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Sample records for 316ln base metal

  1. Assessment of Creep Strain Distribution Across Base Metal of 316LN Austenitic Stainless Steel Weld Joint by an EBSD-Based Parameter

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Ganesan, V.; Ganesh Kumar, J.; Parameswaran, P.; Naveena; Laha, K.

    2015-11-01

    Electron backscatter diffraction (EBSD) analysis has been used to estimate the accumulated strain in base metal region of 316LN austenitic stainless steel weld joints, creep tested at 923 K (650 °C), and at stresses of 175 and 225 MPa. The variation in strength of weld metal, heat-affected zone (HAZ), and base metal-induced stress and strain gradients across the weld joint under creep exposure. Finite element analysis (FEA) of von-Mises stress distribution across the joint has been carried out on incorporating strength of different constituents of the joint, derived by miniature specimen testing techniques. The FEA simulations revealed preferential accumulation of von-Mises stress in the base metal region near to HAZ. The variation in accumulated plastic strain across the base metal has been estimated using a `crystal deformation' ( C d) parameter which quantifies the orientation spread within a grain. This parameter was obtained by EBSD analysis carried out using a scanning electron microscope. The trend in variation of accumulated plastic strain across the base metal accounted well with the von-Mises stress variation, which causes plastic deformation. The plastic strain in the base metal in both the stress levels was found to accumulate preferentially near to the HAZ and reduced steadily toward the ridge at the end of specimen. Transmission electron microscopic study has been carried out to substantiate the findings of the EBSD investigation.

  2. Evaluation of Cavitation-Erosion Resistance of 316LN Stainless Steel in Mercury Containing Metallic Solutes

    SciTech Connect

    Pawel, Steven J; Mansur, Louis K

    2006-08-01

    Room temperature cavitation tests of vacuum annealed type 316LN stainless steel were performed in pure Hg and in Hg with various amounts of metallic solute to evaluate potential mitigation of erosion/wastage. Tests were performed using an ultrasonic vibratory horn with specimens attached at the tip. All of the solutes examined, which included 5 wt% In, 10 wt% In, 4.4 wt% Cd, 2 wt% Ga, and a mixture that included 1 wt% each of Pb, Sn, and Zn, were found to increase cavitation-erosion as measured by increased weight loss and/or surface profile development compared to exposures for the same conditions in pure Hg. Qualitatively, each solute appeared to increase the post-test wetting tenacity of the Hg solutions and render the Hg mixture susceptible to manipulation of droplet shape.

  3. Impression Creep Behavior of 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Mathew, M. D.; Naveena; Vijayanand, D.

    2013-02-01

    Impression creep tests have been carried out at 923 K on 316LN SS containing 0.07, 0.14, and 0.22 wt.% nitrogen, under different applied stress levels. It was observed that the impression creep depth versus time curves were similar to the creep curves obtained from conventional uniaxial creep tests. The impression creep curves were characterized by a loading strain and primary and secondary creep stages similar to uniaxial creep curves. The tertiary stage observed in uniaxial creep curves was absent. The steady-state impression velocity was found to increase with increasing applied stress. The equivalent steady-state creep rates calculated from impression velocities were found to be in good agreement with the steady-state creep rates obtained from conventional uniaxial creep tests. Equivalence between applied stress and steady-state impression velocity with uniaxial creep stress and steady-state creep rate, respectively, has been established based on the laws of mechanics for time-dependent plasticity. It was found that impression velocity was sensitive to the variation in nitrogen content in the steel; impression velocity decreased with increasing nitrogen content, and the results obtained in this study were in agreement with those obtained from uniaxial creep tests.

  4. Preliminary evaluation of cavitation resistance of type 316LN stainless steel in mercury using a vibratory horn

    NASA Astrophysics Data System (ADS)

    Pawel, S. J.; Manneschmidt, E. T.

    2003-05-01

    Type 316LN stainless steel in a variety of conditions (annealed, cold-worked, surface-modified) was exposed to cavitation conditions in stagnant mercury using a vibratory horn. The test conditions included peak-to-peak displacement of the specimen surface of 25 μm at a frequency of 20 kHz and a mercury temperature in the range -5 to 80 °C. Following a brief incubation period in which little or no damage was observed, specimens of annealed 316LN exhibited increasing weight loss and surface roughening with increasing exposure times. Examination of test surfaces with the scanning electron microscope revealed primarily general/uniform wastage in all cases but, for long exposure times, a few randomly oriented 'pits' were also observed. Type 316LN that was 50% cold-worked was considerably more resistant to cavitation erosion damage than annealed material, but the surface modifications (CrN coating, metallic glass coating, laser treatment to form a diamond-like surface) provided little or no protection for the substrate. In addition, the cavitation erosion resistance of other materials - Inconel 718, Nitronic 60, and Stellite 3 - was also compared with that of 316LN for identical screening test conditions.

  5. On the constitutive model of nitrogen-containing austenitic stainless steel 316LN at elevated temperature.

    PubMed

    Zhang, Lei; Feng, Xiao; Wang, Xin; Liu, Changyong

    2014-01-01

    The nitrogen-containing austenitic stainless steel 316LN has been chosen as the material for nuclear main-pipe, which is one of the key parts in 3rd generation nuclear power plants. In this research, a constitutive model of nitrogen-containing austenitic stainless steel is developed. The true stress-true strain curves obtained from isothermal hot compression tests over a wide range of temperatures (900-1250°C) and strain rates (10(-3)-10 s(-1)), were employed to study the dynamic deformational behavior of and recrystallization in 316LN steels. The constitutive model is developed through multiple linear regressions performed on the experimental data and based on an Arrhenius-type equation and Zener-Hollomon theory. The influence of strain was incorporated in the developed constitutive equation by considering the effect of strain on the various material constants. The reliability and accuracy of the model is verified through the comparison of predicted flow stress curves and experimental curves. Possible reasons for deviation are also discussed based on the characteristics of modeling process.

  6. On the Constitutive Model of Nitrogen-Containing Austenitic Stainless Steel 316LN at Elevated Temperature

    PubMed Central

    Zhang, Lei; Feng, Xiao; Wang, Xin; Liu, Changyong

    2014-01-01

    The nitrogen-containing austenitic stainless steel 316LN has been chosen as the material for nuclear main-pipe, which is one of the key parts in 3rd generation nuclear power plants. In this research, a constitutive model of nitrogen-containing austenitic stainless steel is developed. The true stress-true strain curves obtained from isothermal hot compression tests over a wide range of temperatures (900–1250°C) and strain rates (10−3–10 s−1), were employed to study the dynamic deformational behavior of and recrystallization in 316LN steels. The constitutive model is developed through multiple linear regressions performed on the experimental data and based on an Arrhenius-type equation and Zener-Hollomon theory. The influence of strain was incorporated in the developed constitutive equation by considering the effect of strain on the various material constants. The reliability and accuracy of the model is verified through the comparison of predicted flow stress curves and experimental curves. Possible reasons for deviation are also discussed based on the characteristics of modeling process. PMID:25375345

  7. Effect of re-irradiation by neutrons on mechanical properties of un-irradiated/irradiated SS316LN weldments

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Shimizu, M.; Kawamura, H.; Kalinin, G.

    2008-02-01

    Stainless steel of type SS316LN-IG (ITER Grade) is used for the branch pipeline connecting of the module coolant system and for other structures of ITER. One of the most important requirements for the branch pipeline connection is to recover various defects by welding. In the present study, characteristics of irradiated weldments were evaluated. SS316LN-IG specimens irradiated to helium contents of 3 and 10 appm He were prepared by the first neutron irradiation. Thereafter, the SS316LN-IG specimens with three different combinations of un-irradiation and irradiation were welded by a tungsten inert-gas (TIG) welding method. These weldments were re-irradiated at 150 °C up to a fast neutron fluence of about 7.5 × 10 24 n/m 2 ( E > 1 MeV). Tensile tests of the weldments and the base material were carried out at 20 and 150 °C after the re-irradiation. The results of the comparison before and after the re-irradiation showed that tensile properties of all weldment specimens with the different combinations were almost the same as those of the base materials.

  8. Strength of nanostructured austenitic steel 316LN at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Czarkowski, P.; Krawczynska, A. T.; Brynk, T.; Nowacki, M.; Lewandowska, M.; Kurzydłowski, K. J.

    2014-12-01

    The aim of this work was to investigate the effect of nano-refinement on the properties of austenitic steel. The material with the initial grain size of 40-50pm was subjected to hydrostatic extrusion at a room temperature to the total accumulated strain exceeding 1. The microstructure developed was investigated by Transmission Electron Microscopy (TEM) and Focus Ion Beam (FIB). The strength of the extruded samples was tested at 293K, 77K and 4.2K by means of cryostat for static tensile tests. The results show that the hydrostatically extruded steel 316LN has excellent strength in cryogenic conditions, which make this material interesting for applications in cryogenic devices.

  9. Creep Deformation and Rupture Behavior of Single- and Dual-Pass 316LN Stainless-Steel-Activated TIG Weld Joints

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Vasudevan, M.; Ganesan, V.; Parameswaran, P.; Laha, K.; Bhaduri, A. K.

    2016-06-01

    Creep deformation and rupture behavior of single-pass and dual-pass 316LN stainless steel (SS) weld joints fabricated by an autogenous activated tungsten inert gas welding process have been assessed by performing metallography, hardness, and conventional and impression creep tests. The fusion zone of the single-pass joint consisted of columnar zones adjacent to base metals with a central equiaxed zone, which have been modified extensively by the thermal cycle of the second pass in the dual-pass joint. The equiaxed zone in the single-pass joint, as well as in the second pass of the dual-pass joint, displayed the lowest hardness in the joints. In the dual-pass joint, the equiaxed zone of the first pass had hardness comparable to the columnar zone. The hardness variations in the joints influenced the creep deformation. The equiaxed and columnar zone in the first pass of the dual-pass joint was more creep resistant than that of the second pass. Both joints possessed lower creep rupture life than the base metal. However, the creep rupture life of the dual-pass joint was about twofolds more than that of the single-pass joint. Creep failure in the single-pass joint occurred in the central equiaxed fusion zone, whereas creep cavitation that originated in the second pass was blocked at the weld pass interface. The additional interface and strength variation between two passes in the dual-pass joint provides more restraint to creep deformation and crack propagation in the fusion zone, resulting in an increase in the creep rupture life of the dual-pass joint over the single-pass joint. Furthermore, the differences in content, morphology, and distribution of delta ferrite in the fusion zone of the joints favors more creep cavitation resistance in the dual-pass joint over the single-pass joint with the enhancement of creep rupture life.

  10. Corrosion Fatigue Behavior of 316LN SS in Acidified Sodium Chloride Solution at Applied Potential

    NASA Astrophysics Data System (ADS)

    Poonguzhali, A.; Pujar, M. G.; Mallika, C.; Mudali, U. Kamachi

    2015-05-01

    The influence of acidified 1 M NaCl solution by addition of 2 ml/L of HCl on the cyclic plastic deformation of AISI Type 316LN SS containing 0.07 wt.% and 0.22 wt.% N was investigated as a function of the applied potentials. The corrosion fatigue (CF) behavior of stainless steel (SS) was explained vis-a-vis the dislocation behavior, the propensity to form microcracks, and the evolution of the current transients based on the studies carried out at both room-temperature and boiling conditions. CF experiments were conducted using round tensile specimens at a stress ratio of 0.5 and a frequency of 0.1 Hz. Two different kinds of damage mechanisms were observed (I) the damage mechanism in the stable-passive state was correlated with the localization of the anodic dissolution due to a depassivation-repassivation process, whereas (II) the cyclic stress induced pitting corrosion in the metastable pitting state, which resulted in formation of microcracks. The study of the microcracking process and its evolution is a key to the physical mechanism by which the fatigue life of stainless steels would be affected in an aqueous corrosive solution under the applied potential.

