In metal-matrix micro and nanocomposites (MMCs and MMNCs), the presence and interactions of various strengthening mechanisms are not well understood, but grain boundary strengthening is considered as one of the primary means of improving the yield strength of composites. Owing to the importance of grain size on mechanical properties, it is necessary to be able to describe how incorporation of nanoparticles (NPs) in both powder metallurgy (PM) and solidification processing (SP) affects this critical property. In the present work, we provide a basis for an empirical equation that relates particle fraction and particle size to MMNC grain size for both PM and SP synthesis methods. The model suggests that NPs retard grain coarsening in PM MMNCs and also seems to describe the effect of reinforcement concentration on grain size in SP MMCs and MMNCs.

  4. Crack initiation and propagation behavior of WC particles reinforced Fe-based metal matrix composite produced by laser melting deposition

    NASA Astrophysics Data System (ADS)

    Wang, Jiandong; Li, Liqun; Tao, Wang

    2016-08-01

    It is generally believed that cracks in metal matrix composites (MMC) parts manufacturing are crucial to the reliable material properties, especially for the reinforcement particles with high volume fraction. In this paper, WC particles (WCp) reinforced Fe-based metal matrix composites (WCp/Fe) were manufactured by laser melting deposition (LMD) technology to investigate the characteristics of cracks formation. The section morphology of composites were analyzed by optical microscope (OM), and microstructure of WCp, matrix and interface were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), in order to study the crack initiation and propagation behavior under different laser process conditions. The temperature of materials during the laser melting deposition was detected by the infrared thermometer. The results showed that the cracks often appeared after five layers laser deposition in this experiment. The cracks crossed through WC particles rather than the interface, so the strength of interface obtained by the LMD was relatively large. When the thermal stress induced by high temperature gradient during LMD and the coefficient of thermal expansion mismatch between WC and matrix was larger than yield strength of WC, the cracks would initiate inside WC particle. Cracks mostly propagated along the eutectic phases whose brittleness was very large. The obtained thin interface was beneficial to transmitting the stress from particle to matrix. The influence of volume fraction of particles, laser power and scanning speed on cracks were investigated. This paper investigated the influence of WC particles size on cracks systematically, and the smallest size of cracked WC in different laser processing parameters was also researched.

  5. Precipitation reactions in 8090 SiC-particulate reinforced MMC. Technical report

    SciTech Connect

    Hunt, E.; Pitcher, P.D.; Gregson, P.J.

    1990-04-01

    There is currently much interest in SiC particulate reinforcement of aluminium-lithium based alloys such as 8090 (Al-Li-Cu-Mg) to provide a lightweight, high stiffness and isotropic metal matrix composite (MMC). The composite materials may be heat-treated to develop an optimum balance of mechanical properties. 8090/SiC MMCs produced via spray deposition are reported to exhibit similar aging kinetics to those of the matrix alloy, but similar materials produced via solid state powder processing and incorporating a higher volume fraction of particulate reinforcement have been shown to exhibit a more rapid aging response than the unreinforced 8090 matrix. The present research set out to investigate the microstructural changes during age hardening of SiC particulate reinforced 8090 in order to provide a better understanding of the aging kinetics and thereby complement the efforts towards property optimization. (JS)

  6. Aluminium electrodeposition under ambient conditions.

    PubMed

    Abbott, Andrew P; Harris, Robert C; Hsieh, Yi-Ting; Ryder, Karl S; Sun, I-Wen

    2014-07-28

    The electrodeposition of aluminium is demonstrated using a eutectic mixture of aluminium chloride and urea. The mixture is shown to be conducting through the formation of both cationic ([AlCl2·urean](+)) and anionic (AlCl4(-)) species and electrodeposition is achieved through the cationic species. The use of a biphasic system with the ionic liquid and a protective hydrocarbon layer allows metal deposition to be carried out in an environment with ambient moisture without the need for a glove box. A direct comparison is made between the AlCl3:urea and imidazolium chloride:AlCl3 systems and the differences in speciation and mass transport manifest themselves in different deposit morphologies. Brighteners which work in the chloroaluminate system such as toluene and LiCl are shown to be ineffective in the urea based system and the reasons for these differences are ascribed to the mechanism of the anodic reaction which is rate limiting. PMID:24916113

  7. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Straayer, J. W.

    1974-01-01

    A final program summary is reported for test and evaluation activities that were conducted for space shuttle web selection. Large scale advanced composite shear web components were tested and analyzed to evaluate application of advanced composite shear web construction to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron-epoxy reinforced aluminum stiffeners and logitudinal aluminum stiffening. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs.

  8. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application. Phase 1 summary report: Shear web design development

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Zimmerman, D. K.

    1972-01-01

    An advanced composite shear web design concept was developed for the Space Shuttle orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad + or - 45 deg boron/epoxy web plate with vertical boron/epoxy reinforced aluminum stiffeners. The boron-epoxy laminate contributes to the strength and stiffness efficiency of the basic web section. The titanium-cladding functions to protect the polymeric laminate parts from damaging environments and is chem-milled to provide reinforcement in selected areas. Detailed design drawings are presented for both boron/epoxy reinforced and all-metal shear webs. The weight saving offered is 24% relative to all-metal construction at an attractive cost per pound of weight saved, based on the detailed designs. Small scale element tests substantiate the boron/epoxy reinforced design details in critical areas. The results show that the titanium-cladding reliably reinforces the web laminate in critical edge load transfer and stiffener fastener hole areas.

  9. Novel iron metal matrix composite reinforced by quartz sand for the effective dechlorination of aqueous 2-chlorophenol.

    PubMed

    Zhang, Yunfei; Yang, Bo; Han, Yanni; Jiang, Chaojin; Wu, Deli; Fan, Jinhong; Ma, Luming

    2016-03-01

    In this work, we tested a novel iron metal matrix composite (MMC) synthesized by mechanically introducing quartz sand (SiO2) into an iron matrix (denoted as SiO2-Fe MMC). The pseudo-first-order reaction rate constant of the SiO2-Fe MMC (initial pH 5.0) for 20 mg/L of 2-chlorophenol (2-CP) was 0.051 × 10(-3) L/m(2)/min, which was even higher than that of some reported Pd/Fe bimetals. This extraordinary high activity was promoted by the quick iron dissolution rate, which was caused by the formation of Fe-C internal electrolysis from carbonization of process control agent (PCA) and the active reinforcement/metal interfaces during the milling process. In addition, pH has slight effect on the dechlorination rate. The SiO2-Fe MMC retained relatively stable activity, still achieving 71% removal efficiency for 2-CP after six consecutive cycles. The decrease in dechlorination efficiency can be attributed to the rapid consumption of Fe(0). A dechlorination mechanism using the SiO2-Fe MMC was proposed by a direct electron transfer from Fe(0) to 2-CP at the quartz sand/iron interface.

  10. Steady-state creep of bent reinforced metal-composite plates with consideration of their reduced resistance to transverse shear 2. Analysis of calculated results

    NASA Astrophysics Data System (ADS)

    Yankovskii, A. P.

    2014-07-01

    Deformation of annular plates with different structures of helical reinforcement is studied. It is demonstrated that the use of the classical theory for calculating steady-state creep for thick reinforced plates subjected to bending leads to underprediction of the compliance of thin-walled metal-composite structures. It is also shown that there are significant shear strain rates in the binder of such plates, which has to be taken into account and which is mainly responsible for creep strain accumulation. Results calculated by two different models, which take into account the composite structure, are compared.

  11. Synthesis of high performance ceramic fibers by chemical vapor deposition for advanced metallics reinforcing

    NASA Technical Reports Server (NTRS)

    Revankar, Vithal; Hlavacek, Vladimir

    1991-01-01

    The chemical vapor deposition (CVD) synthesis of fibers capable of effectively reinforcing intermetallic matrices at elevated temperatures which can be used for potential applications in high temperature composite materials is described. This process was used due to its advantage over other fiber synthesis processes. It is extremely important to produce these fibers with good reproducible and controlled growth rates. However, the complex interplay of mass and energy transfer, blended with the fluid dynamics makes this a formidable task. The design and development of CVD reactor assembly and system to synthesize TiB2, CrB, B4C, and TiC fibers was performed. Residual thermal analysis for estimating stresses arising form thermal expansion mismatch were determined. Various techniques to improve the mechanical properties were also performed. Various techniques for improving the fiber properties were elaborated. The crystal structure and its orientation for TiB2 fiber is discussed. An overall view of the CVD process to develop CrB2, TiB2, and other high performance ceramic fibers is presented.

  12. Hot isostatic pressing of SiC particulate reinforced metal matrix composites

    SciTech Connect

    Loh, N.L.; Wei, Z.; Xu, Z.

    1996-12-31

    Two as-cast SiC particulate reinforced A359-based composites were hot isostatically pressed for a fixed length of time but at various pressures (in the range 100--150 MPa) and temperatures (in the range 450--550 C). It was found that HIP treatment generally increased the ductility but reduced the yield stress drastically. The improvement of ductility was attributed to a reduction of the porosity levels. Quantitative image analyses showed that the HIP treatment reduced the porosity levels significantly. It is of interest to observe that increasing HIP temperature is more effective than increasing HIP pressure in terms of improvement in strength and ductility. Another interesting observation is that most eutectic Si particles were spheroidized during HIP. The spheroidization of Si was believed to contribute to the improvement of mechanical properties, because fracture initiation of the composites was observed to be related to either the breaking of Si particles or the debonding of Si particles from the nearby SiC particles.

  13. Volatilisation and oxidation of aluminium scraps fed into incineration furnaces.

    PubMed

    Biganzoli, Laura; Gorla, Leopoldo; Nessi, Simone; Grosso, Mario

    2012-12-01

    Ferrous and non-ferrous metal scraps are increasingly recovered from municipal solid waste incineration bottom ash and used in the production of secondary steel and aluminium. However, during the incineration process, metal scraps contained in the waste undergo volatilisation and oxidation processes, which determine a loss of their recoverable mass. The present paper evaluates the behaviour of different types of aluminium packaging materials in a full-scale waste to energy plant during standard operation. Their partitioning and oxidation level in the residues of the incineration process are evaluated, together with the amount of potentially recoverable aluminium. About 80% of post-consumer cans, 51% of trays and 27% of foils can be recovered through an advanced treatment of bottom ash combined with a melting process in the saline furnace for the production of secondary aluminium. The residual amount of aluminium concentrates in the fly ash or in the fine fraction of the bottom ash and its recovery is virtually impossible using the current eddy current separation technology. The average oxidation levels of the aluminium in the residues of the incineration process is equal to 9.2% for cans, 17.4% for trays and 58.8% for foils. The differences between the tested packaging materials are related to their thickness, mechanical strength and to the alloy.

  14. Aluminium in allergen-specific subcutaneous immunotherapy--a German perspective.

    PubMed

    Kramer, Matthias F; Heath, Matthew D

    2014-07-16

    We are living in an "aluminium age" with increasing bioavailability of the metal for approximately 125 years, contributing significantly to the aluminium body burden of humans. Over the course of life, aluminium accumulates and is stored predominantly in the lungs, bones, liver, kidneys and brain. The toxicity of aluminium in humans is briefly summarised, highlighting links and possible causal relationships between a high aluminium body burden and a number of neurological disorders and disease states. Aluminium salts have been used as depot-adjuvants successfully in essential prophylactic vaccinations for almost 100 years, with a convincing positive benefit-risk assessment which remains unchanged. However, allergen-specific immunotherapy commonly consists of administering a long-course programme of subcutaneous injections using preparations of relevant allergens. Regulatory authorities currently set aluminium limits for vaccines per dose, rather than per treatment course. Unlike prophylactic vaccinations, numerous injections with higher proportions of aluminium-adjuvant per injection are applied in subcutaneous immunotherapy (SCIT) and will significantly contribute to a higher cumulative life dose of aluminium. While the human body may cope robustly with a daily aluminium overload from the environment, regulatory cumulative threshold values in immunotherapy need further addressing. Based on the current literature, predisposing an individual to an unusually high level of aluminium, such as through subcutaneous immunotherapy, has the potential to form focal accumulations in the body with the propensity to exert forms of toxicity. Particularly in relation to longer-term health effects, the safety of aluminium adjuvants in immunotherapy remains unchallenged by health authorities - evoking the need for more consideration, guidance, and transparency on what is known and not known about its safety in long-course therapy and what measures can be taken to prevent or

  15. Aluminium in allergen-specific subcutaneous immunotherapy--a German perspective.

    PubMed

    Kramer, Matthias F; Heath, Matthew D

    2014-07-16

    We are living in an "aluminium age" with increasing bioavailability of the metal for approximately 125 years, contributing significantly to the aluminium body burden of humans. Over the course of life, aluminium accumulates and is stored predominantly in the lungs, bones, liver, kidneys and brain. The toxicity of aluminium in humans is briefly summarised, highlighting links and possible causal relationships between a high aluminium body burden and a number of neurological disorders and disease states. Aluminium salts have been used as depot-adjuvants successfully in essential prophylactic vaccinations for almost 100 years, with a convincing positive benefit-risk assessment which remains unchanged. However, allergen-specific immunotherapy commonly consists of administering a long-course programme of subcutaneous injections using preparations of relevant allergens. Regulatory authorities currently set aluminium limits for vaccines per dose, rather than per treatment course. Unlike prophylactic vaccinations, numerous injections with higher proportions of aluminium-adjuvant per injection are applied in subcutaneous immunotherapy (SCIT) and will significantly contribute to a higher cumulative life dose of aluminium. While the human body may cope robustly with a daily aluminium overload from the environment, regulatory cumulative threshold values in immunotherapy need further addressing. Based on the current literature, predisposing an individual to an unusually high level of aluminium, such as through subcutaneous immunotherapy, has the potential to form focal accumulations in the body with the propensity to exert forms of toxicity. Particularly in relation to longer-term health effects, the safety of aluminium adjuvants in immunotherapy remains unchallenged by health authorities - evoking the need for more consideration, guidance, and transparency on what is known and not known about its safety in long-course therapy and what measures can be taken to prevent or

  16. Non-invasive therapy to reduce the body burden of aluminium in Alzheimer's disease.

    PubMed

    Exley, Christopher; Korchazhkina, Olga; Job, Deborah; Strekopytov, Stanislav; Polwart, Anthony; Crome, Peter

    2006-09-01

    There are unexplained links between human exposure to aluminium and the incidence, progression and aetiology of Alzheimer's disease. The null hypothesis which underlies any link is that there would be no Alzheimer's disease in the effective absence of a body burden of aluminium. To test this the latter would have to be reduced to and retained at a level that was commensurate with an Alzheimer's disease-free population. In the absence of recent human interference in the biogeochemical cycle of aluminium the reaction of silicic acid with aluminium has acted as a geochemical control of the biological availability of aluminium. This same mechanism might now be applied to both the removal of aluminium from the body and the reduced entry of aluminium into the body while ensuring that essential metals, such as iron, are unaffected. Based upon the premise that urinary aluminium is the best non-invasive estimate of body burden of aluminium patients with Alzheimer's disease were asked to drink 1.5 L of a silicic acid-rich mineral water each day for five days and, by comparison of their urinary excretion of aluminium pre-and post this simple procedure, the influence upon their body burden of aluminium was determined. Drinking the mineral water increased significantly (P<0.001) their urinary excretion of silicic acid (34.3 +/- 15.2 to 55.7 +/- 14.2 micromol/mmol creatinine) and concomitantly reduced significantly P=0.037) their urinary excretion of aluminium (86.0 +/- 24.3 to 62.2 +/- 23.2 nmol/mmol creatinine). The latter was achieved without any significant (P>0.05) influence upon the urinary excretion of iron (20.7 +/- 9.5 to 21.7 +/- 13.8 nmol/mmol creatinine). The reduction in urinary aluminium supported the future longer-term use of silicic acid as non-invasive therapy for reducing the body burden of aluminium in Alzheimer's disease.

  17. Thermal Infrared Reflective Metal Oxide Sol-Gel Coatings for Carbon Fiber Reinforced Composite Structures

    NASA Astrophysics Data System (ADS)

    Richard, Brandon Demar

    Recent trends in composite research include the development of structural materials with multiple functionalities. In new studies, novel materials are being designed, developed, modified, and implemented into composite designs. Typically, an increase in functionality requires additional material phases within one system. The presence of excessive phases can result in deterioration of individual or overall properties. True multi-functional materials must maintain all properties at or above the minimum operating limit. In this project, samples of antimony and cobalt-doped tin oxide (ATO(Co2O 3)) sol-gel solutions are used to coat carbon fibers and are heat treated at a temperature range of 200 - 500 °C. Results from this research are used to model the implementation of sol-gel coatings into carbon fiber reinforced multifunctional composite systems. This research presents a novel thermo-responsive sol-gel/ (dopant) combination and evaluation of the actuating responses (reflectivity and surface heat dissipation) due to various heat treatment temperatures. While ATO is a well-known transparent conductive material, the implementation of ATO on carbon fibers for infrared thermal reflectivity has not been examined. These coatings serve as actuators capable of reflecting thermal infrared radiation in the near infrared wavelengths of 0.7-1.2 μm. By altering the level of Co2O3 and heat treatment temperatures, optimal optical properties are obtained. While scanning electron microscopy (SEM) is used for imaging, electron diffraction spectroscopy (EDS) is used to verify the compounds present in the coatings. Fourier transform infrared (FT-IR) spectroscopy was performed to analyze the chemical bonds and reflectivity in the infrared spectra after the heat treatments. Total reflection and angle-dependent reflectivity measurements were performed on the coatings in the wavelengths of 0.7-2 μm. Laser induced damage threshold testing was done to investigate the dielectric breakdown

  18. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 2: Structural fatigue, thermal cycling, creep, and residual strength

    NASA Technical Reports Server (NTRS)

    Blichfeldt, B.; Mccarty, J. E.

    1972-01-01

    Specimens representative of metal aircraft structural components reinforced with boron filamentary composites were manufactured and tested under cyclic loading, cyclic temperature, or continuously applied loading to evaluate some of the factors that affect structural integrity under cyclic conditions. Bonded, stepped joints were used throughout to provide composite-to-metal transition regions at load introduction points. Honeycomb panels with titanium or aluminum faces reinforced with unidirectional boron composite were fatigue tested at constant amplitude under completely reversed loading. Results indicated that the matrix material was the most fatigue-sensitive part of the design, with debonding initiating in the stepped joints. However, comparisons with equal weight all-metal specimens show a 10 to 50 times improved fatigue life. Fatigue crack propagation and residual strength were studied for several different stiffened panel concepts, and were found to vary considerably depending on the configuration. Composite-reinforced metal specimens were also subjected to creep and thermal cycling tests. Thermal cycling of stepped joint tensile specimens resulted in a ten percent decrease in residual strength after 4000 cycles.

  19. Investigation and in situ removal of spatter generated during laser ablation of aluminium composites

    NASA Astrophysics Data System (ADS)

    Popescu, A. C.; Delval, C.; Shadman, S.; Leparoux, M.

    2016-08-01

    Spatter generated during laser irradiation of an aluminium alloy nanocomposite (AlMg5 reinforced with Al2O3 nanoparticles) was monitored by high speed imaging. Droplets trajectory and speed were assessed by computerized image analysis. The effects of laser peak power and laser focusing on the plume expansion and expulsed droplet speeds were studied in air or under argon flow. It was found that the velocity of visible droplets expulsed laterally or at the end of the plume emission from the metal surface was not dependent on the plasma plume speed. The neighbouring area of irradiation sites was studied by optical and scanning electron microscopy. Droplets deposited on the surface were classified according to their size and counted using a digital image processing software. It was observed that the number of droplets on surface was 1.5-3 times higher when the laser beam was focused in depth as compared to focused beams, even though the populations average diameter were comparable. Three methods were selected for removing droplets in situ, during plume expansion: an argon gas jet crossing the plasma plume, a fused silica plate collector transparent to the laser wavelength placed parallel to the irradiated surface and a mask placed onto the aluminium composite surface. The argon gas jet was efficient only for low power irradiation conditions, the fused silica plate failed in all tested conditions and the mask was successful for all irradiation regimes.

  20. Corrosion of Continuous Fiber Reinforced Aluminum Metal Matrix Composites (CF-AMCs)

    NASA Astrophysics Data System (ADS)

    Tiwari, Shruti

    The first objective of this research is to study the atmospheric corrosion behavior of continuous reinforced aluminum matrix composites (CF-AMCs). The materials used for this research were alumina (Al2O3) and nickel (Ni) coated carbon (C) fibers reinforced AMCs. The major focus is to identify the correlation between atmospheric parameters and the corrosion rates of CF-AMCs in the multitude of microclimates and environments in Hawai'i. The micro-structures of CF-AMCs were obtained to correlate the microstructures with their corrosion performances. Also electrochemical polarization experiments were conducted in the laboratory to explain the corrosion mechanism of CF-AMCs. In addition, CF-AMCs were exposed to seven different test sites for three exposure periods. The various climatic conditions like temperature (T), relative humidity (RH), rainfall (RF), time of wetness (TOW), chloride (Cl- ) and sulfate (SO42-) deposition rate, and pH were monitored for three exposure period. Likewise, mass losses of CF-AMCs at each test site for three exposure periods were determined. The microstructure of the CF-AMCS showed that Al/C/50f MMCs contained a Ni-rich phase in the matrix, indicating that the Ni coating on the C fiber dissolved in the matrix. The intermetallic phases obtained in Al-2wt% Cu/Al 2O3/50f-T6 MMC and Al-2wt%-T6 monolith were rich in Cu and Fe. The intermetallic phases obtained in Al 7075/Al2O3/50f-T6 MMC and Al 7075-T6 monolith also contained traces of Mg, Zn, Ni, and Si. Electrochemical polarization experiment indicated that the Al/Al 2O3/50f Al-2wt% Cu/Al2O3/50f-T6 and Al 7075/Al2O3/50f-T6 MMC showed similar corrosion trends as their respective monoliths pure Al, Al-2wt%-T6 and Al 7075-T6 in both aerated and deaerated condition. Al2O3 fiber, being an insulator, did not have a great effect on the polarization behavior of the composites. Al/C/50f MMCs corroded at a much faster rate as compared to pure Al monolith due to the galvanic effect between C and Al

  1. Corrosion of Continuous Fiber Reinforced Aluminum Metal Matrix Composites (CF-AMCs)

    NASA Astrophysics Data System (ADS)

    Tiwari, Shruti

    The first objective of this research is to study the atmospheric corrosion behavior of continuous reinforced aluminum matrix composites (CF-AMCs). The materials used for this research were alumina (Al2O3) and nickel (Ni) coated carbon (C) fibers reinforced AMCs. The major focus is to identify the correlation between atmospheric parameters and the corrosion rates of CF-AMCs in the multitude of microclimates and environments in Hawai'i. The micro-structures of CF-AMCs were obtained to correlate the microstructures with their corrosion performances. Also electrochemical polarization experiments were conducted in the laboratory to explain the corrosion mechanism of CF-AMCs. In addition, CF-AMCs were exposed to seven different test sites for three exposure periods. The various climatic conditions like temperature (T), relative humidity (RH), rainfall (RF), time of wetness (TOW), chloride (Cl- ) and sulfate (SO42-) deposition rate, and pH were monitored for three exposure period. Likewise, mass losses of CF-AMCs at each test site for three exposure periods were determined. The microstructure of the CF-AMCS showed that Al/C/50f MMCs contained a Ni-rich phase in the matrix, indicating that the Ni coating on the C fiber dissolved in the matrix. The intermetallic phases obtained in Al-2wt% Cu/Al 2O3/50f-T6 MMC and Al-2wt%-T6 monolith were rich in Cu and Fe. The intermetallic phases obtained in Al 7075/Al2O3/50f-T6 MMC and Al 7075-T6 monolith also contained traces of Mg, Zn, Ni, and Si. Electrochemical polarization experiment indicated that the Al/Al 2O3/50f Al-2wt% Cu/Al2O3/50f-T6 and Al 7075/Al2O3/50f-T6 MMC showed similar corrosion trends as their respective monoliths pure Al, Al-2wt%-T6 and Al 7075-T6 in both aerated and deaerated condition. Al2O3 fiber, being an insulator, did not have a great effect on the polarization behavior of the composites. Al/C/50f MMCs corroded at a much faster rate as compared to pure Al monolith due to the galvanic effect between C and Al

  2. Modeling the Effect of Active Fiber Cooling on the Microstructure of Fiber-Reinforced Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Nguyen, Nguyen Q.; Peterson, Sean D.; Gupta, Nikhil; Rohatgi, Pradeep K.

    2009-08-01

    A modified pressure infiltration process was recently developed to synthesize carbon-fiber-reinforced aluminum matrix composites. In the modified process, the ends of carbon fibers are extended out of the crucible to induce selective cooling. The process is found to be effective in improving the quality of composites. The present work is focused on determining the effect of the induced conductive heat transfer on the composite system through numerical methods. Due to the axisymmetry of the system, a two-dimensional (2-D) model is studied that can be expanded into three dimensions. The variables in this transient analysis include the fiber radius, fiber length, and melt superheat temperature. The results show that the composite system can be tailored to have a temperature on the fiber surface that is lower than the melt, to promote nucleation on the fiber surface. It is also observed that there is a point of inflection in the temperature profile along the particle/melt interface at which there is no temperature gradient in the radial direction. The information about the inflection point can be used to control the diffusion of solute atoms in the system. The result can be used in determining the optimum fiber volume fraction in metal matrix composite (MMC) materials to obtain the desired microstructure.

  3. Aluminium and human breast diseases.

    PubMed

    Darbre, P D; Pugazhendhi, D; Mannello, F

    2011-11-01

    The human breast is exposed to aluminium from many sources including diet and personal care products, but dermal application of aluminium-based antiperspirant salts provides a local long-term source of exposure. Recent measurements have shown that aluminium is present in both tissue and fat of the human breast but at levels which vary both between breasts and between tissue samples from the same breast. We have recently found increased levels of aluminium in noninvasively collected nipple aspirate fluids taken from breast cancer patients (mean 268 ± 28 μg/l) compared with control healthy subjects (mean 131 ± 10 μg/l) providing evidence of raised aluminium levels in the breast microenvironment when cancer is present. The measurement of higher levels of aluminium in type I human breast cyst fluids (median 150 μg/l) compared with human serum (median 6 μg/l) or human milk (median 25 μg/l) warrants further investigation into any possible role of aluminium in development of this benign breast disease. Emerging evidence for aluminium in several breast structures now requires biomarkers of aluminium action in order to ascertain whether the presence of aluminium has any biological impact. To this end, we report raised levels of proteins that modulate iron homeostasis (ferritin, transferrin) in parallel with raised aluminium in nipple aspirate fluids in vivo, and we report overexpression of mRNA for several S100 calcium binding proteins following long-term exposure of MCF-7 human breast cancer cells in vitro to aluminium chlorhydrate.

  4. Aluminium and human breast diseases.

    PubMed

    Darbre, P D; Pugazhendhi, D; Mannello, F

    2011-11-01

    The human breast is exposed to aluminium from many sources including diet and personal care products, but dermal application of aluminium-based antiperspirant salts provides a local long-term source of exposure. Recent measurements have shown that aluminium is present in both tissue and fat of the human breast but at levels which vary both between breasts and between tissue samples from the same breast. We have recently found increased levels of aluminium in noninvasively collected nipple aspirate fluids taken from breast cancer patients (mean 268 ± 28 μg/l) compared with control healthy subjects (mean 131 ± 10 μg/l) providing evidence of raised aluminium levels in the breast microenvironment when cancer is present. The measurement of higher levels of aluminium in type I human breast cyst fluids (median 150 μg/l) compared with human serum (median 6 μg/l) or human milk (median 25 μg/l) warrants further investigation into any possible role of aluminium in development of this benign breast disease. Emerging evidence for aluminium in several breast structures now requires biomarkers of aluminium action in order to ascertain whether the presence of aluminium has any biological impact. To this end, we report raised levels of proteins that modulate iron homeostasis (ferritin, transferrin) in parallel with raised aluminium in nipple aspirate fluids in vivo, and we report overexpression of mRNA for several S100 calcium binding proteins following long-term exposure of MCF-7 human breast cancer cells in vitro to aluminium chlorhydrate. PMID:22099158

  5. The binding, transport and fate of aluminium in biological cells.

    PubMed

    Exley, Christopher; Mold, Matthew J

    2015-04-01

    Aluminium is the most abundant metal in the Earth's crust and yet, paradoxically, it has no known biological function. Aluminium is biochemically reactive, it is simply that it is not required for any essential process in extant biota. There is evidence neither of element-specific nor evolutionarily conserved aluminium biochemistry. This means that there are no ligands or chaperones which are specific to its transport, there are no transporters or channels to selectively facilitate its passage across membranes, there are no intracellular storage proteins to aid its cellular homeostasis and there are no pathways which evolved to enable the metabolism and excretion of aluminium. Of course, aluminium is found in every compartment of every cell of every organism, from virus through to Man. Herein we have investigated each of the 'silent' pathways and metabolic events which together constitute a form of aluminium homeostasis in biota, identifying and evaluating as far as is possible what is known and, equally importantly, what is unknown about its uptake, transport, storage and excretion.

  6. Stability properties of tin-oxide-coated aluminium reflectors

    NASA Astrophysics Data System (ADS)

    Roos, Arne; Hedenqvist, Per

    1990-08-01

    The chemical and mechanical stability of tin oxide coated aluminium reflectors have been investigated. The tin oxide has been applied with the pyrolytic spray technique which results in a hard crystalline coating. Tin oxide is a wide bandgap semiconductor and is transparent in the visible part of the spectrum. The visual appearance of tin oxide coated aluminium is therefore similar to the uncoated metal. Interference effects can give a slightly coloured appearance, and owing to the higher refractive index and extinction coefficient of the tin oxide the reflectance is lower than for an anodized aluminium surface. The tin oxide was applied both on electropolished aluminium and on evaporated aluminium films on glass. In both cases an improved resistance both to alcaline and acid solutions was noted. It was found that the chemical stability was better than for an anodized surface. The mechanical stability of the evaporated film was considerably improved. The electropolished samples were also characterized with respect to film hardness and resistance to erosive and abrasive wear. The hardness of the tin oxide was found to be higher than that of the anodized layer while the opposite relation applied for the erosive wear resistance. The abrasive wear resistance was about equal for tin oxide coated and anodized aluminium.

  7. Aluminium contents in baked meats wrapped in aluminium foil.

    PubMed

    Turhan, Sadettin

    2006-12-01

    In this investigation, the effect of cooking treatments (60min at 150°C, 40min at 200°C, and 20min at 250°C) on aluminium contents of meats (beef, water buffalo, mutton, chicken and turkey) baked in aluminium foil were evaluated. Cooking increased the aluminium concentration of both the white and red meats. The increase was 89-378% in red meats and 76-215% in poultry. The least increase (76-115%) was observed in the samples baked for 60min at 150°C, while the highest increase (153-378%) was in samples baked for 20min at 250°C. It was determined that the fat content of meat in addition to the cooking process affected the migration of aluminium (r(2)=0.83; P<0.01). It was also found that raw chicken and turkey breast meat contained higher amounts of aluminium than the raw chicken and turkey leg meat, respectively. Regarding the suggested provisional tolerable daily intake of 1mg Al/kg body weight per day of the FAO/WHO Expert Committee on Food Additives, there are no evident risks to the health of the consumer from using aluminium foil to cook meats. However, eating meals prepared in aluminium foil may carry a risk to the health by adding to other aluminium sources.

  8. Influence of particle size on Cutting Forces and Surface Roughness in Machining of B4Cp - 6061 Aluminium Matrix Composites

    NASA Astrophysics Data System (ADS)

    Hiremath, Vijaykumar; Badiger, Pradeep; Auradi, V.; Dundur, S. T.; Kori, S. A.

    2016-02-01

    Amongst advanced materials, metal matrix composites (MMC) are gaining importance as materials for structural applications in particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, high thermal conductivity. The present study aims at studying and comparing the machinability aspects of B4Cp reinforced 6061Al alloy metal matrix composites reinforced with 37μm and 88μm particulates produced by stir casting method. The micro structural characterization of the prepared composites is done using Scanning Electron Microscopy equipped with EDX analysis (Hitachi Su-1500 model) to identify morphology and distribution of B4C particles in the 6061Al matrix. The specimens are turned on a conventional lathe machine using a Polly crystalline Diamond (PCD) tool to study the effect of particle size on the cutting forces and the surface roughness under varying machinability parameters viz., Cutting speed (29-45 m/min.), Feed rate (0.11-0.33 mm/rev.) and depth of cut (0.5-1mm). Results of micro structural characterization revealed fairly uniform distribution of B4C particles (in both cases i.e., 37μm and 88μm) in 6061Al matrix. The surface roughness of the composite is influenced by cutting speed. The feed rate and depth of cut have a negative influence on surface roughness. The cutting forces decreased with increase in cutting speed whereas cutting forces increased with increase in feed and depth of cut. Higher cutting forces are noticed while machining Al6061 base alloy compared to reinforced composites. Surface finish is high during turning of the 6061Al base alloy and surface roughness is high with 88μm size particle reinforced composites. As the particle size increases Surface roughness also increases.

  9. Materials characterization of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites. Part 1: Tensile and fatigue behavior

    SciTech Connect

    Liaw, P.K.; Diaz, E.S.; Chiang, K.T.; Loh, D.H.

    1995-12-01

    Flexural fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-ply, continuous silicon carbide (SiC) fibers. The titanium composites had an eight-ply (0, 90, +45, {minus}45 deg) symmetric layup. Fatigue life was found to be sensitive to fiber layup sequence. Increasing the test temperature from 24 C to 427 C decreased fatigue life. Interface debonding and matrix and fiber fracture were characteristic of tensile behavior regardless of test temperature. In the tensile fracture process, interface debonding between SiC and the graphite coating and between the graphite coating and the carbon core could occur. A greater amount of coating degradation at 427 C than at 24 C reduced the Ti/SiC interface bonding integrity, which resulted in lower tensile properties at 427 C. During tensile testing, a crack could initiate from the debonded Ti/SiC interface and extend to the debonded interface of the neighboring fiber. The crack tended to propagate through the matrix and the interface. Dimpled fracture was the prime mode of matrix fracture. Interface debonding, matrix cracking, and fiber bridging were identified as the prime modes of fatigue mechanisms. To a lesser extent, fiber fracture was observed during fatigue. However, fiber fracture was believed to occur near the final stage of fatigue failure. In fatigued specimens, facet-type fracture appearance was characteristic of matrix fracture morphology. Theoretical modeling of the fatigue behavior of Ti/SCS-6 composites is presented in Part 2 of this series of articles.

  10. An ultrafast rechargeable aluminium-ion battery.

    PubMed

    Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

    2015-04-16

    The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay. PMID:25849777

  11. An ultrafast rechargeable aluminium-ion battery.

    PubMed

    Lin, Meng-Chang; Gong, Ming; Lu, Bingan; Wu, Yingpeng; Wang, Di-Yan; Guan, Mingyun; Angell, Michael; Chen, Changxin; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

    2015-04-16

    The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay.

  12. Aluminium toxicity and iron homeostasis.

    PubMed

    Ward, R J; Zhang, Y; Crichton, R R

    2001-11-01

    In an animal model of aluminum overload, (aluminium gluconate), the increases in tissue aluminium content were paralleled by elevations of tissue iron in the kidney, liver heart and spleen as well as in various brain regions, frontal, temporal and parietal cortex and hippocampus. Despite such increases in iron content there were no significant changes in the activities of a wide range of cytoprotective enzymes apart from an increase in superoxide dismutase in the frontal cortex of the aluminium loaded rats. Such increases in tissue iron content may be attributed to the stabilisation of IRP-2 by aluminium thereby promoting transferrin receptor synthesis while blocking ferritin synthesis. Using the radioactive tracer (26)Al less than 1% of the injected dose was recovered in isolated ferritin, supporting previous studies which also found little evidence for aluminium storage within ferritin. The increases in brain iron may well be contributory to neurodegeneration, although the pathogenesis by which iron exerts such an effect is unclear.

  13. Serum aluminium levels in glue-sniffer adolescent and in glue containers.

    PubMed

    Akay, Cemal; Kalman, Süleyman; Dündaröz, Ruşen; Sayal, Ahmet; Aydin, Ahmet; Ozkan, Yalçin; Gül, Hüsamettin

    2008-05-01

    Glue sniffing is a serious medical problem among teenagers. Various chemical substances such as toluene and benzene containing glues have been reported to be toxic. It has been demonstrated that some toxic metals such as lead are elevated in the blood of solvent-addicted patients. Whereas aluminium is an element that has toxic effects on neurological, hematopoetic system and bone metabolism. We want to determine the serum levels of aluminium in glue-sniffer adolescents in comparison with healthy subjects. In addition, we compared aluminium levels of different commercial glue preparations (i.e. metal and plastic containers), to determine which type of container is better for less aluminium toxicity. We measured serum levels of aluminium in 37 glue-sniffer and 37 healthy subjects using atomic absorption spectrophotometry. The average duration of glue-sniffer was 3.8 +/- 0.8 years. We also measured aluminium levels of 10 commercial glue preparations that seven of them with metal and three with plastic containers. We found that serum levels of aluminium were 63.29 +/- 13.20 ng/ml and 36.7 +/- 8.60 ng/ml in glue-sniffer and in control subjects, respectively (P < 0.001). The average aluminium level in the glues was 8.6 +/- 3.24 ng/g in the preparations with metal containers, whereas 3.03 +/- 0.76 ng/g with plastic containers (P < 0.001). Therefore, to decrease the incidence of aluminium toxicity in glue-sniffers, it may be a good step to market of glue preparations in plastic instead of metal containers.

  14. Elevated urinary excretion of aluminium and iron in multiple sclerosis.

    PubMed

    Exley, Christopher; Mamutse, Godwin; Korchazhkina, Olga; Pye, Eleanor; Strekopytov, Stanislav; Polwart, Anthony; Hawkins, Clive

    2006-10-01

    Multiple sclerosis (MS) is a chronic, immune-mediated, demyelinating disease of the central nervous system of as yet unknown aetiology. A consensus of opinion has suggested that the disorder is the result of an interplay between environmental factors and susceptibility genes. We have used a battery of analytical techniques to determine if the urinary excretion of i) markers of oxidative damage; ii) iron and iii) the environmental toxin aluminium and its antagonist, silicon, are altered in relapsing-remitting (RRMS) and secondary progressive MS (SPMS). Urinary concentrations of oxidative biomarkers, MDA and TBARS, were not found to be useful indicators of inflammatory disease in MS. However, urinary concentrations of another potential marker for inflammation and oxidative stress, iron, were significantly increased in SPMS (P<0.01) and insignificantly increased in RRMS (P>0.05). Urinary concentrations of aluminium were also significantly increased in RRMS (P<0.001) and SPMS (P <0.05) such that the levels of aluminium excretion in the former were similar to those observed in individuals undergoing metal chelation therapy. The excretion of silicon was lower in MS and significantly so in SPMS (P<0.05). Increased excretion of iron in urine supported a role for iron dysmetabolism in MS. Levels of urinary aluminium excretion similar to those seen in aluminium intoxication suggested that aluminium may be a hitherto unrecognized environmental factor associated with the aetiology of MS. If aluminium is involved in MS then an increased dietary intake of its natural antagonist, silicon, might be a therapeutic option.

  15. Aluminium and iron air pollution near an iron casting and aluminium foundry in Turin district (Italy).

    PubMed

    Polizzi, Salvatore; Ferrara, Mauro; Bugiani, Massimiliano; Barbero, Domenico; Baccolo, Tiziana

    2007-09-01

    This work reports the results of an environmental survey carried out in an industrial area in the Province of Turin: its main aim is to assess the levels of iron and aluminium in the outside air during the period from July to September to assess the influence of industrial activity (a cast-iron and aluminium foundry) which is interrupted during the month of August, on the level of metals present in the air. Conducting the analysis during this period of time made it possible to avoid the confounding effect of pollution due to domestic central heating. The measurements were taken from nine areas at different distances from the foundry in the area and according to the direction of the prevailing winds, as deduced from the historical data. The results of this survey show a statistically significant difference in iron and aluminium levels in the outside air in the geographic areas between the two main periods examined: during August (no foundry activity) v/s July-September (foundry activity). The values recorded are: Aluminium 0.4+/-0.45 microg/m(3) v/s 1.12+/-1.29 microg/m(3) (p<0.0001); Iron 0.95+/-0.56 microg/m(3) v/s 1.6+/-1.0 microg/m(3) (p<0.0001). There were no statistically significant differences between the nine sampling points from the point of view of the sampling sites, climate conditions and wind directions. We found no correlation with car traffic, in terms of the number of vehicles, and metals. The values of iron tended to be higher in the areas farther away from the foundry site in the areas located along the path of the prevailing winds.

  16. [Photophysical properties and photodynamic activity of nanostructured aluminium phthalocyanines].

    PubMed

    Udartseva, O O; Lobanov, A V; Andeeva, E R; Dmitrieva, G S; Mel'nikov, M Ia; Buravkova, L B

    2014-01-01

    We developed water-soluble supramolecular complexes of aluminium phthalocyanine based on mesoporous silica nanoparticles and polyvinylpirrolidone containing rare photoactive nanoaggregates. Radiative lifetimes, extinction coefficients and energy of electronic transitions of isolated and associated metal phthalocyanine complexes were calculated. Nontoxic concentrations of synthesized nanocomposite photosensibilizers were in vitro determined. In present study we compared photodynamic treatment efficacy using different modifications of aluminium phthalocyanine (Photosens®, AlPc-nSiO2 and AlPc-PVP). Mesenchymal stromal cells were used as a model for photodynamic treatment. Intracellular accumulation of aluminium phthalocyanine based on mesoporous silica nanoparticles AlPc-nSiO2 was the most efficient. Illumination of phthalocyanine-loaded cells led to reactive oxygen species generation and subsequent apoptotic cell death. Silica nanoparticles provided a significant decrease of effective phthalocyanine concentration and enhanced cytotoxicity of photodynamic treatment.

  17. The influences of calcia silica contents to the compressive strength of the Al-7000 aluminium foam

    NASA Astrophysics Data System (ADS)

    Sutarno; Soepriyanto, S.; Korda, A. A.; Dirgantara, T.

    2016-08-01

    This experiment evaluated the effect of calcia alumina and alumina silica that formed as side products involved in metal mixture of aluminium foam. These compounds are formed from additional calcium carbonate and silica in the mixture. Calcium carbonate (CaCO3) roles as a blowing agent source of carbon dioxide (CO2). The formation of calcia alumina (CaO.Al2O3) is desired to improve the viscosity and to strengthen of cell wall of aluminium foam. However, Al-7000 aluminium foam showed a decrease tendency of compressive strength probably due to existence of alumina silica (3Al2O3.SiO2) in the metal mixture. In this case, the silica that thermally combines with alumina compound may degrade the metal mixture of aluminium foam structure.

  18. Tensile and Dry Sliding Wear Behavior of In-Situ Al3Zr + Al2O3-Reinforced Aluminum Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Gautam, G.; Ghose, A. K.; Chakrabarty, I.