  11. Hardness of Carburized Surfaces in 316LN Stainless Steel after Low Temperature Neutron Irradiation

    SciTech Connect

    Byun, TS

    2005-01-31

    A proprietary surface carburization treatment is being considered to minimize possible cavitation pitting of the inner surfaces of the stainless steel target vessel of the SNS. The treatment gives a large supersaturation of carbon in the surface layers and causes substantial hardening of the surface. To answer the question of whether such a hardened layer will remain hard and stable during neutron irradiation, specimens of the candidate materials were irradiated in the High Flux Isotope Reactor (HFIR) to an atomic displacement level of 1 dpa. Considerable radiation hardening occurred in annealed 316LN stainless steel and 20% cold rolled 316LN stainless steel, and lesser radiation hardening in Kolsterised layers on these materials. These observations coupled with optical microscopy examinations indicate that the carbon-supersaturated layers did not suffer radiation-induced decomposition and softening.

  12. Transition in Failure Mechanism Under Cyclic Creep in 316LN Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sarkar, Aritra; Nagesha, A.; Parameswaran, P.; Sandhya, R.; Mathew, M. D.

    2014-06-01

    Cyclic creep behavior of a type 316LN austenitic stainless steel was investigated in the temperature range from 823 K to 923 K (550 °C to 650 °C). A transition from fatigue-dominated to creep-dominated failure mode was observed with an increase in the mean stress. The threshold value of mean stress for the transition was seen to be a strong function of the test temperature. Occurrence of dynamic strain aging proved beneficial owing to a substantial reduction in the strain accumulation during cyclic loading.

  13. Damage structure of austenitic stainless steel 316LN irradiated at low temperature in HFIR

    SciTech Connect

    Hashimoto, N.; Robertson, J.P.; Grossbeck, M.L.; Rowcliffe, A.F.; Wakai, E.

    1998-03-01

    TEM disk specimens of austenitic stainless steel 316LN irradiated to damage levels of about 3 dpa at irradiation temperatures of either about 90 C or 250 C have been investigated by using transmission electron microscopy. The irradiation at 90 C and 250 C induced a dislocation loop density of 3.5 {times} 10{sup 22} m{sup {minus}3} and 6.5 {times} 10{sup 22} m{sup {minus}3}, a black dot density of 2.2 {times} 10{sup 23} m{sup {minus}3} and 1.6 {times} 10{sup 23} m{sup {minus}3}, respectively, in the steels, and a high density (<1 {times} 10{sup 22} m{sup {minus}3}) of precipitates in matrix. Cavities could be observed in the specimens after the irradiation. It is suggested that the dislocation loops, the black dots, and the precipitates cause irradiation hardening, an increase in the yield strength and a decrease in the uniform elongation, in the 316LN steel irradiated at low temperature.

  14. Electron-stimulated desorption from polished and vacuum fired 316LN stainless steel coated with Ti-Zr-Hf-V

    SciTech Connect

    Malyshev, Oleg B. Valizadeh, Reza; Hogan, Benjamin T.; Hannah, Adrian N.

    2014-11-01

    In this study, two identical 316LN stainless steel tubular samples, which had previously been polished and vacuum-fired and then used for the electron-stimulated desorption (ESD) experiments, were coated with Ti-Zr-Hf-V with different morphologies: columnar and dense. ESD measurement results after nonevaporable getter (NEG) activation to 150, 180, 250, and 350 °C indicated that the values for the ESD yields are significantly (2–20 times) lower than the data from our previous study with similar coatings on nonvacuum-fired samples. Based on these results, the lowest pressure and best long-term performance in particle accelerators will be achieved with a vacuum-fired vacuum chamber coated with dense Ti-Zr-Hf-V coating activated at 180 °C. This is likely due to the following facts: after NEG activation, the hydrogen concentration inside the NEG was lower than in the bulk stainless steel substrate; the NEG coating created a barrier for gas diffusion from the sample bulk to vacuum; the dense NEG coating performed better as a barrier than the columnar NEG coating.

  15. Effect of an Aging Heat Treatment on the 4 K Fracture and Fatigue Properties of 316LN and Haynes 242

    SciTech Connect

    Walsh, R. P.; Toplosky, V. J.; Han, K.; Miller, J. R.

    2006-03-31

    Since the introduction of the cable-in-conduit conductor (CICC) concept, a variety of alloys have been proposed for fabricating the jacket. The jacket provides primary containment of the liquid helium coolant and is typically also the primary structural component for the magnet coils. These functions create requirements for strength, toughness, fatigue crack resistance, and fabricability. When the CICC uses Nb3Sn superconductor, the conduit alloy must retain good mechanical properties after exposure to the superconductor's reaction heat treatment. Here we present data from cryogenic fracture toughness and fatigue crack growth rate tests on 316LN and a Cr-Mo-Ni base super-alloy (Haynes 242) at 4 K before and after the exposure to the heat treatment. These alloys are presently being considered as candidates for use in the next-generation series connected hybrid magnet for the NHMFL. Both of the alloys are found to have adequate fatigue and fracture properties for the CICC application while the superalloy has distinctly better elastic properties of modulus and thermal expansion.

  16. Effect of an Aging Heat Treatment on the 4 K Fracture and Fatigue Properties of 316LN and Haynes 242

    NASA Astrophysics Data System (ADS)

    Walsh, R. P.; Toplosky, V. J.; Han, K.; Miller, J. R.

    2006-03-01

    Since the introduction of the cable-in-conduit conductor (CICC) concept, a variety of alloys have been proposed for fabricating the jacket. The jacket provides primary containment of the liquid helium coolant and is typically also the primary structural component for the magnet coils. These functions create requirements for strength, toughness, fatigue crack resistance, and fabricability. When the CICC uses Nb3Sn superconductor, the conduit alloy must retain good mechanical properties after exposure to the superconductor's reaction heat treatment. Here we present data from cryogenic fracture toughness and fatigue crack growth rate tests on 316LN and a Cr-Mo-Ni base super-alloy (Haynes 242) at 4 K before and after the exposure to the heat treatment. These alloys are presently being considered as candidates for use in the next-generation series connected hybrid magnet for the NHMFL. Both of the alloys are found to have adequate fatigue and fracture properties for the CICC application while the superalloy has distinctly better elastic properties of modulus and thermal expansion.

  17. Effect of surface polishing and vacuum firing on electron stimulated desorption from 316LN stainless steel

    SciTech Connect

    Malyshev, Oleg B. Hogan, Benjamin T.; Pendleton, Mark

    2014-09-01

    The reduction of thermal outgassing from stainless steel by surface polishing or vacuum firing is well-known in vacuum technology, and the consequent use of both techniques allows an even further reduction of outgassing. The aim of this study was to identify the effectiveness of surface polishing and vacuum firing for reducing electron-stimulated desorption (ESD) from 316LN stainless steel, which is a frequently used material for particle accelerator vacuum chambers and components. It was found that, unlike for thermal outgassing, surface polishing does not reduce the ESD yield and may even increase it, while vacuum firing of nonpolished sample reduces only the H{sub 2} ESD yield by a factor 2.

  18. Generation of Constant Life Diagram under Elevated Temperature Ratcheting of 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sarkar, Aritra; Nagesha, A.; Sandhya, R.; Mathew, M. D.

    2016-04-01

    Combined influence of mean stress and stress amplitude on the cyclic life under elevated temperature (823-923 K) ratcheting of 316LN austenitic stainless steel is discussed. Constant life Haigh diagrams have been generated, using different combinations of stress amplitude and mean stress. In the plastic domain, the allowable stress was found to increase or decrease with mean stress depending on the temperature and combination of mean stress - stress amplitude employed. Strong influence of dynamic strain aging (DSA) was found at 823 K which affected the mode of deformation of the material in comparison with 923 K. Failure mode expressed through a fracture mechanism map was found to change from fatigue to necking depending on the test temperature as well as combinations of mean stress and stress amplitude. Occurrence of DSA at 823 K proved to be beneficial by way of extending the safe zone of operation to higher R-ratios in comparison with 923 K.

  19. Influence of Heat Treatment on Mercury Cavitation Resistance of Surface Hardened 316LN Stainless Steel

    SciTech Connect

    Pawel, Steven J; Hsu, Julia

    2010-11-01

    The cavitation-erosion resistance of carburized 316LN stainless steel was significantly degraded but not destroyed by heat treatment in the temperature range 500-800 C. The heat treatments caused rejection of some carbon from the carburized layer into an amorphous film that formed on each specimen surface. Further, the heat treatments encouraged carbide precipitation and reduced hardness within the carburized layer, but the overall change did not reduce surface hardness fully to the level of untreated material. Heat treatments as short as 10 min at 650 C substantially reduced cavitation-erosion resistance in mercury, while heat treatments at 500 and 800 C were found to be somewhat less detrimental. Overall, the results suggest that modest thermal excursions perhaps the result of a weld made at some distance to the carburized material or a brief stress relief treatment will not render the hardened layer completely ineffective but should be avoided to the greatest extent possible.

  20. Study of magnetism in Ni-Cr hardface alloy deposit on 316LN stainless steel using magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Kishore, G. V. K.; Kumar, Anish; Chakraborty, Gopa; Albert, S. K.; Rao, B. Purna Chandra; Bhaduri, A. K.; Jayakumar, T.

    2015-07-01

    Nickel base Ni-Cr alloy variants are extensively used for hardfacing of austenitic stainless steel components in sodium cooled fast reactors (SFRs) to avoid self-welding and galling. Considerable difference in the compositions and melting points of the substrate and the Ni-Cr alloy results in significant dilution of the hardface deposit from the substrate. Even though, both the deposit and the substrate are non-magnetic, the diluted region exhibits ferromagnetic behavior. The present paper reports a systematic study carried out on the variations in microstructures and magnetic behavior of American Welding Society (AWS) Ni Cr-C deposited layers on 316 LN austenitic stainless steels, using atomic force microscopy (AFM) and magnetic force microscopy (MFM). The phase variations of the oscillations of a Co-Cr alloy coated magnetic field sensitive cantilever is used to quantitatively study the magnetic strength of the evolved microstructure in the diluted region as a function of the distance from the deposit/substrate interface, with the spatial resolution of about 100 nm. The acquired AFM/MFM images and the magnetic property profiles have been correlated with the variations in the chemical compositions in the diluted layers obtained by the energy dispersive spectroscopy (EDS). The study indicates that both the volume fraction of the ferromagnetic phase and its ferromagnetic strength decrease with increasing distance from the deposit/substrate interface. A distinct difference is observed in the ferromagnetic strength in the first few layers and the ferromagnetism is observed only near to the precipitates in the fifth layer. The study provides a better insight of the evolution of ferromagnetism in the diluted layers of Ni-Cr alloy deposits on stainless steel.

  1. Small Punch Creep Studies for Optimization of Nitrogen Content in 316LN SS for Enhanced Creep Resistance

    NASA Astrophysics Data System (ADS)

    Mathew, M. D.; Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2014-02-01

    Small punch creep (SPC) studies have been carried out to evaluate the creep properties of 316LN stainless steel (SS) at 923 K (650 °C) at various stress levels. The results have been compared with uniaxial creep rupture data obtained from conventional creep tests. The minimum deflection rate was found to obey Norton power law. SPC rupture life was correlated with uniaxial creep rupture life. The influence of nitrogen content on the creep rupture properties of 316LN SS was investigated in the range of 0.07 to 0.14 wt pct. SPC rupture life increased and the minimum deflection rate decreased with the increase in nitrogen content. The trends were found to be in agreement with the results obtained from uniaxial creep rupture tests. These studies have established that SPC is a fast and reliable technique to screen creep properties of different experimental heats of materials for optimizing the chemical composition for developing creep-resistant materials.