    2015-12-01

    In the present study, aluminum-based in-situ intermetallic Al3Zr and Al2O3-reinforced metal matrix composites have been synthesized by direct melt reaction through stir casting of zirconium oxychloride (ZrOCl2·8H2O) powder in commercially pure aluminum. The in-situ reaction produces intermetallic Al3Zr needles that change to feathery morphology with increasing ZrOCl2·8H2O, while the Al2O3 is of fine globular shape. The tensile strengths of these composites increase with increasing volume percent reinforcements, attaining a peak value with 18 pct addition. The dry sliding wear behavior of the composites was evaluated with varying parameters, viz. sliding distance, normal load, and sliding velocities. The wear mechanisms are explained based on the microstructure, the topography of the worn surface, and the interfacial strength of the matrix and reinforcement. The tensile and wear properties are compared with widely used wear resistant hypereutectic Al-17 pct Si cast alloy.

  19. The effect of TiB2 reinforcement on the mechanical properties of an Al-Cu-Li alloy-based metal-matrix composite

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The addition of ceramic particles to aluminum based alloys can substantially improve mechanical properties, especially Young's modulus and room and elevated temperature strengths. However, these improvements typically occur at the expense of tensile ductility. The mechanical properties are evaluated to a metal matrix composite (MMC) consisting of an ultrahigh strength aluminum lithium alloy, Weldalite (tm) 049, reinforced with TiB2 particles produced by an in situ precipitation technique called the XD (tm) process. The results are compared to the behavior of a nonreinforced Weldalite 049 variant. It is shown that both 049 and 049-TiB2 show very attractive warm temperature properties e.g., 625 MPa yield strength at 150 C after 100 h at temperature. Weldalite 049 reinforced with a nominal 4 v pct. TiB2 shows an approx. 8 pct. increase in modulus and a good combination of strength (529 MPa UTS) and ductility (6.5 pct.) in the T3 temper. And the high ductility of Weldalite 049 in the naturally aged and underaged tempers makes the alloy a good, high strength matrix for ceramic reinforcement.

  20. Multi-frequency (S, X, Q and W-band) EPR and ENDOR Study of Vanadium(IV) Incorporation in the Aluminium Metal-Organic Framework MIL-53.

    PubMed

    Nevjestić, Irena; Depauw, Hannes; Leus, Karen; Kalendra, Vidmantas; Caretti, Ignacio; Jeschke, Gunnar; Van Doorslaer, Sabine; Callens, Freddy; Van Der Voort, Pascal; Vrielinck, Henk

    2015-10-01

    Doping the well-known metal-organic framework MIL-53(Al) with vanadium(IV) ions leads to significant changes in the breathing behaviour and might have repercussions on the catalytic behaviour as well. To understand the properties of such a doped framework, it is necessary to determine where dopant ions are actually incorporated. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are applied to reveal the nearest environment of the paramagnetic vanadium(IV) dopant ions. EPR spectra of as-synthesised vanadium-doped MIL-53 are recorded at S-, X-, Q- and W-band microwave frequencies. The EPR spectra suggest that at low dopant concentrations (1.0-2.6 mol %) the vanadium(IV) ions are well dispersed in the matrix. Varying the vanadium dopant concentration within this range or the dopant salt leads to the same dominant EPR component. In the ENDOR spectra, hyperfine (HF) interactions with (1) H, (27) Al and (51) V nuclei are observed. The HF parameters extracted from simulations strongly suggest that the vanadium(IV) ions substitute Al in the framework. PMID:26305910

  1. Preparation of functionalized organoaluminiums by direct insertion of aluminium to unsaturated halides.

    PubMed

    Blümke, Tobias; Chen, Yi-Hung; Peng, Zhihua; Knochel, Paul

    2010-04-01

    The preparation of polyfunctional organometallics is important in organic synthesis as these reagents are very popular nucleophiles. The preparation of functionalized aluminium reagents by direct insertion of aluminium powder is in general not possible. Such a reaction would be of special importance owing to the low price of aluminium compared with magnesium (it is half the price), the low toxicity of this metal and the chemoselectivity of the resultant organoaluminium reagents. We have now found that by adding catalytic amounts of selected metallic chlorides (TiCl(4), BiCl(3), InCl(3) or PbCl(2)) in the presence of LiCl, aluminium powder inserts into various unsaturated iodides and bromides under mild conditions. These resulting new organoaluminium reagents undergo smooth Pd-catalysed cross-coupling and acylation reactions, as well as copper-catalysed allylic substitutions, affording various interesting products for pharmaceutical and material science applications. PMID:21124514

  2. Preparation of functionalized organoaluminiums by direct insertion of aluminium to unsaturated halides

    NASA Astrophysics Data System (ADS)

    Blümke, Tobias; Chen, Yi-Hung; Peng, Zhihua; Knochel, Paul

    2010-04-01

    The preparation of polyfunctional organometallics is important in organic synthesis as these reagents are very popular nucleophiles. The preparation of functionalized aluminium reagents by direct insertion of aluminium powder is in general not possible. Such a reaction would be of special importance owing to the low price of aluminium compared with magnesium (it is half the price), the low toxicity of this metal and the chemoselectivity of the resultant organoaluminium reagents. We have now found that by adding catalytic amounts of selected metallic chlorides (TiCl4, BiCl3, InCl3 or PbCl2) in the presence of LiCl, aluminium powder inserts into various unsaturated iodides and bromides under mild conditions. These resulting new organoaluminium reagents undergo smooth Pd-catalysed cross-coupling and acylation reactions, as well as copper-catalysed allylic substitutions, affording various interesting products for pharmaceutical and material science applications.

  3. Laser micro welding of copper and aluminium using filler materials

    NASA Astrophysics Data System (ADS)

    Esser, Gerd; Mys, Ihor; Schmidt, Michael H.

    2004-10-01

    The most evident trend in electronics production is towards miniaturization. Regarding the materials involved, another trend can be observed: intelligent combinations of different materials. One example is the combination of copper and aluminium. Copper is the material of choice for electronic packaging applications due to its superior electrical and thermal conductivity. On the other hand, aluminium offers technical and economical advantages with respect to cost and component weight -- still providing thermal and electrical properties acceptable for numerous applications. Especially for high volume products, the best solution often seems to be a combination of both materials. This fact raises the question of joining copper and aluminium. With respect to miniaturization laser micro welding is a very promising joining technique. Unfortunately, the metallurgical incompatibility of copper and aluminium easily results in the formation of brittle intermetallic phases and segregations during laser welding, thus generating an unacceptable quality of the joints. This paper presents investigations on enhancing the quality during laser micro welding of copper and aluminium for applications in electronics production. In order to eliminate the formation of brittle intermetallic phases, the addition of a filter material in form of a foil has been investigated. It can be shown that the addition of pure metals such as nickel and especially silver significantly reduces the occurrence of brittle phases in the joining area and therefore leads to an increase in welding quality. The proper control of the volume fractions of copper, aluminium and filler material in the melting zone helps to avoid materials segregation and reduces residual stress, consequently leading to a reduction of crack affinity and a stabilization of the mechanical and electrical properties.

  4. Tensile flow properties of Al-based matrix composites reinforced with a random planar network of continuous metallic fibers

    SciTech Connect

    Boland, F.; Salmon, C.; Delannay, F.; Colin, C.

    1998-11-20

    Squeeze casting was used for processing two new types of composites: pure Al matrix composites reinforced with fibers of Inconel 601, and AS13 (Al-12% Si) matrix composites reinforced with fibers of Inconel 601 or stainless steel 316L. The fibers are continuous with a diameter of 12 {micro}m and their volume fraction in the composites varied from 20 to 80%. The processing conditions were such that no trace of interfacial reaction compound or of matrix precipitate resulting from the dissolution of elements of the fibers could be detected. The quality of the process was attested by Young`s modulus and electrical conductivity measurements. Tensile tests were carried out from room temperature up to 300 C. The composites with the pure Al matrix present a remarkable tensile ductility. They thus constitute convenient materials for assessing continuum plasticity models for composites. Properties of composites with the AS13 matrix are much affected by interface adhesion strength.

  5. The effect of thermal cycling on interfacial bonding in a ceramic matrix composite reinforced with a metallic ribbon

    SciTech Connect

    Lee, T.K.; Subramanian, K.N. )

    1993-06-01

    Ceramic matrix composite materials have great potential for high temperature applications, and are often subject to thermal cycling. As a result, thermal cycling studies on ceramic matrix composites can yield valuable information regarding their potential for high temperature service. The main aim of the present study is to analyze the effects of the maximum temperature used in thermal cycling and the number of such cycles on the interfacial bonding strength of soda lime glass reinforced with Nichrome ribbons.

  6. Carbon nanotubes reinforced composites for biomedical applications.

    PubMed

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo.

  7. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    PubMed Central

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo. PMID:24707488

  8. Pulmonary Fibrosis in an Aluminium Worker

    PubMed Central

    Mitchell, John

    1959-01-01

    Aluminium dust has never been shown to be harmful to man in Great Britain. This paper reports a fatal case of progressive pulmonary fibrosis in a young man occupationally exposed to a heavy concentration of fine aluminium dust. Clinically, radiologically, and pathologically this case was indistinguishable from cases of aluminium fibrosis of the lung described by Shaver in Canada. Images PMID:13651554

  9. In situ nanoindentation study on plasticity and work hardening in aluminium with incoherent twin boundaries.

    PubMed

    Bufford, D; Liu, Y; Wang, J; Wang, H; Zhang, X

    2014-01-01

    Nanotwinned metals have been the focus of intense research recently, as twin boundaries may greatly enhance mechanical strength, while maintaining good ductility, electrical conductivity and thermal stability. Most prior studies have focused on low stacking-fault energy nanotwinned metals with coherent twin boundaries. In contrast, the plasticity of twinned high stacking-fault energy metals, such as aluminium with incoherent twin boundaries, has not been investigated. Here we report high work hardening capacity and plasticity in highly twinned aluminium containing abundant Σ3{112} incoherent twin boundaries based on in situ nanoindentation studies in a transmission electron microscope and corresponding molecular dynamics simulations. The simulations also reveal drastic differences in deformation mechanisms between nanotwinned copper and twinned aluminium ascribed to stacking-fault energy controlled dislocation-incoherent twin boundary interactions. This study provides new insight into incoherent twin boundary-dominated plasticity in high stacking-fault energy twinned metals. PMID:25204688

  10. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application. Phase 3 Summary report: Shear web component testing and analysis

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Straayer, J. W.

    1973-01-01

    Three large scale advanced composite shear web components were tested and analyzed to evaluate application of the design concept to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron/epoxy reinforced aluminum stiffeners. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs. An approximate analysis of prebuckling deflections is presented and computer-aided design results, which consider prebuckling deformations, indicate that the design concept offers a theoretical weight saving of 31 percent relative to all metal construction. Recommendations are made for design concept options and analytical methods that are appropriate for production hardware.

  11. Mechanochemical route to the synthesis of nanostructured Aluminium nitride.

    PubMed

    Rounaghi, S A; Eshghi, H; Scudino, S; Vyalikh, A; Vanpoucke, D E P; Gruner, W; Oswald, S; Kiani Rashid, A R; Samadi Khoshkhoo, M; Scheler, U; Eckert, J

    2016-01-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN. PMID:27650956

  12. Mechanochemical route to the synthesis of nanostructured Aluminium nitride.

    PubMed

    Rounaghi, S A; Eshghi, H; Scudino, S; Vyalikh, A; Vanpoucke, D E P; Gruner, W; Oswald, S; Kiani Rashid, A R; Samadi Khoshkhoo, M; Scheler, U; Eckert, J

    2016-09-21

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN.

  13. Mechanochemical route to the synthesis of nanostructured Aluminium nitride

    NASA Astrophysics Data System (ADS)

    Rounaghi, S. A.; Eshghi, H.; Scudino, S.; Vyalikh, A.; Vanpoucke, D. E. P.; Gruner, W.; Oswald, S.; Kiani Rashid, A. R.; Samadi Khoshkhoo, M.; Scheler, U.; Eckert, J.

    2016-09-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN.

  14. Mechanochemical route to the synthesis of nanostructured Aluminium nitride

    PubMed Central

    Rounaghi, S. A.; Eshghi, H.; Scudino, S.; Vyalikh, A.; Vanpoucke, D. E. P.; Gruner, W.; Oswald, S.; Kiani Rashid, A. R.; Samadi Khoshkhoo, M.; Scheler, U.; Eckert, J.

    2016-01-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN. PMID:27650956

  15. Effects on the nervous system among welders exposed to aluminium and manganese.

    PubMed Central

    Sjögren, B; Iregren, A; Frech, W; Hagman, M; Johansson, L; Tesarz, M; Wennberg, A

    1996-01-01

    OBJECTIVES--The purpose was to study the effects on the nervous system in welders exposed to aluminium and manganese. METHODS--The investigation included questionnaires on symptoms, psychological methods (simple reaction time, finger tapping speed and endurance, digit span, vocabulary, tracking, symbol digit, cylinders, olfactory threshold, Luria-Nebraska motor scale), neurophysiological methods (electroencephalography, event related auditory evoked potential (P-300), brainstem auditory evoked potential, and diadochokinesometry) and assessments of blood and urine concentrations of metals (aluminium, lead, and manganese). RESULTS--The welders exposed to aluminium (n = 38) reported more symptoms from the central nervous system than the control group (n = 39). They also had a decreased motor function in five tests. The effect was dose related in two of these five tests. The median exposure of aluminium welders was 7065 hours and they had about seven times higher concentrations of aluminium in urine than the controls. The welders exposed to manganese (n = 12) had a decreased motor function in five tests. An increased latency of event related auditory evoked potential was also found in this group. The median manganese exposure was 270 hours. These welders did not have higher concentrations of manganese in blood than the controls. CONCLUSIONS--The neurotoxic effects found in the groups of welders exposed to aluminium and manganese are probably caused by the aluminium and manganese exposure, respectively. These effects indicate a need for improvements in the work environments of these welders. PMID:8563855

  16. Control of Microthrix parvicella by aluminium salts addition.

    PubMed

    Durban, N; Juzan, L; Krier, J; Gillot, S

    2016-01-01

    Aluminium and iron chloride were added to a biological nutrient removal pilot plant (1,500 population equivalent) treating urban wastewater to investigate the control of Microthrix parvicella bulking and foaming by metallic salts. Monitoring plant performance over two 6-month periods showed a slight impact on the removal efficiencies. Addition of metallic salts (Me; aluminium or aluminium + iron) at a concentration of 41 mmol Me(kg MLSS·d) (MLSS: mixed liquor suspended solids) over 70 days allowed a stabilization of the diluted sludge volume index (DSVI), whereas higher dosages (94 mmol Me(kg MLSS·d) over 35 days or 137 mmol Me(kg MLSS·d) over 14 days induced a significant improvement of the settling conditions. Microscopic observations showed a compaction of biological aggregates with an embedding of filamentous bacteria into the flocs that is not specific to M. parvicella as bacteria from phylum Chloroflexi are embedded too. The quantitative polymerase chain reaction targeting M. parvicella further indicated a possible growth limitation in addition to the flocculation impact at the high dosages of metallic salts investigated. DSVI appeared to be correlated with the relative abundance of M. parvicella.

  17. Control of Microthrix parvicella by aluminium salts addition.

    PubMed

    Durban, N; Juzan, L; Krier, J; Gillot, S

    2016-01-01

    Aluminium and iron chloride were added to a biological nutrient removal pilot plant (1,500 population equivalent) treating urban wastewater to investigate the control of Microthrix parvicella bulking and foaming by metallic salts. Monitoring plant performance over two 6-month periods showed a slight impact on the removal efficiencies. Addition of metallic salts (Me; aluminium or aluminium + iron) at a concentration of 41 mmol Me(kg MLSS·d) (MLSS: mixed liquor suspended solids) over 70 days allowed a stabilization of the diluted sludge volume index (DSVI), whereas higher dosages (94 mmol Me(kg MLSS·d) over 35 days or 137 mmol Me(kg MLSS·d) over 14 days induced a significant improvement of the settling conditions. Microscopic observations showed a compaction of biological aggregates with an embedding of filamentous bacteria into the flocs that is not specific to M. parvicella as bacteria from phylum Chloroflexi are embedded too. The quantitative polymerase chain reaction targeting M. parvicella further indicated a possible growth limitation in addition to the flocculation impact at the high dosages of metallic salts investigated. DSVI appeared to be correlated with the relative abundance of M. parvicella. PMID:26819398

  18. The prophylactic reduction of aluminium intake.

    PubMed

    Lione, A

    1983-02-01

    The use of modern analytical methods has demonstrated that aluminium salts can be absorbed from the gut and concentrated in various human tissues, including bone, the parathyroids and brain. The neurotoxicity of aluminium has been extensively characterized in rabbits and cats, and high concentrations of aluminium have been detected in the brain tissue of patients with Alzheimer's disease. Various reports have suggested that high aluminium intakes may be harmful to some patients with bone disease or renal impairment. Fatal aluminium-induced neuropathies have been reported in patients on renal dialysis. Since there are no demonstrable consequences of aluminium deprivation, the prophylactic reduction of aluminium intake by many patients would appear prudent. In this report, the major sources of aluminium in foods and non-prescription drugs are summarized and alternative products are described. The most common foods that contain substantial amounts of aluminium-containing additives include some processed cheeses, baking powders, cake mixes, frozen doughs, pancake mixes, self-raising flours and pickled vegetables. The aluminium-containing non-prescription drugs include some antacids, buffered aspirins, antidiarrhoeal products, douches and haemorrhoidal medications. The advisability of recommending a low aluminium diet for geriatric patients is discussed in detail. PMID:6337934

  19. Nouveau procédé de synthèse du nitrure d'aluminium

    NASA Astrophysics Data System (ADS)

    Haussonne, J. M.; Lostec, J.; Bertot, J. P.; Lostec, L.; Sadou, S.

    1993-04-01

    Thermodynamic considerations show that, even at room temperature, pure aluminium can react with nitrogen to form the aluminium nitride AlN. However, pure aluminium does not exist: it is always surrounded by an alumina shell that protects the metal from further reactions. Furthermore, in the hypothesis where one has been able to make aluminium react with nitrogen, an aluminium nitride shell will protect as well the metal core from further oxidation. Prompted by the Lanxide process allowing to form Al/Al2O3 composites, we have mixed aluminium powders with lithium salts, and easily synthesized pure aluminium nitride by heating the mixed powders in nitrogen at temperatures ranging from 800 to 1200 °C. Starting from aluminium powders with a specific area ranging from 0.3 to 4 m^2/g, we have been able to produce aluminium nitride with specific are ranging from 1 to 20 m^2/g. Mixed with Y203-CaO and sintered at 1720 °C in N2, we obtained AIN ceramics owning 92% density and 160 W/m.K thermal conductivity. Les calculs thermodynamiques montrent que, même à température ambiante, l'aluminium pur peut réagir avec l'azote pour former le nitrure d'aluminium AlN. Cependant, la poudre d'aluminium pur n'existe pas : ses grains sont toujours entourés d'une couche d'alumine protectrice. De plus, dans l'hypothèse où l'on pourrait faire réagir de la poudre d'aluminium avec de l'azote, il se formerait de même une couche protectrice de nitrure d'aluminium qui empêcherait le centre des grains de réagir. S'inspirant du “procédé Lanxide” permettant de réaliser des composites Al/Al2O3, nous avons mélangé de la poudre d'aluminium avec des sels de lithium, et synthétisé du nitrure d'aluminium pur en portant ce mélange dans l'azote à une température pouvant être comprise entre 800 et 1 200 °C. Utilisant des poudres d'aluminium possédant une surface spécifique comprise entre 0,3 et 4 m^2/g, nous avons obtenu une poudre de nitrure d'aluminium avec une surface sp

  20. Aluminium toxicity in chronic renal insufficiency

    SciTech Connect

    Savory, J.; Bertholf, R.L.; Wills, M.R.

    1985-08-01

    Aluminium is a ubiquitous element in the environment and has been demonstrated to be toxic, especially in individuals with impaired renal function. Not much is known about the biochemistry of aluminium and the mechanisms of its toxic effects. Most of the interest in aluminium has been in the clinical setting of the hemodialysis unit. Here aluminium toxicity occurs due to contamination of dialysis solutions, and treatment of the patients with aluminium-containing phosphate binding gels. Aluminium has been shown to be the major contributor to the dialysis encephalopathy syndrome and an osteomalacic component of dialysis osteodystrophy. Other clinical disturbances associated with aluminium toxicity are a microcytic anemia and metastatic extraskeletal calcification. Aluminium overload can be treated effectively by chelation therapy with desferrioxamine and hemodialysis. Aluminium is readily transferred from the dialysate to the patient's -bloodstream during hemodialysis. Once transferred, the aluminium is tightly bound to non-dialysable plasma constituents. Very low concentrations of dialysate aluminium in the range of 10-15 micrograms/l are recommended to guard against toxic effects. Very few studies have been directed towards the separation of the various plasma species which bind eluminium. Gel filtration chromatography has been used to identify five major fractions, one of which is of low molecular weight and the others appear to be protein-aluminium complexes. Recommendations on aluminium monitoring have been published and provide safe and toxic concentrations. Also, the frequency of monitoring has been addressed. Major problems exist with the analytical methods for measuring aluminium which result from inaccurate techniques and contamination difficulties. 136 references.

  1. Oxidation and waste-to-energy output of aluminium waste packaging during incineration: A laboratory study.

    PubMed

    López, Félix A; Román, Carlos Pérez; García-Díaz, Irene; Alguacil, Francisco J

    2015-09-01

    This work reports the oxidation behaviour and waste-to-energy output of different semi-rigid and flexible aluminium packagings when incinerated at 850°C in an air atmosphere enriched with 6% oxygen, in the laboratory setting. The physical properties of the different packagings were determined, including their metallic aluminium contents. The ash contents of their combustion products were determined according to standard BS ISO 1171:2010. The net calorific value, the required energy, and the calorific gain associated with each packaging type were determined following standard BS EN 13431:2004. Packagings with an aluminium lamina thickness of >50μm did not fully oxidise. During incineration, the weight-for-weight waste-to-energy output of the packagings with thick aluminium lamina was lower than that of packagings with thin lamina. The calorific gain depended on the degree of oxidation of the metallic aluminium, but was greater than zero for all the packagings studied. Waste aluminium may therefore be said to act as an energy source in municipal solid waste incineration systems.

  2. Oxidation and waste-to-energy output of aluminium waste packaging during incineration: A laboratory study.

    PubMed

    López, Félix A; Román, Carlos Pérez; García-Díaz, Irene; Alguacil, Francisco J

    2015-09-01

    This work reports the oxidation behaviour and waste-to-energy output of different semi-rigid and flexible aluminium packagings when incinerated at 850°C in an air atmosphere enriched with 6% oxygen, in the laboratory setting. The physical properties of the different packagings were determined, including their metallic aluminium contents. The ash contents of their combustion products were determined according to standard BS ISO 1171:2010. The net calorific value, the required energy, and the calorific gain associated with each packaging type were determined following standard BS EN 13431:2004. Packagings with an aluminium lamina thickness of >50μm did not fully oxidise. During incineration, the weight-for-weight waste-to-energy output of the packagings with thick aluminium lamina was lower than that of packagings with thin lamina. The calorific gain depended on the degree of oxidation of the metallic aluminium, but was greater than zero for all the packagings studied. Waste aluminium may therefore be said to act as an energy source in municipal solid waste incineration systems. PMID:26148645

  3. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization.

    PubMed

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g(-1) at 1.2 V in 500 mg l(-1) NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  4. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization

    PubMed Central

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g−1 at 1.2 V in 500 mg l−1 NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  5. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-09-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g‑1 at 1.2 V in 500 mg l‑1 NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications.

  6. Extraction-spectrometric determination of lead in high-purity aluminium salts.

    PubMed

    Koksal, Jiří; Synek, Václav; Janos, Pavel

    2002-08-23

    Trace amounts of lead were determined in high purity aluminium salts (especially in ammonium aluminium sulfate) using inductively coupled plasma-optical emission spectrometry (ICP-OES) after extractive pre-concentration and matrix separation. Metals were extracted from the aluminium matrix in the form of chelates with ammonium pyrolidine dithoocarbamate into methyl isobutyketone. The organic extract was digested with nitric acid and hydrogen peroxide. The limit of detection for the determination of lead in crystalline ammonium aluminium sulfate was ca. 0.044 mug g(-1). The relative expanded uncertainty of the lead determination was ca. 23% at the level of 0.2 mug g(-1) and ca. 16% at the level of 1.0 mug g(-1). The main uncertainty contribution was associated with repeatability of the whole analytical procedure. PMID:18968757

  7. Non-aqueous aluminium-air battery based on ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Revel, Renaud; Audichon, Thomas; Gonzalez, Serge

    2014-12-01

    A promising metal-air secondary battery based on aluminium-oxygen couple is described. In this paper, we observed that an aluminium-air battery employing EMImCl, AlCl3 room temperature ionic liquid (RTIL) as electrolyte and aluminium as negative electrode, has an exceptional reduced self-discharged rate. Due to its new and innovative type of electrolyte, this aluminium-air battery can support relatively high current densities (up to 0.6 mA cm-2) and an average voltage of 0.6-0.8 V. Such batteries may find immediate applications, as they can provide an internal, built-in autonomous and self-sustained energy source.

  8. Aluminium exposure from parenteral nutrition in preterm infants and later health outcomes during childhood and adolescence.

    PubMed

    Fewtrell, Mary S; Edmonds, Caroline J; Isaacs, Elizabeth; Bishop, Nick J; Lucas, Alan

    2011-08-01

    Aluminium is the most common metallic element, but has no known biological role. It accumulates in the body when protective gastrointestinal mechanisms are bypassed, renal function is impaired, or exposure is high - all of which apply frequently to preterm infants. Recognised clinical manifestations of aluminium toxicity include dementia, anaemia and bone disease. Parenteral nutrition (PN) solutions are liable to contamination with aluminium, particularly from acidic solutions in glass vials, notably calcium gluconate. When fed parenterally, infants retain >75% of the aluminium, with high serum, urine and tissue levels. Later health effects of neonatal intravenous aluminium exposure were investigated in a randomised trial comparing standard PN solutions with solutions specially sourced for low aluminium content. Preterm infants exposed for >10 d to standard solutions had impaired neurologic development at 18 months. At 13-15 years, subjects randomised to standard PN had lower lumbar spine bone mass; and, in non-randomised analyses, those with neonatal aluminium intake above the median had lower hip bone mass. Given the sizeable number of infants undergoing intensive care and still exposed to aluminium via PN, these findings have contemporary relevance. Until recently, little progress had been made on reducing aluminium exposure, and meeting Food and Drug Administration recommendations (<5 μg/kg per d) has been impossible in patients <50 kg using available products. Recent advice from the UK Medicines and Healthcare regulatory Authority that calcium gluconate in small volume glass containers should not be used for repeated treatment in children <18 years, including preparation of PN, is an important step towards addressing this problem.

  9. Effect of Hot Working on Structure and Tribological Properties of Aluminium Reinforced with Aluminium Oxide Particulates

    NASA Astrophysics Data System (ADS)

    Venkata Siva, S. B.; Sahoo, K. L.; Ganguly, R. I.; Dash, R. R.

    2012-07-01

    Al-Al2O3 (18%) composite was prepared by stir-cast melt technique. The microstructures showed uniform distribution of particulates, dispersed in the matrix. There exists discontinuity (~0.25 μm) in the interface between particulates and matrix. The composite was hot forged. Hot working resulted in fine recrystallized microstructure with particulates dispersed along grain boundaries. Formation of pancake microstructure with some inhomogeneity in the microstructure along three faces of the forged composite was observed. The discontinuity across the interface between Al-Al2O3 was reduced to 0.125 μm after forging. The as-cast and forged Al-Al2O3 composites showed higher wear resistance than pure Al. In lubricant media, there was no significant wear observed for either the as-cast or forged composite, whereas Al had shown higher wear at 50 N load.

  10. Interfacial morphology of low-voltage anodic aluminium oxide

    SciTech Connect

    Hu, Naiping; Dongcinn, Xuecheng; He, Xueying; Argekar, Sandip; Zhang, Yan; Browning, Jim; Schaefer, Dale

    2013-01-01

    X-ray reflectivity (XRR) and neutron reflectivity (NR), as well as ultra-smallangle X-ray scattering (USAXS), are used to examine the in-plane and surfacenormal structure of anodic films formed on aluminium alloy AA2024 and pure aluminium. Aluminium and alloy films up to 3500 A thick were deposited on Si wafers by electron beam evaporation of ingots. Porous anodic aluminium oxide (AAO) films are formed by polarizing at constant voltage up to 20 V noble to the open circuit potential. The voltage sweet spot (5 V) appropriate for constant-voltage anodization of such thin films was determined for both alloy and pure Al. In addition, a new concurrent voltage- and current-control protocol was developed to prepare films with larger pores (voltages higher than 5 V), but formed at a controlled current so that pore growth is slow enough to avoid stripping the aluminium substrate layer. USAXS shows that the pore size and interpore spacing are fixed in the first 10 s after initiation of anodization. Pores then grow linearly in time, at constant radius and interpore spacing. Using a combination of XRR and NR, the film density and degree of hydration of the films were determined from the ratio of scattering length densities. Assuming a chemical formula Al2O3xH2O, it was found that x varies from 0.29 for the native oxide to 1.29 for AAO grown at 20 V under concurrent voltage and current control. The average AAO film density of the porous film at the air surface is 2.45 (20) g cm3. The density of the barrier layer at the metal interface is 2.9 (4) g cm3, which indicates that this layer is also quite porous

  11. Bumblebee Pupae Contain High Levels of Aluminium

    PubMed Central

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer’s disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline. PMID:26042788

  12. Bumblebee pupae contain high levels of aluminium.

    PubMed

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer's disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline.

  13. Bumblebee pupae contain high levels of aluminium.

    PubMed

    Exley, Christopher; Rotheray, Ellen; Goulson, David

    2015-01-01

    The causes of declines in bees and other pollinators remains an on-going debate. While recent attention has focussed upon pesticides, other environmental pollutants have largely been ignored. Aluminium is the most significant environmental contaminant of recent times and we speculated that it could be a factor in pollinator decline. Herein we have measured the content of aluminium in bumblebee pupae taken from naturally foraging colonies in the UK. Individual pupae were acid-digested in a microwave oven and their aluminium content determined using transversely heated graphite furnace atomic absorption spectrometry. Pupae were heavily contaminated with aluminium giving values between 13.4 and 193.4 μg/g dry wt. and a mean (SD) value of 51.0 (33.0) μg/g dry wt. for the 72 pupae tested. Mean aluminium content was shown to be a significant negative predictor of average pupal weight in colonies. While no other statistically significant relationships were found relating aluminium to bee or colony health, the actual content of aluminium in pupae are extremely high and demonstrate significant exposure to aluminium. Bees rely heavily on cognitive function and aluminium is a known neurotoxin with links, for example, to Alzheimer's disease in humans. The significant contamination of bumblebee pupae by aluminium raises the intriguing spectre of cognitive dysfunction playing a role in their population decline. PMID:26042788

  14. Pulse electrodeposition of adherent nickel coatings onto anodized aluminium surfaces

    NASA Astrophysics Data System (ADS)

    Frantz, Cédric; Vichery, Charlotte; Zechner, Johannes; Frey, Damian; Bürki, Gerhard; Cebeci, Halil; Michler, Johann; Philippe, Laetitia

    2015-03-01

    Aluminium is one of the mostly used elements in the industry because of its abundance and low weight. However, the deposition of a metallic coating requires performing the so-called zincate pre-treatment in order to allow the formation of inter-metallic bonds and thereby achieving sufficient adherence. In this work, porous anodic aluminium oxide (AAO) is used as an anchoring intermediate layer for nickel coatings. AAO is grown anodically in sulfuric acid and nickel coatings are deposited by potentiostatic reverse pulse electrodeposition onto as-anodized aluminium surfaces. The electrodeposition of nickel is initiated onto the electrochemically thinned barrier layer of AAO and pursued until the complete covering of the oxide. The electrochemical behavior of Watts and sulfamate baths is investigated by cyclic voltammetry for different barrier layer thickness, allowing to validate the thinning conditions and to determine the appropriate deposition potential of nickel. GD-OES measurements show that low duty cycles are necessary to achieve high filling ratio of the AAO. SEM micrographs show that a smooth uniform coating is obtained when nickel is deposited in presence of additives.

  15. Novel reactive elastomer-metal oxide composite: Effect of filler size and content on swelling and reinforcement

    NASA Astrophysics Data System (ADS)

    Han, Dingzhi; Yue, Chee Yoon; Qu, Meng; Robisson, Agathe

    2014-05-01

    A novel elastomer-metal oxide composite that swells and stiffens upon hydration will be presented. Conventional water-swellable elastomers filled with hydrogels absorb water and swell upon hydration but their modulus decreases as a result of fluid water diluting the rubber matrix. Reduced stiffness compromise the reliability of swellable elastomers used in sealing applications. One major application of swellable elastomers is fluid containment seals for zonal isolation in the oilfield. For effective sealing, the contact pressure between the seal and the surrounding wall should be high while deformation should be limited when a differential pressure is applied. Both conditions can be achieved by means of swelling and stiffening of the seal; hence, the new reactive elastomer-metal oxide composite is developed such that after it is exposed to water, the composite swells and stiffens simultaneously. Composites filled with different amounts of oxide were studied and it was observed that swelling up to almost 100% with an increase in modulus of about 200% could be achieved for the best performing compound. Composites filled with different sizes of the metal oxide were also studied. The finest filler was found to impart the greatest modulus, both before and after hydration, to the composite although swelling was slightly reduced compared with the larger particles. Another advantage of the composite for sealing purposes is that the swelling is largely retained even after complete removal of the solvent; i.e., drying.

  16. Aluminium in Allergies and Allergen immunotherapy.

    PubMed

    Jensen-Jarolim, Erika

    2015-01-01

    Aluminium is a hot topic in the current debate. Exposure occurs due to environmental, dietary and intentional exposure to aluminium, such as in vaccines where it was introduced in 1926. In spite of the fact that it is a typical Th2 adjuvant, aluminium redirects the immune response in systemic allergen immunotherapy (SIT) upon prolonged immunization. SIT in the US, and SLIT in general, are at present non-adjuvanted therapies, but in Europe aluminium is used as adjuvant in most SIT preparations. It enhances the safety of SIT by local deposition of the allergen. Undesired properties of aluminium adjuvants comprise acute and chronic inflammation at the injection site, its Th2 immune stimulatory capacity, its accumulation besides biodistribution in the body. The adjuvant and safety profile of aluminium adjuvants in allergy vaccines are discussed, as well as the need for putting modern delivery systems and adjuvants on the fast track.

  17. Properties- and applications of quasicrystals and complex metallic alloys.

    PubMed

    Dubois, Jean-Marie

    2012-10-21

    This article aims at an account of what is known about the potential for applications of quasicrystals and related compounds, the so-called family of Complex Metallic Alloys (CMAs‡). Attention is focused at aluminium-based CMAs, which comprise a large number of crystalline compounds and quasicrystals made of aluminium alloyed with transition metals (like Fe or Cu) or normal metals like Mg. Depending on composition, the structural complexity varies from a few atoms per unit cell up to thousands of atoms. Quasicrystals appear then as CMAs of ultimate complexity and exhibit a lattice that shows no periodicity anymore in the usual 3-dimensional space. Properties change dramatically with lattice complexity and turn the metal-type behaviour of simple Al-based crystals into a far more complex behaviour, with a fingerprint of semi-conductors that may be exploited in various applications, potential or realised. An account of the ones known to the author is given in the light of the relevant properties, namely light absorption, reduced adhesion and friction, heat insulation, reinforcement of composites for mechanical devices, and few more exotic ones. The role played by the search for applications of quasicrystals in the development of the field is briefly addressed in the concluding section.

  18. Aluminium toxicokinetics: an updated minireview.

    PubMed

    Yokel, R A; McNamara, P J

    2001-04-01

    This MiniReview updates and expands the MiniReview of aluminium toxicokinetics by Wilhelm et al. published by this journal in 1990. The use of 26Al, analyzed by accelerator mass spectrometry, now enables determination of Al toxicokinetics under physiological conditions. There is concern about aluminium in drinking water. The common sources of aluminium for man are reviewed. Oral Al bioavailability from water appears to be about 0.3%. Food is the primary common source. Al bioavailability from food has not been adequately determined. Industrial and medicinal exposure, and perhaps antiperspirant use, can significantly increase absorbed aluminium. Inhalation bioavailability of airborne soluble Al appears to be about 1.5% in the industrial environment. Al may distribute to the brain from the nasal cavity, but the significance of this exposure route is unknown. Systemic Al bioavailability after single underarm antiperspirant application may be up to 0.012%. All intramuscularly injected Al, e.g. from vaccines, may eventually be absorbed. Al distributes unequally to all tissues. Distribution and renal excretion appear to be enhanced by citrate. Brain uptake of Al may be mediated by Al transferrin and Al citrate complexes. There appears to be carrier-mediated efflux of Al citrate from the brain. Elimination half-lives of years have been reported in man, probably reflecting release from bone. Al elimination is primarily renal with < or = 2% excreted in bile. The contribution of food to absorbed Al needs to be determined to advance our understanding of the major components of Al toxicokinetics.

  19. Grip for fatigue testing pure aluminium

    NASA Astrophysics Data System (ADS)

    Lehmann, P.; Yuan, G. S.; Hartwig, K. T.

    A simple method of clamping pure aluminium for fatigue tests at cryogenic temperatures is described. Easily machined cylindrical specimens are aligned and held firmly by collet grips that counteract sample shrinkage during cooldown. Specimens are quickly mounted and removed after testing without distortion or thermal treatment 99.999% aluminium, aluminium alloys and copper were gripped successfully through tens of thousands of fully reversed tension-compression cycles at 295, 77 and 4.2 K.

  20. A biogeochemical cycle for aluminium?

    PubMed

    Exley, Christopher

    2003-09-15

    The elaboration of biogeochemical cycles for elements which are known to be essential for life has enabled a broad appreciation of the homeostatic mechanisms which underlie element essentiality. In particular they can be used effectively to identify any part played by human activities in element cycling and to predict how such activities might impact upon the lithospheric and biospheric availability of an element in the future. The same criteria were the driving force behind the construction of a biogeochemical cycle for aluminium, a non-essential element which is a known ecotoxicant and a suspected health risk in humans. The purpose of this exercise was to examine the concept of a biogeochemical cycle for aluminium and not to review the biogeochemistry of this element. The cycle as presented is rudimentary and qualitative though, even in this nascent form, it is informative and predictive and, for these reasons alone, it is deserving of future quantification. A fully fledged biogeochemical cycle for aluminium should explain the biospheric abundance of this element and whether we should expect its (continued) active involvement in biochemical evolution.

  1. Influence of physico-chemical factors on leaching of chemical additives from aluminium foils used for packaging of food materials.

    PubMed

    Ojha, Priyanka; Ojha, C S; Sharma, V P

    2007-01-01

    In recent years, the use of aluminium foils to wrap foodstuff and commodities has been increased to a great extent. Aluminium was found to leach out from the foil in different simulants particularly in distilled water, acidic and alkaline medium at 60 +/- 2 degrees C for 2 hours and 40 +/- 2 degrees C for 24 hours. The migration was found to be above the permissible limit as laid down by WHO guidelines, that is of 0.2 mg/L of water. The protocol used for this study was based on the recommendation of Bureau of Indian Standard regarding the migration of chemical additives from packaging materials used to pack food items. Migration of the aluminium metal was found significantly higher in acidic and aqueous medium in comparison to alcoholic and saline medium. Higher temperature conditions also enhanced the rate of migration of aluminium in acidic and aqueous medium. Leaching of aluminium metal occurred in double distilled water, acetic acid 3%, normal saline and sodium carbonate, except ethanol 8%, in which aluminium migration was below the detection limit of the instrument where three brands of the aluminium foil samples studied.

  2. Further evidence of centrophenoxine mediated protection in aluminium exposed rats by biochemical and light microscopy analysis.

    PubMed

    Nehru, Bimla; Bhalla, Punita; Garg, Aarti

    2007-12-01

    The environmental agent aluminium has been intensively investigated in the initiation and progression of various neurological disorders and the role of oxidative stress in these disorders is a widely discussed phenomenon. In this light, the present study is focused on the role of aluminium in mediating oxidative stress, which may help in better understanding its role in neuronal degeneration. Further, we have exploited a known anti-aging drug centrophenoxine to explore its potential in the conditions of metal induced oxidative damage. Aluminium was administered orally at a dose level of 100 mg/kg b.wt./day for a period of 6 weeks followed by a post treatment of centrophenoxine at a dose level of 100 mg/kg b.wt./day for another 6 weeks. Following aluminium exposure, a significant increase in lipid peroxidation levels (estimated by MDA) were observed which was accompanied by a decrease in reduced glutathione content in both cerebrum and cerebellum of rat brain. Post treatment of centrophenoxine significantly reduced the lipid peroxidation levels and also increased the reduced glutathione content in both the regions. Histologically observed marked deteriorations in the organization of various cellular layers in both cerebrum and cerebellum were observed after aluminium administration. Centrophenoxine treated animals showed an appreciable improvement in the histoarchitecture of the cellular layers. Our results indicate that centrophenoxine has an antioxidant potential and should be examined further in aluminium toxic conditions.

  3. Biomechanical comparison of implant retained fixed partial dentures with fiber reinforced composite versus conventional metal frameworks: a 3D FEA study.

    PubMed

    Erkmen, Erkan; Meriç, Gökçe; Kurt, Ahmet; Tunç, Yahya; Eser, Atılım

    2011-01-01

    Fiber reinforced composite (FRC) materials have been successfully used in a variety of commercial applications. These materials have also been widely used in dentistry. The use of fiber composite technology in implant prostheses has been previously presented, since they may solve many problems associated with metal alloy frameworks such as corrosion, complexity of fabrication and high cost. The hypothesis of this study was that an FRC framework with lower flexural modulus provides more even stress distribution throughout the implant retained fixed partial dentures (FPDs) than a metal framework does. A 3-dimensional finite element analysis was conducted to evaluate the stress distribution in bone, implant-abutment complex and prosthetic structures. Hence, two distinctly different models of implant retained 3-unit fixed partial dentures, composed of Cr-Co and porcelain (M-FPD model) or FRC and particulate composite (FRC-FPD model) were utilized. In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal forces were simulated. When the FRC-FPD and M-FPD models were compared, it was found that all investigated stress values in the M-FPD model were higher than the values in the FRC-FPD model except for the stress values in the implant-abutment complex. It can be concluded that the implant supported FRC-FPD could eliminate the excessive stresses in the bone-implant interface and maintain normal physiological loading of the surrounding bone, therefore minimizing the risk of peri-implant bone loss due to stress-shielding. PMID:21094484

  4. Preparation and characterization of water-soluble carbon nanotube reinforced Nafion membranes and so-based ionic polymer metal composite actuators

    NASA Astrophysics Data System (ADS)

    Ru, Jie; Wang, Yanjie; Chang, Longfei; Chen, Hualing; Li, Dichen

    2016-09-01

    In this paper, we developed a new kind of ionic polymer metal composite (IPMC) actuator by doping water-soluble sulfonated multi-walled carbon nanotube (sMWCNT) into Nafion matrix to overcome some major drawbacks of traditional IPMCs, such as relatively low bending deformation and carring capacity at low driving voltages. Firstly, sMWCNT was synthesized via diazotization coupling reaction, and then doped into Nafion matrix by casting method. Subsequently, the electrochemical and electromechanical properties of sMWCNT-reinforced Nafion membranes and the corresponding IPMCs were investigated. Finally, the effects of sMWCNT on the performances of IPMCs were evaluated and analyzed systematacially. The results showed that sMWCNT was homogeneously dispersed in Nafion matrix without any entangled structure or obvious agglomeration. The main factors for superior actuation performances, like water-uptake ratio, proton conductivity and elastic modulus, increased significantly. Compared to the pure Nafion IPMC and MWCNT/Nafion IPMC, much superior electrochemical and electromechanical performances were achieved in the sMWCNT/Nafion IPMC, which were attributed to the numerous insertion sites, high surface conductivity and excellent mechanical strength as well as the homogeneous dispersity of the incorporated sMWCNT. Herein, a trace amount of sMWCNT can improve the performances of IPMCs significantly for realistic applications.

  5. The interface in tungsten fiber reinforced niobium metal-matrix composites. Final Report Ph.D. Thesis - Case Western Reserve Univ., Cleveland, OH

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni L.

    1989-01-01

    The creep resistance of tungsten fiber reinforced niobium metal-matrix composites was evaluated. The interface region between the fiber and matrix was characterized by microhardness and electron probe microanalysis measurements which indicated that its properties were between those of fiber and matrix. However, the measured properties of the composite exceeded those calculated by the rule of mixtures even when the interface zone was assumed to retain all the strength of the fiber. The composite structure appeared to enhance the strengths of both the fibers and the matrix above what they exhibited in stand-alone tests. The effect of fiber orientation and matrix alloy composition on the fiber/matrix interface were also evaluated. Small alloying additions of zirconium and tungsten to the niobium matrix affected the creep resistance of the composites only slightly. A decrease in the creep resistance of the composite with increasing zirconium content in the matrix was ascribed to an increase in the diffusion rate of the fiber/matrix interdiffusion reaction, and a slight increase in the creep resistance of the composite was observed with an addition of 9 w percent tungsten to the matrix. In addition, Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis.

  6. Materials characterization of silicon carbide reinforced titanium (Ti/SCS-6) metal matrix composites. Part 2: Theoretical modeling of fatigue behavior

    SciTech Connect

    Chiang, K.T.; Loh, D.H.; Liaw, P.K.; Diaz, E.S.

    1995-12-01

    Flexural fatigue behavior was investigated on titanium (Ti-15V-3Cr) metal matrix composites reinforced with cross-ply, continuous silicon carbide (SiC) fibers. The titanium composites had an eight-ply (0, 90, +45, {minus}45 deg) symmetric layup. Mechanistic investigation of the fatigue behavior is presented in Part 1 of this series. In Part 2, theoretical modeling of the fatigue behavior was performed using finite element techniques to predict the four stages of fatigue deflection behavior. On the basis of the mechanistic understanding, the fiber and matrix fracture sequence was simulated from ply to ply in finite element modeling. The predicted fatigue deflection behavior was found to be in good agreement with the experimental results. Furthermore, it has been shown that the matrix crack initiation starts in the 90 deg ply first, which is in agreement with the experimental observation. Under the same loading condition, the stress in the 90 deg ply of the transverse specimen is greater than that of the longitudinal specimen. This trend explains whey the longitudinal specimen has a longer fatigue life than the transverse specimen, as observed in Part 1.

  7. Nanostructured composite reinforced material

    DOEpatents

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  8. A 3D printed superconducting aluminium microwave cavity

    NASA Astrophysics Data System (ADS)

    Creedon, Daniel L.; Goryachev, Maxim; Kostylev, Nikita; Sercombe, Timothy B.; Tobar, Michael E.

    2016-07-01

    3D printing of plastics, ceramics, and metals has existed for several decades and has revolutionized many areas of manufacturing and science. Printing of metals, in particular, has found a number of applications in fields as diverse as customized medical implants, jet engine bearings, and rapid prototyping in the automotive industry. Although many techniques are used for 3D printing metals, they commonly rely on computer controlled melting or sintering of a metal alloy powder using a laser or electron beam. The mechanical properties of parts produced in such a way have been well studied, but little attention has been paid to their electrical properties. Here we show that a microwave cavity (resonant frequencies 9.9 and 11.2 GHz) 3D printed using an Al-12Si alloy exhibits superconductivity when cooled below the critical temperature of aluminium (1.2 K), with a performance comparable with the common 6061 alloy of aluminium. Superconducting cavities find application in numerous areas of physics, from particle accelerators to cavity quantum electrodynamics experiments. The result is achieved even with a very large concentration of non-superconducting silicon in the alloy of 12.18%, compared with Al-6061, which has between 0.4% and 0.8%. Our results may pave the way for the possibility of 3D printing superconducting cavity configurations that are otherwise impossible to machine.

  9. Seasonal variations of lead, arsenic, cadmium and aluminium contamination of groundwater in Dhemaji district, Assam, India.

    PubMed

    Buragohain, Mridul; Bhuyan, Bhabajit; Sarma, Hari Prasad

    2010-11-01

    Seasonal variations in the concentrations of groundwater with respect to arsenic, lead, cadmium and aluminium has been studied in Dhemaji district of Assam, India. The water samples were collected from 20 different sites in both dry and wet seasons. The metals were analysed by using atomic absorption spectrometer, Perkin Elmer AAnalyst 200 model. The concentrations of aluminium, lead and cadmium in groundwater were found to be significantly elevated. High concentrations of all the metals were recorded in the dry season than in the wet season. Univariate statistics along with skewness, kurtosis and confidence limit have been calculated for both the seasons to test the distribution normality for each metal. Statistical analyses of the data reveal non-uniform distribution of the metals in the area. The metal contamination of groundwater in the district follows the trend Al>Pb>Cd>As in both the seasons.

  10. Aluminium Diphosphamethanides: Hidden Frustrated Lewis Pairs.

    PubMed

    Styra, Steffen; Radius, Michael; Moos, Eric; Bihlmeier, Angela; Breher, Frank

    2016-07-01

    The synthesis and characterisation of two aluminium diphosphamethanide complexes, [Al(tBu)2 {κ(2) P,P'-Mes*PCHPMes*}] (3) and [Al(C6 F5 )2 {κ(2) P,P'-Mes*PCHPMes*}] (4), and the silylated analogue, Mes*PCHP(SiMe3 )Mes* (5), are reported. The aluminium complexes feature four-membered PCPAl core structures consisting of diphosphaallyl ligands. The silylated phosphine 5 was found to be a valuable precursor for the synthesis of 4 as it cleanly reacts with the diaryl aluminium chloride [(C6 F5 )2 AlCl]2 . The aluminium complex 3 reacts with molecular dihydrogen at room temperature under formation of the acyclic σ(2) λ(3) ,σ(3) λ(3) -diphosphine Mes*PCHP(H)Mes* and the corresponding dialkyl aluminium hydride [tBu2 AlH]3 . Thus, 3 belongs to the family of so-called hidden frustrated Lewis pairs. PMID:27271936

  11. Micromechanics for particulate reinforced composites

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Goldberg, Robert K.; Mital, Subodh K.

    1996-01-01

    A set of micromechanics equations for the analysis of particulate reinforced composites is developed using the mechanics of materials approach. Simplified equations are used to compute homogenized or equivalent thermal and mechanical properties of particulate reinforced composites in terms of the properties of the constituent materials. The microstress equations are also presented here to decompose the applied stresses on the overall composite to the microstresses in the constituent materials. The properties of a 'generic' particulate composite as well as those of a particle reinforced metal matrix composite are predicted and compared with other theories as well as some experimental data. The micromechanics predictions are in excellent agreement with the measured values.

  12. Exposure and inhalation risk assessment in an aluminium cast-house.

    PubMed

    Godderis, L; Vanderheyden, W; Van Geel, J; Moens, G; Masschelein, R; Veulemans, H

    2005-12-01

    To date the exposure, absorption and respiratory health effects of cast-house workers have not been described since most studies performed in the aluminium industry are focused on exposure and health effects of potroom personnel. In the present study, we assessed the external exposure and the absorbed dose of metals in personnel from the aluminium cast house. This was combined with an evaluation of respiratory complaints and the lung function of the personnel. 30 workers from an aluminium casting plant participated and 17 individuals of the packaging and distribution departments were selected as controls. The exposure was assessed by the quantification of total inhalable fume with metal fraction and by the determination of urinary aluminium, chromium, beryllium, manganese and lead concentration. Carbon monoxide (CO), carbon dioxide (CO2), aldehydes and polyaromatic hydrocarbons and man-made mineral fibres concentration were assessed as well. In order to evaluate their respiratory status each participant filled out a questionnaire and their lung function was tested by forced spirometry. Total inhalable fume exposure was maximum 4.37 mg m(-3). Exposure to the combustion gases, man-made mineral fibres and metal fume was well below the exposure limits. Beryllium could not be detected in the urine. The values of aluminium, manganese and lead in the urine were all under the respective reference value. One individual had a urinary chromium excretion above the ACGIH defined biological exposure index (BEI) of 30 microg g(-1) creatinine. There was no significant difference in any of the categories of the respiratory questionnaire and in the results of the spirometry between cast house personnel and referents (Chi-square, all p > 0.05). Exposure in cast houses seem to be acceptable under these conditions. However, peak exposure to fumes cannot be excluded and the potential risk of chromium and beryllium exposure due to the recycling of aluminium requires further attention

  13. Exposure and inhalation risk assessment in an aluminium cast-house.

    PubMed

    Godderis, L; Vanderheyden, W; Van Geel, J; Moens, G; Masschelein, R; Veulemans, H

    2005-12-01

    To date the exposure, absorption and respiratory health effects of cast-house workers have not been described since most studies performed in the aluminium industry are focused on exposure and health effects of potroom personnel. In the present study, we assessed the external exposure and the absorbed dose of metals in personnel from the aluminium cast house. This was combined with an evaluation of respiratory complaints and the lung function of the personnel. 30 workers from an aluminium casting plant participated and 17 individuals of the packaging and distribution departments were selected as controls. The exposure was assessed by the quantification of total inhalable fume with metal fraction and by the determination of urinary aluminium, chromium, beryllium, manganese and lead concentration. Carbon monoxide (CO), carbon dioxide (CO2), aldehydes and polyaromatic hydrocarbons and man-made mineral fibres concentration were assessed as well. In order to evaluate their respiratory status each participant filled out a questionnaire and their lung function was tested by forced spirometry. Total inhalable fume exposure was maximum 4.37 mg m(-3). Exposure to the combustion gases, man-made mineral fibres and metal fume was well below the exposure limits. Beryllium could not be detected in the urine. The values of aluminium, manganese and lead in the urine were all under the respective reference value. One individual had a urinary chromium excretion above the ACGIH defined biological exposure index (BEI) of 30 microg g(-1) creatinine. There was no significant difference in any of the categories of the respiratory questionnaire and in the results of the spirometry between cast house personnel and referents (Chi-square, all p > 0.05). Exposure in cast houses seem to be acceptable under these conditions. However, peak exposure to fumes cannot be excluded and the potential risk of chromium and beryllium exposure due to the recycling of aluminium requires further attention.

  14. Compressive tensile and shear testing of melt-foamed aluminium

    SciTech Connect

    Von Hagen, H.; Bleck, W.

    1998-12-31

    For construction purposes it is utterly important to get detailed information on the possible influence of the foam thickness on the mechanical properties and on the deformation behavior of metallic foams. The effect of compressive, tensile and shear loads on aluminium foam samples has been examined with the testing methods for sandwich material as described in German and ASTM-standards. The aim is to provide more data on these mechanical properties varying the sample density and thickness. Regarding the results the most reliable material parameters as well as steps towards a relationship between the different strength parameters can be obtained.

  15. Biological indicators of exposure to total and respirable aluminium dust fractions in a primary aluminium smelter.

    PubMed Central

    Röllin, H B; Theodorou, P; Cantrell, A C

    1996-01-01

    OBJECTIVES: The study attempts to define biological indicators of aluminium uptake and excretion in workers exposed to airborne aluminium compounds in a primary aluminium smelter. Also, this study defines the total and respirable aluminium dust fractions in two different potrooms, and correlates their concentrations with biological indicators in this group of workers. METHODS: Air was sampled at defined work sites. Non-destructive and conventional techniques were used to find total and respirable aluminium content of the dust. Blood and urine was collected from 84 volunteers employed at various work stations throughout the smelter and from two different cohorts of controls matched for sex, age, and socioeconomic status. Aluminium in serum samples and urine specimens was measured by flameless atomic absorption with a PE 4100 ZL spectrometer. RESULTS: The correlation of aluminium concentrations in serum and urine samples with the degree of exposure was assessed for three arbitrary exposure categories; low (0.036 mg Al/m3), medium (0.35 mg Al/m3) and high (1.47 mg Al/m3) as found in different areas of the smelter. At medium and high exposure, the ratio of respirable to total aluminium in the dust samples varied significantly. At high exposure, serum aluminium, although significantly raised, was still within the normal range of an unexposed population. The workers with low exposure excreted aluminium in urine at levels significantly higher than the controls, but still within the normal range of the population. However, potroom workers with medium and high exposure had significantly higher urinary aluminium than the normal range. CONCLUSIONS: It is concluded that only urinary aluminium constitutes a practical index of occupational exposure at or above 0.35 mg Al/m3, and that the respirable fraction of the dust may play a major role in the biological response to exposure to aluminium in a smelter environment. PMID:8758038

  16. Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition

    NASA Astrophysics Data System (ADS)

    Gül, H.; Kılıç, F.; Uysal, M.; Aslan, S.; Alp, A.; Akbulut, H.

    2012-03-01

    In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000 nm was used as the plating electrolyte. The aim of this work is to obtain Ni-SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200 μm) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280-571 HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (Ø 10 mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55-65%). The results showed that the wear resistance of the nanocomposites was approximately 2-2.2 times more than those of unreinforced Ni.

  17. The influence of thermal degradation on the electrodeposition of aluminium from an air- and water-stable ionic liquid.

    PubMed

    Veder, Jean-Pierre M; Horne, Michael D; Rüther, Thomas; Bond, Alan M; Rodopoulos, Theo

    2013-05-28

    Aluminium electrodeposition is demonstrated from a thermally degraded ionic liquid solution. NMR and voltammetric analyses established that Al(3+) reduction was remarkably similar to that in non-degraded IL solutions suggesting that the electroactive metal-containing species was unaffected by heat treatment. Electron microscopy revealed a significant grain refinement of the deposited metal.

  18. Semi-Solid Processing by Electric Current During Sand Casting of Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Prodhan, Anjan

    2016-02-01

    This study reports the effect of DC and 50Hz AC treatment (ECT) on aluminium or aluminium alloys during solidification in sand moulds i.e., at their semisolid state. Castings, with different geometry, were made in open or closed sand moulds. It is observed that ECT (a) reduces dissolved gas, (b) reduces internal shrinkage and (c) metal mould reactions in castings. It is also observed that the AC treatment is more effective compared to DC treatment. ECT changes the movement of solidification front. The optical microstructures of ECT samples are quite similar to the samples treated in other semisolid processing methods.

  19. Derivation of a water quality guideline for aluminium in marine waters.

    PubMed

    Golding, Lisa A; Angel, Brad M; Batley, Graeme E; Apte, Simon C; Krassoi, Rick; Doyle, Chris J

    2015-01-01

    Metal risk assessment of industrialized harbors and coastal marine waters requires the application of robust water quality guidelines to determine the likelihood of biological impacts. Currently there is no such guideline available for aluminium in marine waters. A water quality guideline of 24 µg total Al/L has been developed for aluminium in marine waters based on chronic 10% inhibition or effect concentrations (IC10 or EC10) and no-observed-effect concentrations (NOECs) from 11 species (2 literature values and 9 species tested including temperate and tropical species) representing 6 taxonomic groups. The 3 most sensitive species tested were a diatom Ceratoneis closterium (formerly Nitzschia closterium; IC10 = 18 µg Al/L, 72-h growth rate inhibition) < mussel Mytilus edulis plannulatus (EC10 = 250 µg Al/L, 72-h embryo development) < oyster Saccostrea echinata (EC10 = 410 µg Al/L, 48-h embryo development). Toxicity to these species was the result of the dissolved aluminium forms of aluminate (Al(OH4 (-) ) and aluminium hydroxide (Al(OH)3 (0) ) although both dissolved, and particulate aluminium contributed to toxicity in the diatom Minutocellus polymorphus and green alga Dunaliella tertiolecta. In contrast, aluminium toxicity to the green flagellate alga Tetraselmis sp. was the result of particulate aluminium only. Four species, a brown macroalga (Hormosira banksii), sea urchin embryo (Heliocidaris tuberculata), and 2 juvenile fish species (Lates calcarifer and Acanthochromis polyacanthus), were not adversely affected at the highest test concentration used.

  20. Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

    NASA Technical Reports Server (NTRS)

    Grove, C. A.; Judd, G.; Ansell, G. S.

    1972-01-01

    Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

  1. Fabrication of fibre reinforced nickel aluminide matrix composites by reactive processing

    SciTech Connect

    Downing, M.; Horsfall, I.

    1994-12-31

    This paper describes the fabrication by reactive processing of short, and continuous, alumina fibre reinforced nickel aluminide matrix composites. The fibre is introduced into the aluminide system to increase toughness and high temperature strength. The short fibre reinforced nickel aluminide is formed by squeeze casting a porous preform containing nickel powder and SAFFIL fibre with an aluminium or aluminium alloy melt. The continuous fibre reinforced nickel aluminide is formed by squeeze casting a jig containing nickel coated ALMAX fibre. The short fibre reinforced composite (containing 10% and 20% volume fibre) reacted during infiltration with an aluminium melt to form a single phase intermetallic. Using an aluminium-copper melt the intermetallic formation was inhibited and a multi-phase composite was obtained. A preliminary study into reactive processing of this system by utilising a hot isostatic pressing (HIP) cycle is presented. HIP was required to prevent the formation of porosity due to an imbalance in the diffusive mobility of the various components. It was found that HIP was only effective on canned samples, the preferred encapsulation material being glass. The continuous fibre reinforced composite did not react to an intermetallic phase when infiltrated with an aluminum melt. Use of an aluminum-copper melt resulted in partial nickel-melt reaction producing various nickel-aluminum (-copper) phases. HIP was then used to form a two phase intermetallic matrix with no evidence of fibre damage.

  2. Evaluation Of Four Welding Arc Processes Applied To 6061 Aluminium Alloy

    SciTech Connect

    Benoit, A.; Paillard, P.; Baudin, T.; Jobez, S.; Castagne, J.-F.

    2011-01-17

    At a time when greenhouse gas emissions must be reduced, the use of the aluminium alloys is expanding, in particular in the transportation industry. In order to extend the possibilities of aluminium assembly design, new Metal Inert Gas (MIG) welding processes have been conceived. They work at lower temperatures than usual arc processes (classic MIG or Tungsten Inert Gas). This study compares four arc welding processes, applied to the 6061 aluminium alloy. These four weld processes have been studied through the metallurgical analysis of the weld beads. Metallography, micro-hardness testings, X Ray radiography have been carried out on the produced weld beads. The processes are classified according to the quality of the beads like geometry of beads, size of the heat affected zone and presence of defects.

  3. Evaluation Of Four Welding Arc Processes Applied To 6061 Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Benoit, A.; Paillard, P.; Baudin, T.; Jobez, S.; Castagné, J.-F.

    2011-01-01

    At a time when greenhouse gas emissions must be reduced, the use of the aluminium alloys is expanding, in particular in the transportation industry. In order to extend the possibilities of aluminium assembly design, new Metal Inert Gas (MIG) welding processes have been conceived. They work at lower temperatures than usual arc processes (classic MIG or Tungsten Inert Gas). This study compares four arc welding processes, applied to the 6061 aluminium alloy. These four weld processes have been studied through the metallurgical analysis of the weld beads. Metallography, micro-hardness testings, X Ray radiography have been carried out on the produced weld beads. The processes are classified according to the quality of the beads like geometry of beads, size of the heat affected zone and presence of defects.

  4. A computational analysis and suitability assessment of cold-gas dynamic spraying of glass-fiber-reinforced poly-amide 6 for use in direct-adhesion polymer metal hybrid components

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Pandurangan, B.; Bell, W. C.; Daqaq, M.; Ma, L.; Seyr, Norbert; Erdmann, Marc; Holzleitner, Jochen

    2008-01-01

    SummaryA transient non-linear dynamics computational analysis of cold-gas dynamic spraying (CGDS) of glass-fiber-reinforced poly-amide (nylon) 6 has been carried out using Ansys-Autodyn [Century Dynamics Inc., Ansys-Autodyn Version 11.0, User Documentation, Century Dynamics Inc. (a subsidiary of ANSYS Inc.), 2007] in order to assess the suitability of this spraying technology for coating of metal stampings used in polymer metal hybrid (PMH) load-bearing automotive component applications. In addition, the suitability of the CGDS is assessed with respect to a need for metal stamping surface preparation/treatment, the ability to deposit polymeric material without significant material degradation, the ability to selectively overcoat the metal stamping, the resulting magnitude of the polymer-to-metal adhesion strength, durability of the polymer/metal bond with respect to prolonged exposure to high-temperature/high-humidity and mechanical/thermal fatigue service conditions, and compatibility with the automotive body-in-white ( BIW) manufacturing process chain. The analysis revealed that CGDS can be considered as a viable technology for coating of metal stampings used in PMH load-bearing automotive component applications.

  5. Aluminium overload after 5 years in skin biopsy following post-vaccination with subcutaneous pseudolymphoma.

    PubMed

    Guillard, Olivier; Fauconneau, Bernard; Pineau, Alain; Marrauld, Annie; Bellocq, Jean-Pierre; Chenard, Marie-Pierre

    2012-10-01

    Aluminium hydroxide is used as an effective adjuvant in a wide range of vaccines for enhancing immune response to the antigen. The pathogenic role of aluminium hydroxide is now recognized by the presence of chronic fatigue syndrome, macrophagic myofasciitis and subcutaneous pseudolymphoma, linked to intramuscular injection of aluminium hydroxide-containing vaccines. The aim of this study is to verify if the subcutaneous pseudolymphoma observed in this patient in the site of vaccine injection is linked to an aluminium overload. Many years after vaccination, a subcutaneous nodule was discovered in a 45-year-old woman with subcutaneous pseudolymphoma. In skin biopsy at the injection site for vaccines, aluminium (Al) deposits are assessed by Morin stain and quantification of Al is performed by Zeeman Electrothermal Atomic Absorption Spectrophotometry. Morin stain shows Al deposits in the macrophages, and Al assays (in μg/g, dry weight) were 768.10±18 for the patient compared with the two control patients, 5.61±0.59 and 9.13±0.057. Given the pathology of this patient and the high Al concentration in skin biopsy, the authors wish to draw attention when using the Al salts known to be particularly effective as adjuvants in single or repeated vaccinations. The possible release of Al may induce other pathologies ascribed to the well-known toxicity of this metal.

  6. Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

    NASA Astrophysics Data System (ADS)

    Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

    2016-01-01

    Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

  7. Glycothermal synthesis of metal oxides

    NASA Astrophysics Data System (ADS)

    Inoue, Masashi

    2004-04-01

    The author has been exploring the synthesis of inorganic materials in organic solvents at temperatures (200-300 °C) higher than their boiling points (solvothermal reaction), and has developed various reaction methods for the synthesis of ultrafine particles of metal oxides. In this paper, the reactions of aluminium compounds (aluminium hydroxide (Al(OH)3; gibbsite), aluminium alkoxides, and aluminium salts) in various organic solvents (alcohols, glycols, aminoalcohols, and inert organic solvents) are first reviewed, and reaction mechanisms and effects of the starting materials and solvents on the products are discussed. Then, the specificity of the use of glycols, especially 1,4-butanediol (glycothermal reaction), is clarified, and glycothermal synthesis of crystalline mixed oxides such as yttrium aluminium garnet is described. Finally, the use of the solvothermally prepared products as the catalyst materials is described.

  8. Aluminium and Alzheimer's disease: An epidemiological approach.

    PubMed

    Martyn, C N

    1990-03-01

    Epidemiological methods have an important role in the investigation of the postulated connection between exposure to aluminium and the development of Alzheimer's disease. We have examined the usefulness of existing data on prevalence and mortality as a resource for studying variations in the rate of the disease with time and geography. Unfortunately, methodological differences between prevalence surveys and errors and biases in mortality data are large. No reliable conclusions can be drawn from these data about geographical differences in rates of dementia in England and Wales nor about time trends in the disease.Aluminium salts are widely used in the UK for the treatment of drinking water. Residual aluminium concentrations vary more than ten fold between different parts of the country. We have estimated diagnostic rates of pre-senile Alzheimer's disease in seven geographical areas and examined the correlation between rates of Alzheimer's disease and water aluminium concentration. PMID:24202582

  9. Aluminium surface treatment with ceramic phases using diode laser

    NASA Astrophysics Data System (ADS)

    Labisz, K.; Tański, T.; Brytan, Z.; Pakieła, W.; Wiśniowski, M.

    2016-07-01

    Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones—remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.

  10. Reinforced rubber composition containing ground coal

    SciTech Connect

    Sperley, R.J.

    1984-10-16

    A reinforced rubber composition is provided comprising a mixture of (a) a sulfur vulcanizable rubber and (b) ground coal having an average mesh size of 25 or more and which produces an aqueous slurry with a pH of less than 7.0, and wherein a metallic reinforcing member is embedded in the rubber mixture of (a) and (b).

  11. A preliminary study of the dermal absorption of aluminium from antiperspirants using aluminium-26.

    PubMed

    Flarend, R; Bin, T; Elmore, D; Hem, S L

    2001-02-01

    Aluminium chlorohydrate (ACH), the active ingredient in many antiperspirants, was labeled with the radioisotope 26Al. The labeled ACH was then fractionated into about 100 samples using gel filtration chromatography. Each fraction was analyzed for 26Al and total aluminium content. Aluminium-26 was only detected in the fractions that also contained aluminium, which verified that the ACH was uniformly labeled. 84 mg of the labeled ACH was then applied to a single underarm of two adult subjects with blood and urine samples being collected over 7 weeks. Tape-stripping and mild washings of the skin were also collected for the first 6 days. Results indicate that only 0.012% of the applied aluminium was absorbed through the skin. At this rate, about 4 microg of aluminium is absorbed from a single use of ACH on both underarms. This is about 2.5% of the aluminium typically absorbed by the gut from food over the same time period. Therefore, a one-time use of ACH applied to the skin is not a significant contribution to the body burden of aluminium.

  12. Microstructure and Mechanical Behaviour of Al6061-ZrB2 In-situ Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Vasanth Kumar, R.; Keshavamurthy, R.; Perugu, Chandra S.

    2016-09-01

    Aluminium matrix composites processed through in-situ molten reaction has emerged as an alternative for eliminating defects existing in ex-situ reinforced metal matrix composites. Development of composites through in-situ method using inorganic salts via liquid metallurgy route is the most widely accepted technique. In the present work, Al6061-ZrB2 in-situ composites have been developed through in-situ reaction of Al-10%Zr and Al-3%B master alloys in Al6061 alloy. Study of microstructure and mechanical properties of in-situ reinforced ZrB2 in Al6061 alloy have been carried out. Composite exhibited grain refinement and improved the mechanical properties of Al6061 alloy. Ductility of composite is reduced with increase in content of ZrB2.

  13. Does aluminium bind to histidine? An NMR investigation of amyloid β12 and amyloid β16 fragments.

    PubMed

    Narayan, Priya; Krishnarjuna, Bankala; Vishwanathan, Vinaya; Jagadeesh Kumar, Dasappa; Babu, Sudhir; Ramanathan, Krishna Venkatachala; Easwaran, Kalpathy Ramaier Katchap; Nagendra, Holenarasipur Gundurao; Raghothama, Srinivasarao

    2013-07-01

    Aluminium and zinc are known to be the major triggering agents for aggregation of amyloid peptides leading to plaque formation in Alzheimer's disease. While zinc binding to histidine in Aβ (amyloid β) fragments has been implicated as responsible for aggregation, not much information is available on the interaction of aluminium with histidine. In the NMR study of the N-terminal Aβ fragments, DAEFRHDSGYEV (Aβ12) and DAEFRHDSGYEVHHQK (Aβ16) presented here, the interactions of the fragments with aluminium have been investigated. Significant chemical shifts were observed for few residues near the C-terminus when aluminium chloride was titrated with Aβ12 and Aβ16 peptides. Surprisingly, it is nonhistidine residues which seem to be involved in aluminium binding. Based on NMR constrained structure obtained by molecular modelling, aluminium-binding pockets in Aβ12 were around charged residues such as Asp, Glu. The results are discussed in terms of native structure propagation, and the relevance of histidine residues in the sequences for metal-binding interactions. We expect that the study of such short amyloid peptide fragments will not only provide clues for plaque formation in aggregated conditions but also facilitate design of potential drugs for these targets.

  14. Does aluminium bind to histidine? An NMR investigation of amyloid β12 and amyloid β16 fragments.

    PubMed

    Narayan, Priya; Krishnarjuna, Bankala; Vishwanathan, Vinaya; Jagadeesh Kumar, Dasappa; Babu, Sudhir; Ramanathan, Krishna Venkatachala; Easwaran, Kalpathy Ramaier Katchap; Nagendra, Holenarasipur Gundurao; Raghothama, Srinivasarao

    2013-07-01

    Aluminium and zinc are known to be the major triggering agents for aggregation of amyloid peptides leading to plaque formation in Alzheimer's disease. While zinc binding to histidine in Aβ (amyloid β) fragments has been implicated as responsible for aggregation, not much information is available on the interaction of aluminium with histidine. In the NMR study of the N-terminal Aβ fragments, DAEFRHDSGYEV (Aβ12) and DAEFRHDSGYEVHHQK (Aβ16) presented here, the interactions of the fragments with aluminium have been investigated. Significant chemical shifts were observed for few residues near the C-terminus when aluminium chloride was titrated with Aβ12 and Aβ16 peptides. Surprisingly, it is nonhistidine residues which seem to be involved in aluminium binding. Based on NMR constrained structure obtained by molecular modelling, aluminium-binding pockets in Aβ12 were around charged residues such as Asp, Glu. The results are discussed in terms of native structure propagation, and the relevance of histidine residues in the sequences for metal-binding interactions. We expect that the study of such short amyloid peptide fragments will not only provide clues for plaque formation in aggregated conditions but also facilitate design of potential drugs for these targets. PMID:23464626

  15. Aluminium and the human breast.

    PubMed

    Darbre, P D

    2016-06-01

    The human population is exposed to aluminium (Al) from diet, antacids and vaccine adjuvants, but frequent application of Al-based salts to the underarm as antiperspirant adds a high additional exposure directly to the local area of the human breast. Coincidentally the upper outer quadrant of the breast is where there is also a disproportionately high incidence of breast cysts and breast cancer. Al has been measured in human breast tissues/fluids at higher levels than in blood, and experimental evidence suggests that at physiologically relevant concentrations, Al can adversely impact on human breast epithelial cell biology. Gross cystic breast disease is the most common benign disorder of the breast and evidence is presented that Al may be a causative factor in formation of breast cysts. Evidence is also reviewed that Al can enable the development of multiple hallmarks associated with cancer in breast cells, in particular that it can cause genomic instability and inappropriate proliferation in human breast epithelial cells, and can increase migration and invasion of human breast cancer cells. In addition, Al is a metalloestrogen and oestrogen is a risk factor for breast cancer known to influence multiple hallmarks. The microenvironment is established as another determinant of breast cancer development and Al has been shown to cause adverse alterations to the breast microenvironment. If current usage patterns of Al-based antiperspirant salts contribute to causation of breast cysts and breast cancer, then reduction in exposure would offer a strategy for prevention, and regulatory review is now justified. PMID:26997127

  16. Zinc modulates aluminium-induced oxidative stress and cellular injury in rat brain.

    PubMed

    Singla, Neha; Dhawan, D K

    2014-10-01

    Dysregulation of metal homeostasis has been perceived as one of the key factors in the progression of neurodegeneration. Aluminium (Al) has been considered as a major risk factor, which is linked to several neurodegenerative diseases, especially Alzheimer's disease, whereas zinc (Zn) has been reported as a vital dietary element, which regulates a number of physiological processes in central nervous system. The present study was conducted to explore the protective potential of zinc, if any, in ameliorating neurotoxicity induced by aluminium. Male Sprague Dawley rats received either aluminium chloride (AlCl3) orally (100 mg kg(-1) b.wt. per day), zinc sulphate (ZnSO4) at a dose level of 227 mg L(-1) in drinking water or combined treatment of aluminium and zinc for 8 weeks. Aluminium treatment significantly elevated the levels of lipid peroxidation and reactive oxygen species as well as the activities of catalase, superoxide dismutase and glutathione reductase, which however were decreased following Zn co-treatment of Al-treated rats. In contrast, Al treatment decreased the activities of glutathione-S-transferase as well as the levels of reduced glutathione, oxidised glutathione and total glutathione, but co-administration of Zn to Al-treated animals increased these levels. Furthermore, Al treatment caused a significant increase in the levels of Fe and Mn as well as of Al but decreased the Zn and metallothionein levels. In the Zn-supplemented animals, the levels of Al, Fe, Mn were found to be significantly decreased, whereas the levels of metallothionein as well as Zn were increased. Moreover, histopathological alterations such as vacuolization and loss of Purkinje cells were also evident following Al treatment, which showed improvement upon Zn supplementation. Therefore, zinc has the potential to alleviate aluminium-induced neurodegeneration.

  17. Performance of commercial aluminium alloys as anodes in gelled electrolyte aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Pino, M.; Chacón, J.; Fatás, E.; Ocón, P.

    2015-12-01

    The evaluation of commercial aluminium alloys, namely, Al2024, Al7475 and Al1085, for Al-air batteries is performed. Pure Al cladded Al2024 and Al7475 are also evaluated. Current rates from 0.8 mA cm-2 to 8.6 mA cm-2 are measured in a gel Al-air cell composed of the commercial alloy sample, a commercial air-cathode and an easily synthesizable gelled alkaline electrolyte. The influence of the alloying elements and the addition to the electrolyte of ZnO and ZnCl2, as corrosion inhibitors is studied and analysed via EDX/SEM. Specific capacities of up to 426 mAh/g are obtained with notably flat potential discharges of 1.3-1.4 V. The competition between self-corrosion and oxidation reactions is also discussed, as well as the influence of the current applied on that process. Al7475 is determined to have the best behaviour as anode in Al-air primary batteries, and cladding process is found to be an extra protection against corrosion at low current discharges. Conversely, Al1085 provided worse results because of an unfavourable metallic composition.

  18. Determination of heavy metal toxicity of finished leather solid waste.

    PubMed

    Aslan, Ahmet

    2009-05-01

    This paper investigates the toxicity in leather products of heavy metals known to be detrimental to the ecosystem. Heavy metal concentrations in leather samples were identified with ICP-OES, and toxicity was determined using a MetPLATE bioassay. Chromium and aluminium were found to constitute 98% of the total concentration of heavy metals in finished leather tanned with chromium and aluminium salts, while in some vegetable-tanned leather, zirconium was the only heavy metal identified. The average inhibition values for chromium, aluminium and vegetable tanned leather were 98.08%, 97.04% and 62.36%, respectively. PMID:19165404

  19. Determination of heavy metal toxicity of finished leather solid waste.

    PubMed

    Aslan, Ahmet

    2009-05-01

    This paper investigates the toxicity in leather products of heavy metals known to be detrimental to the ecosystem. Heavy metal concentrations in leather samples were identified with ICP-OES, and toxicity was determined using a MetPLATE bioassay. Chromium and aluminium were found to constitute 98% of the total concentration of heavy metals in finished leather tanned with chromium and aluminium salts, while in some vegetable-tanned leather, zirconium was the only heavy metal identified. The average inhibition values for chromium, aluminium and vegetable tanned leather were 98.08%, 97.04% and 62.36%, respectively.

  20. Reinforced structural plastics

    NASA Technical Reports Server (NTRS)

    Lubowitz, H. R.; Kendrick, W. P.; Jones, J. F.; Thorpe, R. S.; Burns, E. A. (Inventor)

    1972-01-01

    Reinforced polyimide structures are described. Reinforcing materials are impregnated with a suspension of polyimide prepolymer and bonded together by heat and pressure to form a cured, hard-reinforced, polyimide structure.

  1. Diamond grooving of rapidly solidified optical aluminium

    NASA Astrophysics Data System (ADS)

    Abou-El-Hossein, Khaled; Hsu, Wei-Yao; Ghobashy, Sameh; Cheng, Yuan-Chieh; Mkoko, Zwelinzima

    2015-10-01

    Traditional optical aluminium grades such as Al 6061 are intensively used for making optical components for applications ranging from mould insert fabrication to laser machine making. However, because of their irregular microstructure and relative inhomogeneity of material properties at micro scale, traditional optical aluminium may exhibit some difficulties when ultra-high precision diamond turned. Inhomogeneity and micro-variation in the material properties combined with uneven and coarse microstructure may cause unacceptable surface finish and accelerated tool wear, especially in grooving operation when the diamond tool edge is fully immersed in the material surface. Recently, new grades of optical aluminium that are featured by their ultra-fine microstructure and improved material properties have been developed to overcome the problem of high tool wear rates. The new aluminium grades have been developed using rapid solidification process which results in extremely small grain sizes combined with improved mechanical properties. The current study is concerned with investigating the performance of single-point diamond turning when grooving two grades of rapidly solidified aluminium (RSA) grades: RSA905 which is a high-alloyed aluminium grade and RSA443 which has a high silicon content. In this study, two series of experiments employed to create radial microgrooves on the two RSA grades. The surface roughness obtained on the groove surface is measured when different combinations of cutting parameters are used. Cutting speed is varied while feed rate and depth of cut were kept constant. The results show that groove surface roughness produced on RSA443 is higher than that obtained on RSA905. Also, the paper reports on the effect of cutting speed on surface roughness for each RSA grade.

  2. Reinforced Carbon Nanotubes.

    SciTech Connect

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2005-06-28

    The present invention relates generally to reinforced carbon nanotubes, and more particularly to reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  3. Materials Science Constraints on the Development of Aluminium Reduction Cells

    NASA Astrophysics Data System (ADS)

    Metson, James; McIntosh, Grant; Etzion, Ronny

    The Hall-Heroult process for the production of Aluminium metal is some 125 years old. The process is energy constrained by the need to shed around half of the (electrical) energy supplied to the cell as waste heat. The molten cryolite electrolyte is sufficiently aggressive that the only reliable method of protecting the side wall of the cell is to maintain a frozen layer of electrolyte at the hot face of the sidewall. Thus the lack of a cryolite resistant sidewall is but one of several materials science constraints which still limit the energy efficiency of the process. An inert anode and non-consumable cathode are also significant challenges which limit cell life and energy efficiency. Thus there are major challenges in both materials development and new conceptual cell designs to improve the efficiency of this process.

  4. Microstructure characterization of hypereutectoid aluminium bronze composite coating

    NASA Astrophysics Data System (ADS)

    Kucita, P.; Wang, S. C.; Li, W. S.; Cook, R. B.; Starink, M. J.

    2015-10-01

    Hypereutectoid aluminium bronze coating was deposited onto an E.N. 10503 steel substrate using plasma transferred arc welding (PTA). Microstructure characterisation of the coating and a section near the steel substrate joint was carried out using SEM, EBSD, EDS in conjunction with XRD and depth-sensing nano-indentation. The constituent phases in the coating were identified as: martensitic Cu3Al β1' phase, solid solution of Al in Cu α phase and the intermetallic Fe3Al κ1 phase. The region near the steel substrate was characterised by high hardness, large grains and presence of Cu precipitates. No cracks were observed in this region. The coating has high hardness of 4.9GPa and Young's modulus of 121.7GPa. This is attributed to homogeneous distribution of sub microns size Fe3Al intermetallic phase. The implications of the coating to the engineering application of sheet metal forming are discussed.

  5. Fluence dependent electrical conductivity in aluminium thin films grown by infrared pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Rebollar, Esther; Martínez-Tong, Daniel E.; Sanz, Mikel; Oujja, Mohamed; Marco, José F.; Ezquerra, Tiberio A.; Castillejo, Marta

    2016-11-01

    We studied the effect of laser fluence on the morphology, composition, structure and electric conductivity of deposits generated by pulsed laser ablation of a metallic aluminium target in vacuum using a Q-switched Nd:YAG laser (1064 nm, 15 ns). Upon irradiation for one hour at a repetition rate of 10 Hz, a smooth layer of several tens of nanometres, as revealed by atomic force microscopy (AFM) was deposited on glass. Surface chemical composition was determined by X-ray photoelectron spectroscopy, and to study the conductivity of deposits both I-V curves and conductive-AFM measurements were performed. Irradiation at fluences around 2.7 J/cm2 resulted in deposition of amorphous aluminium oxide films. Differently, at higher fluences above 7 J/cm2, the films are constituted by metallic aluminium. Optical emission spectroscopy revealed that highly ionized species are more abundant in the ablation plumes generated at higher fluences. The results demonstrate the possibility to control by PLD the metal or dielectric character of the films.

  6. Analysis of wear properties of aluminium based journal bearing alloys with and without lubrication.

    NASA Astrophysics Data System (ADS)

    Mathavan, J. Joy; Patnaik, Amar

    2016-09-01

    Apart from classical bearing materials, Aluminium alloys are used as bearing materials these days because of their superior quality. In this analysis, new Aluminium based bearing materials, with filler metals Si, Ni, and Cr are prepared by metal mould casting in burnout furnace machine, and tribological properties of these alloys with and without lubrication were tested. The experiments for wear with lubrication are conducted on multiple specimen tester and experiments without lubrication is conducted on Pin on disk tribometer. The disc material used was SAE 1050 steel. Wear tests were conducted at a sliding speed of 0.785 m/s and at a normal load of 20 N. Coefficient of friction values, temperature changes and wear of the specimens were plotted on graph according to the above mentioned working conditions. Hardness and weight losses of the specimens were calculated. The obtained results demonstrate how the friction and wear properties of these samples have changed with the % addition of Silicon, Chromium and Nickel to the base metal aluminium.