  2. Cryogenic fracture behavior of 316LN in magnetic fields up to 14.6 T

    SciTech Connect

    Chan, J.W.; Chu, D.; Tseng, C.; Morris, J.W. Jr. |

    1993-07-01

    Some of the proposed magnet case alloys for the International Thermonuclear Experimental Reactor (ITER) are metastable austenitic stainless steels. The case will be subjected to high loads and can be as much as 100 mm thick. Case assembly will probably require thick section welding with its attendant chemical inhomogeneity. Even alloys that are thermally stable with respect to martensitic transformation can, under these conditions of high stresses, cryogenic temperature, and high magnetic fields, undergo transformation. Previous work at 8 T has shown a measurable magnetic field effect on the 4.2K tensile and fracture toughness properties of AISI300 series metastable austenitic stainless steels. Thus, it is important to understand how these alloys will behave under conditions of high magnetic fields and cryogenic temperature, particularly at the higher magnetic fields that will be used in ITER. 4.2K data for 316LN indicates that the change in fracture toughness is not monotonic. It initially decreases and then later increases with applied field.

  3. Analyses of Transient and Tertiary Small Punch Creep Deformation of 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2016-09-01

    Creep deformation behavior of 316LN stainless steel (SS) under small punch creep (SPC) and uniaxial creep test has been assessed and compared at 923 K (650 °C). The transient and tertiary creep deformation behaviors have been analyzed according to the equation proposed for SPC deflection, δ = δ0 + δ_{{T}} \\cdot (1 - {{e}}^{ - κ \\cdot t} ) + dot{δ }_{{s}} t + δ3 {{e}}^{{[ {φ ( {t - t_{{r}} } )} ]}} on the basis of Dobes and Cadek equation for uniaxial creep strain. Trends in the variations of (i) rate of exhaustion of transient creep ( κ) with steady-state deflection rate ( dot{δ }_{{s}} ) (ii) ` κ' with time to attain steady-state deflection rate, and (iii) initial creep deflection rate with steady-state deflection rate implied that transient SPC deformation obeyed first-order reaction rate theory. The rate of exhaustion of transient creep ( r') values that were determined from uniaxial creep tests were correlated with those obtained from SPC tests. Master curves representing transient creep deformation in both SPC and uniaxial creep tests have been derived and their near coincidence brings unique equivalence between both the test techniques. The relationships between (i) rate of acceleration of tertiary creep ( φ) and steady-state deflection rate, (ii) ` φ' and time spent in tertiary stage, and (iii) final creep deflection rate and steady-state deflection rate revealed that first-order reaction rate theory governed SPC deformation throughout the tertiary region also. Interrelationship between the transient, secondary, and tertiary creep parameters indicated that the same mechanism prevailed throughout the SPC deformation.

  4. Influence of nitrogen-induced grain refinement on mechanical properties of nitrogen alloyed type 316LN stainless steel

    NASA Astrophysics Data System (ADS)

    Kim, Dae Whan

    2012-01-01

    Tensile, fatigue, and creep tests were conducted to investigate the effect of grain refinement by the addition of nitrogen on mechanical properties of nitrogen alloyed type 316LN stainless steel. Grain size was reduced from 100 μm to 47 μm as nitrogen concentration was increased from 0.04% (N04) to 0.10% (N10). When nitrogen concentration was increased, there was a 20% increase in yield stress and a 14% increase in UTS, respectively. Elongation was not significantly changed with increasing nitrogen concentration. As nitrogen concentration was increased, there was a 41% increase in fatigue life and an approximately sixfold increase in the time to rupture. As grain size was reduced from 100 μm to 47 μm, there was an 8% increase in yield stress and a 3% increase in UTS, respectively. Elongation was little changed with decreasing grain size. As grain size was reduced from 100 μm to 47 μm, there was a 9% increase in fatigue life and a 23% increase in the time to rupture. The grain refinement achieved by the addition of nitrogen improved the high temperature mechanical properties of nitrogen alloyed type 316LN stainless steel but was not the main mechanism for improvement of mechanical properties.

  5. Examination of Compatibility of Potentially Cavitation-Resistant Modifications of Type 316LN Stainless Steel with Mercury in a Thermal Convection Loop

    SciTech Connect

    Pawel, SJ

    2002-08-29

    A 316L stainless steel thermal convection loop (TCL) containing a variety of stainless steel coupons circulated mercury for 2000 h. The TCL conditions included a maximum temperature of 307 C, a maximum temperature gradient of 90 C, and a Hg velocity of about 1.4 m/min. In addition to mill-annealed/surface-ground 316LN coupons serving as the baseline material, other coupons included 316LN that was 50% cold-worked, 316LN that was given a proprietary surface hardening treatment termed ''kolsterizing,'' and Nitronic 60. The purpose of this test was to examine Hg compatibility with these modest variations of annealed 31 6LN stainless steel that are considered potential improvements over annealed 31 6LN for cavitation-erosion resistance in the Spallation Neutron Source (SNS) target containment system. The results indicated negligible weight change for each coupon type, no significant indication of attack or surface roughening, and generally no interaction with Hg.

  6. Comparison of Cavitation-Erosion Resistance of Carburized and Carburized-Plus-Nitrided 316LN Stainless Steel in Mercury

    SciTech Connect

    Pawel, Steven J

    2007-05-01

    Annealed type 316LN stainless steel in the (1) carburized and the (2) carburized plus nitrided conditions was evaluated for cavitation-erosion resistance in ambient temperature mercury using a vibratory horn method. The results indicated that, relative to the specimens receiving only the carburizing treatment, the specimens that received both surface treatments exhibited substantially greater weight loss, general thinning, and profile development as a function of sonication time - with all observed degradation limited to the nitrided layer. Further, the nitride layer was observed to be susceptible to extensive cracking (occasionally leading to spallation), but the cracking was never observed to penetrate into the carburized layer. These screening test results suggest there is no improvement in cavitation-erosion resistance associated with augmentation of the carburizing treatment with plasma nitriding.

  7. Assessment of Cavitation-Erosion Resistance of 316LN Stainless Steel Following a Nitro-Carburizing Surface Treatment

    SciTech Connect

    Pawel, Steven J

    2009-11-01

    A nitro-carburizing surface treatment known domestically as the Melonite process was applied to type 316LN stainless steel test pieces and exposed to sonication conditions in mercury using a vibratory horn technique. Cavitation-erosion damage was evaluated for extended exposures and compared to other surface treatments on the same substrate alloy. The results indicate that the Melonite process substantially retards weight loss and crater development for extended periods, but gradually is eroded/destroyed leading to exposure of the substrate and cavitation-erosion behavior similar to untreated specimens. Compared with other surface treatments, cavitation-erosion results indicate that specimens treated with Melonite perform similarly to specimens treated with a simple nitriding process. Neither the simple nitriding nor the Melonite treatment is quite as effective as a previously evaluated low temperature carburizing treatment, the latter being about a factor of three better than Melonite in terms of weight loss during sonication in mercury.

  8. Constitutive modeling of hot horming of austenitic stainless steel 316LN by accounting for recrystallization in the dislocation evolution

    NASA Astrophysics Data System (ADS)

    Kooiker, H.; Perdahcioğlu, E. S.; van den Boogaard, A. H.

    2016-08-01

    Hot compression test data taken from Zhang [1] of metastable austenitic stainless steel AISI 316LN over a range of strain rates and temperatures shows typical dynamic recovery and recrystallization behavior. It is proposed to model this behavior by incorporating not only the hardening and recovery into the Bergstrom dislocation evolution equation, but also the recrystallization. It is shown that the initial mechanical response before recrystallization can be accurately represented by assuming that the mean free path evolves as the microstructure evolves from homogeneously spaced dislocations to cell-pattern. Results show that this novel continuum mechanical model can predict the observed behavior, showing a good match to the experimental data and capturing the transition from recrystallization to (almost) no recrystallization.

  9. Corrosion Behavior of 316LN and 316 Stainless Steels During Long-term Exposure to Aerated 0.5 M NaCl Using Electrochemical Noise Technique

    NASA Astrophysics Data System (ADS)

    Pujar, M. G.; Parvathavarthini, N.; Jena, Sidhartha S.; Tata, B. V. R.; Dayal, R. K.; Khatak, H. S.

    2008-12-01

    In the present work 316LN as well as 316 stainless steel (SS) coupons each of dimensions (0.025 × 0.018 × 0.006 m3) in well-polished condition were used as two nominal electrodes which were immersed in the aerated solution of 0.5 M NaCl. Correlated current and potential electrochemical noise (EN) signals were collected at 1 Hz sampling frequency for 1 h daily over a period of 30 days. The detrended EN data were used to calculate the noise resistance ( R N) as well as the spectral noise resistance at zero frequency ( R {SN/o}) values and other statistical parameters. To study the nature of pits and distribution of their diameters as well as depths, extensive observations of the pitted and the blank specimens were carried out using Confocal Laser Scanning Microscopy (CLSM). The current and the potential records of the two alloys showed distinct differences in their corrosion behavior. It was observed that within less than 4 h of immersion, 316SS showed signals indicative of unstable pitting and onset of stable pitting was noticed after 48 h of exposure. However, until about 24 h, 316LN showed just the random signals and unstable pitting was observed after 28 h. The signals clearly indicated continuous growth of the stable pits in 316SS as against the repassivation of the unstable pits in 316LN after 7 days exposure. It was observed that R N values showed a continuous decrease in the case of 316SS, but were quite stable in the case of 316LN over the exposure period. Concurrent to these observations it was observed that 316SS specimen was extensively pitted. The frequency distributions of pit diameters as well pit depths were observed to be highest at 10-20 μm and 5-10 μm, respectively. However, pits with as large as 70-80 μm diameter and as deep as 20-25 μm too were observed. No pits were observed in case of 316LN even after 30 days of exposure, an observation that corroborates well with the stable R N values. Thus, in the present investigation, the long

  10. Assessment of surface relief and short cracks under cyclic creep in a type 316LN austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Sarkar, Aritra; Nagesha, A.; Parameswaran, P.; Sandhya, R.; Laha, K.

    2015-12-01

    Formation of surface relief and short cracks under cyclic creep (stress-controlled fatigue) in type 316LN stainless steel was studied at temperatures ranging from ambient to 923 K using scanning electron microscopy technique. The surface topography and crack distribution behaviour under cyclic creep were found to be strong functions of testing temperature due to the difference in strain accumulation. At 823 K, surface relief mainly consisted of fine slip markings due to negligible accumulation of strain as a consequence of dynamic strain ageing (DSA) which led to an increase in the cyclic life. Persistent slip markings (PSM) with distinct extrusions containing minute cracks were seen to prevail in the temperature range 873-923 K, indicating a higher slip activity causing higher strain accumulation in the absence of DSA. Besides, a large number of secondary cracks (both transgranular and intergranular) which were partially accentuated by severe oxidation, were observed. Extensive cavitation-induced grain boundary cracking took place at 923 K, which coalesced with PSM-induced transgranular cracks resulting in failure dominated by creep that in turn led to a drastic reduction in cyclic life. Investigations on the influence of stress rate were also carried out which underlined the presence of DSA at 823 K. At 923 K, lowering the stress rate caused further strengthening of the contribution from creep damage marked by a shift in the damage mechanism from cyclic slip to diffusion.

  11. The Mechanical and material properties of 316LN austenitic stainless steel for the fusion application in cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Sas, J.; Weiss, K.-P.; Jung, A.

    2015-12-01

    Due to the constant increase of claims for all materials used in superconducting magnets in "magnetic fusion reactors", the article deals with the possibilities of increasing the mechanical properties of austenitic stainless steel tested at cryogenic conditions that ensure the transport of Helium to magnets. The aim of the experimental plan was to increase the mechanical properties of the steel grade 316LN tested at 4.2K from the original value Steel A: YS = 1045 MPa, UTS = 1528 MPa, A = 33% to the value of YS = 1204 MPa,UTS = 1642 MPa, A = 34% and Steel B: YS = 1173 MPa, UTS = 1541 MPa, A = 28% to the value of YS = 1351 MPa, UTS = 1645 MPa, A = 17%. The increase in mechanical properties of the steel grade under examination has been made by means of heat processing in the conditions of annealing: Th1 = 625 ° C / th1 = 696 h. The mechanical properties of steel were evaluated using static tension tests at 4,2 K. The samples were placed in a cryostat filled with liquid helium. Except for the mechanical properties, there were also evaluated structural changes depending on the conditions of heat processing by light optical microscopy and EBSD (Electron Backscatter Diffraction). The increase of steel properties used in low temperatures was achieved by heat processing.