  7. Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property

    NASA Astrophysics Data System (ADS)

    Song, Tingting; Liu, Qi; Liu, Jingyuan; Yang, Wanlu; Chen, Rongrong; Jing, Xiaoyan; Takahashi, Kazunobu; Wang, Jun

    2015-11-01

    Inspired by natural plants such as Nepenthes pitcher plants, super slippery surfaces have been developed to improve the attributes of repellent surfaces. In this report, super slippery porous anodic aluminium oxide (AAO) surfaces have fabricated by a simple and reproducible method. Firstly, the aluminium substrates were treated by an anodic process producing micro-nano structured sheet-layered pores, and then immersed in Methyl Silicone Oil, Fluororalkylsilane (FAS) and DuPont Krytox, respectively, generating super slippery surfaces. Such a good material with excellent anti-corrosion property through a simple and repeatable method may be potential candidates for metallic application in anti-corrosion and extreme environment.

  8. Two-photon excitation of aluminium phthalocyanines

    SciTech Connect

    Meshalkin, Yu P; Alfimov, E E; Makukha, V K; Vasil'ev, N E; Denisov, A N; Ogirenko, A P

    1999-12-31

    A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined. (lasers in medicine)

  9. Molecular breeding of cereals for aluminium resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al3+) toxicity is the primary factor limiting crop production on acidic soils worldwide. In addition to an application of lime for soil amelioration, Al3+ resistant plant varieties have been deployed to raise productivity on such hostile soils. This has been possible due to the exploita...

  10. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    PubMed

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

  11. Toxicity of dissolved and precipitated aluminium to marine diatoms.

    PubMed

    Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

    2016-05-01

    Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

  12. The Reinforcement Hierarchy

    ERIC Educational Resources Information Center

    Forness, Steven R.

    1973-01-01

    Reinforcement hierarchy implies movement along a continuum from top to bottom, from primitive levels of reinforcement to more sophisticated levels. Unless it is immediately obvious that a child cannot function without the use of lower-order reinforcers, we should approach him as though he responds to topmost reinforcers until he demonstrates…

  13. Toxicity and aluminium concentration in bone following dietary administration of two sodium aluminium phosphate formulations in rats.

    PubMed

    Hicks, J S; Hackett, D S; Sprague, G L

    1987-07-01

    The effects of dietary administration of the basic sodium aluminium phosphates, KASAL and KASAL II, were examined in male rats. Aluminium levels in bone were determined in order to estimate the possible aluminium deposition by these compounds. Groups of 25 male Sprague-Dawley rats were fed control diet or diets containing 30,000 ppm KASAL, 7000 or 30,000 ppm KASAL II, or 14,470 ppm aluminium hydroxide for 28 days. The mean daily aluminium doses were calculated to be 5, 141, 67, 288 or 302 mg/kg body weight/day, respectively. Neither form of KASAL induced detectable toxicity. No adverse treatment-related clinical signs were observed. Body weights and food consumptions were similar in treated and control groups. No toxicologically significant changes were observed in haematology, clinical chemistry parameters or organ weights. No treatment-related changes were observed at autopsy or in histopathological examination of collected tissues. Femurs collected at autopsy under conditions free of aluminium contamination showed no significant deposition of aluminium after dietary administration of KASAL, KASAL II or aluminium hydroxide. All aluminium values in bone were less than 1 ppm and most values were not quantifiable. Thus, dietary administration of up to 30,000 ppm of either of the basic sodium aluminium phosphate formulations caused neither toxicity nor significant deposition of aluminium in femur.

  14. Fabrication of near-field optical apertures in aluminium by a highly selective corrosion process in the evanescent field.

    PubMed

    Haefliger, D; Stemmer, A

    2003-03-01

    A simple, one-step process to fabricate high-quality apertures for scanning near-field optical microscope probes based on aluminium-coated silicon nitride cantilevers is presented. A thin evanescent optical field at a glass-water interface was used to heat the aluminium at the tip apex due to light absorption. The heat induced a breakdown of the passivating oxide layer and local corrosion of the metal, which selectively exposed the front-most part of the probe tip from the aluminium. Apertures with a protruding silicon nitride tip up to 72 nm in height were fabricated. The height of the protrusion was controlled by the extent of the evanescent field, whereas the diameter depended on the geometry of the probe substrate. The corrosion process proved to be self-terminating, yielding highly reproducible tip heights. Near-field optical resolution in a transmission mode of 85 nm was demonstrated.

  15. Wax Reinforces Honeycomb During Machining

    NASA Technical Reports Server (NTRS)

    Towell, Timothy W.; Fahringer, David T.; Vasquez, Peter; Scheidegger, Alan P.

    1995-01-01

    Method of machining on conventional metal lathe devised for precise cutting of axisymmetric contours on honeycomb cores made of composite (matrix/fiber) materials. Wax filling reinforces honeycomb walls against bending and tearing while honeycomb being contoured on lathe. Innovative method of machining on lathe involves preparation in which honeycomb is placed in appropriate fixture and the fixture is then filled with molten water-soluble wax. Number of different commercial waxes have been tried.

  16. Effects of thermal cycling on density, elastic modulus, and vibrational damping in an alumina particulate reinforced aluminum metal matrix composite (Al{sub 2}O{sub 3p}/2014 Al)

    SciTech Connect

    Wolfenden, A.; Tang, H.H.; Chawla, K.; Hermel, T.

    1999-07-01

    The effects of thermal cycling on the mechanical and physical properties, namely, the density, dynamic elastic modulus and vibrational damping, were measured for a particular reinforced metal matrix composite (MMC). The material was made by Duralcan. Specimens were exposed to up thermal cycles from room temperature to 300 C. The density of the material was measured by the Archimedes technique. The dynamic Young`s Modulus and vibrational damping of the material were determined by the piezoelectric ultrasonic composite oscillator technique (PUCOT). The results showed that the density and elastic modulus of the material increased only slightly due to the thermal cycling while the damping increased significantly. An increase in dislocation concentration near the particle/matrix interfaces caused by the thermal cycling could account for the measured results.

  17. Amidinate aluminium complexes: synthesis, characterization and ring-opening polymerization of rac-lactide.

    PubMed

    Qian, Feng; Liu, Keyin; Ma, Haiyan

    2010-09-14

    A series of aluminium alkyl complexes {PhC(NR')(NR'')}AlR(2) (4a-n, R' = 2,6-(i)Pr(2)C(6)H(3), 2,6-Me(2)C(6)H(3); R'' = aryl groups with various ortho-, para- or meta-substituents, tert-butyl; R = methyl, ethyl) bearing non-symmetrically N-substituted benzamidinate ligands were synthesized via the reaction of trialkylaluminium and the corresponding benzamidine proligands. Complex 5 bearing symmetric amidinate ligand was also obtained for comparison purposes. The X-ray diffraction studies of complexes 4b, 4c and 5 show in each case a distorted tetrahedral geometry around the aluminium center. All the amidinate aluminium complexes were found to catalyze the ring-opening polymerization (ROP) of rac-lactide with moderate activities. The steric and electronic characteristics of the ancillary ligands have a significant influence on the polymerization performance of the corresponding aluminium complexes. The introduction of electron-withdrawing substituents at the ortho-positions of N-phenyl ring of the ligands resulted in an obvious increase in catalytic activity. Complex 4b showed the highest activity among the investigated aluminium complexes due to the high electrophilicity of the metal center induced by the ortho-chloro substituents on the phenyl ring. The existence of ortho-substituents of small steric bulkiness is also beneficial for the increase of activity of these catalysts. However, further increase of steric hindrance of the ligands by introducing bulky ortho-substituents onto the phenyl moieties resulted in a decrease of activity and an increase in the isotactic bias of the obtained polylactides. The broad molecular weight distributions (PDI = 1.13-2.02) of the polymer samples indicated that the ROP of rac-lactide initiated by these complexes was not well-controlled.

  18. Comparative studies of thin film growth on aluminium by AFM, TEM and GDOES characterization

    NASA Astrophysics Data System (ADS)

    Qi, Jiantao; Thompson, George E.

    2016-07-01

    In this present study, comparative studies of trivalent chromium conversion coating formation, associated with aluminium dissolution process, have been investigated using atomic force microscopy (AFM), transmission electron microscopy (TEM) and glow-discharge optical emission spectroscopy (GDOES). High-resolution electron micrographs revealed the evident and uniform coating initiation on the whole surface after conversion treatment for only 30 s, although a network of metal ridges was created by HF etching pre-treatment. In terms of conversion treatment process on electropolished aluminium, constant kinetics of coating growth, ∼0.30 ± 0.2 nm/s, were found after the prolonged conversion treatment for 600 s. The availability of electrolyte anions for coating deposition determined the growth process. Simultaneously, a proceeding process of aluminium dissolution during conversion treatment, of ∼0.11 ± 0.02 nm/s, was found for the first time, indicating constant kinetics of anodic reactions. The distinct process of aluminium consumption was assigned with loss of corrosion protection of the deposited coating material as evidenced in the electrochemical impedance spectroscopy. Based on the present data, a new mechanism of coating growth on aluminium was proposed, and it consisted of an activation period (0-30 s), a linear growth period (0.30 nm/s, up for 600 s) and limited growth period (0.17 nm/s, 600-1200 s). In addition, the air-drying post-treatment and a high-vacuum environment in the microscope revealed a coating shrinkage, especially in the coatings after conversion treatments for longer time.

  19. Microemulsion extraction separation and determination of aluminium species by spectrofluorimetry.

    PubMed

    Lu, Jusheng; Tian, Jiuying; Guo, Na; Wang, Yan; Pan, Yichun

    2011-01-30

    A simple and sensitive microemulsion extraction separation method was developed for the speciation of aluminium in tea samples by spectrofluorimetry. With 8-hydroxyquinoline (8-HQ) as the chelating agent and Triton X-100 Winsor II microemulsion as the extractant, separation of aluminium species in different pH solutions was achieved by microemulsion extraction. The formation of microemulsion, the conditions of extraction and determination of aluminium species were studied. The results showed that, the contents of aluminium species in tea leaves and infusions samples, such as total aluminium, total soluble aluminium, total granular aluminium, inorganic aluminium except Al-F, and (Al-F+Al-org), were obtained successfully under the optimal conditions. The limit of detection was 0.23 μg L(-1) in pH 9.5 solution, and 0.59 μg L(-1) in pH 6.0 solution respectively; the precision (RSD) for 11 replicate measurements of 10 μg L(-1) aluminium was 2.1% in pH 9.5 solution, and 2.8% in pH 6.0 solution respectively; the recoveries for the spiked samples were 96.8-103.5%. The proposed method is simple and efficient, which has been applied to the speciation of aluminium in tea samples with satisfactory results.

  20. Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps.

    PubMed

    Rabah, Mahmoud A

    2004-01-01

    This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 degrees C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 degrees C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 degrees C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics.

  1. Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps

    SciTech Connect

    Rabah, Mahmoud A

    2004-07-01

    This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 deg. C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 deg. C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 deg. C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics.

  2. Recovery of aluminium, nickel-copper alloys and salts from spent fluorescent lamps.

    PubMed

    Rabah, Mahmoud A

    2004-01-01

    This study explores a combined pyro-hydrometallurgical method to recover pure aluminium, nickel-copper alloy(s), and some valuable salts from spent fluorescent lamps (SFLs). It also examines the safe recycling of clean glass tubes for the fluorescent lamp industry. Spent lamps were decapped under water containing 35% acetone to achieve safe capture of mercury vapour. Cleaned glass tubes, if broken, were cut using a rotating diamond disc to a standard shorter length. Aluminium and copper-nickel alloys in the separated metallic parts were recovered using suitable flux to decrease metal losses going to slag. Operation variables affecting the quality of the products and the extent of recovery with the suggested method were investigated. Results revealed that total loss in the glass tube recycling operation was 2% of the SFLs. Pure aluminium meeting standard specification DIN 1712 was recovered by melting at 800 degrees C under sodium chloride/carbon flux for 20 min. Standard nickel-copper alloys with less than 0.1% tin were prepared by melting at 1250 degrees C using a sodium borate/carbon flux. De-tinning of the molten nickel-copper alloy was carried out using oxygen gas. Tin in the slag as oxide was recovered by reduction using carbon or hydrogen gas at 650-700 degrees C. Different valuable chloride salts were also obtained in good quality. Further research is recommended on the thermodynamics of nickel-copper recovery, yttrium and europium recovery, and process economics. PMID:14761750

  3. Fabrication of porous aluminium with directional pores through thermal decomposition method

    NASA Astrophysics Data System (ADS)

    Nakajima, H.; Y Kim, S.; Park, J. S.

    2009-05-01

    Lotus-type porous metals were fabricated by unidirectional solidification in pressurized gas atmosphere. The elongated pres are evolved by insoluble gas resulted from the solubility gap between liquid and solid when the melt is solidified. Recently we developed a novel fabrication technique, in which gas compounds are used as a source of dissolving gas instead of the high pressure. In the present work this gas compound method was applied to fabrication of lotus aluminium. Hydrogen decomposed from calcium hydroxide, sodium bicarbonate and titanium hydride evolves cylindrical pores in aluminium. The porosity is about 20%. The pore size decreases and the pore number density increases with increasing amount of calcium hydroxide, which is explained by increase in pore nucleation sites.

  4. Recovery of actinides from actinide-aluminium alloys by chlorination: Part II

    NASA Astrophysics Data System (ADS)

    Souček, P.; Cassayre, L.; Eloirdi, R.; Malmbeck, R.; Meier, R.; Nourry, C.; Claux, B.; Glatz, J.-P.

    2014-04-01

    A chlorination route is being investigated for recovery of actinides from actinide-aluminium alloys, which originate from pyrochemical recovery of actinides from spent metallic nuclear fuel by electrochemical methods in molten LiCl-KCl. In the present work, the most important steps of this route were experimentally tested using U-Pu-Al alloy prepared by electrodeposition of U and Pu on solid aluminium plate electrodes. The investigated processes were vacuum distillation for removal of the salt adhered on the electrode, chlorination of the alloy by chlorine gas and sublimation of the AlCl3 formed. The processes parameters were set on the base of a previous thermochemical study and an experimental work using pure UAl3 alloy. The present experimental results indicated high efficiency of salt distillation and chlorination steps, while the sublimation step should be further optimised.

  5. Growth of L-Valinium Aluminium Chloride single crystal for OLED and super-capacitor applications

    NASA Astrophysics Data System (ADS)

    Kalaivani, D.; Vijayalakshmi, S.; Theras, J. Elberin Mary; Jayaraman, D.; Joseph, V.

    2015-12-01

    L-Valinium Aluminium Chloride (LVAC), a novel semi-organic material, was grown using slow evaporation under isothermal condition. The single crystal data reveal that the grown crystal belongs to monoclinic system. The SEM micrographs give clear picture about the surface morphology. Further, they confirm the inclusion of aluminium chloride into atomic sites of L-Valine. The compositional elements present in the crystal were identified through EDAX analysis. The mass spectral analysis was carried out to determine the molecular weight of the grown crystal. The optical transparency of the grown crystal was investigated by UV-vis-NIR spectrum. FTIR spectral study was used to identify the functional groups present in the grown material. The luminescence characteristics of grown material were analysed to confirm the effect of metal ion on the ligand. This property makes the material suitable for OLED application. The supercapacitive performance of the grown crystal was finally studied using cyclic voltammetry.

  6. Some aspects related to the presence of aluminium in waters.

    PubMed

    Giordano, R; Costantini, S

    1993-01-01

    Aluminium is present in very small amounts in living organisms but it is abundant in the environment, where it exists in forms with low availability to man and most biological species. Despite its abundance in the earth's crust only a small amount of aluminium is present in waters, with concentrations varying from a few tens to some hundreds of micrograms per liter. High levels of aluminium in drinking water are in most cases due either to acid precipitation or water treatment with aluminium salts. The presence of aluminium in dialysis fluids has been recognized as the major reason for development of aluminium toxicity in patients with renal failure. In subjects with normal renal function, high concentrations of this element in drinking water (> 80 micrograms/l) have been related to an elevated incidence of Alzheimer's disease, even though the real contribution of the element in the development of the disease has not yet been clarified. PMID:8279721

  7. What is the risk of aluminium as a neurotoxin?

    PubMed

    Exley, Christopher

    2014-06-01

    Aluminium is neurotoxic. Its free ion, Al(3+) (aq), is highly biologically reactive and uniquely equipped to do damage to essential cellular (neuronal) biochemistry. This unequivocal fact must be the starting point in examining the risk posed by aluminium as a neurotoxin in humans. Aluminium is present in the human brain and it accumulates with age. The most recent research demonstrates that a significant proportion of individuals older than 70 years of age have a potentially pathological accumulation of aluminium somewhere in their brain. What are the symptoms of chronic aluminium intoxication in humans? What if neurodegenerative diseases such as Alzheimer's disease are the manifestation of the risk of aluminium as a neurotoxin? How might such an (outrageous) hypothesis be tested?

  8. Novel growth of aluminium nitride nanowires.

    PubMed

    Radwan, M; Bahgat, M

    2006-02-01

    This work describes novel growth of aluminium nitride (AIN) nanowires by nitridation of a mixture consists of aluminium and ammonium chloride powders (Al:NH4Cl = 1.5:1 weight ratio) at 1000 degrees C for 1 h in flowing nitrogen gas (1 l/min). XRD analysis of the product showed the formation of pure hexagonal AIN. SEM micrographs of as-synthesized product revealed the growth of homogeneous AIN nanowires (phi 40-150 nm). No droplets were observed at the tips of obtained nanowires which suggests that they were grown mainly by a vapor-phase reactions mechanism. Thermodynamic analysis of possible intermediate reactions in the operating temperatures range illustrates that these nanowires could be grown via spontaneous vapor-phase chlorination-nitridation sequences.

  9. Studies on an aluminium-carbon cell

    NASA Astrophysics Data System (ADS)

    Verma, L. K.

    The current-voltage behaviour of an electrochemical cell that consists of an aluminium anode and a carbon cathode in a medium containing aqueous NH 4SCN has been studied, both in the presence and in the absence of a coating on the carbon electrode. It is found that activation polarization is the main factor that limits the current output when using an untreated carbon electrode. This problem is eliminated by coating the carbon electrode with an in situ deposition of HgI 2. In this condition, the current output is reduced mainly by ohmic polarization. Further studies with a coated HgI 2-carbon cathode and an aluminium anode, in a medium containing SCN - and Cl - ions together with a complexing agent (EDTA, sodium salt), revealed that a cell performance close to ideal, (i.e, showing no appreciable polarization) can be obtained at currents up to 0.6 mA/cm 2 and above.

  10. Thermodynamic properties of uranium in gallium-aluminium based alloys

    NASA Astrophysics Data System (ADS)

    Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Chukin, A. V.; Smolenski, V. V.; Novoselova, A. V.; Osipenko, A. G.

    2015-10-01

    Activity, activity coefficients and solubility of uranium was determined in gallium-aluminium alloys containing 1.6 (eutectic), 5 and 20 wt.% aluminium. Additionally, activity of uranium was determined in aluminium and Ga-Al alloys containing 0.014-20 wt.% Al. Experiments were performed up to 1073 K. Intermetallic compounds formed in the alloys were characterized by X-ray diffraction. Partial and excess thermodynamic functions of U in the studied alloys were calculated.

  11. The aluminium content of infant formulas remains too high

    PubMed Central

    2013-01-01

    Background Recent research published in this journal highlighted the issue of the high content of aluminium in infant formulas. The expectation was that the findings would serve as a catalyst for manufacturers to address a significant problem of these, often necessary, components of infant nutrition. It is critically important that parents and other users have confidence in the safety of infant formulas and that they have reliable information to use in choosing a product with a lower content of aluminium. Herein, we have significantly extended the scope of the previous research and the aluminium content of 30 of the most widely available and often used infant formulas has been measured. Methods Both ready-to-drink milks and milk powders were subjected to microwave digestion in the presence of 15.8 M HNO3 and 30% w/v H2O2 and the aluminium content of the digests was measured by TH GFAAS. Results Both ready-to-drink milks and milk powders were contaminated with aluminium. The concentration of aluminium across all milk products ranged from ca 100 to 430 μg/L. The concentration of aluminium in two soya-based milk products was 656 and 756 μg/L. The intake of aluminium from non-soya-based infant formulas varied from ca 100 to 300 μg per day. For soya-based milks it could be as high as 700 μg per day. Conclusions All 30 infant formulas were contaminated with aluminium. There was no clear evidence that subsequent to the problem of aluminium being highlighted in a previous publication in this journal that contamination had been addressed and reduced. It is the opinion of the authors that regulatory and other non-voluntary methods are now required to reduce the aluminium content of infant formulas and thereby protect infants from chronic exposure to dietary aluminium. PMID:24103160

  12. Plasmonic enhancement of photoluminescence from aluminium nitride

    NASA Astrophysics Data System (ADS)

    Flynn, Chris; Stewart, Matthew

    2016-03-01

    Aluminium nitride (AlN) films were grown on c-plane sapphire wafers by molecular beam epitaxy (MBE) under aluminium-rich conditions. The excess aluminium (Al) accumulated on the surface of the films as micro-scale droplets 1-10 μm in size, and as Al nanoparticles with diameters in the range 10-110 nm. Photoluminescence (PL) measurements were performed on the AlN samples using a 193 nm Excimer laser as the excitation source. Prior to PL measurements the wafers were cleaved in half. One half of each wafer was submitted to a 10 min treatment in H3PO4 heated to 70 °C to remove the excess Al from the film surface. The remaining half was left in the as-deposited condition. The mean intensities of the near-band-edge PL peaks of the as-deposited samples were 2.0-3.4 times higher compared to the samples subjected to the H3PO4 Al-removal treatment. This observation motivated calculations to determine the optimal Al surface nanosphere size for plasmonic enhancement of PL from AlN. The PL enhancement was found to peak for an Al nanosphere radius of 15 nm, which is within the range of the experimentally-observed Al nanoparticle sizes.

  13. Reinforcement, Expectancy, and Learning

    ERIC Educational Resources Information Center

    Bolles, Robert

    1972-01-01

    Surveys some of the difficulties currently confronting the reinforcement concept and cosiders some alternatives to reinforcement as the fundamental basis of learning. Two specific alternatives considered are: an incentive motivation approach and a cognitive approach. (Author)

  14. Epitaxial growth of silicon nanowires using an aluminium catalyst.

    PubMed

    Wang, Yewu; Schmidt, Volker; Senz, Stephan; Gösele, Ulrich

    2006-12-01

    Silicon nanowires have been identified as important components for future electronic and sensor nanodevices. So far gold has dominated as the catalyst for growing Si nanowires via the vapour-liquid-solid (VLS) mechanism. Unfortunately, gold traps electrons and holes in Si and poses a serious contamination problem for Si complementary metal oxide semiconductor (CMOS) processing. Although there are some reports on the use of non-gold catalysts for Si nanowire growth, either the growth requires high temperatures and/or the catalysts are not compatible with CMOS requirements. From a technological standpoint, a much more attractive catalyst material would be aluminium, as it is a standard metal in Si process lines. Here we report for the first time the epitaxial growth of Al-catalysed Si nanowires and suggest that growth proceeds via a vapour-solid-solid (VSS) rather than a VLS mechanism. It is also found that the tapering of the nanowires can be strongly reduced by lowering the growth temperature. PMID:18654184

  15. Reinforcement of Learning

    ERIC Educational Resources Information Center

    Jones, Peter

    1977-01-01

    A company trainer shows some ways of scheduling reinforcement of learning for trainees: continuous reinforcement, fixed ratio, variable ratio, fixed interval, and variable interval. As there are problems with all methods, he suggests trying combinations of various types of reinforcement. (MF)

  16. General level of reinforcement.

    PubMed

    Cautela, J R

    1984-06-01

    A concept of General Level of Reinforcement (GLR) is introduced. This concept is defined as the number, quality and duration of reinforcements per unit time. The assumptions of this theory are discussed. A crucial assumption is that the theory is related to psychological and physiological well-being. Ways to measure general level of reinforcement are described, and clinical implications presented. Methods to increase the level of reinforcement, such as covert reinforcement and the Self-Control Triad, are specified. Finally, suggestions for research are provided.

  17. Speciation analysis of aluminium and aluminium fluoride complexes by HPIC-UVVIS.

    PubMed

    Frankowski, Marcin; Zioła-Frankowska, Anetta

    2010-10-15

    The study presents a new analytical method for speciation analysis in fractionation of aluminium fluoride complexes and free Al(3+) in soil samples. Aluminium speciation was studied in model solutions and soil extract samples by means of high performance ion chromatography (HPIC) with UV-VIS detection using post-column reaction with tiron for the separation and detection of aluminium fluoride complex and Al(3+) forms during one analysis. The paper presents particular stages of the chromatographic process optimization involving selecting the appropriate eluent strength, type of elution or concentration and quantity of derivatization reagent. HPIC was performed on a bifunctional analytical column Dionex IonPac CS5A. The use of gradient elution and the eluents A: 1M NH(4)Cl and B: water acidified to pH of eluent phase, enabled full separation of fluoride aluminium forms as AlF(2)(+), AlF(3)(0), AlF(4)(-) (first signal), AlF(2+) (second signal) and form Al(3+) in a single analytical procedure. The proposed new method HPIC-UVVIS was applied successfully in the quantitative and qualitative analysis of soil samples.

  18. Surface formation in direct chill (DC) casting of 6082 aluminium alloys

    NASA Astrophysics Data System (ADS)

    Bayat, N.; Carlberg, T.

    2016-03-01

    Surface defects in aluminium billet production are a real problem for the subsequent extrusion procedure. Extrusion productivity can be influenced by the surface properties, which is defined as surface appearance, surface segregation zone depth and large Mg2Si and β-particles (Al5FeSi). In this research the surface formation during DC casting of 6082 aluminium billets produced by the air slip technology is studied. The surface microstructures of 6082 aluminium alloys with smooth and wavy surface appearances were investigated, including segregation zone depths and phase formation. The results were discussed based on the exudation of liquid metal through the mushy zone. The specific appearance of the wavy surface of 6082 alloys was correlated to how the oxide skin adheres to the underlying mushy zone and coupled to the dendritic coherency and surface tension of the skin. The occurrence of different phases at the very surface and in the layer just below was explained by variations in solidification directions and subsequent segregation patterns.

  19. Aluminium exposure induces Alzheimer's disease-like histopathological alterations in mouse brain.

    PubMed

    Rodella, L F; Ricci, F; Borsani, E; Stacchiotti, A; Foglio, E; Favero, G; Rezzani, R; Mariani, C; Bianchi, R

    2008-04-01

    Aluminium (Al) is a neurotoxic metal and Al exposure may be a factor in the aetiology of various neurodegenerative diseases such as Alzheimer's disease (AD). The major pathohistological findings in the AD brain are the presence of neuritic plaques containing beta-amyloid (Abeta) which may interfere with neuronal communication. Moreover, it has been observed that GRP78, a stress-response protein induced by conditions that adversely affect endoplasmic reticulum (ER) function, is reduced in the brain of AD patients. In this study, we investigated the correlation between the expression of Abeta and GRP78 in the brain cortex of mice chronically treated with aluminium sulphate. Chronic exposure over 12 months to aluminium sulphate in drinking water resulted in deposition of Abeta similar to that seen in congophilic amyloid angiopathy (CAA) in humans and a reduction in neuronal expression of GRP78 similar to what has previously been observed in Alzheimer's disease. So, we hypothesise that chronic Al administration is responsible for oxidative cell damage that interferes with ER functions inducing Abeta accumulation and neurodegenerative damage.

  20. Aluminium removal from wastewater by refused beach cast seaweed. Equilibrium and dynamic studies.

    PubMed

    Lodeiro, Pablo; Gudiña, Angel; Herrero, Luz; Herrero, Roberto; Sastre de Vicente, Manuel E

    2010-06-15

    Aluminium removal has been investigated in synthetic and real wastewaters provided by an aluminium surface treatment plant. Marine algae, obtained as beach cast seaweed (a refuse substance) were used as adsorption material. The influence of pH, metal concentration and time for aluminium elimination was studied by use of synthetic solutions. The optimum pH value was 4.0, which provided a maximum adsorption capacity of 22.5 mg g(-1). The adsorption percentage surpassed 80% in less than 30 min of contact time. Real solutions from the industrial unit were fully characterized and tested in two different fixed-bed columns. One column was filled with 27.5 g of dried beach cast seaweed. Three cycles of adsorption and two of desorption were carried out. The first cycle (12 mg g(-1) maximum sorption capacity) was enough to reach the maximum adsorption capacity at 15 mL min(-1) flow rate. The second column was packed with 1100 g of seaweed and its behaviour was compared to another column filled with activated charcoal, following both the same experimental procedure. Maximum sorption capacity was 14 mg g(-1) for seaweed, whereas the activated charcoal only reached 1.6 mg g(-1) (flow rate of 250 mL min(-1)). PMID:20189715

  1. Aluminium removal from water after defluoridation with the electrocoagulation process.

    PubMed

    Sinha, Richa; Mathur, Sanjay; Brighu, Urmila

    2015-01-01

    Fluoride is the most electronegative element and has a strong affinity for aluminium. Owing to this fact, most of the techniques used for fluoride removal utilized aluminium compounds, which results in high concentrations of aluminium in treated water. In the present paper, a new approach is presented to meet the WHO guideline for residual aluminium concentration as 0.2 mg/L. In the present work, the electrocoagulation (EC) process was used for fluoride removal. It was found that aluminium content in water increases with an increase in the energy input. Therefore, experiments were optimized for a minimum energy input to achieve the target value (0.7 mg/L) of fluoride in resultant water. These optimized sets were used for further investigations of aluminium control. The experimental investigations revealed that use of bentonite clay as coagulant in clariflocculation brings down the aluminium concentration of water below the WHO guideline. Bentonite dose of 2 g/L was found to be the best for efficient removal of aluminium.

  2. Aluminium removal from water after defluoridation with the electrocoagulation process.

    PubMed

    Sinha, Richa; Mathur, Sanjay; Brighu, Urmila

    2015-01-01

    Fluoride is the most electronegative element and has a strong affinity for aluminium. Owing to this fact, most of the techniques used for fluoride removal utilized aluminium compounds, which results in high concentrations of aluminium in treated water. In the present paper, a new approach is presented to meet the WHO guideline for residual aluminium concentration as 0.2 mg/L. In the present work, the electrocoagulation (EC) process was used for fluoride removal. It was found that aluminium content in water increases with an increase in the energy input. Therefore, experiments were optimized for a minimum energy input to achieve the target value (0.7 mg/L) of fluoride in resultant water. These optimized sets were used for further investigations of aluminium control. The experimental investigations revealed that use of bentonite clay as coagulant in clariflocculation brings down the aluminium concentration of water below the WHO guideline. Bentonite dose of 2 g/L was found to be the best for efficient removal of aluminium. PMID:25903166

  3. Influence of zinc on calcium-dependent signal transduction pathways during aluminium-induced neurodegeneration.

    PubMed

    Singla, Neha; Dhawan, D K

    2014-10-01

    Metals perform important functions in the normal physiological system, and alterations in their levels may lead to a number of diseases. Aluminium (Al) has been implicated as a major risk factor, which is linked to several neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. On the other hand, zinc (Zn) is considered as a neuromodulator and an essential dietary element that regulates a number of biological activities in our body. The aim of the present study was to investigate the effects of Zn supplementation, if any, in ameliorating the changes induced by Al on calcium signalling pathway. Male Sprague Dawley rats weighing 140-160 g were divided into four different groups viz.: normal control, aluminium treated (100 mg/kg b.wt./day via oral gavage), zinc treated (227 mg/l in drinking water) and combined aluminium and zinc treated. All the treatments were carried out for a total duration of 8 weeks. Al treatment decreased the Ca(2+) ATPase activity whereas increased the levels of 3', 5'-cyclic adenosine monophosphate, intracellular calcium and total calcium content in both the cerebrum and cerebellum, which, however, were modulated upon Zn supplementation. Al treatment exhibited a significant elevation in the protein expressions of phospholipase C, inositol triphosphate and protein kinase A but decreased the expression of protein kinase C, which, however, was reversed upon Zn co-treatment. Al treatment also revealed alterations in neurohistoarchitecture in the form of calcium deposits, which were improved upon zinc co-administration. The present study, therefore, suggests that zinc regulates the intracellular calcium signalling pathway during aluminium-induced neurodegeneration.

  4. The Relationship of Aluminium and Silver to Neural Tube Defects; a Case Control

    PubMed Central

    Ramírez-Altamirano, María de Jesús; Fenton-Navarro, Patricia; Sivet-Chiñas, Elvira; Harp-Iturribarria, Flor de María; Martínez-Cruz, Ruth; Cruz, Pedro Hernández; Cruz, Margarito Martínez; Pérez-Campos, Eduardo

    2012-01-01

    Objective The purpose of this study was to identify the relationship of neurotoxic inorganic elements in the hair of patients with the diagnosis of Neural Tube Defects. Our initial hypothesis was that neurotoxic inorganic elements were associated with Neural Tube Defects. Methods Twenty-three samples of hair from newborns were obtained from the General Hospital, “Aurelio Valdivieso” in the city of Oaxaca, Mexico. The study group included 8 newborn infants with neural tube pathology. The control group was composed of 15 newborns without this pathology. The presence of inorganic elements in the hair samples was determined by inductively-coupled plasma spectroscopy (spectroscopic emission of the plasma). Findings The population of newborns with Neural Tube Defects showed significantly higher values of the following elements than the control group: Aluminium, Neural Tube Defects 152.77±51.06 µg/g, control group 76.24±27.89 µg/g; Silver, Neural Tube Defects 1.45±0.76, control group 0.25±0.53 µg/g; Potassium, Neural Tube Defects 553.87±77.91 µg/g, control group 341.13±205.90 µg/g. Association was found at 75 percentile between aluminium plus silver, aluminium plus potassium, silver plus potassium, and potassium plus sodium. Conclusion In the hair of newborns with Neural Tube Defects, the following metals were increased: aluminium, silver. Given the neurotoxicity of the same, and association of Neural Tube Defects with aluminum and silver, one may infer that they may be participating as factors in the development of Neural Tube Defects. PMID:23400307

  5. Diffusion of aluminium in MgO from first principles

    NASA Astrophysics Data System (ADS)

    Ammann, M. W.; Brodholt, J. P.; Dobson, D. P.

    2012-06-01

    We have calculated the diffusivity of aluminium in periclase, MgO, under pressures relevant to deep planetary interiors from first principles. We reconcile differences between experimental migration enthalpies and those obtained with previous theoretical studies by finding a lower energy saddle point for the aluminium atom migration. Previous studies did not recognise a bifurcation at the saddle point. We also explain differences between experimental and theoretical binding enthalpies of an aluminium with a magnesium vacancy. We find that binding enthalpies continuously increase with decreasing aluminium concentrations, such that the difference between experimental and theoretical binding energies can be attributed to differing concentrations. We also find that binding energies increase with pressure as the permittivity decreases. Aluminium therefore not only causes extrinsic vacancy formation but also binds some of them, effectively removing them for magnesium diffusion. We discuss the implications for how other 3+ ions affect diffusion in oxides and silicates.

  6. Usage of Neural Network to Predict Aluminium Oxide Layer Thickness

    PubMed Central

    Michal, Peter; Vagaská, Alena; Gombár, Miroslav; Kmec, Ján; Spišák, Emil; Kučerka, Daniel

    2015-01-01

    This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A·dm−2 and 3 A·dm−2 for creating aluminium oxide layer. PMID:25922850

  7. Experimental and Numerical Study on the Tensile Behaviour of UACS/Al Fibre Metal Laminate

    NASA Astrophysics Data System (ADS)

    Xue, Jia; Wang, Wen-Xue; Zhang, Jia-Zhen; Wu, Su-Jun; Li, Hang

    2015-10-01

    A new fibre metal laminate fabricated with aluminium sheets and unidirectionally arrayed chopped strand (UACS) plies is proposed. The UACS ply is made by cutting parallel slits into a unidirectional carbon fibre prepreg. The UACS/Al laminate may be viewed as aluminium laminate reinforced by highly aligned, discontinuous carbon fibres. The tensile behaviour of UACS/Al laminate, including thermal residual stress and failure progression, is investigated through experiments and numerical simulation. Finite element analysis was used to simulate the onset and propagation of intra-laminar fractures occurring within slits of the UACS plies and delamination along the interfaces. The finite element models feature intra-laminar cohesive elements inserted into the slits and inter-laminar cohesive elements inserted at the interfaces. Good agreement are obtained between experimental results and finite element analysis, and certain limitations of the finite element models are observed and discussed. The combined experimental and numerical studies provide a detailed understanding of the tensile behaviour of UACS/Al laminates.

  8. Habituation of reinforcer effectiveness

    PubMed Central

    Lloyd, David R.; Medina, Douglas J.; Hawk, Larry W.; Fosco, Whitney D.; Richards, Jerry B.

    2014-01-01

    In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect “accelerated-HRE.” Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior. PMID:24409128

  9. Solar cell having improved front surface metallization

    SciTech Connect

    Lillington, D.R.; Mardesich, N.; Dill, H.G.; Garlick, G.F.J.

    1987-09-15

    This patent describes a solar cell comprising: a first layer of gallium arsenide semiconductor material of an N+ conductivity; a second layer of gallium arsenide semiconductor material of an N conductivity overlying the first layer; a third layer of gallium arsenide semiconductor material of a P conductivity overlying the N conductivity layer and forming a P-N junction therebetween. A layer of aluminium gallium arsenide semiconductor material of a p conductivity overlying the front major surface of the P conductivity third layer and having an exposed surface essentially parallel to the front major surface and at least one edge; a plurality of metallic contact lines made of a first metal alloy composition and being spaced apart by a first predetermined distance traversing the exposed surface and extending through the aluminium gallium arsenide layer to the front major surface and making electrical contact to the third layer; a plurality of longitudinally disposed metallic grid lines made of a second metal alloy composition and being spaced apart by a second predetermined distance located on the exposed surface of the aluminium gallium arsenide layer and which cross the metallic contact lines and make electrical contact to the metallic lines; a flat metallic strip disposed on the aluminium gallium arsenide layer exposed surface near the edge, the strip electrically coupling the metallic grid lines to one another; and a back contact located on the back major surface.

  10. Carbon fibre reinforced plastic applied to prosthetics and orthotics.

    PubMed

    Nelham, R L

    1981-10-01

    This paper describes the work carried out at the Rehabilitation Engineering Unit, Chailey Heritage Hospital, in applying carbon fibre reinforced plastic CFRP to prosthetics and orthotics. The prosthetic application relates to the construction of the Chailey Harness which was used to mount externally powered, upper limb prostheses to the torso of limb deficient children damaged by the drug Thalidomide. The application to orthotics was limited to Hip-Knee-Ankle-Orthoses (HKAO) as worn by severely handicapped children with spina bifida and led to the development of a shapable CFRP/aluminium alloy hybrid composite bar. The construction of the composite, its properties and the assembly and performance of the first orthoses are described. Some of the practical problems experienced with the use of carbon fibre reinforced plastic are identified.

  11. Assessment of potentially reactive pools of aluminium in poor forest soils using two methods of fractionation analysis.

    PubMed

    Walna, Barbara; Spychalski, Waldemar; Siepak, Jerzy

    2005-09-01

    The research was carried out in a pine-covered area of the Wielkopolski National Park (Poland), for years exposed to acid rain. The soils under study are sands and loamy sands with a pH of 3.3-4.4. To assess potentially reactive pools of aluminium in those soils, two methods were employed: sequential and single extraction. For the exchangeable form the results obtained by single extraction using KCl greatly exceeded the figures yielded by sequential extraction, in which the conditions under which the process was executed (pH 7) led to an underestimation of the results. The soil profile displayed a lithogenically dichotomous structure which was reflected in the aluminium content, especially in Al extracted by pyrophosphate (single extraction) and in the so-called oxidisable fraction (sequential extraction). In both cases there was a jump in Al concentrations resulted from the release of aluminium from interlayer spaces of clay minerals. The labile percentage obtained for mean values in the profile amounted from 8.1% for single extraction to 12.1% for sequential extraction, which may indicate the metal's considerable pool of potentially reactive aluminium. Single extraction seems to be more reliable in evaluating Al forms.

  12. Hearing conservation in the primary aluminium industry

    PubMed Central

    Frisch, N.; Dixon-Ernst, C.; Chesson, B. J.; Cullen, M. R.

    2016-01-01

    Background Noise-induced hearing loss has been an intractable problem for heavy industry. Aims To report our experience in reducing the incidence of age-corrected confirmed 10 dB hearing shifts (averaged over 2, 3 and 4kHz) in employees in the primary aluminium industry in Australia over the period 2006–13. Methods We analysed annual audiometric data to determine the number of permanent hearing shifts that occurred in employees in two bauxite mines, three alumina refineries and two aluminium smelters. Annual hearing shift rates were calculated based on the number of employees tested per year. Hearing conservation initiatives undertaken during the study period are described. An assessment of similar exposure group noise exposures was also undertaken to determine the magnitude of noise exposure reduction during the study period. Results Across all operations, hearing shift rates declined from 5.5% per year in 2006 to 1.3% per year in 2013 (P < 0.001). The decline in shift rates was greater in mines and refineries, where baseline shift rates were higher, than in smelter workers. Modest reductions in noise exposure occurred during the study period. Conclusions We observed a substantial decline in hearing shift rates during the study period. We describe the hearing conservation initiatives that were collectively associated with this decline. We suspect these initiatives could be deployed relatively easily and at modest cost in other industries with noise-exposed employees. PMID:26470945

  13. Aluminium exposure disrupts elemental homeostasis in Caenorhabditis elegans†

    PubMed Central

    Page, Kathryn E.; White, Keith N.; McCrohan, Catherine R.

    2013-01-01

    Aluminium (Al) is highly abundant in the environment and can elicit a variety of toxic responses in biological systems. Here we characterize the effects of Al on Caenorhabditis elegans by identifying phenotypic abnormalities and disruption in whole-body metal homeostasis (metallostasis) following Al exposure in food. Widespread changes to the elemental content of adult nematodes were observed when chronically exposed to Al from the first larval stage (L1). Specifically, we saw increased barium, chromium, copper and iron content, and a reduction in calcium levels. Lifespan was decreased in worms exposed to low levels of Al, but unexpectedly increased when the Al concentration reached higher levels (4.8 mM). This bi-phasic phenotype was only observed when Al exposure occurred during development, as lifespan was unaffected by Al exposure during adulthood. Lower levels of Al slowed C. elegans developmental progression, and reduced hermaphrodite self-fertility and adult body size. Significant developmental delay was observed even when Al exposure was restricted to embryogenesis. Similar changes in Al have been noted in association with Al toxicity in humans and other mammals, suggesting that C. elegans may be of use as a model for understanding the mechanisms of Al toxicity in mammalian systems. PMID:22534883

  14. Absence of aluminium in neuritic plaque cores in Alzheimer's disease.

    PubMed

    Landsberg, J P; McDonald, B; Watt, F

    1992-11-01

    Controversy exists over whether aluminium has a role in the aetiology of Alzheimer's disease. Alzheimer's disease is neuropathologically characterized by the occurrence of a minimum density of neurofibrillary tangles and neuritic plaques in the hippocampus and the association cortex of the brain. The purported association of aluminium with Alzheimer's disease is based on: (1) the experimental induction of fibrillary changes in the neurons of animals by the injection of aluminium salts into brain tissue; (2) reported detection of aluminium in neuritic plaques and tangle-bearing neurons; (3) epidemiological studies linking aluminium levels in the environment, notably water supplies, with an increased prevalence of dementia; and (4) a reported decrease in the rate of disease progression following the administration of desferroxamine, an aluminium chelator, to clinically diagnosed sufferers of Alzheimer's disease. Here we use nuclear microscopy, a new analytical technique involving million-volt nuclear particles, to identify and analyse plaques in postmortem tissue from patients with Alzheimer's disease without using chemical staining techniques and fail to demonstrate the presence of aluminium in plaque cores in untreated tissue. PMID:1436075

  15. Does allergen-specific immunotherapy induce contact allergy to aluminium?

    PubMed

    Netterlid, Eva; Hindsén, Monica; Siemund, Ingrid; Björk, Jonas; Werner, Sonja; Jacobsson, Helene; Güner, Nuray; Bruze, Magnus

    2013-01-01

    Persistent, itching nodules have been reported to appear at the injection site after allergen-specific immuno-therapy with aluminium-precipitated antigen extract, occasionally in conjunction with contact allergy to aluminium. This study aimed to quantify the development of contact allergy to aluminium during allergen-specific immunotherapy. A randomized, controlled, single-blind multicentre study of children and adults entering allergen-specific immunotherapy was performed using questionnaires and patch-testing. A total of 205 individuals completed the study. In the 3 study groups all subjects tested negative to aluminium before allergen-specific immunotherapy and 4 tested positive after therapy. In the control group 4 participants tested positive to aluminium. Six out of 8 who tested positive also had atopic dermatitis. Positive test results were found in 5/78 children and 3/127 adults. Allergen-specific immunotherapy was not shown to be a risk factor for contact allergy to aluminium. Among those who did develop aluminium allergy, children and those with atopic dermatitis were more highly represented.

  16. Unexpected loss of contact allergy to aluminium induced by vaccine

    PubMed Central

    Gente Lidholm, Anette; Bergfors, Elisabet; Inerot, Annica; Blomgren, Ulla; Gillstedt, Martin; Trollfors, Birger

    2013-01-01

    Background In studies in Gothenburg, Sweden, in the 1990s of an aluminium hydroxide-adsorbed pertussis toxoid vaccine, 745 of ∼76 000 vaccinated children developed long-lasting itchy subcutaneous nodules at the vaccination site. Of 495 children with itchy nodules patch tested for aluminium allergy, 376 (76%) were positive. Objectives To study the prognosis of the vaccine-induced aluminium allergy. Patients and methods Two hundred and forty-one children with demonstrated aluminium allergy in the previous study were patch tested again 5–9 years after the initial test, with the same procedure as used previously. Results Contact allergy to aluminium was no longer demonstrable in 186 of the retested 241 children (77%). A negative test result was more common in children who no longer had itching at the vaccination site; it was also related to the age of the child, the time after the first aluminium-adsorbed vaccine dose, and the strength of the reaction in the first test. Conclusions Patch test reactivity to aluminium seems to disappear or weaken with time. PMID:23601064

  17. Dietary exposure to aluminium of the Hong Kong population.

    PubMed

    Wong, Waiky W K; Chung, Stephen W C; Kwong, K P; Yin Ho, Yuk; Xiao, Ying

    2010-04-01

    A total of 256 individual food samples were collected in Hong Kong for aluminium testing. Most of food samples were analysed in ready-to-eat form. High aluminium levels were found in steamed bread/bun/cake (mean: 100-320 mg kg(-1)), some bakery products such as muffin, pancake/waffle, coconut tart and cake (mean: 250, 160, 120 and 91 mg kg(-1), respectively), and jellyfish (ready-to-eat form) (mean: 1200 mg kg(-1)). The results demonstrated that aluminium-containing food additives have been widely used in these food products. The average dietary exposure to aluminium for a 60 kg adult was estimated to be 0.60 mg kg(-1) bw week(-1), which amounted to 60% of the new PTWI established by JECFA. The main dietary source was "steamed bread/bun/cake", which contributed to 60% of the total exposure, followed by "bakery products" and "jellyfish", which contributed to 23 and 10% of the total exposure, respectively. However, the estimation did not include the intake of aluminium from natural food sources, food contact materials or other sources (e.g. drinking water). Although the results indicated that aluminium it is unlikely to cause adverse health effect for the general population, the risk to some populations who regularly consume foods with aluminium-containing food additives cannot be ruled out.

  18. The varied functions of aluminium-activated malate transporters-much more than aluminium resistance.

    PubMed

    Palmer, Antony J; Baker, Alison; Muench, Stephen P

    2016-06-15

    The ALMT (aluminium-activated malate transporter) family comprises a functionally diverse but structurally similar group of ion channels. They are found ubiquitously in plant species, expressed throughout different tissues, and located in either the plasma membrane or tonoplast. The first family member identified was TaALMT1, discovered in wheat root tips, which was found to be involved in aluminium resistance by means of malate exudation into the soil. However, since this discovery other family members have been shown to have many other functions such as roles in stomatal opening, general anionic homoeostasis, and in economically valuable traits such as fruit flavour. Recent evidence has also shown that ALMT proteins can act as key molecular actors in GABA (γ-aminobutyric acid) signalling, the first evidence that GABA can act as a signal transducer in plants. PMID:27284052

  19. Thickness Evaluation of Aluminium Plate Using Pulsed Eddy Current Technique

    NASA Astrophysics Data System (ADS)

    Singh, Gurpartap; Bapat, Harsh Madhukar; Singh, Bhanu Pratap; Bandyopadhyay, Manojit; Puri, Rakesh Kumar; Badodkar, Deepak Narayanrao

    2013-10-01

    This paper describes a pulsed eddy current (PEC) based non-destructive testing system used for detection of thickness variation in aluminium plate. A giant magneto-resistive sensor has been used instead of pick up coil for detecting resultant magnetic field. The PEC response signals obtained from 1 to 5 mm thickness change in aluminium plate were investigated. Two time domain features, namely peak value and time to peak, of PEC response were used for extracting information about thickness variation in aluminium plate. The variation of peak value and time to peak with thickness was compared. A program was developed to display the thickness variation of the tested sample.

  20. Acidic deposition: decline in mobilization of toxic aluminium.

    PubMed

    Palmer, Sheila M; Driscoll, Charles T

    2002-05-16

    The mobilization of aluminium from acidic forest soils is arguably the most ecologically important consequence of acid deposition in the environment because of its adverse effects on soils, forest vegetation and surface water. Here we show that there has been a significant decline in the concentrations of aluminium species in soil solutions at medium-to-high elevations in a northern hardwood forest in the United States in response to decreasing acidic deposition. Streamwater aluminium concentrations have also fallen and, if this rate of recovery persists, will within 10 years no longer pose a threat to fish.

  1. Reinforced plastics durability

    SciTech Connect

    Pritchard, G.

    1999-01-01

    Written especially for first-time users of reinforced plastics. The book offers substantial introductory information with key concepts. Chapters examine the long-term threats to the integrity of reinforced plastics: outdoor weathering, solvent/water attack, high temperatures, and repetitive stress.

  2. Lipid peroxidation as pathway of aluminium cytotoxicity in human skin fibroblast cultures: prevention by superoxide dismutase+catalase and vitamins E and C.

    PubMed

    Anane, R; Creppy, E E

    2001-09-01

    Lipid peroxidation is one of the main manifestations of oxidative damage and has been found to play an important role in the toxicity and carcinogenicity of many xenobiotics. In the present study, we investigated the possible induction of lipid peroxidation by aluminium in human foreskin fibroblast cultures by assaying the malondialdehyde (MDA) produced inside the cells. The MDA-thiobarbituric acid (TBA) adduct was assayed by HPLC using fluorometric quantification after extraction in n-butanol. Lactate dehydrogenase (LDH) release was used as a marker of aluminium toxicity. MDA production was significantly increased after 24 h incubation with aluminium and paralleled LDH release. Superoxide dismutase (SOD)+catalase and vitamins C and E added in the culture medium as oxygen radical and free radical scavengers were efficient in preventing MDA production by aluminium, indicating that oxidative processes are one of the main pathways whereby this metal induces cytotoxicity. The latter is also largely prevented, thus confirming the link between oxidative stress induced by aluminium and its cytotoxicity in human skin fibroblasts.

  3. "Reinforcement" in behavior theory.

    PubMed

    Schoenfeld, W N

    1978-01-01

    In its Pavlovian context, "reinforcement" was actually a descriptive term for the functional relation between an unconditional and a conditional stimulus. When it was adopted into operant conditioning, "reinforcement" became the central concept and the key operation, but with new qualifications, new referents, and new expectations. Some behavior theorists believed that "reinforcers" comprise a special and limited class of stimuli or events, and they speculated about what the essential "nature of reinforcement" might be. It is now known that any stimulus can serve a reinforcing function, with due recognition of such parameters as subject species characteristics, stimulus intensity, sensory modality, and schedule of application. This paper comments on these developments from the standpoint of reflex behavior theory.

  4. "Reinforcement" in behavior theory.

    PubMed

    Schoenfeld, W N

    1995-01-01

    In its Pavlovian context, "reinforcement" was actually a descriptive term for the functional relation between an unconditional and a conditional stimulus. When it was adopted into operant conditioning, "reinforcement" became the central concept and the key operation, but with new qualifications, new referents, and new expectations. Some behavior theorists believed that "reinforcers" comprise a special and limited class of stimuli or events, and they speculated about what the essential "nature of reinforcement" might be. It is now known that any stimulus can serve a reinforcing function, with due recognition of such parameters as subject species characteristics, stimulus intensity, sensory modality, and schedule of application. This paper comments on these developments from the stand-point of reflex behavior theory.

  5. Composite Intersection Reinforcement

    NASA Technical Reports Server (NTRS)

    Misciagna, David T. (Inventor); Fuhrer, Jessica J. (Inventor); Funk, Robert S. (Inventor); Tolotta, William S. (Inventor)

    2013-01-01

    An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

  6. Composite intersection reinforcement

    NASA Technical Reports Server (NTRS)

    Misciagna, David T. (Inventor); Fuhrer, Jessica J. (Inventor); Funk, Robert S. (Inventor); Tolotta, William S. (Inventor)

    2010-01-01

    An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

  7. Aluminium alloys in municipal solid waste incineration bottom ash.

    PubMed

    Hu, Yanjun; Rem, Peter

    2009-05-01

    With the increasing growth of incineration of household waste, more and more aluminium is retained in municipal solid waste incinerator bottom ash. Therefore recycling of aluminium from bottom ash becomes increasingly important. Previous research suggests that aluminium from different sources is found in different size fractions resulting in different recycling rates. The purpose of this study was to develop analytical and sampling techniques to measure the particle size distribution of individual alloys in bottom ash. In particular, cast aluminium alloys were investigated. Based on the particle size distribution it was computed how well these alloys were recovered in a typical state-of-the-art treatment plant. Assessment of the cast alloy distribution was carried out by wet physical separation processes, as well as chemical methods, X-ray fluorescence analysis and electron microprobe analysis. The results from laboratory analyses showed that cast alloys tend to concentrate in the coarser fractions and therefore are better recovered in bottom ash treatment plants. PMID:19423581

  8. The management of Frey's syndrome with aluminium chloride hexahydrate antiperspirant.

    PubMed Central

    Black, M. J.; Gunn, A.

    1990-01-01

    Nine patients suffering from gustatory sweating (Frey's syndrome) following parotidectomy have been treated by topical applications of aluminium chloride hexahydrate. Treatment has successfully controlled gustatory sweating using application intervals varying from 1 to 50 days. Images Figure 1 PMID:2301903

  9. Aluminium leaching from red mud by filamentous fungi.

    PubMed

    Urík, Martin; Bujdoš, Marek; Milová-Žiaková, Barbora; Mikušová, Petra; Slovák, Marek; Matúš, Peter

    2015-11-01

    This contribution investigates the efficient and environmentally friendly aluminium leaching from red mud (bauxite residue) by 17 species of filamentous fungi. Bioleaching experiments were examined in batch cultures with the red mud in static, 7-day cultivation. The most efficient fungal strains in aluminium bioleaching were Penicillium crustosum G-140 and Aspergillus niger G-10. The A. niger G-10 strain was capable to extract up to approximately 141 mg·L(-1) of aluminium from 0.2 g dry weight red mud. Chemical leaching with organic acids mixture, prepared according to A. niger G-10 strain's respective fungal excretion during cultivation, proved that organic acids significantly contribute to aluminium solubilization from red mud.

  10. Aspects of the bioinorganic chemistry of silicon in conjunction with the biometals calcium, iron and aluminium.

    PubMed

    Perry, C C; Keeling-Tucker, T

    1998-02-15

    Silicon, in its various forms (silicic acid (Si(OH)4) through to hydrated amorphous silica (SiOn(OH)4-2n, n = 2-4) is important in geological and biological processes. Silicon is considered to be an 'essential' element for some plants and higher animals and when present as silica imparts structural, defensive and photosynthetic advantages to many plants. For the majority of essential elements specific molecular binding sites have been identified, but this is not the case for silicon. This has lead to the proposal that silicon may not act directly on biological systems but may exert its influence via interactions with biometals. Metals for which this may be a viable option include aluminium, iron and calcium, all of which can be found co-located with silicon in both minerals and living organisms. This article briefly reviews the pertinent solution and solid state chemistry of silicon in relation to aluminium, iron and calcium. Examples where silicon and an additional metal are found in solid state phases are described. The biological systems where these deposits are found are extremely complex and preliminary results from a model system designed to study silicon-biometal interactions are described.

  11. Aluminium assay and evaluation of the local reaction at several time points after intramuscular administration of aluminium containing vaccines in the Cynomolgus monkey.

    PubMed

    Verdier, François; Burnett, Roger; Michelet-Habchi, Claire; Moretto, Philippe; Fievet-Groyne, Françoise; Sauzeat, Elisabeth

    2005-02-01

    Aluminium hydroxide and aluminium phosphate have been widely used as vaccine adjuvants with a good safety record for several decades. The recent observation in human deltoid muscle of macrophage aggregates containing aluminium hydroxide spicules and termed Macrophagic Myofasciitis (MMF) has encouraged research on aluminium salts. This study was conducted in order to further investigate the clearance of aluminium at the vaccine injection site and the features of induced histopathological lesions. Two groups of 12 monkeys were immunised in the quadriceps muscle with Diphtheria-Tetanus vaccines, which were adjuvanted with either aluminium hydroxide or aluminium phosphate. Three, six or twelve months after vaccination, four monkeys from each group were sacrificed and histopathological examination and aluminium assays were performed on quadriceps muscle sections. Histopathological lesions, similar to the MMF described in humans, were observed and were still present 3 months after aluminium phosphate and 12 months after aluminium hydroxide adjuvanted vaccine administration. An increase in aluminium concentration, more marked in the area of the lesions, was also observed at the 3- and 6-month time points. These findings were localised at the injection site and no similar changes were observed in the distal or proximal muscle fragments. We conclude from this study that aluminium adjuvanted vaccines administered by the intramuscular route trigger histopathological changes restricted to the area around the injection site which persist for several months but are not associated with abnormal clinical signs. PMID:15661384

  12. The green alga Zygogonium ericetorum (Zygnematophyceae, Charophyta) shows high iron and aluminium tolerance: protection mechanisms and photosynthetic performance.

    PubMed

    Herburger, Klaus; Remias, Daniel; Holzinger, Andreas

    2016-08-01

    Streptophyte green algae, ancestors of Embryophytes, occur frequently in terrestrial habitats being exposed to high light intensities, water scarcity and potentially toxic metal cations under acidic conditions. The filamentous Zygogonium ericetorum synthesizes a purple vacuolar ferrous pigment, which is lost after aplanospore formation. However, it is unknown whether this cellular reorganization also removes excessive iron from the protoplast and how Z. ericetorum copes with high concentrations of aluminium. Here we show that aplanospore formation shifts iron into the extracellular space of the algal filament. Upon germination of aplanospores, aluminium is bound in the parental cell wall. Both processes reduce iron and aluminium in unpigmented filaments. Comparison of the photosynthetic oxygen production in response to light and temperature gradients in two different Z. ericetorum strains from an Austrian alpine and a Scottish highland habitat revealed lower values in the latter strain. In contrast, the Scottish strain showed a higher optimum quantum yield of PSII during desiccation stress followed by rehydration. Furthermore, pigmented filaments of both strains exhibited a higher light and temperature dependent oxygen production when compared to the unpigmented phenotype. Our results demonstrate a high metal tolerance of Z. ericetorum, which is crucial for surviving in acidic terrestrial habitats. PMID:27178434

  13. The green alga Zygogonium ericetorum (Zygnematophyceae, Charophyta) shows high iron and aluminium tolerance: protection mechanisms and photosynthetic performance

    PubMed Central

    Herburger, Klaus; Remias, Daniel; Holzinger, Andreas

    2016-01-01

    Streptophyte green algae, ancestors of Embryophytes, occur frequently in terrestrial habitats being exposed to high light intensities, water scarcity and potentially toxic metal cations under acidic conditions. The filamentous Zygogonium ericetorum synthesizes a purple vacuolar ferrous pigment, which is lost after aplanospore formation. However, it is unknown whether this cellular reorganization also removes excessive iron from the protoplast and how Z. ericetorum copes with high concentrations of aluminium. Here we show that aplanospore formation shifts iron into the extracellular space of the algal filament. Upon germination of aplanospores, aluminium is bound in the parental cell wall. Both processes reduce iron and aluminium in unpigmented filaments. Comparison of the photosynthetic oxygen production in response to light and temperature gradients in two different Z. ericetorum strains from an Austrian alpine and a Scottish highland habitat revealed lower values in the latter strain. In contrast, the Scottish strain showed a higher optimum quantum yield of PSII during desiccation stress followed by rehydration. Furthermore, pigmented filaments of both strains exhibited a higher light and temperature dependent oxygen production when compared to the unpigmented phenotype. Our results demonstrate a high metal tolerance of Z. ericetorum, which is crucial for surviving in acidic terrestrial habitats. PMID:27178434

  14. The green alga Zygogonium ericetorum (Zygnematophyceae, Charophyta) shows high iron and aluminium tolerance: protection mechanisms and photosynthetic performance.

    PubMed

    Herburger, Klaus; Remias, Daniel; Holzinger, Andreas

    2016-08-01

    Streptophyte green algae, ancestors of Embryophytes, occur frequently in terrestrial habitats being exposed to high light intensities, water scarcity and potentially toxic metal cations under acidic conditions. The filamentous Zygogonium ericetorum synthesizes a purple vacuolar ferrous pigment, which is lost after aplanospore formation. However, it is unknown whether this cellular reorganization also removes excessive iron from the protoplast and how Z. ericetorum copes with high concentrations of aluminium. Here we show that aplanospore formation shifts iron into the extracellular space of the algal filament. Upon germination of aplanospores, aluminium is bound in the parental cell wall. Both processes reduce iron and aluminium in unpigmented filaments. Comparison of the photosynthetic oxygen production in response to light and temperature gradients in two different Z. ericetorum strains from an Austrian alpine and a Scottish highland habitat revealed lower values in the latter strain. In contrast, the Scottish strain showed a higher optimum quantum yield of PSII during desiccation stress followed by rehydration. Furthermore, pigmented filaments of both strains exhibited a higher light and temperature dependent oxygen production when compared to the unpigmented phenotype. Our results demonstrate a high metal tolerance of Z. ericetorum, which is crucial for surviving in acidic terrestrial habitats.

  15. Choice and conditioned reinforcement.

    PubMed

    Fantino, E; Freed, D; Preston, R A; Williams, W A

    1991-03-01

    A potential weakness of one formulation of delay-reduction theory is its failure to include a term for rate of conditioned reinforcement, that is, the rate at which the terminal-link stimuli occur in concurrent-chains schedules. The present studies assessed whether or not rate of conditioned reinforcement has an independent effect upon choice. Pigeons responded on either modified concurrent-chains schedules or on comparable concurrent-tandem schedules. The initial link was shortened on only one of two concurrent-chains schedules and on only one of two corresponding concurrent-tandem schedules. This manipulation increased rate of conditioned reinforcement sharply in the chain but not in the tandem schedule. According to a formulation of delay-reduction theory, when the outcomes chosen (the terminal links) are equal, as in Experiment 1, choice should depend only on rate of primary reinforcement; thus, choice should be equivalent for the tandem and chain schedules despite a large difference in rate of conditioned reinforcement. When the outcomes chosen are unequal, however, as in Experiment 2, choice should depend upon both rate of primary reinforcement and relative signaled delay reduction; thus, larger preferences should occur in the chain than in the tandem schedules. These predictions were confirmed, suggesting that increasing the rate of conditioned reinforcement on concurrent-chains schedules may have no independent effect on choice.

  16. Role of magnesium in alleviation of aluminium toxicity in plants.

    PubMed

    Bose, Jayakumar; Babourina, Olga; Rengel, Zed

    2011-04-01

    Magnesium is pivotal for activating a large number of enzymes; hence, magnesium plays an important role in numerous physiological and biochemical processes affecting plant growth and development. Magnesium can also ameliorate aluminium phytotoxicity, but literature reports on the dynamics of magnesium homeostasis upon exposure to aluminium are rare. Herein existing knowledge on the magnesium transport mechanisms and homeostasis maintenance in plant cells is critically reviewed. Even though overexpression of magnesium transporters can alleviate aluminium toxicity in plants, the mechanisms governing such alleviation remain obscure. Possible magnesium-dependent mechanisms include (i) better carbon partitioning from shoots to roots; (ii) increased synthesis and exudation of organic acid anions; (iii) enhanced acid phosphatase activity; (iv) maintenance of proton-ATPase activity and cytoplasmic pH regulation; (v) protection against an aluminium-induced cytosolic calcium increase; and (vi) protection against reactive oxygen species. Future research should concentrate on assessing aluminium toxicity and tolerance in plants with overexpressed or antisense magnesium transporters to increase understanding of the aluminium-magnesium interaction.

  17. A mechanism for acute aluminium toxicity in fish.

    PubMed

    Exley, C; Chappell, J S; Birchall, J D

    1991-08-01

    Aluminium is acutely toxic to fish in acid waters. The gill is the principal target organ and death is due to a combination of ionoregulatory, osmoregulatory and respiratory dysfunction. The toxic mechanism has hitherto received little direct consideration and is unknown. In this paper the mechanism of acute aluminium toxicity is approached from a chemical perspective. Symptomatic evidence of toxicity is taken from the literature and combined with our own research to elucidate a biochemically sound model to describe a possible mechanism of acute aluminium toxicity in fish. The proposed model delineates the chemical conditions immediately adjacent to the gill surface and emphasizes their importance in aluminium's toxic mode of action. The mechanism is shown to be bipartite. Aluminium binding to functional groups both apically located at the gill surface and intracellularly located within lamellar epithelial cells disrupts the barrier properties of the gill epithelium. The concomitant iono- and osmoregulatory dysfunction results in accelerated cell necrosis, sloughing and death of the fish. The mechanism of epithelial cell death is proposed as a general mechanism of aluminium-induced accelerated cell death.

  18. Surface roughness when diamond turning RSA 905 optical aluminium

    NASA Astrophysics Data System (ADS)

    Otieno, T.; Abou-El-Hossein, K.; Hsu, W. Y.; Cheng, Y. C.; Mkoko, Z.

    2015-08-01

    Ultra-high precision machining is used intensively in the photonics industry for the production of various optical components. Aluminium alloys have proven to be advantageous and are most commonly used over other materials to make various optical components. Recently, the increasing demand from optical systems for optical aluminium with consistent material properties has led to the development of newly modified grades of aluminium alloys produced by rapid solidification in the foundry process. These new aluminium grades are characterised by their finer microstructures and refined mechanical and physical properties. However the machining database of these new optical aluminium grades is limited and more research is still required to investigate their machinability performance when they are diamond turned in ultrahigh precision manufacturing environment. This work investigates the machinability of rapidly solidified aluminium RSA 905 by varying a number of diamond-turning cutting parameters and measuring the surface roughness over a cutting distance of 4 km. The machining parameters varied in this study were the cutting speed, feed rate and depth of cut. The results showed a common trend of decrease in surface roughness with increasing cutting distance. The lowest surface roughness Ra result obtained after 4 km in this study was 3.2 nm. This roughness values was achieved using a cutting speed of 1750 rpm, feed rate of 5 mm/min and depth of cut equal to 25 μm.

  19. Synthesis of nanowires and nanoparticles of cubic aluminium nitride

    NASA Astrophysics Data System (ADS)

    Balasubramanian, C.; Godbole, V. P.; Rohatgi, V. K.; Das, A. K.; Bhoraskar, S. V.

    2004-03-01

    Nanostructures of cubic aluminium nitride were synthesized by DC arc-plasma-induced melting of aluminium in a nitrogen-argon ambient. The material flux ejected from the molten aluminium surface was found to react with nitrogen under highly non-equilibrium conditions and subsequently condense on a water-cooled surface to yield a mixture of nanowires and nanoparticles of crystalline cubic aluminium nitride. Both x-ray diffraction and electron diffraction measurements revealed that the as-synthesized nitrides adopted the cubic phase. Fourier transform infrared spectroscopy was used to understand the bonding configuration. Microstructural features of the synthesized material were best studied by transmission electron microscopy. From these analyses cubic aluminium nitride was found to be the dominating phase for both nanowires and nanoparticles synthesized at low currents. The typical particle size distribution was found to range over 15-80 nm, whereas the wires varied from 30 to 100 nm in diameter and 500 to 700 nm in length, depending upon the process parameters such as arc current and the nitrogen pressure. The reaction products inside the plasma zone were also obtained theoretically by minimization of free energy and the favourable zone temperature necessary for the formation of aluminium nitride was found to be {\\sim } 6000 K. Results are discussed in view of the highly non-equilibrium conditions that prevail during the arc-plasma synthesis.

  20. Zirconium behaviour during electrorefining of actinide-zirconium alloy in molten LiCl-KCl on aluminium cathodes

    NASA Astrophysics Data System (ADS)

    Meier, R.; Souček, P.; Malmbeck, R.; Krachler, M.; Rodrigues, A.; Claux, B.; Glatz, J.-P.; Fanghänel, Th.

    2016-04-01

    A pyrochemical electrorefining process for the recovery of actinides from metallic nuclear fuel based on actinide-zirconium alloys (An-Zr) in a molten salt is being investigated. In this process actinides are group-selectively recovered on solid aluminium cathodes as An-Al alloys using a LiCl-KCl eutectic melt at a temperature of 450 °C. In the present study the electrochemical behaviour of zirconium during electrorefining was investigated. The maximum amount of actinides that can be oxidised without anodic co-dissolution of zirconium was determined at a selected constant cathodic current density. The experiment consisted of three steps to assess the different stages of the electrorefining process, each of which employing a fresh aluminium cathode. The results indicate that almost a complete dissolution of the actinides without co-dissolution of zirconium is possible under the applied experimental conditions.

  1. Effect of Ultrasonic Treatment on the Microstructure of A201 Aluminium Alloy for Thixoforming

    SciTech Connect

    Kandemir, Sinan; Atkinson, Helen V.; Lawes, Simon D. A.

    2011-05-04

    It is known that the introduction of high intensity ultrasonic waves into liquid and solidifying metals leads to a non-dendritic and fine grain structure which is the requirement for semi-solid feedstock production. The effect of vibration time on the semi-solid microstructure of the A201 aluminium alloy billets fabricated with the ultrasonic treatment in the liquid state was studied in this paper. It was observed that the application of ultrasound technology can break up and distribute the dendrites which are present in the as-cast alloy. A suitable thixotropic microstructure with relatively rounded and fine globules could be obtained by ultrasonically treating liquid metal at 690 deg. C for a treatment time of 1 minute, cooling to room temperature and then reheating to the semi-solid state. This shows the ultrasonic treatment could be an economic and alternative route to produce A201 semi-solid feedstock for thixoforming.

  2. Aluminium content of some foods and food products in the USA, with aluminium food additives.

    PubMed

    Saiyed, Salim M; Yokel, Robert A

    2005-03-01

    The primary objective was to determine the aluminium (Al) content of selected foods and food products in the USA which contain Al as an approved food additive. Intake of Al from the labeled serving size of each food product was calculated. The samples were acid or base digested and analysed for Al using electrothermal atomic absorption spectrometry. Quality control (QC) samples, with matrices matching the samples, were generated and used to verify the Al determinations. Food product Al content ranged from <1-27,000 mg kg(-1). Cheese in a serving of frozen pizzas had up to 14 mg of Al, from basic sodium aluminium phosphate; whereas the same amount of cheese in a ready-to-eat restaurant pizza provided 0.03-0.09 mg. Many single serving packets of non-dairy creamer had approximately 50-600 mg Al kg(-1) as sodium aluminosilicate, providing up to 1.5 mg Al per serving. Many single serving packets of salt also had sodium aluminosilicate as an additive, but the Al content was less than in single-serving non-dairy creamer packets. Acidic sodium aluminium phosphate was present in many food products, pancakes and waffles. Baking powder, some pancake/waffle mixes and frozen products, and ready-to-eat pancakes provided the most Al of the foods tested; up to 180 mg/serving. Many products provide a significant amount of Al compared to the typical intake of 3-12 mg/day reported from dietary Al studies conducted in many countries.

  3. Reinforcement learning in scheduling

    NASA Technical Reports Server (NTRS)

    Dietterich, Tom G.; Ok, Dokyeong; Zhang, Wei; Tadepalli, Prasad

    1994-01-01

    The goal of this research is to apply reinforcement learning methods to real-world problems like scheduling. In this preliminary paper, we show that learning to solve scheduling problems such as the Space Shuttle Payload Processing and the Automatic Guided Vehicle (AGV) scheduling can be usefully studied in the reinforcement learning framework. We discuss some of the special challenges posed by the scheduling domain to these methods and propose some possible solutions we plan to implement.

  4. Covert Reinforcement: A Partial Replication.

    ERIC Educational Resources Information Center

    Ripstra, Constance C.; And Others

    A partial replication of an investigation of the effect of covert reinforcement on a perceptual estimation task is described. The study was extended to include an extinction phase. There were five treatment groups: covert reinforcement, neutral scene reinforcement, noncontingent covert reinforcement, and two control groups. Each subject estimated…

  5. Early Loaded Single Implant Reinforced Mandibular Overdenture

    PubMed Central

    Chowdhary, R.

    2016-01-01

    Rehabilitating atrophied mandible with two-implant supported denture is a common treatment modality for implant retained removable overdenture in mandible. This paper aims to design a treatment modality where single implant reinforced overdenture is fabricated for a severely atrophied mandibular ridge with early loading protocol. Results of studies have shown that a single implant mandibular overdenture significantly increases the satisfaction and quality of life of patients with edentulism. Midline fracture of the prosthesis is the most common complication related to single implant and two-implant retained mandibular overdentures. To manage such complication, a thin metal mesh is used to reinforce the overdenture and also to make the prostheses lighter and cost effective as compared to conventional cast metal framework. PMID:27403350

  6. Processes for fabricating composite reinforced material

    SciTech Connect

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2015-11-24

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  7. The substitutability of reinforcers.

    PubMed

    Green, Leonard; Freed, Debra E

    1993-07-01

    Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included. PMID:16812696

  8. Preference pulses without reinforcers.

    PubMed

    McLean, Anthony P; Grace, Randolph C; Pitts, Raymond C; Hughes, Christine E

    2014-05-01

    Preference pulses are thought to represent strong, short-term effects of reinforcers on preference in concurrent schedules. However, the general shape of preference pulses is substantially determined by the distributions of responses-per-visit (visit lengths) for the two choice alternatives. In several series of simulations, we varied the means and standard deviations of distributions describing visits to two concurrently available response alternatives, arranged "reinforcers" according to concurrent variable-interval schedules, and found a range of different preference pulses. Because characteristics of these distributions describe global aspects of behavior, and the simulations assumed no local effects of reinforcement, these preference pulses derive from the visit structure alone. This strongly questions whether preference pulses should continue to be interpreted as representing local effects of reinforcement. We suggest an alternative approach whereby local effects are assessed by subtracting the artifactual part, which derives from visit structure, from the observed preference pulses. This yields "residual" preference pulses. We illustrate this method in application to published data from mixed dependent concurrent schedules, revealing evidence that the delivery of reinforcers had modest lengthening effects on the duration of the current visit, a conclusion that is quantitatively consistent with early research on short-term effects of reinforcement.

  9. The substitutability of reinforcers

    PubMed Central

    Green, Leonard; Freed, Debra E.

    1993-01-01

    Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included. PMID:16812696

  10. Aluminium-related osteodystrophy and desferrioxamine treatment: role of phosphorus.

    PubMed

    Jorgetti, V; Soeiro, N M; Mendes, V; Pereira, R C; Crivellari, M E; Coutris, G; Borelli, A; Leite, M O; Nussenzweig, I; Marcondes, M

    1994-01-01

    We investigated (1) the prevalence of aluminium overload among 96 patients with symptomatic bone disease haemodialysed from 1987 to 1989 in the Sao Paulo area, Brazil; (2) the effect of 6 months desferrioxamine (DFO) treatment (1-2g/week). All patients underwent a first bone biopsy. Aluminium overload (extent of stainable bone aluminium more than 20% trabecular surface) was observed in 74 of 96 patients. Forty overloaded patients were divided into patients with high bone formation rate (BFR) (group 1; n = 17) and patients with low BFR (group 2; n = 23), and had a second biopsy after DFO therapy. In both groups aluminium surface was reduced after treatment (P < 0.001), osteoblast surface (P < 0.02-P < 0.01) and plasma parathyroid hormone (iPTH) (P < 0.01) increased. In group 1 BFR remained high. In group 2 BFR remained low in 16 patients (2a) and increased in seven (P < 0.02) (2b). In group 2a plasma phosphorus was below that in group 2b patients, before (P < 0.03) and after (P < 0.01) DFO. The histological features of group 2a patients resembled hypophosphataemic osteomalacia, those of group 2b patients aluminium osteodystrophy. These data show a high prevalence of aluminium overload in Brazilian patients. Low-dose DFO therapy was safe, decreased bone pain, prevented fractures, and reduced stainable bone aluminium. Bone lesions only partially improved, suggesting that low phosphorus intake and/or plasma calcitriol concentrations may have prevented improvement of bone formation and mineralization.

  11. Role of phytohormones in aluminium rhizotoxicity.

    PubMed

    Kopittke, Peter M

    2016-10-01

    Elevated concentrations of soluble aluminium (Al) reduce root growth in acid soils, but much remains unknown regarding the toxicity of this Al as well as the mechanisms by which plants respond. This review examines changes in phytohormones in Al-stressed plants. Al often results in a rapid 'burst' of ethylene in root apical tissues within 15-30 min, with this regulating an increase in auxin. This production of ethylene and auxin seems to be a component of a plant-response to toxic Al, resulting in cell wall modification or regulation of organic acid release. There is also evidence of a role of auxin in the expression of Al toxicity itself, with Al decreasing basipetal transport of auxin, thereby potentially decreasing wall loosening as required for elongation. Increasingly, changes in abscisic acid in root apices also seem to be involved in plant-responses to toxic Al. Changes in cytokinins, gibberellins and jasmonates following exposure to Al are also examined, although little information is available. Finally, although not a phytohormone, concentrations of nitric oxide change rapidly in Al-exposed tissues. The information presented in this review will assist in focusing future research efforts in examining the importance of phytohormones in plant tissues exposed to toxic levels of Al. PMID:27352002

  12. A systematic review of aluminium phosphide poisoning.

    PubMed

    Mehrpour, Omid; Jafarzadeh, Mostafa; Abdollahi, Mohammad

    2012-03-01

    Every year, about 300,000 people die because of pesticide poisoning worldwide. The most common pesticide agents are organophosphates and phosphides, aluminium phosphide (AlP) in particular. AlP is known as a suicide poison that can easily be bought and has no effective antidote. Its toxicity results from the release of phosphine gas as the tablet gets into contact with moisture. Phosphine gas primarily affects the heart, lungs, gastrointestinal tract, and kidneys. Poisoning signs and symptoms include nausea, vomiting, restlessness, abdominal pain, palpitation, refractory shock, cardiac arrhythmias, pulmonary oedema, dyspnoea, cyanosis, and sensory alterations. Diagnosis is based on clinical suspicion, positive silver nitrate paper test to phosphine, and gastric aspirate and viscera biochemistry. Treatment includes early gastric lavage with potassium permanganate or a combination with coconut oil and sodium bicarbonate, administration of charcoal, and palliative care. Specific therapy includes intravenous magnesium sulphate and oral coconut oil. Moreover, acidosis can be treated with early intravenous administration of sodium bicarbonate, cardiogenic shock with fluid, vasopresor, and refractory cardiogenic shock with intra-aortic baloon pump or digoxin. Trimetazidine may also have a useful role in the treatment, because it can stop ventricular ectopic beats and bigeminy and preserve oxidative metabolism. This article reviews the epidemiological, toxicological, and clinical/pathological aspects of AlP poisoning and its management.

  13. Fuzzy Multicriteria Ranking of Aluminium Coating Methods

    NASA Astrophysics Data System (ADS)

    Batzias, A. F.

    2007-12-01

    This work deals with multicriteria ranking of aluminium coating methods. The alternatives used are: sulfuric acid anodization, A1; oxalic acid anodization, A2; chromic acid anodization, A3; phosphoric acid anodization, A4; integral color anodizing, A5; chemical conversion coating, A6; electrostatic powder deposition, A7. The criteria used are: cost of production, f1; environmental friendliness of production process, f2; appearance (texture), f3; reflectivity, f4; response to coloring, f5; corrosion resistance, f6; abrasion resistance, f7; fatigue resistance, f8. Five experts coming from relevant industrial units set grades to the criteria vector and the preference matrix according to a properly modified Delphi method. Sensitivity analysis of the ranked first alternative A1 against the `second best', which was A3 at low and A7 at high resolution levels proved that the solution is robust. The dependence of anodized products quality on upstream processes is presented and the impact of energy price increase on industrial cost is discussed.

  14. Aluminium, iron and copper in human brain tissues donated to the Medical Research Council's Cognitive Function and Ageing Study.

    PubMed

    House, Emily; Esiri, Margaret; Forster, Gill; Ince, Paul G; Exley, Christopher

    2012-01-01

    Aluminium, iron and copper are all implicated in the aetiology of neurodegenerative diseases including Alzheimer's disease. However, there are very few large cohort studies of the content of these metals in aged human brains. We have used microwave digestion and TH GFAAS to measure aluminium, iron and copper in the temporal, frontal, occipital and parietal lobes of 60 brains donated to the Cognitive Function and Ageing Study. Every precaution was taken to reduce contamination of samples and acid digests to a minimum. Actual contamination was estimated by preparing a large number of (170+) method blanks which were interspersed within the full set of 700+ tissue digests. Subtraction of method blank values (MBV) from tissue digest values resulted in metal contents in all tissues in the range, MBV to 33 μg g(-1) dry wt. for aluminium, 112 to 8305 μg g(-1) dry wt. for iron and MBV to 384 μg g(-1) dry wt. for copper. While the median aluminium content for all tissues was 1.02 μg g(-1) dry wt. it was informative that 41 brains out of 60 included at least one tissue with an aluminium content which could be considered as potentially pathological (> 3.50 μg g(-1) dry wt.). The median content for iron was 286.16 μg g(-1) dry wt. and overall tissue iron contents were generally high which possibly reflected increased brain iron in ageing and in neurodegenerative disease. The median content for copper was 17.41 μg g(-1) dry wt. and overall tissue copper contents were lower than expected for aged brains but they were commensurate with aged brains showing signs of neurodegenerative disease. In this study we have shown, in particular, the value of carrying out significant numbers of method blanks to identify unknown sources of contamination. When these values are subtracted from tissue digest values the absolute metal contents could be considered as conservative and yet they may still reflect aspects of ageing and neurodegenerative disease in individual brains.

  15. Every reinforcer counts: reinforcer magnitude and local preference.

    PubMed Central

    Davison, Michael; Baum, William M

    2003-01-01

    Six pigeons were trained on concurrent variable-interval schedules. Sessions consisted of seven components, each lasting 10 reinforcers, with the conditions of reinforcement differing between components. The component sequence was randomly selected without replacement. In Experiment 1, the concurrent-schedule reinforcer ratios in components were all equal to 1.0, but across components reinforcer-magnitude ratios varied from 1:7 through 7:1. Three different overall reinforcer rates were arranged across conditions. In Experiment 2, the reinforcer-rate ratios varied across components from 27:1 to 1:27, and the reinforcer-magnitude ratios for each alternative were changed across conditions from 1:7 to 7:1. The results of Experiment 1 replicated the results for changing reinforcer-rate ratios across components reported by Davison and Baum (2000, 2002): Sensitivity to reinforcer-magnitude ratios increased with increasing numbers of reinforcers in components. Sensitivity to magnitude ratio, however, fell short of sensitivity to reinforcer-rate ratio. The degree of carryover from component to component depended on the reinforcer rate. Larger reinforcers produced larger and longer postreinforcer preference pulses than did smaller reinforcers. Similar results were found in Experiment 2, except that sensitivity to reinforcer magnitude was considerably higher and was greater for magnitudes that differed more from one another. Visit durations following reinforcers measured either as number of responses emitted or time spent responding before a changeover were longer following larger than following smaller reinforcers, and were longer following sequences of same reinforcers than following other sequences. The results add to the growing body of research that informs model building at local levels. PMID:13677611

  16. Up-regulation in the expression of renin gene by the influence of aluminium.

    PubMed

    Ezomo, Ojeiru F; Matsushima, Fumiko; Meshitsuka, Shunsuke

    2009-11-01

    The excretion of aluminium in urine was significantly increased after intake of analgesics containing aluminium, confirming increased absorption and hence exposure to aluminium with such medication. The effect of aluminium on the kidney was further investigated by study of gene expression in mice. After a single dose of aluminium, an up-regulation of renin gene was found by DNA sequencing of the products of differential display analysis. The up-regulation of renin was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting experiments in the dose dependent treatments and the time course observation after aluminium citrate injection. The up-regulation of the renin expression by aluminium is a strong indication of the influence of aluminium on the renin-angiotensin-aldosterone-system, resulting in possible induction of essential hypertension.

  17. Online monitoring of aluminium in drinking water with fluorimetric detection.

    PubMed

    Alonso-Mateos, A; Almendral-Parra, M J; Curto-Serrano, Y; Rodríguez-Martín, F J

    2008-01-01

    We report a procedure for the online monitoring of aluminium in drinking water by flow injection analysis. The reaction used is the formation of a complex with morin. Under the working conditions, this can be accomplished in an ethanol-rich hydroalcoholic medium, which modifies the fluorescent characteristics of the complex, allowing the determination of aluminium concentrations higher than 3.1 microgl(-1), with a linear application range between 2 and 250 microgl(-1), an R.S.D. of 2.3% (n=10, 120 microgl(-1)) and a sampling frequency of 90 h(-1). The method can thus be considered one of the most sensitive and fastest for the continuous determination of aluminium. In the presence of anionic surfactants, the sensitivity of the determination is increased. In this form, aluminium is detected at concentrations higher than 2.8 microgl(-1), with a linear application range of 2-50 microgl(-1). The procedure was applied to the analysis of aluminium in drinking, river, and underground water. Under the proposed working conditions, only Fe(III), fluoride and phosphates interfere. The interference of Fe(III) can be avoided with hydroxylamine and that of phosphates and polyphosphates by acid digestion of the samples.