  12. Corrosion behavior and tensile properties of AISI 316LN stainless steel exposed to flowing sodium at 823 K

    SciTech Connect

    Pillai, S.R.; Barasi, N.S.; Khatak, H.S.; Terrance, A.L.E.; Kale, R.D.; Rajan, M.; Rajan, K.K.

    2000-02-01

    Austenitic stainless steel of the grade AISI 316 LN was exposed to flowing sodium in a loop at 823 K for 6,000 h to examine the corrosion and mass-transfer behavior. The specimens were incorporated in specially designed sample holders in the loop. These were retrieved and examined by various metallurgical techniques. Specimens were also subjected to thermal aging in the same sample holder to aid in separating the consequences of exposure to sodium from those cause by mere thermal effects. Microstructural investigations have revealed that thermal aging caused the precipitation of carbides at the grain boundaries. Exposure to sodium caused the leaching of elements such as chromium and nickel from the specimen. Loss of nickel from the austenite phase promoted the generation of ferrite phase. Microhardness investigation revealed the hardening of the sodium-exposed surface. Analysis using an electron Probe Microanalyzer revealed that the surface of the steel was both carburized and nitrided. Tensile tests indicated that there is no appreciable difference in the yield strength (YS) and ultimate tensile strength (UTS) of the thermally aged and sodium-exposed specimens when compared with the material in the as-received condition. However, the thermally aged and sodium-exposed specimens showed a decrease in the uniform elongation and total elongation at rupture, perhaps due to carburization and nitridation.

  13. Thick-section weldments in 21-6-9 and 316LN stainless steel for fusion energy applications

    NASA Astrophysics Data System (ADS)

    Alexander, D. J.; Goodwin, G. M.

    The Burning Plasma Experiment (BPX), formerly known as the Compact Ignition Tokomak, will be a major advance in the design of a fusion reactor. The successful construction of fusion reactors will require extensive welding of thick-section stainless steel plates. Severe service conditions will be experienced by the structure. Operating temperatures will range from room temperature (300 K) to liquid nitrogen temperature (77 K), and perhaps even lower. The structure will be highly stressed, and subject to sudden impact loads if plasma disruptions occur. This demands a combination of high strength and high toughness from the weldments. Significant portions of the welding will be done in the field, so preweld and postweld heat treatments will be difficult. The thick sections to be welded will require a high deposition rate process, and will result in significant residual stresses in the materials. Inspection of these thick sections in complex geometries will be very difficult. All of these constraints make it essential that the welding procedures and alloys be well understood, and the mechanical properties of the welds and their heat-affected zones must be adequately characterized. The candidate alloy for structural applications in the BPX such as the magnet cases was initially selected as 21-6-9 austenitic stainless steel, and later changed to 316LN stainless steel. This study examined several possible filler materials for thick-section (25 to 50 mm) weldments in these two materials. The tensile and Charpy V-notch properties were measured at room temperature and 77 K. The fracture toughness was measured for promising materials.

  14. Thick-section weldments in 21-6-9 and 316LN stainless steel for fusion energy applications

    SciTech Connect

    Alexander, D.J.; Goodwin, G.M.

    1991-01-01

    The Burning Plasma Experiment (BPX), formerly known as the Compact Ignition Tokomak, will be a major advance in the design of a fusion reactor. The successful construction of fusion reactors will require extensive welding of thick-section stainless steel plates. Severe service conditions will be experienced by the structure. Operating temperatures will range from room temperature (300 K) to liquid nitrogen temperature (77 K), and perhaps even lower. The structure will be highly stressed, and subject to sudden impact loads if plasma disruptions occur. This demands a combination of high strength and high toughness from the weldments. Significant portions of the welding will be done in the field, so preweld and postweld heat treatments will be difficult. The thick sections to be welded will require a high deposition rate process, and will result in significant residual stresses in the materials. Inspection of these thick sections in complex geometries will be very difficult. All of these constraints make it essential that the welding procedures and alloys be well understood, and the mechanical properties of the welds and their heat-affected zones must be adequately characterized. The candidate alloy for structural applications in the BPX such as the magnet cases was initially selected as 21-6-9 austenitic stainless steel, and later changed to 316LN stainless steel. This study examined several possible filler materials for thick-section (25 to 50 mm) weldments in these two materials. The tensile and Charpy V-notch properties were measured at room temperature and 77 K. The fracture toughness was measured for promising materials.

  15. Effects of environment and frequency on the fatigue behavior of the spallation neutron source (SNS) target container material - 316 LN stainless steel

    NASA Astrophysics Data System (ADS)

    Tian, Hongbo

    As the candidate target container material of the new Spallation Neutron Source (SNS) being designed and constructed at the Oak Ridge National Laboratory (ORNL), Type 316 low-carbon nitrogen-added (LN) stainless steel (SS) will operate in an aggressive environment, subjected to intense fluxes of high-energy protons and neutrons while exposed to liquid mercury. The current project is oriented toward materials studies regarding the effects of test environment and frequency on the fatigue behavior of 316 LN SS. In order to study the structural applications of this material and improve the fundamental understanding of the fatigue damage mechanisms, fatigue tests were performed in air and mercury environments at various frequencies and R ratios (R = sigma min/sigmamax, sigmamin and sigmamax are the applied minimum and maximum stresses, respectively). Fatigue data were developed for the structural design and engineering applications of this material. Specifically, high-cycle fatigue tests, fatigue crack-propagation tests, and ultrahigh cycle fatigue tests up to 10 9 cycles were conducted in air and mercury with test frequencies from 10 Hz to 700 Hz. Microstructure characterizations were performed using optical microscopy (OM), scanning-electron microscopy (SEM), and transmission-electron microscopy (TEM). It was found that mercury doesn't seem to have a large impact on the crack-initiation behavior of 316 LN SS. However, the crack-propagation mechanisms in air and mercury are different in some test conditions. Transgranular cracks seem to be the main mechanism in air, and intergranular in mercury. A significant specimen self-heating effect was found during high-cycle faituge. Theoretical calculation was performed to predict temperature responses of the material subjected to cyclic deformation. The predicted cyclic temperature evolution seems to be in good agreement with the experimental results.

  16. Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

    NASA Astrophysics Data System (ADS)

    Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

    2016-04-01

    The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

  17. Effects of mercury on fatigue behavior of Type 316 LN stainless steel: application in the spallation neutron source

    NASA Astrophysics Data System (ADS)

    Tian, H.; Liaw, P. K.; Strizak, J. P.; Mansur, L. K.

    2003-05-01

    The high-cycle fatigue behavior of Type 316 stainless steel (SS), the prime candidate target-container material for the spallation neutron source (SNS), was investigated in air and mercury at frequencies of 0.2 and 10 Hz with a R ratio of -1, and at 10 and 700 Hz with a R ratio of 0.1. Here R equals the ratio of the applied minimum to maximum loads during fatigue experiments. A decrease in the fatigue life in mercury was observed, relative to that in air, at 0.2 Hz. Correspondingly, intergranular fracture was found on the fracture surfaces of specimens tested in mercury at 0.2 Hz, which is a typical fracture mode caused by liquid metal embrittlement (LME). Heating by mechanical working was observed during fatigue tests at 10 Hz and a R of -1, and at 700 Hz and a R of 0.1, which resulted in great increases in specimen temperatures and shorter fatigue lives for large stress amplitudes (⩾210 MPa), relative to those in mercury. However, in the fatigue tests at 10 and 700 Hz, the fatigue lives in air with cooling and those in mercury seemed to be comparable, indicating little influence of the mercury. Thus, both specimen self-heating and LME need to be considered in understanding fatigue behavior of Type 316 SS in air and mercury.

  18. Adaptive Neuro-Fuzzy Inference System (ANFIS)-Based Models for Predicting the Weld Bead Width and Depth of Penetration from the Infrared Thermal Image of the Weld Pool

    NASA Astrophysics Data System (ADS)

    Subashini, L.; Vasudevan, M.

    2012-02-01

    Type 316 LN stainless steel is the major structural material used in the construction of nuclear reactors. Activated flux tungsten inert gas (A-TIG) welding has been developed to increase the depth of penetration because the depth of penetration achievable in single-pass TIG welding is limited. Real-time monitoring and control of weld processes is gaining importance because of the requirement of remoter welding process technologies. Hence, it is essential to develop computational methodologies based on an adaptive neuro fuzzy inference system (ANFIS) or artificial neural network (ANN) for predicting and controlling the depth of penetration and weld bead width during A-TIG welding of type 316 LN stainless steel. In the current work, A-TIG welding experiments have been carried out on 6-mm-thick plates of 316 LN stainless steel by varying the welding current. During welding, infrared (IR) thermal images of the weld pool have been acquired in real time, and the features have been extracted from the IR thermal images of the weld pool. The welding current values, along with the extracted features such as length, width of the hot spot, thermal area determined from the Gaussian fit, and thermal bead width computed from the first derivative curve were used as inputs, whereas the measured depth of penetration and weld bead width were used as output of the respective models. Accurate ANFIS models have been developed for predicting the depth of penetration and the weld bead width during TIG welding of 6-mm-thick 316 LN stainless steel plates. A good correlation between the measured and predicted values of weld bead width and depth of penetration were observed in the developed models. The performance of the ANFIS models are compared with that of the ANN models.

  19. Gold based bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Schroers, Jan; Lohwongwatana, Boonrat; Johnson, William L.; Peker, Atakan

    2005-08-01

    Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5mm in the best glassformer. Au49Ag5.5Pd2.3Cu26.9Si16.3 has a liquidus temperature of 644K, a glass transition temperature of 401K, and a supercooled liquid region of 58K. The Vickers hardness of the alloys in this system is ˜350Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry.

  20. SOLDERING OF ALUMINUM BASE METALS

    DOEpatents

    Erickson, G.F.

    1958-02-25

    This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

  1. Metal detector technology data base

    SciTech Connect

    Porter, L.K.; Gallo, L.R.; Murray, D.W.

    1990-08-01

    The tests described in this report were conducted to obtain information on the effects target characteristics have on portal type metal detector response. A second purpose of the tests was to determine the effect of detector type and settings on the detection of the targets. Although in some cases comparison performance of different types and makes of metal detectors is found herein, that is not the primary purpose of the report. Further, because of the many variables that affect metal detector performance, the information presented can be used only in a general way. The results of these tests can show general trends in metal detection, but do little for making accurate predictions as to metal detector response to a target with a complex shape such as a handgun. The shape of an object and its specific metal content (both type and treatment) can have a significant influence on detection. Thus it should not be surprising that levels of detection for a small 100g stainless steel handgun are considerably different than for detection of the 100g stainless steel right circular cylinder that was used in these tests. 7 figs., 1 tab.

  2. METHOD OF JOINING CARBIDES TO BASE METALS

    DOEpatents

    Krikorian, N.H.; Farr, J.D.; Witteman, W.G.

    1962-02-13

    A method is described for joining a refractory metal carbide such as UC or ZrC to a refractory metal base such as Ta or Nb. The method comprises carburizing the surface of the metal base and then sintering the base and carbide at temperatures of about 2000 deg C in a non-oxidizing atmosphere, the base and carbide being held in contact during the sintering step. To reduce the sintering temperature and time, a sintering aid such as iron, nickel, or cobait is added to the carbide, not to exceed 5 wt%. (AEC)

  3. Physiologically based models of metal kinetics.

    PubMed

    O'Flaherty, E J

    1998-05-01

    The issues confronting the modeler of metals kinetics are somewhat different from those with which the modeler of organic chemical behavior is faced. Particularly important features of metals kinetics include metal-protein binding and metal-metal interactions. Reduction, and for some metals oxidation, is frequently an intrinsic part of metal metabolism. Alkylation/dealkylation reactions may or may not render the metal less active, and the behavior of alkylated or dealkylated metabolites must often be included in a complete kinetic model. Despite these complexities, the kinetics of metals are as amenable to the techniques of physiologically based modeling as are the kinetics of organic chemicals. Like all models, those for metals kinetics have the potential to organize a variety of observations, sometimes including apparently inconsistent observations, into a coherent framework of behavior, to identify needs for more complete experimental information, and to assist the risk assessor in making judgments concerning dose-response relationships. Development of physiologically based models of the kinetic behavior of metals is in its very early stages. The kinetics of only four metals, arsenic, chromium, mercury, and lead, have been modeled with any degree of completeness. Of these, the lead model is the most fully realized at the present time. The chromium and mercury models are still in the process of development, and experimental data are being gathered to support further development and refinement of the arsenic model. We may expect to see continued progress made on these models and their practical applications, as well as the development of new models for other toxicologically significant metals such as cadmium, manganese, nickel, and aluminum. PMID:9631283

  4. p-type metal-base transistor

    NASA Astrophysics Data System (ADS)

    Delatorre, R. G.; Munford, M. L.; Zandonay, R.; Zoldan, V. C.; Pasa, A. A.; Schwarzacher, W.; Meruvia, M. S.; Hümmelgen, I. A.