  18. Internal stresses and the cyclic deformation of an aluminium matrix composite

    SciTech Connect

    Johannesson, B.

    1992-01-01

    The development of internal stresses in planar random Saffil fibre reinforced aluminum with a range of fibre volume fraction has been studied theoretically and in monotonic and cyclic deformation (Bauschinger) experiments at room temperature and 77K. The Eshelby S tensor for a planar random array of fibres is calculated. Because the aluminum/Saffil composites are not isotropic in the transverse directions, the plastic strain used in the calculations has to be determined experimentally. A method for quantifying the anisotropic plastic flow of aluminium/Saffil composites is proposed and the results are used in calculations of the mean stress hardening rate. The measurements of the thermal stresses obtained in the Bauschinger experiments are in quantitative agreement with results obtained in monotomic tests. The magnitude of the thermal stress at room temperature or 77K is independent of fibre volume fraction and a comparison with predictions shows that relaxation of the thermal stress increase with fibre volume fraction. Cycling in the Bauschinger experiments reduces the thermal stress and hence the separation of the mean and thermal stresses is essential or a reliable measurement of the mean stress hardening rate. Matrix hardening contributes considerably to the overall hardening of the composite, both at room temperature and 77K. The modified Orowan-Wilson model, which enables the plastic friction coefficient to be measured in copper-tungsten composites, has been applied to the aluminium/Saffil composites. The model requires both the mean stress and the peak stress curve obtained in Bauschinger experiments to be linear in plastic strain. The temperature dependence of the mean stress hardening rate suggests that relaxation is thermally activated. A model for relaxation of the mean stress is proposed. An equation is derived for the number of Orowan loops per fibre and it is assumed that the rate controlling mechanism of relaxation is cross slip of screw dislocations.

  19. Aluminium speciation in streams and lakes of the UK Acid Waters Monitoring Network, modelled with WHAM.

    PubMed

    Tipping, E; Carter, H T

    2011-03-15

    The Windermere Humic Aqueous Model (WHAM) incorporating Humic Ion-Binding Model VI was applied to analytical data from the United Kingdom Acid Waters Monitoring Network, collected for 22 streams and lakes over the period 1988-2007, to calculate the chemical speciation of monomeric aluminium (Al(mon)) in 3087 water samples. Model outputs were compared with analytical measurements of labile and non-labile Al(mon) concentrations, the former being equated with inorganic forms of Al(mon) and the latter with organically-complexed metal. Raw analytical data were used, and also data produced by applying a correction for the possible dissociation of organically-complexed Al(mon), and therefore its underestimation, during passage through the analytical cation-exchange column. Model calibration was performed by finding the conversion factor, F(FADOC), between the concentration of isolated fulvic acid, with default ion-binding properties, required by the model, and the measured concentration of dissolved organic carbon, [DOC]. For both uncorrected and corrected data, the value of F(FADOC) for streams was greater than for lakes, indicating greater binding activity towards aluminium. Model fits were better using uncorrected analytical data, but the values of F(FADOC) obtained from corrected data agreed more closely with previous estimates. The model provided reasonably good explanations of differences in aluminium speciation between sampling sites, and of temporal variations at individual sites. With total monomeric concentration as input, WHAM calculations might substitute for analytical speciation measurements, or aid analytical quality control. Calculated Al(3+) activities, a(Al3+), showed a pH-dependence similar to that previously found for other surface waters, and the modelling exercise identified differences between waters of up to two orders of magnitude in the value of a(Al3+) at a given pH. The model gives the net charge of dissolved organic matter, which is calculated

  20. Cooling rate dependence of solidification for liquid aluminium: a large-scale molecular dynamics simulation study.

    PubMed

    Hou, Z Y; Dong, K J; Tian, Z A; Liu, R S; Wang, Z; Wang, J G

    2016-06-29

    The effect of the cooling rate on the solidification process of liquid aluminium is studied using a large-scale molecular dynamics method. It is found that there are various types of short-range order (SRO) structures in the liquid, among which the icosahedral (ICO)-like structures are dominant. These SRO structures are in dynamic fluctuation and transform each other. The effect of the cooling rate on the microstructure is very weak at high temperatures and in supercooled liquids, and it appears only below the liquid-solid transition temperature. Fast cooling rates favour the formation of amorphous structures with ICO-like features, while slow cooling rates favour the formation of FCC crystalline structures. Furthermore, FCC and HCP structures can coexist in crystalline structures. It is also found that nanocrystalline aluminium can be achieved at appropriate cooling rates, and its formation mechanism is thoroughly investigated by tracing the evolution of nanoclusters. The arrangement of FCC and HCP atoms in the nanograins displays various twinned structures as observed using visualization analysis, which is different from the layering or phase separation structures observed in the solidification of Lennard-Jones fluids and some metal liquids. PMID:27302145

  1. Effects on the nervous system in different groups of workers exposed to aluminium

    PubMed Central

    Iregren, A; Sjogren, B; Gustafsson, K; Hagman, M; Nylen, L; Frech, W; Andersson, M; Ljunggren, K; Wennberg, A

    2001-01-01

    OBJECTIVE—To investigate possible neurotoxic effects in groups of aluminium pot room and foundry workers, aluminium welders, and a small group of workers exposed to aluminium in the production of flake powder.
METHODS—Exposure to aluminium was evaluated with aluminium concentrations in blood and urine as well as a questionnaire. The groups exposed to aluminium were compared with a group of mild steel welders. Neurotoxic effects were studied with mood and symptom questionnaires and several psychological and neurophysiological tests.
RESULTS—The pot room and foundry workers showed very low aluminium uptake as their aluminium concentrations in blood and urine were close to normal, and no effects on the nervous system were detected. The group of workers exposed to flake powder had high concentrations of aluminium in blood and urine, even higher than those of the aluminium welders. However, aluminium could not be shown to affect the functioning of the nervous system in flake powder producers. Although significant effects could not be shown in the present analysis of the data on welders, the performance of the welders exposed to high concentrations of aluminium was affected according to the analyses in the original paper from this group.
CONCLUSIONS—For the pot room and foundry workers no effects related to the exposure to aluminium could be found. For the group of flake powder producers exposed for a short term no effects on the nervous systems were evident despite high levels of exposure. Due to the high concentrations of aluminium in the biological samples of this group, measures to reduce the exposure to aluminium are recommended, as effects on the central nervous system might develop after protracted exposures. However, this assumption needs to be verified in further studies.


Keywords: aluminium; workers; nervous system PMID:11404450

  2. Does antiperspirant use increase the risk of aluminium-related disease, including Alzheimer's disease?

    PubMed

    Exley, C

    1998-03-01

    Aluminium salts are the major constituent of many widely used antiperspirant products. The use of such antiperspirants has been linked with the systemic accumulation of aluminium and an increased risk of Alzheimer's disease. But can the frequent use of aluminium-based antiperspirants lead to the accumulation of toxic levels of aluminium? And are there measures that we can take to reduce such accumulation without reducing the effectiveness of antiperspirants? PMID:9575492

  3. Identification of aluminium transport-related genes via genome-wide phenotypic screening of Saccharomyces cerevisiae.

    PubMed

    Tun, Nay M; O'Doherty, Patrick J; Chen, Zhong-Hua; Wu, Xi-Yang; Bailey, Trevor D; Kersaitis, Cindy; Wu, Ming J

    2014-08-01

    Genome-wide screening using gene deletion mutants has been widely carried out with numerous toxicants including oxidants and metal ions. The focus of such studies usually centres on identifying sensitive phenotypes against a given toxicant. Here, we screened the complete collection of yeast gene deletion mutants (5047) with increasing concentrations of aluminium sulphate (0.4, 0.8, 1.6 and 3.2 mM) in order to discover aluminium (Al(3+)) tolerant phenotypes. Fifteen genes were found to be associated with Al(3+) transport because their deletion mutants exhibited Al(3+) tolerance, including lem3Δ, hal5Δ and cka2Δ. Deletion of CKA2, a catalytic subunit of tetrameric protein kinase CK2, gives rise to the most pronounced resistance to Al(3+) by showing significantly higher growth compared to the wild type. Functional analysis revealed that both molecular regulation and endocytosis are involved in Al(3+) transport for yeast. Further investigations were extended to all the four subunits of CK2 (CKA1, CKA2, CKB1 and CKB2) and the other 14 identified mutants under a spectrum of metal ions, including Al(3+), Zn(2+), Mn(2+), Fe(2+), Fe(3+), Co(3+), Ga(3+), Cd(2+), In(3+), Ni(2+) and Cu(2+), as well as hydrogen peroxide and diamide, in order to unravel cross-tolerance amongst metal ions and the effect of the oxidants. Finally, the implication of the findings in Al(3+) transport for the other species like plants and humans is discussed.

  4. From Science to Industry: The Sites of Aluminium in France from the Nineteenth to the Twentieth Century.

    PubMed

    Le Roux, Muriel

    2015-05-01

    This paper explores the history of the isolation and industrial production of aluminium in France, from the work of Henri Sainte-Claire Deville in the 1850s to the latter part of the twentieth century, focusing on the relationships between academic research and industrial exploitation. In particular, it identifies a culture and organisation of research and development, "learning-by-doing," that emerged in the French aluminium industry following the establishment of the first electrolytic production facilities in the late 1880s by Paul Héroult, who, along with the American Charles Hall, patented the electrolytic method of producing the metal. This French method of R&D was a product both of a scientific culture that saw a continuity between scientific research and industrial application, and of a state policy that, unlike in Germany or the United States, was late to recognise the importance of fostering, on a large scale, the relations between academic chemistry and industry. It was only after World War II that the French state came fully to recognise the importance of underpinning industry with scientific research. And it was only from the 1960s, in the face of intensifying global competition, the risks of pollution, and the cost of energy, that the major aluminium firm Pechiney et Cie was able to replace a culture of "learning-by-doing" by one that integrated fundamental science with the production process.

  5. Influence of Nanowire Diameter on Structural and Optical Properties of cu Nanowire Synthesized in Anodic Aluminium Oxide Film

    NASA Astrophysics Data System (ADS)

    Cetinel, A.; Özcelik, Z.

    2016-11-01

    Copper (Cu) nanowire arrays embedded in anodic aluminium oxide films (AAO) on aluminium substrate have been synthesized by alternating current electrochemical deposition. Two-step anodization process has been performed to get the through-hole AAO with ordered nanochannels in 0.3M oxalic acids at DC voltages 30, 40, 50 and 60V, respectively. Structural characterization of the Cu nanowires has been analyzed by scanning electron microscopy (SEM) and X-ray diffraction (or) X-ray diffractometer (XRD). Our SEM analysis has revealed that the diameters of vertically oriented Cu nanowires are 15, 25, 45 and 60nm and the length of Cu nanowires having high packing density is about 15μm. XRD measurement has indicated that polycrystalline Cu nanowires prefer growth orientation along the (111) direction. Optical measurements show that reflection of the Cu nanowires/AAO on aluminium reduces with decreasing diameter of the Cu nanowires. This effect can be associated with increased light scattering from metal nanoparticles near their localized plasmon resonance frequency depending on the size and shape of the nanoparticles.

  6. From Science to Industry: The Sites of Aluminium in France from the Nineteenth to the Twentieth Century.

    PubMed

    Le Roux, Muriel

    2015-05-01

    This paper explores the history of the isolation and industrial production of aluminium in France, from the work of Henri Sainte-Claire Deville in the 1850s to the latter part of the twentieth century, focusing on the relationships between academic research and industrial exploitation. In particular, it identifies a culture and organisation of research and development, "learning-by-doing," that emerged in the French aluminium industry following the establishment of the first electrolytic production facilities in the late 1880s by Paul Héroult, who, along with the American Charles Hall, patented the electrolytic method of producing the metal. This French method of R&D was a product both of a scientific culture that saw a continuity between scientific research and industrial application, and of a state policy that, unlike in Germany or the United States, was late to recognise the importance of fostering, on a large scale, the relations between academic chemistry and industry. It was only after World War II that the French state came fully to recognise the importance of underpinning industry with scientific research. And it was only from the 1960s, in the face of intensifying global competition, the risks of pollution, and the cost of energy, that the major aluminium firm Pechiney et Cie was able to replace a culture of "learning-by-doing" by one that integrated fundamental science with the production process. PMID:26309196

  7. Evaluation of lead—calcium—tin—aluminium grid alloys for valve-regulated lead/acid batteries

    NASA Astrophysics Data System (ADS)

    Zhong, S.; Liu, H. K.; Dou, S. X.; Skyllas-Kazacos, M.

    Cast lead-calcium alloys have been generally employed in valve-regulated lead/acid (VRLA)_batteries since they appeared in the early 1970s. Some minor elements such as aluminium, silver, bismuth and some alkaline earth metals are also added to lead-calcium alloys to improve the alloy properties and the battery performance. A convenient method for the addition of aluminium into the alloy, compared with other methods reported, is presented. On addition to lead—calcium alloys,bismuth can form a BiCa compound according to the de-bismuthizing equation: 3Pb 3Ca+2Bi→Bi 2Ca 3+9Pb. There is a slight solubility of Bi 2Ca 3 in the lead at its melting point (327°C) with an amount of 0.048 wt.% resident bismuth. It is confirmed that the creep strength and the corrosion resistance is distinctly increased by the addition of silver into the grid alloy, but the associated gassing problem should be considered when such alloys are employed in VRLA batteries. Addition of sodium can refine grain sizes and increase the mechanical properties of the grid alloy, but the corrosion resistance of sodium-contained grids is inferior. A general description of experiments and application of tin, aluminium, bismuth, silver and sodium as additives in lead—calcium alloys is given.

  8. Determination of aluminium in groundwater samples by GF-AAS, ICP-AES, ICP-MS and modelling of inorganic aluminium complexes.

    PubMed

    Frankowski, Marcin; Zioła-Frankowska, Anetta; Kurzyca, Iwona; Novotný, Karel; Vaculovič, Tomas; Kanický, Viktor; Siepak, Marcin; Siepak, Jerzy

    2011-11-01

    The paper presents the results of aluminium determinations in ground water samples of the Miocene aquifer from the area of the city of Poznań (Poland). The determined aluminium content amounted from <0.0001 to 752.7 μg L(-1). The aluminium determinations were performed using three analytical techniques: graphite furnace atomic absorption spectrometry (GF-AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The results of aluminium determinations in groundwater samples for particular analytical techniques were compared. The results were used to identify the ascent of ground water from the Mesozoic aquifer to the Miocene aquifer in the area of the fault graben. Using the Mineql+ program, the modelling of the occurrence of aluminium and the following aluminium complexes: hydroxy, with fluorides and sulphates was performed. The paper presents the results of aluminium determinations in ground water using different analytical techniques as well as the chemical modelling in the Mineql+ program, which was performed for the first time and which enabled the identification of aluminium complexes in the investigated samples. The study confirms the occurrence of aluminium hydroxy complexes and aluminium fluoride complexes in the analysed groundwater samples. Despite the dominance of sulphates and organic matter in the sample, major participation of the complexes with these ligands was not stated based on the modelling.

  9. Determination of aluminium in groundwater samples by GF-AAS, ICP-AES, ICP-MS and modelling of inorganic aluminium complexes.

    PubMed

    Frankowski, Marcin; Zioła-Frankowska, Anetta; Kurzyca, Iwona; Novotný, Karel; Vaculovič, Tomas; Kanický, Viktor; Siepak, Marcin; Siepak, Jerzy

    2011-11-01

    The paper presents the results of aluminium determinations in ground water samples of the Miocene aquifer from the area of the city of Poznań (Poland). The determined aluminium content amounted from <0.0001 to 752.7 μg L(-1). The aluminium determinations were performed using three analytical techniques: graphite furnace atomic absorption spectrometry (GF-AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The results of aluminium determinations in groundwater samples for particular analytical techniques were compared. The results were used to identify the ascent of ground water from the Mesozoic aquifer to the Miocene aquifer in the area of the fault graben. Using the Mineql+ program, the modelling of the occurrence of aluminium and the following aluminium complexes: hydroxy, with fluorides and sulphates was performed. The paper presents the results of aluminium determinations in ground water using different analytical techniques as well as the chemical modelling in the Mineql+ program, which was performed for the first time and which enabled the identification of aluminium complexes in the investigated samples. The study confirms the occurrence of aluminium hydroxy complexes and aluminium fluoride complexes in the analysed groundwater samples. Despite the dominance of sulphates and organic matter in the sample, major participation of the complexes with these ligands was not stated based on the modelling. PMID:21274747

  10. IEC 61267: Feasibility of type 1100 aluminium and a copper/aluminium combination for RQA beam qualities.

    PubMed

    Leong, David L; Rainford, Louise; Zhao, Wei; Brennan, Patrick C

    2016-01-01

    In the course of performance acceptance testing, benchmarking or quality control of X-ray imaging systems, it is sometimes necessary to harden the X-ray beam spectrum. IEC 61267 specifies materials and methods to accomplish beam hardening and, unfortunately, requires the use of 99.9% pure aluminium (Alloy 1190) for the RQA beam quality, which is expensive and difficult to obtain. Less expensive and more readily available filters, such as Alloy 1100 (99.0% pure) aluminium and copper/aluminium combinations, have been used clinically to produce RQA series without rigorous scientific investigation to support their use. In this paper, simulation and experimental methods are developed to determine the differences in beam quality using Alloy 1190 and Alloy 1100. Additional simulation investigated copper/aluminium combinations to produce RQA5 and outputs from this simulation are verified with laboratory tests using different filter samples. The results of the study demonstrate that although Alloy 1100 produces a harder beam spectrum compared to Alloy 1190, it is a reasonable substitute. A combination filter of 0.5 mm copper and 2 mm aluminium produced a spectrum closer to that of Alloy 1190 than Alloy 1100 with the added benefits of lower exposures and lower batch variability.

  11. Stimulation of eryptosis by aluminium ions.

    PubMed

    Niemoeller, Olivier M; Kiedaisch, Valentin; Dreischer, Peter; Wieder, Thomas; Lang, Florian

    2006-12-01

    Aluminium salts are utilized to impede intestinal phosphate absorption in chronic renal failure. Toxic side effects include anemia, which could result from impaired formation or accelerated clearance of circulating erythrocytes. Erythrocytes may be cleared secondary to suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and exposure of phosphatidylserine (PS) at the erythrocyte surface. As macrophages are equipped with PS receptors, they bind, engulf and degrade PS-exposing cells. The present experiments have been performed to explore whether Al(3+) ions trigger eryptosis. The PS exposure was estimated from annexin binding and cell volume from forward scatter in FACS analysis. Exposure to Al(3+) ions (> or =10 microM Al(3+) for 24 h) indeed significantly increased annexin binding, an effect paralleled by decrease of forward scatter at higher concentrations (> or =30 microM Al(3+)). According to Fluo3 fluorescence Al(3+) ions (> or =30 microM for 3 h) increased cytosolic Ca(2+) activity. Al(3+) ions (> or =10 microM for 24 h) further decreased cytosolic ATP concentrations. Energy depletion by removal of glucose similarly triggered annexin binding, an effect not further enhanced by Al(3+) ions. The eryptosis was paralleled by release of hemoglobin, pointing to loss of cell membrane integrity. In conclusion, Al(3+) ions decrease cytosolic ATP leading to activation of Ca(2+)-permeable cation channels, Ca(2+) entry, stimulation of cell membrane scrambling and cell shrinkage. Moreover, Al(3+) ions lead to loss of cellular hemoglobin, a feature of hemolysis. Both effects are expected to decrease the life span of circulating erythrocytes and presumably contribute to the development of anemia during Al(3+) intoxication. PMID:17055015

  12. Aluminium in parenteral nutrition: a systematic review.

    PubMed

    Hernández-Sánchez, A; Tejada-González, P; Arteta-Jiménez, M

    2013-03-01

    Aluminium (Al) toxicity problem in parenteral nutrition solutions (PNS) is decades old and is still unresolved. The aim of this review is to gather updated information about this matter, regarding legislation, manifestations, diagnostics and treatment, patient population at risk and the actions to be taken to limit its accumulation. A structured search using MeSH vocabulary and Title/Abstract searches was conducted in PubMed (http://www.pubmed.gov) up to November 2012. Al is ubiquitous, facilitating its potential for exposure. Nevertheless, humans have several mechanisms to prevent significant absorption and to aid its elimination; therefore, the vast majority of the population is not at risk for Al toxicity. However, when protective gastrointestinal mechanisms are bypassed (for example, parenteral fluids), renal function is impaired (for example, adult patients with renal compromise and neonates) or exposure is high (for example, long-term PNS), Al is prone to accumulate in the body, including manifestations such as impaired neurological development, Alzheimer's disease, metabolic bone disease, dyslipemia and even genotoxic activity. A high Al content in PNS is largely the result of three parenteral nutrient additives: calcium gluconate, inorganic phosphates and cysteine hydrochloride. Despite the legislative efforts, some factors make difficult to comply with the rule and, therefore, to limit the Al toxicity. Unfortunately, manufacturers have not universally changed their processes to obtain a lower Al content of parenteral drug products (PDP). In addition, the imprecise information provided by PDP labels and the high lot-to-lot variation make the prediction of Al content rather inaccurate.

  13. Stimulation of eryptosis by aluminium ions

    SciTech Connect

    Niemoeller, Olivier M.; Kiedaisch, Valentin; Dreischer, Peter; Wieder, Thomas; Lang, Florian . E-mail: florian.lang@uni-tuebingen.de

    2006-12-01

    Aluminium salts are utilized to impede intestinal phosphate absorption in chronic renal failure. Toxic side effects include anemia, which could result from impaired formation or accelerated clearance of circulating erythrocytes. Erythrocytes may be cleared secondary to suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and exposure of phosphatidylserine (PS) at the erythrocyte surface. As macrophages are equipped with PS receptors, they bind, engulf and degrade PS-exposing cells. The present experiments have been performed to explore whether Al{sup 3+} ions trigger eryptosis. The PS exposure was estimated from annexin binding and cell volume from forward scatter in FACS analysis. Exposure to Al{sup 3+} ions ({>=} 10 {mu}M Al{sup 3+} for 24 h) indeed significantly increased annexin binding, an effect paralleled by decrease of forward scatter at higher concentrations ({>=} 30 {mu}M Al{sup 3+}). According to Fluo3 fluorescence Al{sup 3+} ions ({>=} 30 {mu}M for 3 h) increased cytosolic Ca{sup 2+} activity. Al{sup 3+} ions ({>=} 10 {mu}M for 24 h) further decreased cytosolic ATP concentrations. Energy depletion by removal of glucose similarly triggered annexin binding, an effect not further enhanced by Al{sup 3+} ions. The eryptosis was paralleled by release of hemoglobin, pointing to loss of cell membrane integrity. In conclusion, Al{sup 3+} ions decrease cytosolic ATP leading to activation of Ca{sup 2+}-permeable cation channels, Ca{sup 2+} entry, stimulation of cell membrane scrambling and cell shrinkage. Moreover, Al{sup 3+} ions lead to loss of cellular hemoglobin, a feature of hemolysis. Both effects are expected to decrease the life span of circulating erythrocytes and presumably contribute to the development of anemia during Al{sup 3+} intoxication.

  14. Modelling of micro- and macrosegregation for industrial multicomponent aluminium alloys

    NASA Astrophysics Data System (ADS)

    Ellingsen, K.; Mortensen, D.; M'Hamdi, M.

    2015-06-01

    Realistic predictions of macrosegregation formation during casting of aluminium alloys requires an accurate modeling of solute microsegregation accounting for multicomponent phase diagrams and secondary phase formation. In the present work, the stand alone Alstruc model, a microsegregation model for industrial multicomponent aluminium alloys, is coupled with the continuum model ALSIM which calculates the macroscopic transport of mass, enthalpy, momentum, and solutes as well as stresses and deformation during solidification of aluminium. Alstruc deals with multicomponent alloys accounting for temperature dependent partition coefficients, liquidus slopes and the precipitation of secondary phases. The challenge associated with computation of microsegregation for multicomponent alloys is solved in Alstruc by approximating the phase diagram data by simple, analytical expressions which allows for a CPU-time efficient coupling with the macroscopic transport model. In the present work, the coupled model has been applied in a study of macrosegregation including thermal and solutal convection, solidification shrinkage and surface exudation on an industrial DC-cast billet.

  15. Different Approach to the Aluminium Oxide Topography Characterisation

    SciTech Connect

    Poljacek, Sanja Mahovic; Gojo, Miroslav; Raos, Pero; Stoic, Antun

    2007-04-07

    Different surface topographic techniques are being widely used for quantitative measurements of typical industrial aluminium oxide surfaces. In this research, specific surface of aluminium oxide layer on the offset printing plate has been investigated by using measuring methods which have previously not been used for characterisation of such surfaces. By using two contact instruments and non-contact laser profilometer (LPM) 2D and 3D roughness parameters have been defined. SEM micrographs of the samples were made. Results have shown that aluminium oxide surfaces with the same average roughness value (Ra) and mean roughness depth (Rz) typically used in the printing plate surface characterisation, have dramatically different surface topographies. According to the type of instrument specific roughness parameters should be used for defining the printing plate surfaces. New surface roughness parameters were defined in order to insure detailed characterisation of the printing plates in graphic reproduction process.

  16. Constitutive modelling of aluminium alloy sheet at warm forming temperatures

    NASA Astrophysics Data System (ADS)

    Kurukuri, S.; Worswick, M. J.; Winkler, S.

    2016-08-01

    The formability of aluminium alloy sheet can be greatly improved by warm forming. However predicting constitutive behaviour under warm forming conditions is a challenge for aluminium alloys due to strong, coupled temperature- and rate-sensitivity. In this work, uniaxial tensile characterization of 0.5 mm thick fully annealed aluminium alloy brazing sheet, widely used in the fabrication of automotive heat exchanger components, is performed at various temperatures (25 to 250 °C) and strain rates (0.002 and 0.02 s-1). In order to capture the observed rate- and temperature-dependent work hardening behaviour, a phenomenological extended-Nadai model and the physically based (i) Bergstrom and (ii) Nes models are considered and compared. It is demonstrated that the Nes model is able to accurately describe the flow stress of AA3003 sheet at different temperatures, strain rates and instantaneous strain rate jumps.

  17. Synthesis and characterization of a new aluminium-based compound.

    PubMed

    Pascual-Cosp, José; Artiaga, Ramón; Corpas-Iglesias, Francisco; Benítez-Guerrero, Mónica

    2009-08-28

    A new aluminium polynuclear crystalline species, Al(13)(OH)(30)(H(2)O)(15)Cl(9) has been synthesized and characterized. It is a particular case of the Al(13)(OH)(30-y)(H(2)O)(18-x)Cl(9) x zH(2)O family. It has been obtained from aluminium waste cans treated with HCl solution in strong acid media, followed by an ageing period. The crystalline structure of the complex was determined by XRD spectroscopy. Twelve reflections were found and indexed with the DICVOL04 software. Morphologically, a flattened preferred orientation was observed by SEM and FESEM. The chemical structure was studied by several absorption spectroscopy techniques: FTIR, ATR-FTIR and Raman dispersion spectroscopy. The coordination of the aluminium nuclei was determined by Al-MAS-NMR. Only octahedral sites were observed. Thermal characterization of the compound was performed by evolved gas analysis (EGA) coupled to simultaneous TGA-DSC.

  18. Synthesis and characterization of a new aluminium-based compound.

    PubMed

    Pascual-Cosp, José; Artiaga, Ramón; Corpas-Iglesias, Francisco; Benítez-Guerrero, Mónica

    2009-08-28

    A new aluminium polynuclear crystalline species, Al(13)(OH)(30)(H(2)O)(15)Cl(9) has been synthesized and characterized. It is a particular case of the Al(13)(OH)(30-y)(H(2)O)(18-x)Cl(9) x zH(2)O family. It has been obtained from aluminium waste cans treated with HCl solution in strong acid media, followed by an ageing period. The crystalline structure of the complex was determined by XRD spectroscopy. Twelve reflections were found and indexed with the DICVOL04 software. Morphologically, a flattened preferred orientation was observed by SEM and FESEM. The chemical structure was studied by several absorption spectroscopy techniques: FTIR, ATR-FTIR and Raman dispersion spectroscopy. The coordination of the aluminium nuclei was determined by Al-MAS-NMR. Only octahedral sites were observed. Thermal characterization of the compound was performed by evolved gas analysis (EGA) coupled to simultaneous TGA-DSC. PMID:19655063

  19. Time-resolved aluminium laser-induced plasma temperature measurements

    NASA Astrophysics Data System (ADS)

    Surmick, D. M.; Parigger, C. G.

    2014-11-01

    We seek to characterize the temperature decay of laser-induced plasma near the surface of an aluminium target from laser-induced breakdown spectroscopy measurements of aluminium alloy sample. Laser-induced plasma are initiated by tightly focussing 1064 nm, nanosecond pulsed Nd:YAG laser radiation. Temperatures are inferred from aluminium monoxide spectra viewed at systematically varied time delays by comparing experimental spectra to theoretical calculations with a Nelder Mead algorithm. The temperatures are found to decay from 5173 ± 270 to 3862 ± 46 Kelvin from 10 to 100 μs time delays following optical breakdown. The temperature profile along the plasma height is also inferred from spatially resolved spectral measurements and the electron number density is inferred from Stark broadened Hβ spectra.

  20. Galvanic corrosion behavior of dissimilar metals in tropical marine environment

    SciTech Connect

    Subramanian, G.; Palraj, S.; Sundaram, M.; Balakrishnan, K.

    1995-11-01

    The galvanic corrosion behavior of aluminium 3004-70/30 brass and aluminium 3004-copper have been studied in the tropical marine environment of Mandapam, over a period of 436 days, under different area ratios. The area ratios, viz. A{sub Al} : A{sub brass} and A{sub Al} : A{sub copper}, studied are 0.125, 0.25, 0.5, 1, 2, 4 an 8. The galvanic corrosion behavior of the metals are studied in terms of the relative increase in the corrosion rate of Al due to galvanic coupling with brass and copper, the relative decrease in the corrosion rates of brass and copper due to galvanic coupling with aluminium, and the susceptibility of aluminium to pitting owing to galvanic coupling with brass and copper. The galvanic potential and galvanic current of the systems are monitored. Pits of different dimensions ranging from mild etchings to perforations are experienced on the borders and the surfaces of the interface of aluminium in contact with copper and brass. The weathering parameters and the environmental pollutants have a major role in influencing the galvanic corrosion of metals are also been monitored. The corrosion products resulting from galvanic corrosion are analyzed with XRD and the pitting on aluminium resulting from galvanic corrosion is highlighted in terms of pit depth, size and density of pit, using a high resolution microscope.

  1. Reinforcement pathology and obesity.

    PubMed

    Carr, Katelyn A; Daniel, Tinuke Oluyomi; Lin, Henry; Epstein, Leonard H

    2011-09-01

    Obesity is, in part, a result of positive energy balance or energy intake exceeding physiological needs. Excess energy intake is determined by a series of food choices over time. These choices involve both motivational and executive function processes. Problems arise when there is excessive motivation to eat and low impulse control, a situation we have termed reinforcement pathology. Motivational and executive function processes have also been implicated in the development of drug dependence and addiction. In this review we discuss the application of reinforcement pathology to obesity, and implications of this approach for obesity treatment. PMID:21999693

  2. History of reinforced plastics

    SciTech Connect

    Milewski, J.V.; Rosato, D.V.

    1981-01-01

    This history of reinforced plastics is told by combining the individual histories of each reinforcement and the way in which they added to and changed the direction and rate of growth of the industry. The early history is based on all resins, fillers, and fibers found in nature. Then came the Baekeland revolution with the first synthetic resin which lasted about 25 years, at which time synthetic fiber glass and polyester resin dramatically changed the industry. Now, for the 1980s, the high modulus fibers developed 10 to 20 years ago are reshaping the industry. 32 figures.

  3. Reinforcement pathology and obesity.

    PubMed

    Carr, Katelyn A; Daniel, Tinuke Oluyomi; Lin, Henry; Epstein, Leonard H

    2011-09-01

    Obesity is, in part, a result of positive energy balance or energy intake exceeding physiological needs. Excess energy intake is determined by a series of food choices over time. These choices involve both motivational and executive function processes. Problems arise when there is excessive motivation to eat and low impulse control, a situation we have termed reinforcement pathology. Motivational and executive function processes have also been implicated in the development of drug dependence and addiction. In this review we discuss the application of reinforcement pathology to obesity, and implications of this approach for obesity treatment.

  4. Evaluating the influence of postsession reinforcement on choice of reinforcers.

    PubMed

    Kodak, Tiffany; Lerman, Dorothea C; Call, Nathan

    2007-01-01

    Factors that influence reinforcer choice have been examined in a number of applied studies (e.g., Neef, Mace, Shea, & Shade, 1992; Shore, Iwata, DeLeon, Kahng, & Smith, 1997; Tustin, 1994). However, no applied studies have evaluated the effects of postsession reinforcement on choice between concurrently available reinforcers, even though basic findings indicate that this is an important factor to consider (Hursh, 1978; Zeiler, 1999). In this bridge investigation, we evaluated the influence of postsession reinforcement on choice of two food items when task responding was reinforced on progressive-ratio schedules. Participants were 3 children who had been diagnosed with developmental disabilities. Results indicated that response allocation shifted from one food item to the other food item under thinner schedules of reinforcement when no postsession reinforcement was provided. These findings suggest that the efficacy of instructional programs or treatments for problem behavior may be improved by restricting reinforcers outside treatment sessions. PMID:17970264

  5. Evaluating The Influence of Postsession Reinforcement on Choice of Reinforcers

    PubMed Central

    Kodak, Tiffany; Lerman, Dorothea C; Call, Nathan

    2007-01-01

    Factors that influence reinforcer choice have been examined in a number of applied studies (e.g., Neef, Mace, Shea, & Shade, 1992; Shore, Iwata, DeLeon, Kahng, & Smith, 1997; Tustin, 1994). However, no applied studies have evaluated the effects of postsession reinforcement on choice between concurrently available reinforcers, even though basic findings indicate that this is an important factor to consider (Hursh, 1978; Zeiler, 1999). In this bridge investigation, we evaluated the influence of postsession reinforcement on choice of two food items when task responding was reinforced on progressive-ratio schedules. Participants were 3 children who had been diagnosed with developmental disabilities. Results indicated that response allocation shifted from one food item to the other food item under thinner schedules of reinforcement when no postsession reinforcement was provided. These findings suggest that the efficacy of instructional programs or treatments for problem behavior may be improved by restricting reinforcers outside treatment sessions. PMID:17970264

  6. Evaluating the influence of postsession reinforcement on choice of reinforcers.

    PubMed

    Kodak, Tiffany; Lerman, Dorothea C; Call, Nathan

    2007-01-01

    Factors that influence reinforcer choice have been examined in a number of applied studies (e.g., Neef, Mace, Shea, & Shade, 1992; Shore, Iwata, DeLeon, Kahng, & Smith, 1997; Tustin, 1994). However, no applied studies have evaluated the effects of postsession reinforcement on choice between concurrently available reinforcers, even though basic findings indicate that this is an important factor to consider (Hursh, 1978; Zeiler, 1999). In this bridge investigation, we evaluated the influence of postsession reinforcement on choice of two food items when task responding was reinforced on progressive-ratio schedules. Participants were 3 children who had been diagnosed with developmental disabilities. Results indicated that response allocation shifted from one food item to the other food item under thinner schedules of reinforcement when no postsession reinforcement was provided. These findings suggest that the efficacy of instructional programs or treatments for problem behavior may be improved by restricting reinforcers outside treatment sessions.

  7. Ultrasonic energy welds copper to aluminium

    SciTech Connect

    Flood, G.

    1997-01-01

    Attempting to weld copper to aluminum by conventional means through the application of thermal energy to melt and fuse the two metals (fusion welding) can result in an unreliable weld. The oxide layer on aluminum is difficult to remove, the melt temperatures of the two metals are not close, the two metals exhibit high thermal conductivity and alloying of the two metals creates a brittle intermetallic that is mechanically and electrically unreliable. An alternative for design engineers is to weld copper to aluminum by applying ultrasonic energy, which joins the metals without melting. The ultrasonic process creates a high quality weld both mechanically and electrically without forming a brittle intermetallic and without intermediate steps. Ultrasonic welding of copper to aluminum has been shown to be efficient and effective as demonstrated by a number of practical production applications. The problems of tough oxides, high thermal conductivity, high electrical conductivity, intermetallics and brittle alloys are not significant with the ultrasonic welding process. And similarly, the problems associated with pre and postweld cleaning, fluxes, hot metal and high energy costs are eliminated. Modern ultrasonic welding equipment is capable of monitoring energy and controlling the critical welding process variables.

  8. Weldability aspects in the design and fabrication of aluminium structures subjected to fatigue loads. Part 1: Effect of welding on the structural integrity of joint types designed for repairing aluminium ship sections

    NASA Astrophysics Data System (ADS)

    Nevasmaa, P.; Peltonen, J.; Kuitunen, R.; Rahka, K.

    1993-05-01

    The Laboratory of Production Engineering and the Metals Laboratory of the Technical Research Center of Finland (VTT) have participated in a Nordic research project entitled 'New methods for joining of aluminium'. The results from Finnish work of the project will be presented in a report to be published in two parts. Part 1 of the report will evaluate the effects of welding on the structural integrity of some joint types primarily designed for repairing ship sections and sea crafts made from 6xxx (AlSiMg) series alloys.

  9. Carbon treated commercial aluminium alloys as anodes for aluminium-air batteries in sodium chloride electrolyte

    NASA Astrophysics Data System (ADS)

    Pino, M.; Herranz, D.; Chacón, J.; Fatás, E.; Ocón, P.

    2016-09-01

    An easy treatment based in carbon layer deposition into aluminium alloys is presented to enhance the performance of Al-air primary batteries with neutral pH electrolyte. The jellification of aluminate in the anode surface is described and avoided by the carbon covering. Treated commercial Al alloys namely Al1085 and Al7475 are tested as anodes achieving specific capacities above 1.2 Ah g-1vs 0.5 Ah g-1 without carbon covering. The influence of the binder proportion in the treatment as well as different carbonaceous materials, Carbon Black, Graphene and Pyrolytic Graphite are evaluated as candidates for the covering. Current densities of 1-10 mA cm-2 are measured and the influence of the alloy explored. A final battery design of 4 cells in series is presented for discharges with a voltage plateau of 2 V and 1 Wh g-1 energy density.

  10. Evaluating the Influence of Postsession Reinforcement on Choice of Reinforcers

    ERIC Educational Resources Information Center

    Kodak, Tiffany; Lerman, Dorothea C.; Call, Nathan

    2007-01-01

    Factors that influence reinforcer choice have been examined in a number of applied studies (e.g., Neef, Mace, Shea, & Shade, 1992; Shore, Iwata, DeLeon, Kahng, & Smith, 1997; Tustin, 1994). However, no applied studies have evaluated the effects of postsession reinforcement on choice between concurrently available reinforcers, even though basic…

  11. Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

    ERIC Educational Resources Information Center

    Trosclair-Lasserre, Nicole M.; Lerman, Dorothea C.; Call, Nathan A.; Addison, Laura R.; Kodak, Tiffany

    2008-01-01

    Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current…

  12. Do oral aluminium phosphate binders cause accumulation of aluminium to toxic levels?

    PubMed Central

    2011-01-01

    Background Aluminium (Al) toxicity was frequent in the 1980s in patients ingesting Al containing phosphate binders (Alucaps) whilst having HD using water potentially contaminated with Al. The aim of this study was to determine the risk of Al toxicity in HD patients receiving Alucaps but never exposed to contaminated dialysate water. Methods HD patients only treated with Reverse Osmosis(RO) treated dialysis water with either current or past exposure to Alucaps were given standardised DFO tests. Post-DFO serum Al level > 3.0 μmol/L was defined to indicate toxic loads based on previous bone biopsy studies. Results 39 patients (34 anuric) were studied. Mean dose of Alucap was 3.5 capsules/d over 23.0 months. Pre-DFO Al levels were > 1.0 μmol/L in only 2 patients and none were > 3.0 μmol/L. No patients had a post DFO Al levels > 3.0 μmol/L. There were no correlations between the serum Al concentrations (pre-, post- or the incremental rise after DFO administration) and the total amount of Al ingested. No patients had unexplained EPO resistance or biochemical evidence of adynamic bone. Conclusions Although this is a small study, oral aluminium exposure was considerable. Yet no patients undergoing HD with RO treated water had evidence of Al toxicity despite doses equivalent to 3.5 capsules of Alucap for 2 years. The relationship between the DFO-Al results and the total amount of Al ingested was weak (R2 = 0.07) and not statistically significant. In an era of financial prudence, and in view of the recognised risk of excess calcium loading in dialysis patients, perhaps we should re-evaluate the risk of using Al-based phosphate binders in HD patients who remain uric. PMID:21992770

  13. Cascade ultrafiltration and competing ligand exchange for kinetic speciation of aluminium, iron, and nickel in fresh water.

    PubMed

    Hassan, Nouri M; Murimboh, John D; Sekaly, Amina L R; Mandal, Rupasri; Chakrabarti, Chuni L; Grégoire, D Conrad

    2006-04-01

    Kinetic speciation of nickel, aluminium, and iron in fresh water has been investigated by cascade ultrafiltration followed by competing ligand exchange of the ultrafiltered fractions. Graphite furnace atomic absorption spectrometry was used to measure the kinetics of metal complex dissociation. Dissolved metal species were fractionated by cascade ultrafiltration. Metal speciation in each ultrafiltered fraction was then characterized as free metal ions, "labile" metal complexes (with dissociation rate constants >/=10(-3) s(-1)), "slowly labile" metal complexes (with dissociation rate constants >10(-6) s(-1)), and "inert" metal complexes (with dissociation rate constants <10(-6) s(-1)). The experimental results were compared with the predictions of a computer-based equilibrium speciation model, the Windermere humic aqueous model (WHAM) V. Cascade ultrafiltration coupled with kinetic speciation of the metal species in each molecular weight cut-off (MWCO) fraction provided a more comprehensive picture and insight into the physical and the chemical characteristics of the metal species than either ultrafiltration or measurement of dissociation kinetics alone.

  14. Turbomachine blade reinforcement

    DOEpatents

    Garcia Crespo, Andres Jose

    2016-09-06

    Embodiments of the present disclosure include a system having a turbomachine blade segment including a blade and a mounting segment coupled to the blade, wherein the mounting segment has a plurality of reinforcement pins laterally extending at least partially through a neck of the mounting segment.

  15. Reinforcing Saccadic Amplitude Variability

    ERIC Educational Resources Information Center

    Paeye, Celine; Madelain, Laurent

    2011-01-01

    Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…

  16. A Numerical Analysis of the Resistance and Stiffness of the Aluminium and Concrete Composite Beam

    NASA Astrophysics Data System (ADS)

    Polus, Łukasz; Szumigała, Maciej

    2015-03-01

    In this paper a numerical analysis of the resistance and stiffness of the aluminium and concrete composite beam is presented. Composite aluminium and concrete structures are quite new and they have not been thoroughly tested. Composite structures have a lot of advantages. The composite aluminium and concrete beam is more corrosion-resistant, fire-resistant and stiff than the aluminium beam. The contemporary idea of sustainable buildings relies on new solutions which are more environmentally friendly. Aluminium is lighter and more resistant to corrosion than steel, which is often used in composite structures.

  17. Quasicrystalline particulate reinforced aluminum composite

    SciTech Connect

    Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.

    1997-07-01

    Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.

  18. Droplet impinging behavior on surfaces: Part II - Water on aluminium and cast iron surfaces

    NASA Astrophysics Data System (ADS)

    Sangavi, S.; Balaji, S.; Mithran, N.; Venkatesan, M.

    2016-09-01

    Droplet cooling of metal surfaces is an important area of research in industrial applications such as material quenching, nozzle spraying, etc. Fluids (water) act as an excellent agent in heat transfer to remove excess heat in various processes by convection and conduction. Such cooling process varies the material properties. The bubbles formed during droplet impinging on the surface act as heat sink and causes variation of height and spreading radius of the droplet with increase in temperature. In the present work, an experimental study of the droplet impinging behavior on Aluminium and Cast iron surfaces is reported. The water droplets are made to fall on the surface of the specimens from a specific height, which also influences the spreading radius. The effect of temperature on droplet height and droplet spreading radius is detailed.

  19. Reinforcing aspects of androgens.

    PubMed

    Wood, Ruth I

    2004-11-15

    Are androgens reinforcing? Androgenic-anabolic steroids (AAS) are drugs of abuse. They are taken in large quantities by athletes and others to increase performance, often with negative long-term health consequences. As a result, in 1991, testosterone was declared a controlled substance. Recently, Brower [K.J. Brower, Anabolic steroid abuse and dependence. Curr. Psychiatry Rep. 4 (2002) 377-387.] proposed a two-stage model of AAS dependence. Users initiate steroid use for their anabolic effects on muscle growth. With continued exposure, dependence on the psychoactive effects of AAS develops. However, it is difficult in humans to separate direct psychoactive effects of AAS from the user's psychological dependence on the anabolic effects of AAS. Thus, studies in laboratory animals are useful to explore androgen reinforcement. Testosterone induces a conditioned place preference in rats and mice, and is voluntarily consumed through oral, intravenous, and intracerebroventricular self-administration in hamsters. Active, gonad-intact male and female hamsters will deliver 1 microg/microl testosterone into the lateral ventricles. Indeed, some individuals self-administer testosterone intracerebroventricularly to the point of death. Male rats develop a conditioned place preference to testosterone injections into the nucleus accumbens, an effect blocked by dopamine receptor antagonists. These data suggest that androgen reinforcement is mediated by the brain. Moreover, testosterone appears to act through the mesolimbic dopamine system, a common substrate for drugs of abuse. Nonetheless, androgen reinforcement is not comparable to that of cocaine or heroin. Instead, testosterone resembles other mild reinforcers, such as caffeine, nicotine, or benzodiazepines. The potential for androgen addiction remains to be determined.

  20. Matching and Conditioned Reinforcement Rate

    ERIC Educational Resources Information Center

    Shahan, Timothy A.; Podlesnik, Christopher A.; Jimenez-Gomez, Corina

    2006-01-01

    Attempts to examine the effects of variations in relative conditioned reinforcement rate on choice have been confounded by changes in rates of primary reinforcement or changes in the value of the conditioned reinforcer. To avoid these problems, this experiment used concurrent observing responses to examine sensitivity of choice to relative…

  1. Developmental Reinforcement and Special Education.

    ERIC Educational Resources Information Center

    Garris, Raymond P.

    The author uses a developmental model (1) to describe the developmental reinforcement process as it occurs in a child's life, using a hierarchical concept, and (2) to discuss some educational consequences of a reinforcement deficit. The developmental reinforcement process is composed of a hierarchy of four levels. Development takes place in…

  2. Classroom Management and Negative Reinforcement.

    ERIC Educational Resources Information Center

    Tauber, Robert T.

    Of the four simple consequences for behavior, none is more misunderstood than negative reinforcement. A Negative Reinforcement Quiz administered to 233 student teachers from two universities revealed that the vast majority of respondents mistakenly viewed negative reinforcement as a synonym for punishment, and believe that negative reinforcement…

  3. Assessment of bisphenol A released from reusable plastic, aluminium and stainless steel water bottles.

    PubMed

    Cooper, James E; Kendig, Eric L; Belcher, Scott M

    2011-10-01

    Bisphenol A (BPA) is a ubiquitous high volume industrial chemical that is an estrogen and an environmental endocrine disrupting chemical. Bisphenol A is used extensively in the production of consumer goods, polycarbonate plastics, epoxy resins and coatings used to line metallic food and beverage cans. There is great concern regarding the possible harmful effects from exposures that result from BPA leaching into foods and beverages from packaging or storage containers. The objective of this study was to independently assess whether BPA contamination of water was occurring from different types of reusable drinking bottles marketed as alternatives to BPA-containing polycarbonate plastics. Using a sensitive and quantitative BPA-specific competitive enzyme-linked immunosorbent assay we evaluated whether BPA migrated into water stored in polycarbonate or copolyester plastic bottles, and different lined or unlined metallic reusable water bottles. At room temperature the concentration of BPA migrating from polycarbonate bottles ranged from 0.2 to 0.3 mg L⁻¹. Under identical conditions BPA migration from aluminium bottles lined with epoxy-based resins was variable depending on manufacturer ranging from 0.08 to 1.9 mg L⁻¹. Boiling water significantly increased migration of BPA from the epoxy lined bottles. No detectable BPA contamination was observed in water stored in bottles made from Tritan™ copolyester plastic, uncoated stainless steel, or aluminium lined with EcoCare™. The results from this study demonstrate that when used according to manufacturers' recommendations reusable water bottles constructed from "BPA-free" alternative materials are suitable for consumption of beverages free of BPA contamination.

  4. Assessment of Bisphenol A Released from Reusable Plastic, Aluminium and Stainless Steel Water Bottles

    PubMed Central

    Cooper, James E.; Kendig, Eric L.; Belcher, Scott M.

    2011-01-01

    Bisphenol A(BPA) is a ubiquitous high volume industrial chemical that is an estrogen and an environmental endocrine disrupting chemical. Bisphenol A is used extensively in the production of consumer goods, polycarbonate plastics, epoxy resins, coating used to line metallic food and beverage cans, and other products.There is great concern regarding the possible harmful effects from exposures that result from BPAleaching into foods and beverages from packaging or storage containers. The objective of this study was to independently assesswhether BPA contamination of water was occurring from different types of reusable drinking bottlesmarketed as alternatives to BPA-containing polycarbonate plastics. Using a sensitive and quantitative BPA-specific competitive enzyme-linked immunosorbent assaywe evaluated whether BPA migrated into water stored inpolycarbonateor copolyester plastic bottles, and different lined or unlined metallic reusable water bottles. At room temperature the concentration of BPA migrating from polycarbonate bottles ranged from 0.2–0.3 mg/L. Under identical conditions BPA migration from aluminium bottles lined with epoxy-based resins was variable depending on manufacturer ranging from 0.08 to 1.9 mg/L.Boiling water significantly increased migration of BPA from the epoxy lined bottles. No detectable BPA contamination was observed in water stored in bottles made from Tritan™ copolyester plastic, uncoated stainless steel, or aluminium lined with EcoCare™. The results from this study demonstrate that when used according to manufactures’ recommendations reusable water bottles constructed from “BPA-free” alternative materials are suitable for consumption of beverages free of BPA contamination. PMID:21741673

  5. Studies on the best alkaline electrolyte for aluminium/air batteries

    NASA Astrophysics Data System (ADS)

    Kapali, V.; Venkatakrishna Iyer, S.; Balaramachandran, V.; Sarangapani, K. B.; Ganesan, M.; Anbu Kulandainathan, M.; Sheik Mideen, A.

    Two types of alkaline electrolyte, based on 4 M NaOH have been developed for use in aluminium/air cells or batteries. They contain either alkaline citrate or alkaline citrate cum stannate as an additive to suppress the self-corrosion of aluminium without any deleterious effects on the efficient functioning of aluminium anode at a high negative potential. The alkaline citrate cum stannate solution has been adjudged the best electrolyte in terms of electrochemical characteristics and electrolyte management. Hence, results pertaining to the use of alkaline citrate cum stannate are presented in this paper. An aluminium/air battery with this electrolyte can be used safely and effectively at ambient temperature. An added advantage is the employment of 99.8% pure aluminium for the preparation of alloy anodes. This is expected to reduce the cost of aluminium/air batteries. The best anode based on 99.8% pure aluminium is a quaternary alloy containing lead, gallium and indium.

  6. What is wrong with aluminium? The J.D. Birchall Memorial Lecture.

    PubMed

    Williams, R J

    1999-08-30

    Aluminium chemistry has features in common with two other groups of elements: (1) divalent magnesium and calcium, and (2) trivalent chromium and iron. The essential differences between the first group and aluminium are explored and it is shown that the much higher acidity of aluminium makes it such a powerful competitor for oxygen-donor ligands, opposite functions of both magnesium and calcium, in cells that its presence is damaging. By way of contrast aluminium is a weaker acid than ferric ions but it is more available. It was necessary for iron to be utilised in the presence of aluminium so special methods had to be devised to distinguish between them. In essence aluminium has always, throughout evolution, been a threat to the biological chemistry of all these three elements. We shall examine this chemistry and then explore the relationship of calcium and aluminium under acid rain conditions.

  7. Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

    PubMed Central

    Trosclair-Lasserre, Nicole M; Lerman, Dorothea C; Call, Nathan A; Addison, Laura R; Kodak, Tiffany

    2008-01-01

    Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current study was to evaluate the relations among reinforcer magnitude, preference, and efficacy by drawing on the procedures and results of basic experimentation in this area. Three children who engaged in problem behavior that was maintained by social positive reinforcement (attention, access to tangible items) participated. Results indicated that preference for different magnitudes of social reinforcement may predict reinforcer efficacy and that magnitude effects may be mediated by the schedule requirement. PMID:18595284

  8. Aluminium in food and daily dietary intake estimate in Greece.

    PubMed

    Bratakos, Sotirios M; Lazou, Andriana E; Bratakos, Michael S; Lazos, Evangelos S

    2012-01-01

    Aluminium content of foods, as well as dietary aluminium intake of the Greek adult population, was determined using graphite furnace atomic absorption spectroscopy after microwave sample digestion and food consumption data. Al content ranged from 0.02 to 741.2 mg kg⁻¹, with spices, high-spice foods, cereal products, vegetables and pulses found to be high in Al. Differences in aluminium content were found between different food classes from Greece and those from some other countries. Aluminium intake of Greeks is 3.7 mg/day based on DAFNE Food Availability Databank, which uses data from the Household Budget Surveys. On the other hand, according to the per capita food consumption data collected by both national and international organisations, Al intake is 6.4 mg day⁻¹. Greek adult population has an Al intake lower than the Provisional Tolerable Weekly Intake of 7 mg kg⁻¹ body weight established by EFSA. Cereals and vegetables are the main Al contributors, providing 72.4% of daily intake.

  9. Treatment of dairy effluents by electrocoagulation using aluminium electrodes.

    PubMed

    Tchamango, Serge; Nanseu-Njiki, Charles P; Ngameni, Emmanuel; Hadjiev, Dimiter; Darchen, André

    2010-01-15

    This work sets out to examine the efficiency of an electrolytic treatment: electrocoagulation, applied to dairy effluents. The experiments were carried out using a soluble aluminium anode on artificial wastewater derived from solutions of milk powder. The flocks generated during this treatment were separated by filtration. The analysis of the filtrates showed that the chemical oxygen demand (COD) was reduced by up to 61% while the removal of phosphorus, nitrogen contents, and turbidity were 89, 81 and 100%, respectively. An analogous treatment applied to phosphate and lactose solutions revealed that lactose was not eliminated, a fact that could account for the rather poor lowering of the COD. Compared to the chemical coagulation treatment with aluminium sulphate, the efficiency of the electrocoagulation technique was almost identical. However the wastewaters treated by electrocoagulation differed by the fact that they exhibited a lower conductivity and a neutral pH value (by contrast to the acid nature of the solution treated by the chemical coagulation). This result (low conductivity, neutral pH) tends to show that it may be possible to recycle the treated water for some industrial uses. Moreover, the electrocoagulation process uses fewer reagents: the mass of the aluminium anode dissolved during the treatment is lower compared to the quantity of the aluminium salt used in chemical coagulation. These two observations clearly show that the electrocoagulation technique is more performing. PMID:19900696

  10. LASERS IN MEDICINE: Two-photon excitation of aluminium phthalocyanines

    NASA Astrophysics Data System (ADS)

    Meshalkin, Yu P.; Alfimov, E. E.; Vasil'ev, N. E.; Denisov, A. N.; Makukha, V. K.; Ogirenko, A. P.

    1999-12-01

    A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined.

  11. On the anodic aluminium oxide refractive index of nanoporous templates

    NASA Astrophysics Data System (ADS)

    Hierro-Rodriguez, A.; Rocha-Rodrigues, P.; Valdés-Bango, F.; Alameda, J. M.; Jorge, P. A. S.; Santos, J. L.; Araujo, J. P.; Teixeira, J. M.; Guerreiro, A.

    2015-11-01

    In the present study, we have determined the intrinsic refractive index of anodic aluminium oxide, which is originated by the formation of nanoporous alumina templates. Different templates have been fabricated by the conventional two-step anodization procedure in oxalic acid. Their porosities were modified by chemical wet etching allowing the tuning of their effective refractive indexes (air-filled nanopores  +  anodic aluminium oxide). By standard spectroscopic light transmission measurements, the effective refractive index for each different template was extracted in the VIS-NIR region. The determination of the intrinsic anodic aluminium oxide refractive index was performed by using the Maxwell-Garnett homogenization theory. The results are coincident for all the fabricated samples. The obtained refractive index (~1.55) is quite lower (~22%) than the commonly used Al2O3 handbook value (~1.75), showing that the amorphous nature of the anodic oxide structure strongly conditions its optical properties. This difference is critical for the correct design and modeling of optical plasmonic metamaterials based on anodic aluminium oxide nanoporous templates.

  12. Synthesis of Cyclic Carbonates Catalysed by Aluminium Heteroscorpionate Complexes.

    PubMed

    Martínez, Javier; Castro-Osma, José A; Earlam, Amy; Alonso-Moreno, Carlos; Otero, Antonio; Lara-Sánchez, Agustín; North, Michael; Rodríguez-Diéguez, Antonio

    2015-06-26

    New aluminium scorpionate based complexes have been prepared and used for the synthesis of cyclic carbonates from epoxides and carbon dioxide. Bimetallic aluminium(heteroscorpionate) complexes 9-14 were synthesised in very high yields. The single-crystal X-ray structures of 12 and 13 confirm an asymmetric κ(2)-NO-μ-O arrangement in a dinuclear molecular disposition. These bimetallic aluminium complexes were investigated as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide in the presence of ammonium salts. Under the optimal reaction conditions, complex 9 in combination with tetrabutylammonium bromide acts as a very efficient catalyst system for the conversion of both monosubstituted and internal epoxides into the corresponding cyclic carbonates showing broad substrate scope. Complex 9 and tetrabutylammonium bromide is the second most efficient aluminium-based catalyst system for the reaction of internal epoxides with carbon dioxide. A kinetic study has been carried out and showed that the reactions were first order in complex 9 and tetrabutylammonium bromide concentrations. Based on the kinetic study, a catalytic cycle is proposed.

  13. Molecular Characterization of Aluminium (aluminum) Tolerance in Rye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminium (Al) toxicity, affecting around half of the world’s arable land, severely hinders the ability of crop plants to utilize moisture and nutrients by restricting root growth and function. Among the cultivated cereals, rye is the most Al-tolerant and represents an important potential source of ...

  14. Treatment of dairy effluents by electrocoagulation using aluminium electrodes.

    PubMed

    Tchamango, Serge; Nanseu-Njiki, Charles P; Ngameni, Emmanuel; Hadjiev, Dimiter; Darchen, André

    2010-01-15

    This work sets out to examine the efficiency of an electrolytic treatment: electrocoagulation, applied to dairy effluents. The experiments were carried out using a soluble aluminium anode on artificial wastewater derived from solutions of milk powder. The flocks generated during this treatment were separated by filtration. The analysis of the filtrates showed that the chemical oxygen demand (COD) was reduced by up to 61% while the removal of phosphorus, nitrogen contents, and turbidity were 89, 81 and 100%, respectively. An analogous treatment applied to phosphate and lactose solutions revealed that lactose was not eliminated, a fact that could account for the rather poor lowering of the COD. Compared to the chemical coagulation treatment with aluminium sulphate, the efficiency of the electrocoagulation technique was almost identical. However the wastewaters treated by electrocoagulation differed by the fact that they exhibited a lower conductivity and a neutral pH value (by contrast to the acid nature of the solution treated by the chemical coagulation). This result (low conductivity, neutral pH) tends to show that it may be possible to recycle the treated water for some industrial uses. Moreover, the electrocoagulation process uses fewer reagents: the mass of the aluminium anode dissolved during the treatment is lower compared to the quantity of the aluminium salt used in chemical coagulation. These two observations clearly show that the electrocoagulation technique is more performing.

  15. Sources and speciation of aluminium and silicon in natural waters.

    PubMed

    Farmer, V C

    1986-01-01

    The aluminosilicate minerals of igneous and metamorphic rocks are mostly unstable in earth-surface weathering conditions. In the tropics and subtropics, they are transformed to stable end-products (crystalline clay minerals, oxides and hydroxides) that largely conserve aluminium and iron. In noncalcareous soils in temperature and boreal climates, aluminium can be markedly mobile, and is precipitated as metastable products that include hydrous aluminosilicates, hydroxyaluminium polymers in or on 2:1 layer silicates, and complexes with soil organic matter. The aluminosilicate precipitates formed at pH less than 5.5 have structures related to imogolite, a unidimensional crystal in the form of a tube of 2.3 nm outer diameter. These metastable precipitates, both organic and inorganic, are readily remobilized on further acidification, and can release aluminium into streams if the solutions are not neutralized in the subsoil. Three classes of soluble aluminium species in natural waters have been distinguished by their rate of reaction with complexing reagents, and their rate of adsorption on cation-exchange columns. These are: (a) unreactive, acid-soluble, Al, (b) labile monomeric Al, and (c) non-liable monomeric Al. Group (b) includes simple inorganic species (e.g. Al3+, AlOH2+, AlF2+), and group (c) is thought to include organic complexes. In contrast, silicon occurs dominantly as Si(OH)4 monomers in natural water. Its metastable precipitates include hydrous aluminosilicates and biogenic opal.

  16. Wear Behaviour of Al-6061/SiC Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Mishra, Ashok Kumar; Srivastava, Rajesh Kumar

    2016-06-01

    Aluminium Al-6061 base composites, reinforced with SiC particles having mesh size of 150 and 600, which is fabricated by stir casting method and their wear resistance and coefficient of friction has been investigated in the present study as a function of applied load and weight fraction of SiC varying from 5, 10, 15, 20, 25, 30, 35 and 40 %. The dry sliding wear properties of composites were investigated by using Pin-on-disk testing machine at sliding velocity of 2 m/s and sliding distance of 2000 m over a various loads of 10, 20 and 30 N. The result shows that the reinforcement of the metal matrix with SiC particulates up to weight percentage of 35 % reduces the wear rate. The result also show that the wear of the test specimens increases with the increasing load and sliding distance. The coefficient of friction slightly decreases with increasing weight percentage of reinforcements. The wear surfaces are examined by optical microscopy which shows that the large grooved regions and cavities with ceramic particles are found on the worn surface of the composite alloy. This indicates an abrasive wear mechanism, which is essentially a result of hard ceramic particles exposed on the worn surfaces. Further, it was found from the experimentation that the wear rate decreases linearly with increasing weight fraction of SiC and average coefficient of friction decreases linearly with increasing applied load, weight fraction of SiC and mesh size of SiC. The best result has been obtained at 35 % weight fraction and 600 mesh size of SiC.

  17. An oxygen pumping anode for electrowinning aluminium.

    PubMed

    Liu, Changqing; Ji, Xiaobo; Zhang, Pingmin; Chen, Qiyuan; Banks, Craig E

    2013-05-01

    The chemical potential of oxygen ions at the novel oxygen pumping anode for electrowinning aluminum was manipulated by the electromotive forces to create thermodynamic stability. It is our anticipation that this newly designed anode can be applied to electrochemical metallurgy of other metals, such as the direct electrochemical reduction of TiO2 in the FFC process. PMID:23519386

  18. Conditioned Reinforcement and Response Strength

    PubMed Central

    Shahan, Timothy A

    2010-01-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration. PMID:20885815

  19. Conditioned reinforcement and response strength.

    PubMed

    Shahan, Timothy A

    2010-03-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration.

  20. Conditioned reinforcement and response strength.

    PubMed

    Shahan, Timothy A

    2010-03-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration. PMID:20885815

  1. Robust reinforcement learning.

    PubMed

    Morimoto, Jun; Doya, Kenji

    2005-02-01

    This letter proposes a new reinforcement learning (RL) paradigm that explicitly takes into account input disturbance as well as modeling errors. The use of environmental models in RL is quite popular for both offline learning using simulations and for online action planning. However, the difference between the model and the real environment can lead to unpredictable, and often unwanted, results. Based on the theory of H(infinity) control, we consider a differential game in which a "disturbing" agent tries to make the worst possible disturbance while a "control" agent tries to make the best control input. The problem is formulated as finding a min-max solution of a value function that takes into account the amount of the reward and the norm of the disturbance. We derive online learning algorithms for estimating the value function and for calculating the worst disturbance and the best control in reference to the value function. We tested the paradigm, which we call robust reinforcement learning (RRL), on the control task of an inverted pendulum. In the linear domain, the policy and the value function learned by online algorithms coincided with those derived analytically by the linear H(infinity) control theory. For a fully nonlinear swing-up task, RRL achieved robust performance with changes in the pendulum weight and friction, while a standard reinforcement learning algorithm could not deal with these changes. We also applied RRL to the cart-pole swing-up task, and a robust swing-up policy was acquired.

  2. Microstructure and mechanical behavior of 6061Al reinforced with silicon nitride particles, processed by powder metallurgy

    SciTech Connect

    Amigo, V.; Ortiz, J.L.; Salvador, M.D.

    2000-01-31

    A critical step in the processing of Metal Matrix Composites (MMCs) reinforced with ceramic particles is the insertion of these particles into the metal matrix alloy. This greatly influences the strength of the composite since it is controlled by the metal-particle interfacial bond strength. Because of the difficulty in wetting ceramic particles with molten metal, the Powder Metallurgy or PM route was developed. Powder Extrusion consolidates the composite to over 98% dense, and can be carried out below the Solidus Temperature of the alloy. The most important aspect of the microstructure is the distribution of the reinforcing particles, and this depends on the processing and fabrication routes involved, as well as the relative size of the matrix and reinforcing particles. Extrusion can homogenize the structure to some extent, but minimizing reinforcement inhomogeneity during initial processing is important to achieve optimum properties.

  3. Development and Mechanical Behavior of FML/Aluminium Foam Sandwiches

    NASA Astrophysics Data System (ADS)

    Baştürk, S. B.; Tanoğlu, M.

    2013-10-01

    In this study, the Fiber-Metal Laminates (FMLs) containing glass fiber reinforced polypropylene (GFPP) and aluminum (Al) sheet were consolidated with Al foam cores for preparing the sandwich panels. The aim of this article is the comparison of the flexural properties of FML/Al foam sandwich panels bonded with various surface modification approaches (silane treatment and combination of silane treatment with polypropylene (PP) based film addition). The FML/foam sandwich systems were fabricated by laminating the components in a mould at 200 °C under 1.5 MPa pressure. The energy absorbtion capacities and flexural mechanical properties of the prepared sandwich systems were evaluated by mechanical tests. Experiments were performed on samples of varying foam thicknesses (8, 20 and 30 mm). The bonding among the sandwich components were achieved by various surface modification techniques. The Al sheet/Al foam sandwiches were also consolidated by bonding the components with an epoxy adhesive to reveal the effect of GFPP on the flexural performance of the sandwich structures.

  4. Protective effect of curcumin (Curcuma longa), against aluminium toxicity: Possible behavioral and biochemical alterations in rats.

    PubMed

    Kumar, Anil; Dogra, Samrita; Prakash, Atish

    2009-12-28

    Aluminium is a potent neurotoxin and has been associated with Alzheimer's disease (AD) causality for decades. Prolonged aluminium exposure induces oxidative stress and increases amyloid beta levels in vivo. Current treatment modalities for AD provide only symptomatic relief thus necessitating the development of new drugs with fewer side effects. The aim of the study was to demonstrate the protective effect of chronic curcumin administration against aluminium-induced cognitive dysfunction and oxidative damage in rats. Aluminium chloride (100 mg/kg, p.o.) was administered to rats daily for 6 weeks. Rats were concomitantly treated with curcumin (per se; 30 and 60 mg/kg, p.o.) daily for a period of 6 weeks. On the 21st and 42nd day of the study behavioral studies to evaluate memory (Morris water maze and elevated plus maze task paradigms) and locomotion (photoactometer) were done. The rats were sacrificed on 43rd day following the last behavioral test and various biochemical tests were performed to assess the extent of oxidative damage. Chronic aluminium chloride administration resulted in poor retention of memory in Morris water maze, elevated plus maze task paradigms and caused marked oxidative damage. It also caused a significant increase in the acetylcholinesterase activity and aluminium concentration in aluminium treated rats. Chronic administration of curcumin significantly improved memory retention in both tasks, attenuated oxidative damage, acetylcholinesterase activity and aluminium concentration in aluminium treated rats (P<0.05). Curcumin has neuroprotective effects against aluminium-induced cognitive dysfunction and oxidative damage.

  5. Laminated sheet composites reinforced with modular filament sheet

    NASA Technical Reports Server (NTRS)

    Reece, O. Y.

    1968-01-01

    Aluminum and magnesium composite sheet laminates reinforced with low density, high strength modular filament sheets are produced by diffusion bonding and explosive bonding. Both processes are accomplished in normal atmosphere and require no special tooling or cleaning other than wire brushing the metal surfaces just prior to laminating.

  6. Solar-Array Substrate From Glass-Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Eirls, J. L.

    1985-01-01

    Design elminiates glass superstrate and associated metal framing. Panel has two trapezoidal stiffening ribs for structural support. Strategic placement of ribs with embedded support tubes (standard PVC tubing) minimizes bending moments and resulting stresses produced by installation and windloads. Glass-reinforced concrete panel has smooth flat surface suitable for solar substrate and includes structural bracing for rigidity and design adaptable to mass production.

  7. Reinforcement magnitude and responding during treatment with differential reinforcement.

    PubMed Central

    Lerman, Dorothea C; Kelley, Michael E; Vorndran, Christina M; Kuhn, Stephanie A C; LaRue, Robert H

    2002-01-01

    Basic findings indicate that the amount or magnitude of reinforcement can influence free-operant responding prior to and during extinction. In this study, the relation between reinforcement magnitude and adaptive behavior was evaluated with 3 children as part of treatment with differential reinforcement. In the first experiment, a communicative response was shaped and maintained by the same reinforcer that was found to maintain problem behavior. Two reinforcement magnitudes (20-s or 60-s access to toys or escape from demands) were compared and found to be associated with similar levels of resistance to extinction. The relation between reinforcement magnitude and response maintenance was further evaluated in the second experiment by exposing the communicative response to 20-s or 300-s access to toys or escape. Results for 2 participants suggested that this factor may alter the duration of postreinforcement pauses. PMID:11936544

  8. Reinforcement magnitude and responding during treatment with differential reinforcement.

    PubMed

    Lerman, Dorothea C; Kelley, Michael E; Vorndran, Christina M; Kuhn, Stephanie A C; LaRue, Robert H

    2002-01-01

    Basic findings indicate that the amount or magnitude of reinforcement can influence free-operant responding prior to and during extinction. In this study, the relation between reinforcement magnitude and adaptive behavior was evaluated with 3 children as part of treatment with differential reinforcement. In the first experiment, a communicative response was shaped and maintained by the same reinforcer that was found to maintain problem behavior. Two reinforcement magnitudes (20-s or 60-s access to toys or escape from demands) were compared and found to be associated with similar levels of resistance to extinction. The relation between reinforcement magnitude and response maintenance was further evaluated in the second experiment by exposing the communicative response to 20-s or 300-s access to toys or escape. Results for 2 participants suggested that this factor may alter the duration of postreinforcement pauses.

  9. Aluminium content of foods originating from aluminium-containing food additives.

    PubMed

    Ogimoto, Mami; Suzuki, Kumi; Haneishi, Nahoko; Kikuchi, Yuu; Takanashi, Mayu; Tomioka, Naoko; Uematsu, Yoko; Monma, Kimio

    2016-09-01

    Aluminium (Al) levels of 90 food samples were investigated. Nineteen samples contained Al levels exceeding the tolerable weekly intake (TWI) for young children [body weight (bw): 16 kg] when consuming two servings/week. These samples were purchased multiple times at specific intervals and were evaluated for Al levels. Al was detected in 27 of the 90 samples at levels ranging from 0.01 (limit of quantitation) to 1.06 mg/g. Of these, the Al intake levels in two samples (cookie and scone mix, 1.3 and 2 mg/kg bw/week, respectively) exceeded the TWI as established by European Food Safety Authority, although the level in the scone mix was equivalent to the provisional TWI (PTWI) as established by Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives. The Al levels markedly decreased in 14 of the 19 samples with initially high Al levels. These results indicated reductions in the Al levels to below the PTWI limits in all but two previously identified food samples.

  10. Aluminium content of foods originating from aluminium-containing food additives.

    PubMed

    Ogimoto, Mami; Suzuki, Kumi; Haneishi, Nahoko; Kikuchi, Yuu; Takanashi, Mayu; Tomioka, Naoko; Uematsu, Yoko; Monma, Kimio

    2016-09-01

    Aluminium (Al) levels of 90 food samples were investigated. Nineteen samples contained Al levels exceeding the tolerable weekly intake (TWI) for young children [body weight (bw): 16 kg] when consuming two servings/week. These samples were purchased multiple times at specific intervals and were evaluated for Al levels. Al was detected in 27 of the 90 samples at levels ranging from 0.01 (limit of quantitation) to 1.06 mg/g. Of these, the Al intake levels in two samples (cookie and scone mix, 1.3 and 2 mg/kg bw/week, respectively) exceeded the TWI as established by European Food Safety Authority, although the level in the scone mix was equivalent to the provisional TWI (PTWI) as established by Joint Food and Agriculture Organization of the United Nations/World Health Organization Expert Committee on Food Additives. The Al levels markedly decreased in 14 of the 19 samples with initially high Al levels. These results indicated reductions in the Al levels to below the PTWI limits in all but two previously identified food samples. PMID:27092423

  11. On the hot cracking susceptibility of a semisolid aluminium 6061 weld: Application of a coupled solidification- thermomechanical model

    NASA Astrophysics Data System (ADS)

    Zareie Rajani, H. R.; Phillion, A. B.

    2015-06-01

    A coupled solidification-thermomechanical model is presented that investigates the hot tearing susceptibility of an aluminium 6061 semisolid weld. Two key phenomena are considered: excessive deformation of the semisolid weld, initiating a hot tear, and the ability of the semisolid weld to heal the hot tear by circulation of the molten metal. The model consists of two major modules: weld solidification and thermomechanical analysis. 1) By means of a multi-scale model of solidification, the microstructural evolution of the semisolid weld is simulated in 3D. The semisolid structure, which varies as a function of welding parameters, is composed of solidifying grains and a network of micro liquid channels. The weld solidification module is utilized to obtain the solidification shrinkage. The size of the micro liquid channels is used as an indicator to assess the healing ability of the semisolid weld. 2) Using the finite element method, the mechanical interaction between the weld pool and the base metal is simulated to capture the transient force field deforming the semisolid weld. Thermomechanical stresses and shrinkage stresses are both considered in the analysis; the solidification contractions are extracted from the weld solidification module and applied to the deformation simulation as boundary conditions. Such an analysis enables characterization of the potential for excessive deformation of the weld. The outputs of the model are used to study the effect of welding parameters including welding current and speed, and also welding constraint on the hot cracking susceptibility of an aluminium alloy 6061 semisolid weld.

  12. Separation of actinides from irradiated An-Zr based fuel by electrorefining on solid aluminium cathodes in molten LiCl-KCl

    NASA Astrophysics Data System (ADS)

    Souček, P.; Murakami, T.; Claux, B.; Meier, R.; Malmbeck, R.; Tsukada, T.; Glatz, J.-P.

    2015-04-01

    An electrorefining process for metallic spent nuclear fuel treatment is being investigated in ITU. Solid aluminium cathodes are used for homogeneous recovery of all actinides within the process carried out in molten LiCl-KCl eutectic salt at a temperature of 500 °C. As the selectivity, efficiency and performance of solid Al has been already shown using un-irradiated An-Zr alloy based test fuels, the present work was focused on laboratory-scale demonstration of the process using irradiated METAPHIX-1 fuel composed of U67-Pu19-Zr10-MA2-RE2 (wt.%, MA = Np, Am, Cm, RE = Nd, Ce, Gd, Y). Different electrorefining techniques, conditions and cathode geometries were used during the experiment yielding evaluation of separation factors, kinetic parameters of actinide-aluminium alloy formation, process efficiency and macro-structure characterisation of the deposits. The results confirmed an excellent separation and very high efficiency of the electrorefining process using solid Al cathodes.

  13. The nature of sexual reinforcement.

    PubMed Central

    Crawford, L L; Holloway, K S; Domjan, M

    1993-01-01

    Sexual reinforcers are not part of a regulatory system involved in the maintenance of critical metabolic processes, they differ for males and females, they differ as a function of species and mating system, and they show ontogenetic and seasonal changes related to endocrine conditions. Exposure to a member of the opposite sex without copulation can be sufficient for sexual reinforcement. However, copulatory access is a stronger reinforcer, and copulatory opportunity can serve to enhance the reinforcing efficacy of stimulus features of a sexual partner. Conversely, under certain conditions, noncopulatory exposure serves to decrease reinforcer efficacy. Many common learning phenomena such as acquisition, extinction, discrimination learning, second-order conditioning, and latent inhibition have been demonstrated in sexual conditioning. These observations extend the generality of findings obtained with more conventional reinforcers, but the mechanisms of these effects and their gender and species specificity remain to be explored. PMID:8354970

  14. [Reinforcement learning by striatum].

    PubMed

    Kunisato, Yoshihiko; Okada, Go; Okamoto, Yasumasa

    2009-04-01

    Recently, computational models of reinforcement learning have been applied for the analysis of neuroimaging data. It has been clarified that the striatum plays a key role in decision making. We review the reinforcement learning theory and the biological structures such as the brain and signals such as neuromodulators associated with reinforcement learning. We also investigated the function of the striatum and the neurotransmitter serotonin in reward prediction. We first studied the brain mechanisms for reward prediction at different time scales. Our experiment on the striatum showed that the ventroanterior regions are involved in predicting immediate rewards and the dorsoposterior regions are involved in predicting future rewards. Further, we investigated whether serotonin regulates both the reward selection and the striatum function are specialized reward prediction at different time scales. To this end, we regulated the dietary intake of tryptophan, a precursor of serotonin. Our experiment showed that the activity of the ventral part of the striatum was correlated with reward prediction at shorter time scales, and this activity was stronger at low serotonin levels. By contrast, the activity of the dorsal part of the striatum was correlated with reward prediction at longer time scales, and this activity was stronger at high serotonin levels. Further, a higher proportion of small reward choices, together with a higher rate of discounting of delayed rewards is observed in the low-serotonin condition than in the control and high-serotonin conditions. Further examinations are required in future to assess the relation between the disturbance of reward prediction caused by low serotonin and mental disorders related to serotonin such as depression.

  15. Exchangeable and secondary mineral reactive pools of aluminium in coastal lowland acid sulfate soils.

    PubMed

    Yvanes-Giuliani, Yliane A M; Waite, T David; Collins, Richard N

    2014-07-01

    The use of coastal floodplain sulfidic sediments for agricultural activities has resulted in the environmental degradation of many areas worldwide. The generation of acidity and transport of aluminium (Al) and other metals to adjacent aquatic systems are the main causes of adverse effects. Here, a five-step sequential extraction procedure (SEP) was applied to 30 coastal lowland acid sulfate soils (CLASS) from north-eastern New South Wales, Australia. This enabled quantification of the proportion of aluminium present in 'water-soluble', 'exchangeable', 'organically-complexed', 'reducible iron(III) (oxyhydr)oxide/hydroxysulfate-incorporated' and 'amorphous Al mineral' fractions. The first three extractions represented an average of 5% of 'aqua regia' extractable Al and their cumulative concentrations were extremely high, reaching up to 4000 mg·kg(-1). Comparison of Al concentrations in the final two extractions indicated that 'amorphous Al minerals' are quantitatively a much more important sink for the removal of aqueous Al derived from the acidic weathering of these soils than reducible Fe(III) minerals. Correlations were observed between soil pH, dissolved and total organic carbon (DOC and TOC) and Al concentrations in organic carbon-rich CLASS soil horizons. These results suggest that complexation of Al by dissolved organic matter significantly increases soluble Al concentrations at pH values >5.0. As such, present land management practices would benefit with redefinition of an 'optimal' soil from pH ≥5.5 to ~4.8 for the preservation of aquatic environments adjacent to organic-rich CLASS where Al is the sole or principle inorganic contaminant of concern. Furthermore, it was observed that currently-accepted standard procedures (i.e. 1 M KCl extraction) to measure exchangeable Al concentrations in these types of soils severely underestimate exchangeable Al and a more accurate representation may be obtained through the use of 0.2 M CuCl2.

  16. Extrusion Die Design and Process Simulation of High Strength Aluminium Alloy

    NASA Astrophysics Data System (ADS)

    Sheu, Jinn-Jong; Chen, Yan-Hong; Su, Guan-Cheng

    2011-01-01

    Aluminium alloy 7075 is an excellent metal with the features of high strength and light weight. The solid extruded parts of AL 7075 are commonly used in the structure members of airplanes and bicycles. The seamless tubes of AL 7075 are also used, while tubes with welding line (seamed) are mainly made by the other types of aluminium alloy. This research is focused on the extrusion die design and process simulation of the rectangular seamed AL 7075 tubes. A new die design concept is proposed to increase the welding pressure in the chamber to solve the problem of poor welding ability of AL 7075. The key points of welding ability improvement are the higher welding pressure, the crucial billet temperature, and the extrusion speed. The designed extrusion die should have some features to control the material flow and achieve the higher welding pressure. In this paper, not only use the traditional die bearing and the welding chamber, but also add a conical guiding chamber (specified with chamber height and width) to improve the material flow control. Finite element method is used to simulate the extrusion process and evaluate the effect of die design parameters for a seamed rectangular 7075 tube extrusion. The die stress should be considered carefully because of increasing the welding pressure also increases the die stress. Taguchi method is used to obtain the optimum combination of die design parameters to get higher welding pressure and keep the die stress at a reasonable low level. The method proposed in this paper is able to increase the welding pressure with the cost of reasonable die stress.

  17. Aluminium in food and daily dietary intake assessment from 15 food groups in Zhejiang Province, China.

    PubMed

    Zhang, Hexiang; Tang, Jun; Huang, Lichun; Shen, Xianghong; Zhang, Ronghua; Chen, Jiang

    2016-06-01

    Aluminium was measured in 2580 samples of 15 food groups and dietary exposure was estimated. Samples were purchased and analysed during 2010 to 2014. High aluminium levels were found in jellyfish (mean 4862 mg/kg), laver (mean 455.2 mg/kg) and fried twisted cruller (mean 392.4 mg/kg). Dietary exposure to aluminium was estimated for Zhejiang residents. The average dietary exposure to aluminium via 15 food groups in Zhejiang Province was 1.15 mg/kg bw/week, which is below the provisional tolerable weekly intake of 2 mg/kg bw /week. Jellyfish is the main Al contributor, providing 37.6% of the daily intake via these 15 food groups. This study provided new information on aluminium levels and assessment of aluminium (Al) dietary exposure in Zhejiang Province of China. PMID:26727195

  18. RESPONSE OF PHENOLIC METABOLISM INDUCED BY ALUMINIUM TOXICITY IN FAGOPYRUM ESCULENTUM MOENCH. PLANTS.

    PubMed

    Smirnov, O E; Kosyan, A M; Kosyk, O I; Taran, N Yu

    2015-01-01

    Buckwheat genus (Fagopyrum Mill.) is one of the aluminium tolerant taxonomic units of plants. The aim of the study was an evaluation of the aluminium (50 μM effect on phenolic accumulation in various parts of buckwheat plants (Fagopyrum esculentum Moench). Detection of increasing of total phenolic content, changes in flavonoid and anthocyanin content and phenylalanine ammonia-lyase activity (PAL) were revealed over a period of 10 days of exposure to aluminium. The most significant effects of aluminium treatment on phenolic compounds accumulation were total phenolic content increasing (by 27.2%) and PAL activity rising by 2.5 times observed in leaves tissues. Received data could be helpful to understand the aluminium tolerance principles and relationships of phenolic compounds to aluminium phytotoxicity.

  19. RESPONSE OF PHENOLIC METABOLISM INDUCED BY ALUMINIUM TOXICITY IN FAGOPYRUM ESCULENTUM MOENCH. PLANTS.

    PubMed

    Smirnov, O E; Kosyan, A M; Kosyk, O I; Taran, N Yu

    2015-01-01

    Buckwheat genus (Fagopyrum Mill.) is one of the aluminium tolerant taxonomic units of plants. The aim of the study was an evaluation of the aluminium (50 μM effect on phenolic accumulation in various parts of buckwheat plants (Fagopyrum esculentum Moench). Detection of increasing of total phenolic content, changes in flavonoid and anthocyanin content and phenylalanine ammonia-lyase activity (PAL) were revealed over a period of 10 days of exposure to aluminium. The most significant effects of aluminium treatment on phenolic compounds accumulation were total phenolic content increasing (by 27.2%) and PAL activity rising by 2.5 times observed in leaves tissues. Received data could be helpful to understand the aluminium tolerance principles and relationships of phenolic compounds to aluminium phytotoxicity. PMID:27025067

  20. Fiber reinforced superalloys

    NASA Technical Reports Server (NTRS)

    Petrasek, Donald W.; Signorelli, Robert A.; Caulfield, Thomas; Tien, John K.