    2006-06-01

    In this work we present data from a novel p-type metal-base transistor with common-base gain α ˜1, fabricated at ambient temperature and pressure by electrodepositing sequentially on a p-type Si collector, a Co base and a Cu2O emitter. The high gain and the dependence of potential between emitter and base (VEB) on the potential between collector and base (VCB) when the emitter current (IE) is held constant both suggest that the device functions as a natural permeable base transistor for very thin metal bases.

  5. Graphene oxide-based flexible metal-insulator-metal capacitors

    NASA Astrophysics Data System (ADS)

    Bag, A.; Hota, M. K.; Mallik, S.; Maiti, C. K.

    2013-05-01

    This work explores the fabrication of graphene oxide (GO)-based metal-insulator-metal (MIM) capacitors on flexible polyethylene terephthalate (PET) substrates. Electrical properties are studied in detail. A high capacitance density of ˜4 fF µm-2 measured at 1 MHz and permittivity of ˜6 have been obtained. A low voltage coefficient of capacitance, VCC-α, and a low dielectric loss tangent indicate the potential of GO-based MIM capacitors for RF applications. The constant voltage stressing study has shown a high reliability against degradation up to a projected period of 10 years. Degradation in capacitance of the devices on flexible substrates has been studied by bending radius down to 1 cm even up to 6000 times of repeated bending.

  6. Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum

    DOEpatents

    Ray, Siba P.; Liu, Xinghua

    2000-01-01

    An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

  7. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  8. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  9. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  10. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  11. 21 CFR 872.3710 - Base metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that...

  12. Thulium-based bulk metallic glass

    SciTech Connect

    Yu, H. B.; Yu, P.; Wang, W. H.; Bai, H. Y.

    2008-04-07

    We report the formation and properties of a thulium-based bulk metallic glass (BMG). Compared with other known rare-earth (RE) based BMGs, Tm-based BMGs show features of excellent glass formation ability, considerable higher elastic modulus, smaller Poisson's ratio, high mechanical strength, and intrinsic brittleness. The reasons for the different properties between the Tm-based and other RE-based BMGs are discussed. It is expected that the Tm-based glasses with the unique properties are appropriate candidates for studying some important issues in BMGs.

  13. Biomimetic cavity-based metal complexes.

    PubMed

    Rebilly, Jean-Noël; Colasson, Benoit; Bistri, Olivia; Over, Diana; Reinaud, Olivia

    2015-01-21

    The design of biomimetic complexes for the modeling of metallo-enzyme active sites is a fruitful strategy for obtaining fundamental information and a better understanding of the molecular mechanisms at work in Nature's chemistry. The classical strategy for modeling metallo-sites relies on the synthesis of metal complexes with polydentate ligands that mimic the coordination environment encountered in the natural systems. However, it is well recognized that metal ion embedment in the proteic cavity has key roles not only in the recognition events but also in generating transient species and directing their reactivity. Hence, this review focuses on an important aspect common to enzymes, which is the presence of a pocket surrounding the metal ion reactive sites. Through selected examples, the following points are stressed: (i) the design of biomimetic cavity-based complexes, (ii) their corresponding host-guest chemistry, with a special focus on problems related to orientation and exchange mechanisms of the ligand within the host, (iii) cavity effects on the metal ion binding properties, including 1st, 2nd, and 3rd coordination spheres and hydrophobic effects and finally (iv) the impact these factors have on the reactivity of embedded metal ions. Important perspectives lie in the use of this knowledge for the development of selective and sensitive probes, new reactions, and green and efficient catalysts with bio-inspired systems.

  14. Chemoelectronic circuits based on metal nanoparticles.

    PubMed

    Yan, Yong; Warren, Scott C; Fuller, Patrick; Grzybowski, Bartosz A

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the 'jammed' nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems 'chemoelectronic'. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also 'green', in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions. PMID:26974958

  15. Chemoelectronic circuits based on metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Yan, Yong; Warren, Scott C.; Fuller, Patrick; Grzybowski, Bartosz A.

    2016-07-01

    To develop electronic devices with novel functionalities and applications, various non-silicon-based materials are currently being explored. Nanoparticles have unique characteristics due to their small size, which can impart functions that are distinct from those of their bulk counterparts. The use of semiconductor nanoparticles has already led to improvements in the efficiency of solar cells, the processability of transistors and the sensitivity of photodetectors, and the optical and catalytic properties of metal nanoparticles have led to similar advances in plasmonics and energy conversion. However, metals screen electric fields and this has, so far, prevented their use in the design of all-metal nanoparticle circuitry. Here, we show that simple electronic circuits can be made exclusively from metal nanoparticles functionalized with charged organic ligands. In these materials, electronic currents are controlled by the ionic gradients of mobile counterions surrounding the ‘jammed’ nanoparticles. The nanoparticle-based electronic elements of the circuitry can be interfaced with metal nanoparticles capable of sensing various environmental changes (humidity, gas, the presence of various cations), creating electronic devices in which metal nanoparticles sense, process and ultimately report chemical signals. Because the constituent nanoparticles combine electronic and chemical sensing functions, we term these systems ‘chemoelectronic’. The circuits have switching times comparable to those of polymer electronics, selectively transduce parts-per-trillion chemical changes into electrical signals, perform logic operations, consume little power (on the scale of microwatts), and are mechanically flexible. They are also ‘green’, in the sense that they comprise non-toxic nanoparticles cast at room temperature from alcohol solutions.

  16. Effects of Winding Strain and Heat Treatment on Properties of 316 LN and Haynes 242

    NASA Astrophysics Data System (ADS)

    Han, K.; Walsh, R. P.; Toplosky, V. J.; Goddard, R. E.; Lu, J.; Dixon, I. R.

    2008-03-01

    The outer coils of the hybrid magnets at the NHMFL are superconducting magnet and use Cable-in-Conduit-Conductor (CICC) technology. This technology requires us to wind the coils before the Nb3Sn heat treatment is undertaken. The winding introduces both tensile and compressive stresses to the conduit alloys. The subsequent heat treatment has to be done when the conduit alloys are under the pre-stress. We have simulated the conduit heat treatments with the alloys under various stress levels, and undertaken tensile tests at 4 K and microstructure examinations. The results indicate that the pre-stress before the heat treatment influences the microstructure and therefore tensile test properties of the conduit alloys at 4 K. The tensile test property changes are related to the grain boundary precipitation variation introduced by pre-stress.

  17. Base metal dehydrogenation of amine-boranes

    DOEpatents

    Blacquiere, Johanna Marie; Keaton, Richard Jeffrey; Baker, Ralph Thomas

    2009-06-09

    A method of dehydrogenating an amine-borane having the formula R.sup.1H.sub.2N--BH.sub.2R.sup.2 using base metal catalyst. The method generates hydrogen and produces at least one of a [R.sup.1HN--BHR.sup.2].sub.m oligomer and a [R.sup.1N--BR.sup.2].sub.n oligomer. The method of dehydrogenating amine-boranes may be used to generate H.sub.2 for portable power sources, such as, but not limited to, fuel cells.

  18. A Heteroepitaxial Perovskite Metal-Base Transistor

    SciTech Connect

    Yajima, T.; Hikita, Y.; Hwang, H.Y.; /Tokyo U. /JST, PRESTO /SLAC

    2011-08-11

    'More than Moore' captures a concept for overcoming limitations in silicon electronics by incorporating new functionalities in the constituent materials. Perovskite oxides are candidates because of their vast array of physical properties in a common structure. They also enable new electronic devices based on strongly-correlated electrons. The field effect transistor and its derivatives have been the principal oxide devices investigated thus far, but another option is available in a different geometry: if the current is perpendicular to the interface, the strong internal electric fields generated at back-to-back heterojunctions can be used for oxide electronics, analogous to bipolar transistors. Here we demonstrate a perovskite heteroepitaxial metal-base transistor operating at room temperature, enabled by interface dipole engineering. Analysis of many devices quantifies the evolution from hot-electron to permeable-base behaviour. This device provides a platform for incorporating the exotic ground states of perovskite oxides, as well as novel electronic phases at their interfaces.

  19. Chemical Sensors Based on Metal Oxide Nanostructures

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

    2006-01-01

    This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

  20. Efficient waveguide coupler based on metal materials

    NASA Astrophysics Data System (ADS)

    Wu, Wenjun; Yang, Junbo; Chang, Shengli; Zhang, Jingjing; Lu, Huanyu

    2015-10-01

    Because of the diffraction limit of light, the scale of optical element stays in the order of wavelength, which makes the interface optics and nano-electronic components cannot be directly matched, thus the development of photonics technology encounters a bottleneck. In order to solve the problem that coupling of light into the subwavelength waveguide, this paper proposes a model of coupler based on metal materials. By using Surface Plasmon Polaritons (SPPs) wave, incident light can be efficiently coupled into waveguide of diameter less than 100 nm. This paper mainly aims at near infrared wave band, and tests a variety of the combination of metal materials, and by changing the structural parameters to get the maximum coupling efficiency. This structure splits the plane incident light with wavelength of 864 nm, the width of 600 nm into two uniform beams, and separately coupled into the waveguide layer whose width is only about 80 nm, and the highest coupling efficiency can reach above 95%. Using SPPs structure will be an effective method to break through the diffraction limit and implement photonics device high-performance miniaturization. We can further compress the light into small scale fiber or waveguide by using the metal coupler, and to save the space to hold more fiber or waveguide layer, so that we can greatly improve the capacity of optical communication. In addition, high-performance miniaturization of the optical transmission medium can improve the integration of optical devices, also provide a feasible solution for the photon computer research and development in the future.

  1. Progress in base-metal water oxidation catalysis.

    PubMed

    Parent, Alexander Rene; Sakai, Ken

    2014-08-01

    This minireview provides a brief overview of the progress that has been made in developing homogeneous water oxidation catalysts based on base metals (manganese, iron, cobalt, nickel, and copper) from the 1990s to mid-2014. The impact of each contribution is analyzed, and opportunities for further improvement are noted. In addition, the relative stabilities of the base-metal catalysts that have been reported are compared to illustrate the importance of developing more robust catalytic systems by using these metals. This manuscript is intended to provide a firm foundation for researchers entering the field of water oxidation based on base metals and a useful reference for those currently involved in the field.

  2. Antibacterial and antifungal metal based triazole Schiff bases.

    PubMed

    Chohan, Zahid H; Hanif, Muhammad

    2013-10-01

    A new series of four biologically active triazole derived Schiff base ligands (L(1)-L(4)) and their cobalt(II), nickel(II), copper(II) and zinc(II) complexes (1-16) have been synthesized and characterized. The ligands were prepared by the condensation reaction of 3-amino-5-methylthio-1H-1,2,4-triazole with chloro-, bromo- and nitro-substituted 2-hydroxybenzaldehyde in an equimolar ratio. The antibacterial and antifungal bioactivity data showed the metal(II) complexes to be more potent antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal species.