    1987-01-01

    Improved performance of heat engines is largely dependent upon maximum cycle temperatures. Tungsten fiber reinforced superalloys (TFRS) are the first of a family of high temperature composites that offer the potential for significantly raising hot component operating temperatures and thus leading to improved heat engine performance. This status review of TFRS research emphasizes the promising property data developed to date, the status of TFRS composite airfoil fabrication technology, and the areas requiring more attention to assure their applicability to hot section components of aircraft gas turbine engines.

  1. Numerical Modelling of Drawbeads for Forming of Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Joshi, Y.; Christiansen, P.; Masters, I.; Bay, N.; Dashwood, R.

    2016-08-01

    The drawbeads in stamping tools are usually designed based on experience from the forming of steel. However, aluminium alloys display different forming behaviour to steels, which is not reflected in the drawbead design for tools used for stamping aluminium. This paper presents experimental results from different semi-circular drawbead geometries commonly encountered in automotive dies and compares them to those obtained from Stoughton's analytical drawbead model and the 2D plane strain drawbead model set up using LS-DYNA. The study was conducted on lubricated NG5754 strips. The results presented are in terms of drawbead restraining force versus strip displacement, as a function of drawbead depth. The FE drawbead model agrees well with the experiments whereas the analytical model overpredicted the drawbead forces.

  2. Prediction of the ballistic limit of an aluminium sandwich panel

    NASA Astrophysics Data System (ADS)

    Campbell, J.; De Vuyst, T.; Vignjevic, R.; Hughes, K.

    2016-08-01

    This paper presents research on modelling the impact of a 150g projectile on a 35mm thick aluminium sandwich panel. The objective of the work is a predictive modelling capability for the ballistic limit of the panel. A predictive modelling capability supports the design of capture and deorbit missions for large items of space debris such as satellites and rocket upper stages. A detailed explicit finite element model was built using the LSDYNA software and results were compared with experimental data for the projectile exit velocity to establish key parameters. The primary parameters influencing the model behaviour were the strength and failure of the aluminium face sheets and the friction between projectile and panel. The model results showed good agreement with experimental results for ogive nose projectiles, but overestimated the exit velocity for flat nose projectiles.

  3. Evaluation of femtosecond LIBS for spectrochemical microanalysis of aluminium alloys.

    PubMed

    Cravetchi, Igor V; Taschuk, Mike T; Tsui, Ying Y; Fedosejevs, Robert

    2006-05-01

    The analytical performance of femtosecond laser-induced breakdown spectroscopy (LIBS) for elemental microanalysis of aluminium alloys and for mapping precipitate distribution on the sample surface has been studied in detail. A Ti-sapphire laser system producing pulses of 130 fs at 800 nm was used to generate the laser-induced plasma. Multi-element microanalysis of commercially available aluminium alloys was performed in air at atmospheric pressure. Crater characteristics such as diameter and crater morphology were characterized by optical and scanning-electron microscopy. Scaling of plasma emission and limit of detection as a function of laser pulse energy was also investigated. Current experimental results are presented and are compared with previous nanosecond microLIBS measurements.

  4. Experimental evidence for a dynamical crossover in liquid aluminium.

    PubMed

    Demmel, F; Fraile, A; Szubrin, D; Pilgrim, W-C; Morkel, C

    2015-11-18

    The temperature dependence of the dynamic structure factor at next-neighbour distances has been investigated for liquid aluminium. This correlation function is a sensitive parameter for changes in the local environment and its Fourier transform was measured in a coherent inelastic neutron scattering experiment. The zero frequency amplitude decreases in a nonlinear way and indicates a change in dynamics around 1.4 ∙ Tmelting. From that amplitude a generalized viscosity can be derived which is a measure of local stress correlations on next-neighbour distances. The derived generalized longitudinal viscosity shows a changing slope at the same temperature range. At this temperature the freezing out of degrees of freedom for structural relaxation upon cooling sets in which can be understood as a precursor towards the solid state. That crossover in dynamics of liquid aluminium shows the same signatures as previously observed in liquid rubidium and lead, indicating an universal character. PMID:26465204

  5. Modelling of aluminium sheet forming at elevated temperatures

    NASA Astrophysics Data System (ADS)

    van den Boogaard, A. H.; Huétink, J.

    2004-06-01

    The formability of Al-Mg sheet can be improved considerably, by increasing the temperature. By heating the sheet in areas with large shear strains, but cooling it on places where the risk of necking is high, the limiting drawing ratio can be increased to values above 2.5. At elevated temperatures, the mechanical response of the material becomes strain rate dependent. To accurately simulate warm forming of aluminium sheet, a material model is required that incorporates the temperature and strain-rate dependency. In this paper simulations are presented of the deep drawing of a cylindrical cup, using shell elements. It is demonstrated that the familiar quadratic Hill yield function is not capable of describing the plastic deformation of aluminium. Hardening can be described successfully with a physically based material model for temperatures up to 200 °C. At higher temperatures and very low strain rates, the flow curve deviates significantly from the model.

  6. Histopathological changes in cases of aluminium phosphide poisoning.

    PubMed

    Sinha, U S; Kapoor, A K; Singh, A K; Gupta, A; Mehrotra, Ravi

    2005-04-01

    Of a total of 205 poisoning deaths in our hospital in 2003, 83 cases were due to Aluminium phosphide poisoning and were further analyzed. Most vulnerable age group was 21-40 years and M:F ratio was 2:1. On naked eye examination, almost all the vital organs were found to be congested. On microscopic study, the liver showed central venous congestion, degeneration, haemorrhage, sinusoidal dilation, bile stasis, centrilobular necrosis, Kupffer cell hyperplasia, infiltration by mononuclear cells and fatty change. Microscopy of the lungs revealed alveolar thickening, oedema, dilated capillaries, collapsed alveoli and haemorrhage. In the kidney, changes were degeneration, infiltration, tubular dilation and cloudy swelling. Changes in the brain included congestion and coagulative necrosis and in the stomach, congestion and haemorrhage. Easy availability of this cheap and highly toxic substance was responsible for the sudden spurt of poisoning with aluminium phosphide. PMID:16758658

  7. Structural elucidation of crystallization centers in aluminium inoculated with titanium

    SciTech Connect

    Banerji, A.; Reif, W. . Inst. fuer Metallforschung-Metallkunde); Feng, Q. . Dept. of Materials Science and Engineering)

    1993-08-01

    The heterogeneous nucleation process in commercially pure aluminium (99.7%) castings inoculated with hypoperitectic titanium additions (<0.15%) was investigated. Electron diffraction of the crystallization center particles, which formed in situ by reaction of added titanium with carbon impurity in the melt and subsequently nucleated [alpha]-aluminium, showed that they were essentially composed of Ti[sub 2]C, having orthorhombic lattice with a = 1.2 nm, b = 1.06 nm and c = 0.50 nm, and stoichiometric TiC, having cubic lattice with a = 0.4380 nm. Traces of Ti[sub 3]AlC and Al[sub 4]C[sub 3] were recorded only in rare cases.

  8. [The systems process of reinforcement].

    PubMed

    Sudakov, K V

    1996-01-01

    The process of reinforcement is considered in the context of the general theory of functional systems as an important part of behavioural act organization closely interacting with the dominant motivation. It is shown that reinforcement substantially changes the activities of separate neurons in different brain structures involved in dominant motivation. After a preliminary reinforcement under the influence of corresponding motivation the ribosomal apparatus of neurons begins to synthesize special molecular engrams of the action acceptor. The sensory mechanisms of reinforcement and, especially, the role of emotions are considered in details in the paper.

  9. The precipitation of potassium aluminium sulphate from aqueous solution

    NASA Astrophysics Data System (ADS)

    Mullin, J. W.; Žáček, S.

    1981-06-01

    A precipitation study has been made with potassium aluminium sulphate (potash alum) produced by mixing aqueous solutions of its constituent salts. Rates of nucleation, as indicated by the induction period, were measured for both agitated and non-agitated solutions over the temperature range 15-35°C. Nucleation rates increase with increases in agitation, temperature and supersaturation, but the latter has the dominant effect, as predicted by classical nucleation theory. The temperature-dependence of the interfacial tension is evaluated.

  10. Lewis acid fragmentation of a lithium aryloxide cage: generation of new heterometallic aluminium-lithium species.

    PubMed

    Muñoz, Ma Teresa; Urbaneja, Carmen; Temprado, Manuel; Mosquera, Marta E G; Cuenca, Tomás

    2011-11-14

    Heterometallic aluminium-lithium species were prepared by the fragmentation reaction of the hexametallic cage compound [Li{2,6-(MeO)(2)C(6)H(3)O}](6) (1) with alkyl aluminium derivatives. Depending on the aluminium precursor, the species formed present different nuclearities in the solid state as shown by single crystal X-ray analysis. Spectroscopic and computational studies have been performed to study the nuclearity of the synthesized compounds in solution.

  11. High rate constitutive modeling of aluminium alloy tube

    NASA Astrophysics Data System (ADS)

    Salisbury, C. P.; Worswick, M. J.; Mayer, R.

    2006-08-01

    As the need for fuel efficient automobiles increases, car designers are investigating light-weight materials for automotive bodies that will reduce the overall automobile weight. Aluminium alloy tube is a desirable material to use in automotive bodies due to its light weight. However, aluminium suffers from lower formability than steel and its energy absorption ability in a crash event after a forming operation is largely unknown. As part of a larger study on the relationship between crashworthiness and forming processes, constitutive models for 3mm AA5754 aluminium tube were developed. A nominal strain rate of 100/s is often used to characterize overall automobile crash events, whereas strain rates on the order of 1000/s can occur locally. Therefore, tests were performed at quasi-static rates using an Instron test fixture and at strain rates of 500/s to 1500/s using a tensile split Hopkinson bar. High rate testing was then conducted at rates of 500/s, 1000/s and 1500/s at 21circC, 150circC and 300circC. The generated data was then used to determine the constitutive parameters for the Johnson-Cook and Zerilli-Armstrong material models.

  12. Stock dynamics and emission pathways of the global aluminium cycle

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  13. Toxicity of indium arsenide, gallium arsenide, and aluminium gallium arsenide.

    PubMed

    Tanaka, Akiyo

    2004-08-01

    Gallium arsenide (GaAs), indium arsenide (InAs), and aluminium gallium arsenide (AlGaAs) are semiconductor applications. Although the increased use of these materials has raised concerns about occupational exposure to them, there is little information regarding the adverse health effects to workers arising from exposure to these particles. However, available data indicate these semiconductor materials can be toxic in animals. Although acute and chronic toxicity of the lung, reproductive organs, and kidney are associated with exposure to these semiconductor materials, in particular, chronic toxicity should pay much attention owing to low solubility of these materials. Between InAs, GaAs, and AlGaAs, InAs was the most toxic material to the lung followed by GaAs and AlGaAs when given intratracheally. This was probably due to difference in the toxicity of the counter-element of arsenic in semiconductor materials, such as indium, gallium, or aluminium, and not arsenic itself. It appeared that indium, gallium, or aluminium was toxic when released from the particles, though the physical character of the particles also contributes to toxic effect. Although there is no evidence of the carcinogenicity of InAs or AlGaAs, GaAs and InP, which are semiconductor materials, showed the clear evidence of carcinogenic potential. It is necessary to pay much greater attention to the human exposure of semiconductor materials.

  14. Research progress of aluminium alloy endplates for PEMFCs

    NASA Astrophysics Data System (ADS)

    Fu, Yu; Hou, Ming; Yan, Xiqiang; Hou, Junbo; Luo, Xiaokuan; Shao, Zhigang; Yi, Baolian

    The endplate is a crucial component in a proton exchange membrane fuel cell (PEMFC) stack. It can provide the necessary rigidity and strength for the stack. An aluminium alloy is one of the ideal materials for PEMFC endplates because of its low density and high rigidity. But it does not meet the requirements of corrosion resistance and electrical insulation in PEMFC environments. In this work, methods of sealing treatments and the conditions of aluminium alloy anodization were investigated. Corrosion resistances of the samples prepared by different technologies were evaluated in simulated PEMFC environments. The results showed that the corrosion resistance of the samples sealed by epoxy resin was greatly improved compared with those sealed in boiling water, and the samples anodized at a constant current density performed better than those anodized at a constant voltage. By insulation measurements, all of the samples showed good electrical insulation. The aluminium alloy endplate anodized at a constant current density and sealed with thermosetting bisphenol-A epoxy resin exhibited promising potential for practical applications by assembling it in a PEMFC stack and applying a life test.

  15. Modelling of detonation cellular structure in aluminium suspensions

    NASA Astrophysics Data System (ADS)

    Briand, A.; Veyssiere, B.; Khasainov, B. A.

    2010-12-01

    Heterogeneous detonations involving aluminium suspensions have been studied for many years for industrial safety policies, and for military and propulsion applications. Owing to their weak detonability and to the lack of available experimental results on the detonation cellular structure, numerical simulations provide a convenient way to improve the knowledge of such detonations. One major difficulty arising in numerical study of heterogeneous detonations involving suspensions of aluminium particles in oxidizing atmospheres is the modelling of aluminium combustion. Our previous two-step model provided results on the effect on the detonation cellular structure of particle diameter and characteristic chemical lengths. In this study, a hybrid model is incorporated in the numerical code EFAE, combining both kinetic and diffusion regimes in parallel. This more realistic model provides good agreement with the previous two-step model and confirms the correlations found between the detonation cell width, and particle diameter and characteristic lengths. Moreover, the linear dependence found between the detonation cell width and the induction length remains valid with the hybrid model.

  16. Aluminium localization in root tips of the aluminium-accumulating plant species buckwheat (Fagopyrum esculentum Moench).

    PubMed

    Klug, Benjamin; Specht, André; Horst, Walter J

    2011-11-01

    Aluminium (Al) uptake and transport in the root tip of buckwheat is not yet completely understood. For localization of Al in root tips, fluorescent dyes and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were compared. The staining of Al with morin is an appropriate means to study qualitatively the radial distribution along the root tip axis of Al which is complexed by oxalate and citrate in buckwheat roots. The results compare well with the distribution of total Al determined by LA-ICP-MS which could be reliably calibrated to compare with Al contents by conventional total Al determination using graphite furnace atomic absorption spectrometry. The Al localization in root cross-sections along the root tip showed that in buckwheat Al is highly mobile in the radial direction. The root apex predominantly accumulated Al in the cortex. The subapical root section showed a homogenous Al distribution across the whole section. In the following root section Al was located particularly in the pericycle and the xylem parenchyma cells. With further increasing distance from the root apex Al could be detected only in individual xylem vessels. The results support the view that the 10 mm apical root tip is the main site of Al uptake into the symplast of the cortex, while the subapical 10-20 mm zone is the main site of xylem loading through the pericycle and xylem parenchyma cells. Progress in the better molecular understanding of Al transport in buckwheat will depend on the consideration of the tissue specificity of Al transport and complexation.

  17. The effects of aluminium on plant growth in a temperate and deciduous aluminium accumulating species

    PubMed Central

    Schmitt, Marco; Watanabe, Toshihiro; Jansen, Steven

    2016-01-01

    Aluminium (Al) is a phytotoxic element affecting the growth and yield of many crop plants, especially in the tropics. Yet, some plants are able to accumulate high levels of Al. The monogeneric family Symplocaceae represents an Al accumulating family including many tropical and evergreen species with high Al levels in their above ground plant tissues. It is unclear, however, whether Al accumulation also characterises temperate species of Symplocos, and whether or not the uptake has a beneficial growth effect. Here, we investigate if the temperate, deciduous species Symplocos paniculata is able to accumulate Al by growing seedlings and saplings in a hydroponic setup at pH 4 with and without Al. Pyrocatechol-violet (PCV) and aluminon staining was performed to visualize Al accumulation in various plant tissues. Both seedlings and saplings accumulate Al in their tissues if available. Mean Al levels in leaves were 4107 (±1474 mg kg−1) and 4290 (±4025 mg kg−1) for the seedlings and saplings, respectively. The saplings treated without Al showed a high mortality rate unlike the Al accumulating ones. The seedlings, however, showed no difference in growth and vitality between the two treatments. The saplings treated with Al showed new twig, leaf and root development, resulting in a considerable biomass increase. PCV and aluminon staining indicated the presence of Al in leaf, wood and bark tissue of the plants. S. paniculata shares the capacity to accumulate Al with its tropical sister species and is suggested to be a facultative accumulator. Whether or not Al has a beneficial effect remains unclear, due to developmental differences between seedlings and saplings. Al is suggested to be transported via the xylem transport system into the leaves, which show the highest Al levels. Radial transport via ray parenchyma to bark tissue is also likely given the high Al concentrations in the bark tissue. PMID:27613876

  18. Material efficiency: rare and critical metals.

    PubMed

    Ayres, Robert U; Peiró, Laura Talens

    2013-03-13

    In the last few decades, progress in electronics, especially, has resulted in important new uses for a number of geologically rare metals, some of which were mere curiosities in the past. Most of them are not mined for their own sake (gold, the platinum group metals and the rare Earth elements are exceptions) but are found mainly in the ores of the major industrial metals, such as aluminium, copper, zinc and nickel. We call these major metals 'attractors' and the rare accompanying metals 'hitch-hikers'. The key implication is that rising prices do not necessarily call forth greater output because that would normally require greater output of the attractor metal. We trace the geological relationships and the functional uses of these metals. Some of these metals appear to be irreplaceable in the sense that there are no known substitutes for them in their current functional uses. Recycling is going to be increasingly important, notwithstanding a number of barriers. PMID:23359734

  19. Quantum reinforcement learning.

    PubMed

    Dong, Daoyi; Chen, Chunlin; Li, Hanxiong; Tarn, Tzyh-Jong

    2008-10-01

    The key approaches for machine learning, particularly learning in unknown probabilistic environments, are new representations and computation mechanisms. In this paper, a novel quantum reinforcement learning (QRL) method is proposed by combining quantum theory and reinforcement learning (RL). Inspired by the state superposition principle and quantum parallelism, a framework of a value-updating algorithm is introduced. The state (action) in traditional RL is identified as the eigen state (eigen action) in QRL. The state (action) set can be represented with a quantum superposition state, and the eigen state (eigen action) can be obtained by randomly observing the simulated quantum state according to the collapse postulate of quantum measurement. The probability of the eigen action is determined by the probability amplitude, which is updated in parallel according to rewards. Some related characteristics of QRL such as convergence, optimality, and balancing between exploration and exploitation are also analyzed, which shows that this approach makes a good tradeoff between exploration and exploitation using the probability amplitude and can speedup learning through the quantum parallelism. To evaluate the performance and practicability of QRL, several simulated experiments are given, and the results demonstrate the effectiveness and superiority of the QRL algorithm for some complex problems. This paper is also an effective exploration on the application of quantum computation to artificial intelligence.

  20. Recycling of Reinforced Plastics

    NASA Astrophysics Data System (ADS)

    Adams, R. D.; Collins, Andrew; Cooper, Duncan; Wingfield-Digby, Mark; Watts-Farmer, Archibald; Laurence, Anna; Patel, Kayur; Stevens, Mark; Watkins, Rhodri

    2014-02-01

    This work has shown is that it is possible to recycle continuous and short fibre reinforced thermosetting resins while keeping almost the whole of the original material, both fibres and matrix, within the recyclate. By splitting, crushing hot or cold, and hot forming, it is possible to create a recyclable material, which we designate a Remat, which can then be used to remanufacture other shapes, examples of plates and tubes being demonstrated. Not only can remanufacturing be done, but it has been shown that over 50 % of the original mechanical properties, such as the E modulus, tensile strength, and interlaminar shear strength, can be retained. Four different forms of composite were investigated, a random mat Glass Fibre Reinforced Plastic (GFRP) bathroom component and boat hull, woven glass and carbon fibre cloth impregnated with an epoxy resin, and unidirectional carbon fibre pre-preg. One of the main factors found to affect composite recyclability was the type of resin matrix used in the composite. Thermoset resins tested were shown to have a temperature range around the Glass Transition Temperature (Tg) where they exhibit ductile behaviour, hence aiding reforming of the material. The high-grade carbon fibre prepreg was found to be less easy to recycle than the woven of random fibre laminates. One method of remanufacturing was by heating the Remat to above its glass transition temperature, bending it to shape, and then cooling it. However, unless precautions are taken, the geometric form may revert. This does not happen with the crushed material.

  1. Quantum reinforcement learning.

    PubMed

    Dong, Daoyi; Chen, Chunlin; Li, Hanxiong; Tarn, Tzyh-Jong

    2008-10-01

    The key approaches for machine learning, particularly learning in unknown probabilistic environments, are new representations and computation mechanisms. In this paper, a novel quantum reinforcement learning (QRL) method is proposed by combining quantum theory and reinforcement learning (RL). Inspired by the state superposition principle and quantum parallelism, a framework of a value-updating algorithm is introduced. The state (action) in traditional RL is identified as the eigen state (eigen action) in QRL. The state (action) set can be represented with a quantum superposition state, and the eigen state (eigen action) can be obtained by randomly observing the simulated quantum state according to the collapse postulate of quantum measurement. The probability of the eigen action is determined by the probability amplitude, which is updated in parallel according to rewards. Some related characteristics of QRL such as convergence, optimality, and balancing between exploration and exploitation are also analyzed, which shows that this approach makes a good tradeoff between exploration and exploitation using the probability amplitude and can speedup learning through the quantum parallelism. To evaluate the performance and practicability of QRL, several simulated experiments are given, and the results demonstrate the effectiveness and superiority of the QRL algorithm for some complex problems. This paper is also an effective exploration on the application of quantum computation to artificial intelligence. PMID:18784007

  2. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Mackenzie, A.; Dance, D. R.; Young, K. C.

    2013-04-01

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

  3. Dietary exposure to aluminium and health risk assessment in the residents of Shenzhen, China.

    PubMed

    Yang, Mei; Jiang, Lixin; Huang, Huiping; Zeng, Shengbo; Qiu, Fen; Yu, Miao; Li, Xiaorong; Wei, Sheng

    2014-01-01

    Although there are great changes of dietary in the past few decades in China, few are known about the aluminium exposure in Chinese diet. The aim of this study is to systematically evaluate the dietary aluminium intake level in residents of Shenzhen, China. A total of 853 persons from 244 household were investigated their diet by three days food records. Finally, 149 kinds of foods in 17 food groups were selected to be the most consumed foods. From them, 1399 food samples were collected from market to test aluminium concentration. High aluminium levels were found in jellyfish (median, 527.5 mg/kg), fried twisted cruller (median, 466.0 mg/kg), shell (median, 107.1 mg/kg). The Shenzhen residents' average dietary aluminium exposure was estimated at 1.263 mg/kg bw/week which is lower than the PTWI (provisional tolerable weekly intake). But 0-2 and 3-13 age groups have the highest aluminium intake exceeding the PTWI (3.356 mg/kg bw/week and 3.248 mg/kg bw/week) than other age groups. And the main dietary aluminium exposure sources are fried twisted cruller, leaf vegetables and bean products. Our study suggested that even three decades rapid economy development, children in Shenzhen still have high dietary aluminium exposure risk. How to control high dietary aluminium exposure still is a great public health challenge in Shenzhen, China.

  4. Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate.

    PubMed

    Warren, L M; Mackenzie, A; Dance, D R; Young, K C

    2013-04-01

    Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

  5. Neuroprotective effect of Allium cepa L. in aluminium chloride induced neurotoxicity.

    PubMed

    Singh, Tanveer; Goel, Rajesh Kumar

    2015-07-01

    The present study was envisaged to investigate the neuroprotective potential of Allium cepa (A. cepa) in aluminium chloride induced neurotoxicity. Aluminium chloride (50 mg/kg/day) was administered orally in mice supplemented with different doses of A. cepa hydroethanolic extract for a period of 60 days. Various behavioural, biochemical and histopathological parameters were estimated in aluminium exposed animals. Chronic aluminium administration resulted in significant motor incoordination and memory deficits, which were also endorsed biochemically as there was increased oxidative stress as well as elevated acetylcholinesterase (AChE) and aluminium levels in the brain. Supplementation with A. cepa in aluminium exposed animals significantly improved muscle coordination and memory deficits as well as reduced oxidative stress, AChE and decreased abnormal aluminium deposition in the brain. Histopathologically, there was marked deterioration visualized as decreased vacuolated cytoplasm as well as decreased pyramidal cells in the hippocampal area of mice brain which were found to be reversed with A. cepa supplementation. Administration of BADGE (PPARγ antagonist) in aluminium exposed animals reversed the neuroprotective potential of A. cepa as assessed with various behavioural, biochemical, neurochemical and histopathological estimations. In conclusion, finding of this study suggested significant neuroprotective potential of A. cepa in aluminium induced neurotoxicity. Further, the role of PPARγ receptor agonism has also been suggested as a putative neuroprotective mechanism of A. cepa, which needs further studies for confirmation.

  6. Dietary Exposure to Aluminium and Health Risk Assessment in the Residents of Shenzhen, China

    PubMed Central

    Yang, Mei; Jiang, Lixin; Huang, Huiping; Zeng, Shengbo; Qiu, Fen; Yu, Miao; Li, Xiaorong; Wei, Sheng

    2014-01-01

    Although there are great changes of dietary in the past few decades in China, few are known about the aluminium exposure in Chinese diet. The aim of this study is to systematically evaluate the dietary aluminium intake level in residents of Shenzhen, China. A total of 853 persons from 244 household were investigated their diet by three days food records. Finally, 149 kinds of foods in 17 food groups were selected to be the most consumed foods. From them, 1399 food samples were collected from market to test aluminium concentration. High aluminium levels were found in jellyfish (median, 527.5 mg/kg), fried twisted cruller (median, 466.0 mg/kg), shell (median, 107.1 mg/kg). The Shenzhen residents' average dietary aluminium exposure was estimated at 1.263 mg/kg bw/week which is lower than the PTWI (provisional tolerable weekly intake). But 0–2 and 3–13 age groups have the highest aluminium intake exceeding the PTWI (3.356 mg/kg bw/week and 3.248 mg/kg bw/week) than other age groups. And the main dietary aluminium exposure sources are fried twisted cruller, leaf vegetables and bean products. Our study suggested that even three decades rapid economy development, children in Shenzhen still have high dietary aluminium exposure risk. How to control high dietary aluminium exposure still is a great public health challenge in Shenzhen, China. PMID:24594670

  7. Do aluminium-based phosphate binders continue to have a role in contemporary nephrology practice?

    PubMed Central

    2011-01-01

    Background Aluminium-containing phosphate binders have long been used for treatment of hyperphosphatemia in dialysis patients. Their safety became controversial in the early 1980's after reports of aluminium related neurological and bone disease began to appear. Available historical evidence however, suggests that neurological toxicity may have primarily been caused by excessive exposure to aluminium in dialysis fluid, rather than aluminium-containing oral phosphate binders. Limited evidence suggests that aluminium bone disease may also be on the decline in the era of aluminium removal from dialysis fluid, even with continued use of aluminium binders. Discussion The K/DOQI and KDIGO guidelines both suggest avoiding aluminium-containing binders. These guidelines will tend to promote the use of the newer, more expensive binders (lanthanum, sevelamer), which have limited evidence for benefit and, like aluminium, limited long-term safety data. Treating hyperphosphatemia in dialysis patients continues to represent a major challenge, and there is a large body of evidence linking serum phosphate concentrations with mortality. Most nephrologists agree that phosphate binders have the potential to meaningfully reduce mortality in dialysis patients. Aluminium is one of the cheapest, most effective and well tolerated of the class, however there are no prospective or randomised trials examining the efficacy and safety of aluminium as a binder. Aluminium continues to be used as a binder in Australia as well as some other countries, despite concern about the potential for toxicity. There are some data from selected case series that aluminium bone disease may be declining in the era of reduced aluminium content in dialysis fluid, due to rigorous water testing. Summary This paper seeks to revisit the contemporary evidence for the safety record of aluminium-containing binders in dialysis patients. It puts their use into the context of the newer, more expensive binders and increasing

  8. BEHAVIORAL MECHANISMS UNDERLYING NICOTINE REINFORCEMENT

    PubMed Central

    Rupprecht, Laura E.; Smith, Tracy T.; Schassburger, Rachel L.; Buffalari, Deanne M.; Sved, Alan F.; Donny, Eric C.

    2015-01-01

    Cigarette smoking is the leading cause of preventable deaths worldwide and nicotine, the primary psychoactive constituent in tobacco, drives sustained use. The behavioral actions of nicotine are complex and extend well beyond the actions of the drug as a primary reinforcer. Stimuli that are consistently paired with nicotine can, through associative learning, take on reinforcing properties as conditioned stimuli. These conditioned stimuli can then impact the rate and probability of behavior and even function as conditioning reinforcers that maintain behavior in the absence of nicotine. Nicotine can also act as a conditioned stimulus, predicting the delivery of other reinforcers, which may allow nicotine to acquire value as a conditioned reinforcer. These associative effects, establishing non-nicotine stimuli as conditioned stimuli with discriminative stimulus and conditioned reinforcing properties as well as establishing nicotine as a conditioned stimulus, are predicted by basic conditioning principles. However, nicotine can also act non-associatively. Nicotine directly enhances the reinforcing efficacy of other reinforcing stimuli in the environment, an effect that does not require a temporal or predictive relationship between nicotine and either the stimulus or the behavior. Hence, the reinforcing actions of nicotine stem both from the primary reinforcing actions of the drug (and the subsequent associative learning effects) as well as the reinforcement enhancement action of nicotine which is non-associative in nature. Gaining a better understanding of how nicotine impacts behavior will allow for maximally effective tobacco control efforts aimed at reducing the harm associated with tobacco use by reducing and/or treating its addictiveness. PMID:25638333

  9. Temperature and thermal stress fields during the pulse train of long-pulse laser irradiating aluminium alloy plate

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Jin, Guangyong; Gu, Xiu-ying

    2014-12-01

    Based on Von Mises yield criterion and elasto-plastic constitutive equations, an axisymmetric finite element model of a Gaussian laser beam irradiating a metal substrate was established. In the model of finite element, the finite difference hybrid algorithm is used to solve the problem of transient temperature field and stress field. Taking nonlinear thermal and mechanical properties into account, transient distributions of temperature field and stress fields generated by the pulse train of long-pulse laser in a piece of aluminium alloy plate were computed by the model. Moreover,distributions as well as histories of temperature and stress fields were obtained. Finite element analysis software COMSOL is used to simulate the Temperature and thermal stress fields during the pulse train of long-pulse laser irradiating 7A04 aluminium alloy plate. By the analysis of the results, it is found that Mises equivalent stress on the target surface distribute within the scope of the center of a certain radius. However, the stress is becoming smaller where far away from the center. Futhermore, the Mises equivalent stress almost does not effect on stress damage while the Mises equivalent stress is far less than the yield strength of aluminum alloy targets. Because of the good thermal conductivity of 7A04 aluminum alloy, thermal diffusion is extremely quick after laser irradiate. As a result, for the multi-pulsed laser, 7A04 aluminum alloy will not produce obvious temperature accumulation when the laser frequency is less than or equal to 10 Hz. The result of this paper provides theoretical foundation not only for research of theories of 7A04 aluminium alloy and its numerical simulation under laser radiation but also for long-pulse laser technology and widening its application scope.

  10. Influence of Hot Deformation on Mechanical Properties and Microstructure of a Twin-Roll Cast Aluminium Alloy EN AW-6082

    NASA Astrophysics Data System (ADS)

    Grydin, O.; Stolbchenko, M.; Nürnberger, F.; Schaper, M.

    2014-03-01

    Thin strips of medium- and high-strength age-hardening aluminium alloys are widely used in the automotive industry. Reducing their production costs caused by high energy consumption is an actual challenge. The implementation of the twin-roll casting technology is promising. However, mechanical properties of directly cast high-alloyed thin aluminium strips are oftentimes inadequate to standard specifications. In this work, the influence of a hot deformation following a twin-roll cast strip process on the mechanical properties and microstructure is investigated. For this study strips of age-hardening aluminium alloy EN AW-6082—manufactured at a laboratory scaled twin-roll caster—were single-pass rolled at temperatures of 420 °C and true strains of up to 0.5. The mechanical properties of the as-cast and by different strains hot deformed material in the soft-annealed and age-hardened states were characterized by tensile tests. The results reveal that the twin-roll cast material features the necessary strength properties, though it does not meet the standard requirements for ductility. Furthermore, the required minimum strain during hot rolling that is necessary to ascertain the standard specifications has been determined. Based on micrographs, the uniformity of the mechanical properties and of the microstructure as a result of recrystallization due to hot metal forming and heat treatment were determined. A fine-grain microstructure and satisfactory material ductility after prior rolling with a true strain above 0.41 for the age-hardened state T6 and above 0.1 for the soft-annealed state O have been established.

  11. Adsorption of ammonia on graphite oxide/aluminium polycation and graphite oxide/zirconium-aluminium polyoxycation composites.

    PubMed

    Seredych, Mykola; Bandosz, Teresa J

    2008-08-01

    Graphite oxide (GO) synthesized from commercial graphite was modified with aluminium or zirconium-aluminium polyoxycations and then calcined at 350 degrees C. On the samples obtained adsorption of ammonia from moist air was investigated. The surface of materials before and after exposure to ammonia was characterized using adsorption of nitrogen, XRD, SEM, FTIR, TA, CHN analysis, and potentiometric titration. The results showed that in spite of the fact that graphite composites/pillared graphites (PG) have Keggin-like ions located between the layers, that space blocked for nitrogen molecules used to determine the specific surface area. During calcinations, the deflagration of layers occurred as a result of decomposition of epoxy groups. This results in formation of disordered graphitic carbons with some mesoporosity. Even though these materials were not porous, the significant amount of ammonia was retained on the surface. Since ammonia molecule is able to specifically interact with oxygen groups of graphite oxide and Brønsted centers of inorganic pillars, it is likely intercalated between the composite layers. While the best performance was found for GO modified with aluminium-zirconium species, after calcinations the samples containing Keggin Al(13) like cations revealed the high capacity which is linked to the high acidity of incorporated inorganic compounds. PMID:18501918

  12. Adsorption of ammonia on graphite oxide/aluminium polycation and graphite oxide/zirconium-aluminium polyoxycation composites.

    PubMed

    Seredych, Mykola; Bandosz, Teresa J

    2008-08-01

    Graphite oxide (GO) synthesized from commercial graphite was modified with aluminium or zirconium-aluminium polyoxycations and then calcined at 350 degrees C. On the samples obtained adsorption of ammonia from moist air was investigated. The surface of materials before and after exposure to ammonia was characterized using adsorption of nitrogen, XRD, SEM, FTIR, TA, CHN analysis, and potentiometric titration. The results showed that in spite of the fact that graphite composites/pillared graphites (PG) have Keggin-like ions located between the layers, that space blocked for nitrogen molecules used to determine the specific surface area. During calcinations, the deflagration of layers occurred as a result of decomposition of epoxy groups. This results in formation of disordered graphitic carbons with some mesoporosity. Even though these materials were not porous, the significant amount of ammonia was retained on the surface. Since ammonia molecule is able to specifically interact with oxygen groups of graphite oxide and Brønsted centers of inorganic pillars, it is likely intercalated between the composite layers. While the best performance was found for GO modified with aluminium-zirconium species, after calcinations the samples containing Keggin Al(13) like cations revealed the high capacity which is linked to the high acidity of incorporated inorganic compounds.

  13. Studies on Nanostructure Aluminium Thin Film Coatings Deposited using DC magnetron Sputtering Process

    NASA Astrophysics Data System (ADS)

    Singh M, Muralidhar; G, Vijaya; MS, Krupashankara; Sridhara, B. K.; Shridhar, T. N.

    2016-09-01

    Nanostructured thin film metallic coatings has become an area of intense research particularly in applications related solar, sensor technologies and many other optical applications such as laser windows, mirrors and reflectors. Thin film metallic coatings were deposited using DC magnetron sputtering process. The deposition rate was varied to study its influence on optical behavior of Aluminum thin films at a different argon flow rate. Studies on the optical response of these nanostructure thin film coatings were characterized using UV-VIS-NIR spectrophotometer with integrating sphere in the wavelength range of (250-2500nm) and Surface morphology were carried out using atomic force microscope with roughness ranging from 2 to 20nm and thickness was measured using Dektak measuring instrument. The reflection behavior of aluminium coatings on polycarbonate substrates has been evaluated. UV-VIS-NIR Spectrophotometer analysis indicates higher reflectance of 96% for all the films in the wavelength range of 250 nm to 2500 nm. Nano indentation study revealed that there was a considerable change in hardness values of the films prepared at different conditions.

  14. Sublethal effects in Atlantic salmon (Salmo salar) exposed to mixtures of copper, aluminium and gamma radiation.

    PubMed

    Heier, Lene Sørlie; Teien, Hans Christian; Oughton, Deborah; Tollefsen, Knut-Erik; Olsvik, Pål A; Rosseland, Bjørn Olav; Lind, Ole Christian; Farmen, Eivind; Skipperud, Lindis; Salbu, Brit

    2013-07-01

    The present study was designed to investigate the effects in presmolt of Atlantic salmon (Salmo salar) exposed to copper (Cu), aluminium (Al) and gamma radiation, individually or in combination. Fish were exposed for 48 h to metals added to lake water; 10, 40 and 80 μg Cu/L, 250 μg Al/L and a combination of 40 μg Cu/L and 250 μg Al/L. In addition, gamma radiation (4-70 mGy delivered over 48 h) was added as an additional exposure stressor. Selected endpoints were chosen to reveal different toxic mechanisms and included Cu and Al accumulation on gills, blood chemistry and haematological variables (plasma sodium and chloride, haematocrit, glucose), hepatic levels of reduced and oxidised glutathione (GSH and GSSG) and hepatic transcriptional response of glutathione peroxidase (GPx), gamma-glutamylcysteine synthetase (GCS), metallothionein (MT) and ubiquitin. Exposure to Cu alone resulted in gill accumulation of Cu, reduction of plasma ions and increased transcriptional response of GPx, MT and ubiquitin. Exposure to Al alone reduced plasma ion levels but did not affect any of the hepatic biomarkers except for ubiquitin. The combined metal exposure (Cu + Al) altered the GSH levels, however GPx and MT were not affected suggesting a different mode of detoxification in the combined exposure. Gamma radiation appeared to influence GSH and ubiquitin levels. The observed effects seemed to be both stressor and concentration dependent. PMID:22583837

  15. If exposure to aluminium in antiperspirants presents health risks, its content should be reduced.

    PubMed

    Pineau, Alain; Fauconneau, Bernard; Sappino, André-Pascal; Deloncle, Roger; Guillard, Olivier

    2014-04-01

    Since aluminium (Al) pervades our environment, the scientific community has for many years raised concerns regarding its safety in humans. Al is present in numerous cosmetics such as antiperspirants, lipsticks and sunscreens. Al chlorohydrate is the active antiperspirant agent in underarm cosmetics and may constitute for Al a key exposure route to the human body and a potential source of damage. An in vitro study has demonstrated that Al from antiperspirant can be absorbed through viable human stripped skin. The potential toxicity of Al has been clearly shown and recent works convincingly argue that Al could be involved in cancerogenic processes. Nowadays, for example, Al is suspected of being involved in breast cancer. Recent work in cells in culture has lent credence to the hypothesis that this metal could accumulate in the mammary gland and selectively interfere with the biological properties of breast epithelial cells, thereby promoting a cascade of alterations reminiscent of the early phases of malignant transformation. In addition, several studies suggest that the presence of Al in human breast could influence metastatic process. As a consequence, given that the toxicity of Al has been widely recognized and that it is not a physiological component in human tissues, reducing the concentration of this metal in antiperspirants is a matter of urgency.

  16. R&D on glass fiber reinforced epoxy resin composites for superconducting Tokamak.

    PubMed

    Hu, Nannan; Wang, Ke; Ma, Hongming; Pan, Wanjiang; Chen, Qingqing

    2016-01-01

    The glass fiber reinforced epoxy resin composites play an important role in superconducting Tokamak, which are used to insulate the metal components, such as superconducting winding, cooling pipes, metal electrodes and so on. For the components made of metal and glass fiber reinforced epoxy resin composites, thermal shrinkage leads to non-ignorable thermal stress, therefore, much attention should be paid on the thermal shrinkage rate of glass fiber reinforced epoxy resin composites. The structural design of glass fiber reinforced epoxy resin composites should aim at reducing thermal stress. In this paper, the density, glass fiber content and thermal shrinkage rate of five insulation tubes were tested. The testing results will be applied in structural design and mechanical analysis of isolators for superconducting Tokamak. PMID:27652137

  17. Microstructure and Tensile Behaviour of B4C Reinforced ZA43 Alloy Composites

    NASA Astrophysics Data System (ADS)

    Adaveesh, B.; Halesh, G. M.; Nagaral, Madeva; Mohan Kumar, T. S.

    2016-09-01

    The work is carried out to investigate and study the mechanical properties of B4C reinforced ZA43 alloy metal matrix composites. In the present work ZA43 alloy is taken as the base matrix and B4C particulates as reinforcement material to prepare metal matrix composites by stir casting method. For metal matrix composites the reinforcement material was varied from 0 to 6 wt.% in steps of 3 wt.%. For each composite, the reinforcement particulates were preheated to a temperature of 300°C and dispersed into a vortex of molten ZA43 alloy. The microstructural characterization was done using scanning electron microscope. Mechanical properties like hardness, ultimate tensile strength and yield strength were evaluated as per ASTM standards. Further, scanning electron microphotographs revealed that there was uniform distribution of B4C particulates in ZA43 alloy matrix. Hardness, ultimate tensile strength and yield strength increased as wt.% of B4C increased in the base matrix.

  18. R&D on glass fiber reinforced epoxy resin composites for superconducting Tokamak.

    PubMed

    Hu, Nannan; Wang, Ke; Ma, Hongming; Pan, Wanjiang; Chen, Qingqing

    2016-01-01

    The glass fiber reinforced epoxy resin composites play an important role in superconducting Tokamak, which are used to insulate the metal components, such as superconducting winding, cooling pipes, metal electrodes and so on. For the components made of metal and glass fiber reinforced epoxy resin composites, thermal shrinkage leads to non-ignorable thermal stress, therefore, much attention should be paid on the thermal shrinkage rate of glass fiber reinforced epoxy resin composites. The structural design of glass fiber reinforced epoxy resin composites should aim at reducing thermal stress. In this paper, the density, glass fiber content and thermal shrinkage rate of five insulation tubes were tested. The testing results will be applied in structural design and mechanical analysis of isolators for superconducting Tokamak.

  19. Stochastic Reinforcement Benefits Skill Acquisition

    ERIC Educational Resources Information Center

    Dayan, Eran; Averbeck, Bruno B.; Richmond, Barry J.; Cohen, Leonardo G.

    2014-01-01

    Learning complex skills is driven by reinforcement, which facilitates both online within-session gains and retention of the acquired skills. Yet, in ecologically relevant situations, skills are often acquired when mapping between actions and rewarding outcomes is unknown to the learning agent, resulting in reinforcement schedules of a stochastic…

  20. Conditioned Reinforcement and Response Strength

    ERIC Educational Resources Information Center

    Shahan, Timothy A.

    2010-01-01

    Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in…