  3. Preparation of non-metals properties for data base

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The development of non-metallic material properties data bases is discussed. The data bases consist of the non-metallic material classes of adhesives, adhesive/sealants, plastics, and elastomers. A specifications data base was also developed to incorporate material specifications data as a supplement to the Elastomers Data Base. Examples of the forms used are provided to show the properties of the materials which appear in the data base.

  4. Metal-based impurities in graphenes: application for electroanalysis.

    PubMed

    Chee, Sze Yin; Pumera, Martin

    2012-05-01

    We show here that metallic impurities presented in graphenes prepared from graphite can be usefully employed for electroanalysis. We demonstrate that cumene hydroperoxide electrochemical reduction on graphene containing iron-based impurities provides significantly larger voltammetric currents than the same experiment using iron oxide nanoparticles. This opens doors for turning metallic impurities into potentially useful components of graphene based electrochemical systems.

  5. Development of metal based thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Il

    In this work, metal-based thermal barrier coatings (MBTBCs) have been produced, using high frequency induction plasma spraying (IPS) of iron-based nanostructured alloy powders. Important advances have been made over recent years to the development of ceramic-based thermal barrier coatings (TBCs) for internal combustion engines application, but they are not yet applied in mass production situations. Besides the important economic considerations, the reliability of ceramic: TBCs is also an issue, being associated with the difficulty of predicting their "in-service" lifetime. Through engineering of the nano/amorphous structure of MBTBCs, their thermal conductivity can be made as low as those of ceramic-based TBCs, with reduced mean free paths of the electrons/phonons scattering. In this work, nano/amorphous structured coatings were deposited by IPS using the following spray parameters: spraying distance (210 ˜ 270 mm), plasma gas composition (Ar/N2), IPS torch power (24kW), and powder feed-rate (16g/min.). The structure and properties of the deposited layers were characterized through SEM (Scanning Electron Microscopy) observations. The thermal diffusivity (alpha) properties of the MBTBCs were measured using a laser flash method. Density (rho) and specific heat (Cp) of the MBTBCs were also measured, and their thermal conductivity (k) calculated (k =alpharhoCp). The thermal conductivity of MBTBCs was found to be as low as 1.99 W/m/K. The heat treatment study showed that crystal structure changes, and grain size growth from a few nanometers to tenth of nanometers occurred at 550°C under static exposure conditions. Thermal expansion coefficient (TEC) of MBTBCs was 13E-6/K, which is close to the TEC of cast iron and thus, closer to the TEC values of aluminium alloys than are conventional TBCs. Fracture toughness of MBTBCs has also been assessed by use of Vickers hardness tests, with a 500 g load for 15 s, and the results show that there are no measurable crack

  6. Nanomotor-based biocatalytic patterning of helical metal microstructures.

    PubMed

    Manesh, Kalayil Manian; Campuzano, Susana; Gao, Wei; Lobo-Castañón, María Jesús; Shitanda, Isao; Kiantaj, Kiarash; Wang, Joseph

    2013-02-21

    A new nanomotor-based surface-patterning technique based on the movement of a magnetically powered enzyme-functionalized flexible nanowire swimmer offers the ability to create complex helical metal microstructures.

  7. Laser -Based Joining of Metallic and Non-metallic Materials

    NASA Astrophysics Data System (ADS)

    Padmanabham, G.; Shanmugarajan, B.

    Laser as a high intensity heat source can be effectively used for joining of materials by fusion welding and brazing in autogenous or in hybrid modes. In autogenous mode, welding is done in conduction , deep penetration , and keyhole mode. However, due to inherently high energy density available from a laser source, autogenous keyhole welding is the most popular laser welding mode. But, it has certain limitations like need for extremely good joint fit-up, formation of very hard welds in steel , keyhole instability, loss of alloying elements, etc. To overcome these limitations, innovative variants such as laser-arc hybrid welding , induction-assisted welding , dual beam welding , etc., have been developed. Using laser heat, brazing can be performed by melting a filler to fill the joints, without melting the base materials. Accomplishing laser-based joining as mentioned above requires appropriate choice of laser source, beam delivery system, processing head with appropriate optics and accessories. Basic principles of various laser-based joining processes, laser system technology, process parameters, metallurgical effects on different base materials, joint performance, and applications are explained in this chapter.

  8. Microfluidic platforms for gallium-based liquid metal alloy

    NASA Astrophysics Data System (ADS)

    Kim, Daeyoung

    As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non

  9. Cell Surface-based Sensing with Metallic Nanoparticles

    PubMed Central

    Jiang, Ziwen; Rotello, Vincent M.

    2015-01-01

    Metallic nanoparticles provide versatile scaffolds for biosensing applications. In this review, we focus on the use of metallic nanoparticles for cell surface sensings. Examples of the use of both specific recognition and array-based “chemical nose” approaches to cell surface sensing will be discussed. PMID:25853985

  10. Surface/structure functionalization of copper-based catalysts by metal-support and/or metal-metal interactions

    NASA Astrophysics Data System (ADS)

    Konsolakis, Michalis; Ioakeimidis, Zisis

    2014-11-01

    Cu-based catalysts have recently attracted great attention both in catalysis and electro-catalysis fields due to their excellent catalytic performance and low cost. Given that their performance is determined, to a great extent, by Cu sites local environment, considerable efforts have been devoted on the strategic modifications of the electronic and structural properties of Cu sites. In this regard, the feasibility of tuning the local structure of Cu entities by means of metal-support or metal-metal interactions is investigated. More specifically, the physicochemical properties of Cu entities are modified by employing: (i) different oxides (CeO2, La2O3, Sm2O3), or (ii) ceria-based mixed oxides (Ce1-xSmxOδ) as supporting carriers, and (iii) a second metal (Cobalt) adjacent to Cu (bimetallic Cu-Co/CeO2). A characterization study, involving BET, XRD, TPR, and XPS, reveal that significant modifications on structural, redox and electronic properties of Cu sites can be induced by adopting either different oxide carriers or bimetallic complexes. Fundamental insights into the tuning of Cu local environment by metal-support or metal-metal interactions are provided, paving the way for real-life industrial applications.

  11. SILANE-BASED CONVERSION COATING FOR METALS

    EPA Science Inventory

    For the past three years, a project to develop new pretreatment rinses for metals was carried out by the U.S. Environmental Protection Agency and the University of Cincinnati. The project involved optimization of laboratory rinses with dilute aqueous solutions organofunctional s...

  12. Asymmetric Schiff bases derived from diaminomaleonitrile and their metal complexes

    NASA Astrophysics Data System (ADS)

    Yang, Jianjie; Shi, Rufei; Zhou, Pei; Qiu, Qiming; Li, Hui

    2016-02-01

    Asymmetric Schiff bases, due to its asymmetric structure, can be used as asymmetric catalyst, antibacterial, and mimic molecules during simulate biological processes, etc. In recent years, research on synthesis and properties of asymmetric Schiff bases have become an increase interest of chemists. This review summarizes asymmetric Schiff bases derived from diaminomaleonitrile (DAMN) and DAMN-based asymmetric Schiff bases metal complexes. Applications of DAMN-based asymmetric Schiff bases are also discussed in this review.

  13. OXIDATION BEHAVIOR OF WELDED AND BASE METAL UNS N06025

    SciTech Connect

    Pint, Bruce A; Paul, Larry D.

    2007-01-01

    The oxidation behavior of specimens containing tungsten inert gas welds of UNS N06025 (NiCrFeAlY) was investigated in air for up to 5,000h at 900 -1000 C and 1,000h at 1100 -1200 C. In general, the microstructure was very homogeneous in the weld with smaller carbides and the Al2O3 penetrations were similar or smaller compared to those formed in the base metal. Above 1000 C, significant spallation was observed and Al and Cr depletion in the metal was observed to a similar extent in the weld and base metal. The maximum internal oxidation depth of the base metal at 900 and 1100 C was lower than several other commercial Ni-base alloys.

  14. Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection

    PubMed Central

    Kanan, Sofian M.; El-Kadri, Oussama M.; Abu-Yousef, Imad A.; Kanan, Marsha C.

    2009-01-01

    A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented. PMID:22408500

  15. Metal-based nanosystems for diagnosis.

    PubMed

    Popescu, Roxana Cristina; Fufă, Mariana Oana Mihaela; Grumezescu, Alexandru Mihai

    2015-01-01

    The impressive diversity related to etiologic factors and the distinctive genetic and immunological behavior attained by various conditions represent the fundamental reasons for high-rated inefficient and eventual hazardous strategies entailed by conventional healthcare practice. Thanks to the tremendous progress reported in nanotechnology during the last decades, various unconventional and promising strategies have been successfully developed and examined with respect to potential genuine biomedical applications. Given the amazing possibility to manipulate matter at a molecular and atomic level and the incessant need to design and implement personalized therapies, various nanosized systems have thus been engineered. Among the newly developed nanomaterials, metallic nanoparticles have gain attention during the intense biomedical research activity, thanks to their peculiar size-conditioned properties. An efficient therapeutic strategy begins with an accurate diagnosis result, so the immediate requirement of such specific detection tools is conspicuous. The use of silver and gold in day-to-day activities is acknowledged since ancient times, but the novel technological opportunities extended their particular applications towards personalized medicine. It is worthy to mention that the unexpected nanodimension-related features of the aforementioned noble metals strongly recommend them for a large number of current applications in nanomedicine, including novel and specific metallic nanostructures used in diagnostics.

  16. Transition-Metal-Free Biomolecule-Based Flexible Asymmetric Supercapacitors.

    PubMed

    Yang, Yun; Wang, Hua; Hao, Rui; Guo, Lin

    2016-09-01

    A transition-metal-free asymmetric supercapacitor (ASC) is successfully fabricated based on an earth-abundant biomass derived redox-active biomolecule, named lawsone. Such an ASC exhibits comparable or even higher energy densities than most of the recently reported transition-metal-based ASCs, and this green ASC generation from renewable resources is promising for addressing current issues of electronic hazard processing, high cost, and unsustainability. PMID:26890876

  17. Metal dusting and carburization resistance of nickel-base alloys

    SciTech Connect

    Kloewer, J.; Grabke, H.J.; Mueller-Lorenz, E.M.; Agarwal, D.C.

    1997-08-01

    Severe material failures caused by so-called metal dusting have been reported during recent years. The reason for these failures were strongly carburizing CO-H{sub 2} gas mixtures such as encountered in chemical plants for the synthesis of hydrocarbons, methanol, ammonia etc. as well as in plants for the reduction of iron ores. The carburization behavior of nine commercial nickel-base alloys and four iron-nickel-chromium alloys was investigated at 650 C in a carburizing H{sub 2}-CO-H{sub 2}O-gas with a carbon activity of a{sub c} {much_gt} 1. The iron-nickel-chromium alloys suffered severe metal dusting after a very short test period. Nickel base alloys were generally less susceptible to metal dusting than iron-base alloys. However, their corrosion behavior was found to depend sensitively on the chromium concentration of the respective alloys. Alloys like alloy 600H, with a chromium concentration of only 16%, suffered wastage rates which were similar to those of the more resistant iron-base alloys. Nickel-base alloys with chromium concentrations of 25% and above, on the other hand, showed no significant evidence of metal dusting even after 10,000 hours of exposure. It was found that these alloys are protected against metal dusting by the formation of a dense, self-healing chromia scale, which prevents the penetration of carbon into the base metal.

  18. Metal-dielectric-metal based narrow band absorber for sensing applications.

    PubMed

    Lu, Xiaoyuan; Wan, Rengang; Zhang, Tongyi

    2015-11-16

    We have investigated numerically the narrowband absorption property of a metal-dielectric-metal based structure which includes a top metallic nanoring arrays, a metal backed plate, and a middle dielectric spacer. Its absorption is up to 90% with linewidth narrower than 10 nm. This can be explained in terms of surface lattice resonance of the periodic structure. The spectrum with the sharp absorption dip, i.e. the lattice resonance, strongly depends on the refractive index of media surrounding the nanorings. This feature can be explored to devise a refractive index sensor, of which the bulk sensitivity factor is one order larger than that based on gap resonance mode, while the surface sensitivity factor can be two times larger. The proposed narrowband absorber has potential in applications of plasmonic biosensors. PMID:26698467

  19. In Situ Synthesis of Metal Sulfide Nanoparticles Based on 2D Metal-Organic Framework Nanosheets.

    PubMed

    Lu, Qipeng; Zhao, Meiting; Chen, Junze; Chen, Bo; Tan, Chaoliang; Zhang, Xiao; Huang, Ying; Yang, Jian; Cao, Feifei; Yu, Yifu; Ping, Jianfeng; Zhang, Zhicheng; Wu, Xue-Jun; Zhang, Hua

    2016-09-01

    A facile in situ synthetic method is developed to synthesize metal sulfide nanoparticles based on 2D M-TCPP (M = Cu, Cd, or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin)) metal-organic framework nanosheets. The obtained CuS/Cu-TCPP composite nanosheet is used as the active material in photoelectrochemical cells, showing notably increased photocurrent due to the improved exciton separation and charge carrier transport.

  20. Detection of heavy metal by paper-based microfluidics.

    PubMed

    Lin, Yang; Gritsenko, Dmitry; Feng, Shaolong; Teh, Yi Chen; Lu, Xiaonan; Xu, Jie

    2016-09-15

    Heavy metal pollution has shown great threat to the environment and public health worldwide. Current methods for the detection of heavy metals require expensive instrumentation and laborious operation, which can only be accomplished in centralized laboratories. Various microfluidic paper-based analytical devices have been developed recently as simple, cheap and disposable alternatives to conventional ones for on-site detection of heavy metals. In this review, we first summarize current development of paper-based analytical devices and discuss the selection of paper substrates, methods of device fabrication, and relevant theories in these devices. We then compare and categorize recent reports on detection of heavy metals using paper-based microfluidic devices on the basis of various detection mechanisms, such as colorimetric, fluorescent, and electrochemical methods. To finalize, the future development and trend in this field are discussed. PMID:27131999

  1. Detection of heavy metal by paper-based microfluidics.

    PubMed

    Lin, Yang; Gritsenko, Dmitry; Feng, Shaolong; Teh, Yi Chen; Lu, Xiaonan; Xu, Jie

    2016-09-15

    Heavy metal pollution has shown great threat to the environment and public health worldwide. Current methods for the detection of heavy metals require expensive instrumentation and laborious operation, which can only be accomplished in centralized laboratories. Various microfluidic paper-based analytical devices have been developed recently as simple, cheap and disposable alternatives to conventional ones for on-site detection of heavy metals. In this review, we first summarize current development of paper-based analytical devices and discuss the selection of paper substrates, methods of device fabrication, and relevant theories in these devices. We then compare and categorize recent reports on detection of heavy metals using paper-based microfluidic devices on the basis of various detection mechanisms, such as colorimetric, fluorescent, and electrochemical methods. To finalize, the future development and trend in this field are discussed.

  2. Metal-oxide-based energetic materials and synthesis thereof

    DOEpatents

    Tillotson, Thomas M. , Simpson; Randall L.; Hrubesh, Lawrence W.

    2006-01-17

    A method of preparing energetic metal-oxide-based energetic materials using sol-gel chemistry has been invented. The wet chemical sol-gel processing provides an improvement in both safety and performance. Essentially, a metal-oxide oxidizer skeletal structure is prepared from hydrolyzable metals (metal salts or metal alkoxides) with fuel added to the sol prior to gelation or synthesized within the porosity metal-oxide gel matrix. With metal salt precursors a proton scavenger is used to destabilize the sol and induce gelation. With metal alkoxide precursors standard well-known sol-gel hydrolysis and condensation reactions are used. Drying is done by standard sol-gel practices, either by a slow evaporation of the liquid residing within the pores to produce a high density solid nanocomposite, or by supercritical extraction to produce a lower density, high porous nanocomposite. Other ingredients may be added to this basic nanostructure to change physical and chemical properties, which include organic constituents for binders or gas generators during reactions, burn rate modifiers, or spectral emitters.

  3. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P.

    2016-05-01

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  4. Metal-based nanotoxicity and detoxification pathways in higher plants.

    PubMed

    Ma, Chuanxin; White, Jason C; Dhankher, Om Parkash; Xing, Baoshan

    2015-06-16

    The potential risks from metal-based nanoparticles (NPs) in the environment have increased with the rapidly rising demand for and use of nanoenabled consumer products. Plant's central roles in ecosystem function and food chain integrity ensure intimate contact with water and soil systems, both of which are considered sinks for NPs accumulation. In this review, we document phytotoxicity caused by metal-based NPs exposure at physiological, biochemical, and molecular levels. Although the exact mechanisms of plant defense against nanotoxicity are unclear, several relevant studies have been recently published. Possible detoxification pathways that might enable plant resistance to oxidative stress and facilitate NPs detoxification are reviewed herein. Given the importance of understanding the effects and implications of metal-based NPs on plants, future research should focus on the following: (1) addressing key knowledge gaps in understanding molecular and biochemical responses of plants to NPs stress through global transcriptome, proteome, and metablome assays; (2) designing long-term experiments under field conditions at realistic exposure concentrations to investigate the impact of metal-based NPs on edible crops and the resulting implications to the food chain and to human health; and (3) establishing an impact assessment to evaluate the effects of metal-based NPs on plants with regard to ecosystem structure and function.

  5. Hard and fragile holmium-based bulk metallic glasses

    SciTech Connect

    Luo, Q.; Zhao, D.Q.; Pan, M.X.; Wang, R.J.; Wang, W.H.

    2006-05-01

    A family of holmium-based bulk metallic glasses (BMGs) with high glass-forming ability is obtained. The Ho-based BMGs exhibit much larger elastic moduli and high thermal stability in contrast to other known rare-earth (RE)-based BMGs. In particular, the BMGs show a large value of fragility. It is expected that the hard RE-based glasses with high glass-forming ability and fragile behaviors make them the appropriate candidate for glass transition study.

  6. Detuned Plasmonic Bragg Grating Sensor Based on a Defect Metal-Insulator-Metal Waveguide

    PubMed Central

    Qu, Shinian; Song, Ci; Xia, Xiushan; Liang, Xiuye; Tang, Baojie; Hu, Zheng-Da; Wang, Jicheng

    2016-01-01

    A nanoscale Bragg grating reflector based on the defect metal-insulator-metal (MIM) waveguide is developed and numerically simulated by using the finite element method (FEM). The MIM-based structure promises a highly tunable broad stop-band in transmission spectra. The narrow transmission window is shown to appear in the previous stop-band by changing the certain geometrical parameters. The central wavelengths can be controlled easily by altering the geographical parameters. The development of surface plasmon polarition (SPP) technology in metallic waveguide structures leads to more possibilities of controlling light at deep sub-wavelengths. Its attractive ability of breaking the diffraction limit contributes to the design of optical sensors. PMID:27240381

  7. Thermal behaviors of liquid La-based bulk metallic glasses

    SciTech Connect

    Zhang, D. W.; Wang, X. D. E-mail: jiangjz@zju.edu.cn; Lou, H. B.; Cao, Q. P.; Jiang, J. Z. E-mail: jiangjz@zju.edu.cn; Wang, L. W.; Zhang, D. X.

    2014-12-14

    Thermal behaviors of liquid La-based bulk metallic glasses have been measured by using the dilatometer with a self-sealed sample cell. It is demonstrated that the strong glass forming liquid not only has the small thermal expansion coefficient but also shows the slow variation rate. Moreover, the strong glass former has relatively dense atomic packing and also small density change in the liquid state. The results suggest that the high glass forming ability of La-based metallic glasses would be closely related to the slow atomic rearrangements in liquid melts.

  8. Weld induced base metal microfissuring in high temperature alloys

    SciTech Connect

    Lingenfelter, A.C.; Shoemaker, L.E.

    1984-06-22

    Three variables control the weld-induced, base-metal microfissuring sensitivity of Ni-Cr and Ni-Cr-Fe: thermal/mechanical history of the base material, chemical analysis of the base material, and the welding process used. Elements which tend to segregate to the grain boundaries such as B, C, and Zr, and to a lesser extent P, Si, S and Mg, increase the sensitivity. Welding processes listed from most to least severe in their tendency to produce microfissures are: gas metal arc - spray transfer, electron beam, gas metal arc - pulsed transfer, gas metal arc - short circuiting transfer, gas tungsten arc, submerged arc, and shielded metal arc. Microfissuring is always intergranular in nature. Coarse-grain size, whether arrived at by hot-working procedures or pre-weld annealing treatment, increases the sensitivity to microfissuring. Literature data and data for alloy 617 developed at Huntington Alloys suggest that microfissures, at least to 0.030 in. in length, do not affect the fatigue life, room-temperature tensile, and stress-rupture properties of a weldment.

  9. High responsivity 4H-SiC based metal-semiconductor-metal ultraviolet photodetectors

    NASA Astrophysics Data System (ADS)

    Yang, Weifeng; Zhang, Feng; Liu, Zhuguang; Lü, Ying; Wu, Zhengyun

    2008-11-01

    4H-SiC based metal-semiconductor-metal (MSM) photodetectors with diverse spacing were designed, fabricated, and characterized, in which nickel Schottky contacts were needed. Current-voltage and spectral responsivity measurements were carried out at room temperature. The fabricated 4 μm-spacing device showed a very low dark current (0.25 pA at 5 V bias voltage), a typical responsivity of 0.103 A/W at 20 V, and a peak response wavelength at 290 nm. The fabricated devices held a high DUV to visible rejection ratio of >103.

  10. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

    2015-12-01

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)-based metal-organic frameworks, Zn3L3(DMF)2 (1) and Zn3L3(DMA)2(H2O)3 (2) (L=4,4‧-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe3+ and Al3+ by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe3+. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity.

  11. Nanomesh electrode on MgZnO-based metal-semiconductor-metal ultraviolet photodetectors

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Ting; Lin, Heng-Yu; Tseng, Chun-Yen

    2015-09-01

    In this work, the nano-scaled mesh electrodes are fabricated by obliquely depositing metals through the highly ordered polystyrene nanosphere mask. Furthermore, the intrinsic MgZnO film is deposited as the absorption layer for the metal-semiconductor-metal ultraviolet photodetectors (MSM-UV-PDs) using the vapor cooling condensation system. The 100-nm-linewidth nanomesh electrodes with metal occupying a roughly 10% of the device surface region consequently render PDs with a high transmittance in the ultraviolet (UV) wavelength range. The photoresponsivity of MgZnO-based MSM-UV-PDs evaluated at the wavelength of 330 nm with the operating bias voltage of 5 V is elevated from 0.135 to 0.248 A/W when the thin metal electrode is replaced by the nanomesh electrode, and the corresponding quantum efficiency is improved from 50.75 to 93.23%. Finally, adopting the nanomesh electrode also helps to enhance the UV-visible rejection ratio (R330nm/R450nm) and the detectivity from 1663 and 1.78 × 1010 cmHz0.5W-1 to 2480 and 2.43 × 1010 cmHz0.5W-1, respectively.

  12. Synthesis and heavy metal immobilization behaviors of slag based geopolymer.

    PubMed

    Yunsheng, Zhang; Wei, Sun; Qianli, Chen; Lin, Chen

    2007-05-01

    In this paper, two aspects of studies are carried out: (1) synthesis of geopolymer by using slag and metakaolin; (2) immobilization behaviors of slag based geopolymer in a presence of Pb and Cu ions. As for the synthesis of slag based geopolymer, four different slag content (10%, 30%, 50%, 70%) and three types of curing regimes (standard curing, steam curing and autoclave curing) are investigated to obtain the optimum synthesis condition based on the compressive and flexural strength. The testing results showed that geopolymer mortar containing 50% slag that is synthesized at steam curing (80 degrees C for 8h), exhibits higher mechanical strengths. The compressive and flexural strengths of slag based geopolymer mortar are 75.2 MPa and 10.1 MPa, respectively. Additionally, Infrared (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques are used to characterize the microstructure of the slag based geopolymer paste. IR spectra show that the absorptive band at 1086 cm(-1) shifts to lower wave number around 1007 cm(-1), and some six-coordinated Als transforms into four-coordination during the synthesis of slag based geopolymer paste. The resulting slag based geopolymeric products are X-ray amorphous materials. SEM observation shows that it is possible to have geopolymeric gel and calcium silicate hydrate (C-S-H) gel forming simultaneously within slag based geopolymer paste. As for immobilization of heavy metals, the leaching tests are employed to investigate the immobilization behaviors of the slag based geopolymer mortar synthesized under the above optimum condition. The leaching tests show that slag based geopolymer mortar can effectively immobilize Cu and Pb heavy metal ions, and the immobilization efficiency reach 98.5% greater when heavy metals are incorporated in the slag geopolymeric matrix in the range of 0.1-0.3%. The Pb exhibits better immobilization efficiency than the Cu in the case of large dosages of heavy metals.

  13. Advanced optical interference filters based on metal and dielectric layers.

    PubMed

    Begou, Thomas; Lemarchand, Fabien; Lumeau, Julien

    2016-09-01

    In this paper, we investigate the design and the fabrication of an advanced optical interference filter based on metal and dielectric layers. This filter respects the specifications of the 2016 OIC manufacturing problem contest. We study and present all the challenges and solutions that allowed achieving a low deviation between the fabricated prototype and the target. PMID:27607695

  14. Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh

    2012-11-01

    New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL1 and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL2 derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML(1-2)2 have been synthesized, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate ? coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mn < Zn < Cu < Co < Ni. The ligands and their complexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu > Mn > Ni > Co > Zn.

  15. Laser based metal and plastics joining for lightweight design

    NASA Astrophysics Data System (ADS)

    Kahmann, Max; Quentin, Ulf; Kirchhoff, Marc; Brockmann, Rüdiger; Löffler, Klaus

    2015-03-01

    One of the most important issues in automotive industry is lightweight design, especially since the CO2 emission of new cars has to be reduced by 2020. Plastic and fiber reinforced plastics (e.g. CFRP and GFRP) receive besides new manufacturing methods and the employment of high-strength steels or non-ferrous metals increasing interest. Especially the combination of different materials such as metals and plastics to single components exhausts the entire potential on weight reduction. This article presents an approach based on short laser pulses to join such dissimilar materials in industrial applications.

  16. Formability Evaluation of Sheet Metals Based on Global Strain Distribution

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Lin, Jianping; Min, Junying; Ye, You; Kang, Liugen

    2016-06-01

    According to the conventional methods for formability evaluation, e.g., forming limit curve (FLC), limit dome height, and total elongation, inconsistent results are observed when comparing the formability of four advanced high-strength steels (AHSS) with an ultimate tensile strength grade of 1000 MPa. The strain distribution analysis with the aid of digital image correlation technique shows that different uniform deformation capabilities of sheet metals under the same loading conditions are responsible for this inconsistency. In addition, metallurgical analysis suggests that inhomogeneous microstructure distribution and phase transformation during deformation in some materials play important roles in the uniform deformation capability of sheet metal. Limit strains on the commonly used FLC only relate to the major and minor strains of local deforming elements associated with the onset of necking. However, the formability of a sheet metal component is determined by the strain magnitudes of all deforming elements involved during the forming process. Hence, the formability evaluation of sheet metals from a global aspect is more applicable for practical engineering. A new method based on two indices (i.e., which represent global formability and uniform deformation capability, respectively) is proposed to evaluate the formability of sheet metals based on global strain distribution. The formability and evolution of deformation uniformity of the investigated AHSS at different stress states are studied with this new method. Compared with other formability evaluation methods, the new method is demonstrated to be more appropriate for practical engineering, and it is applicable to both in-plane and out-of-plane deformation. Additionally, the global formability of sheet metals can be more comprehensively understood with this new method.

  17. A four-port plasmonic quasi-circulator based on metal-insulator-metal waveguides.

    PubMed

    Wen, Kunhua; Yan, Lianshan; Pan, Wei; Luo, Bin; Guo, Zhen; Guo, Yinghui

    2012-12-17

    A metal-insulator-metal (MIM)-based four-port quasi-circulator consisting of four bus waveguides and eight narrow inside/outside slits is proposed without using nonreciprocity. Once the input port is defined, only a specific output port could be obtained by proper the design of parameters of the waveguides and slits. Simulation results based on finite-different time-domain (FDTD) method demonstrate that the transmittance at the center wavelength of the appropriate output port can reach 0.63 while those of the other two output ports are lower than 0.06. Through adjusting the slits spacing or optimizing the insulator material in the slits, the isolation of the circulator could be further improved with a slight sacrifice of the transmission. Such structure could also be used for wavelength demultiplexing with the center wavelength determined by the length of the bus waveguides and slits.

  18. Bifacial Base-Pairing Behaviors of 5-Hydroxyuracil DNA Bases through Hydrogen Bonding and Metal Coordination.

    PubMed

    Takezawa, Yusuke; Nishiyama, Kotaro; Mashima, Tsukasa; Katahira, Masato; Shionoya, Mitsuhiko

    2015-10-12

    A novel bifacial ligand-bearing nucleobase, 5-hydroxyuracil (U(OH) ), which forms both a hydrogen-bonded base pair (U(OH) -A) and a metal-mediated base pair (U(OH) -M-U(OH) ) has been developed. The U(OH) -M-U(OH) base pairs were quantitatively formed in the presence of lanthanide ions such as Gd(III) when U(OH) -U(OH) pairs were consecutively incorporated into DNA duplexes. This result established metal-assisted duplex stabilization as well as DNA-templated assembly of lanthanide ions. Notably, a duplex possessing U(OH) -A base pairs was destabilized by addition of Gd(III) ions. This observation suggests that the hybridization behaviors of the U(OH) -containing DNA strands are altered by metal complexation. Thus, the U(OH) nucleobase with a bifacial base-pairing property holds great promise as a component for metal-responsive DNA materials.

  19. Development of magnetic Fe-based metallic glasses without metalloids

    SciTech Connect

    Mastrogiacomo, Giovanni; Kradolfer, Juerg; Loeffler, Joerg F.

    2006-01-15

    The glass-forming ability of Fe-based metallic glasses has a direct relationship with their metalloid content. A good glass-former usually needs a metalloid content of approximately 20 at. %. However, a high metalloid content causes deterioration not only in magnetic properties but also in elasticity and plasticity. Based on destabilization of the solid state we have developed a series of metalloid-free Fe-based metallic glasses of composition (Fe{sub 0.582}Co{sub 0.418}){sub 100-x-y}Cr{sub x}Zr{sub y} (10{<=}x{<=}28 and 8{<=}y{<=}11). Via this destabilization the liquid state is stabilized, which results in a decreasing liquidus temperature. The mechanical and magnetic properties of the metalloid-free Fe-based metallic glass with the highest Fe and Co fractions were analyzed. The alloy of composition (Fe{sub 0.582}Co{sub 0.418}){sub 80}Cr{sub 10}Zr{sub 10} exhibits bending elasticity and plasticity. Magnetization measurements reveal a saturation magnetization of up to 1.1 T and an inverted hysteresis. The origin of this inverted hysteresis presumably lies in the inclination to decompose in a ferromagnetic iron-rich {alpha}{sub 1} phase and an antiferromagnetic chromium-rich {alpha}{sub 2} phase.

  20. Metallomics insights for in vivo studies of metal based nanomaterials.

    PubMed

    Wang, Bing; Feng, Weiyue; Zhao, Yuliang; Chai, Zhifang

    2013-06-01

    With the rapid development of engineered nanomaterials (NMs) and wide biomedical applications for new types of multifunctional NMs, an understanding of the behavior patterns of NMs in vivo and clarification of their potential health impact as a result of their novel physicochemical properties is essential for ensuring safety in biomedical applications of nanotechnology. NMs have heterogeneous characteristics in that they combine the bulk properties of solids with the mobility of molecules, and present phase transformation, dissolution, oxidation/reduction as well as nano-bio interface reactions in biological milieu, which affect their in vivo behaviors and biological effects. The accurate study of identification, quantification, transformation state of NMs and their biological effects in vivo remains a challenge. This review aims to provide a "metallomics" (an integrated metal-assisted function bioscience) insight into the in vivo behavior and biological effects of NMs, particularly for metal-based nanomaterials (MNMs) and is based mainly on our own research and other previous works.

  1. Acceptorless dehydrogenation of small molecules through cooperative base metal catalysis.

    PubMed

    West, Julian G; Huang, David; Sorensen, Erik J

    2015-01-01

    The dehydrogenation of unactivated alkanes is an important transformation both in industrial and biological systems. Recent efforts towards this reaction have revolved around high temperature, organometallic C-H activation by noble metal catalysts that produce alkenes and hydrogen gas as the sole products. Conversely, natural desaturase systems proceed through stepwise hydrogen atom transfer at physiological temperature; however, these transformations require a terminal oxidant. Here we show combining tetra-n-butylammonium decatungstate (TBADT) and cobaloxime pyridine chloride (COPC) can catalytically dehydrogenate unactivated alkanes and alcohols under near-UV irradiation at room temperature with hydrogen as the sole by-product. This noble metal-free process follows a nature-inspired pathway of high- and low-energy hydrogen atom abstractions. The hydrogen evolution ability of cobaloximes is leveraged to render the system catalytic, with cooperative turnover numbers up to 48 and yields up to 83%. Our results demonstrate how cooperative base metal catalysis can achieve transformations previously restricted to precious metal catalysts. PMID:26656087

  2. Acceptorless dehydrogenation of small molecules through cooperative base metal catalysis

    PubMed Central

    West, Julian G.; Huang, David; Sorensen, Erik J.

    2015-01-01

    The dehydrogenation of unactivated alkanes is an important transformation both in industrial and biological systems. Recent efforts towards this reaction have revolved around high temperature, organometallic C–H activation by noble metal catalysts that produce alkenes and hydrogen gas as the sole products. Conversely, natural desaturase systems proceed through stepwise hydrogen atom transfer at physiological temperature; however, these transformations require a terminal oxidant. Here we show combining tetra-n-butylammonium decatungstate (TBADT) and cobaloxime pyridine chloride (COPC) can catalytically dehydrogenate unactivated alkanes and alcohols under near-UV irradiation at room temperature with hydrogen as the sole by-product. This noble metal-free process follows a nature-inspired pathway of high- and low-energy hydrogen atom abstractions. The hydrogen evolution ability of cobaloximes is leveraged to render the system catalytic, with cooperative turnover numbers up to 48 and yields up to 83%. Our results demonstrate how cooperative base metal catalysis can achieve transformations previously restricted to precious metal catalysts. PMID:26656087

  3. Preparation of molecule-based magnets from metal thiocyanate complexes

    NASA Astrophysics Data System (ADS)

    Shurdha, Endrit

    2011-07-01

    The study of magnetism has enabled many technological applications that are ubiquitous in our daily life. Presently, most of the magnetic applications use metal/metal oxide magnets, which are readily available. In the last few decades, research has focused on a new class of magnetic materials, molecule-based magnets. This class of materials has diverse physical and chemical properties, which can be controlled by synthetic methods. Utilizing a variety of metals and ligands, researchers can control and fine tune various aspects of these magnetic materials, such as structural connections and possibly magnetic properties. Tetracyanoethylene (TCNE) is widely used in the preparation of molecule-based magnets due to its unique electronic and connectivity properties. TCNE has multiple binding sites, which gives it a diverse range of structural connectivity. Also, TCNE can be reduced easily to form a radical anion, which facilitates spin communication between metal centers allowing isolation of magnetically ordered systems such as V(TCNE)2 (a room temperature molecule-based magnet). M-TCNE magnets are prepared from solvated MII complexes or a metal carbonyl and TCNE in dichloromethane. The reaction involves the oxidation of the MII to MIII and the reduction of TCNE. More coordinating solvents used to prepare TCNE molecule-based magnets facilitate the dimerization of the radical TCNE, which does not allow for long-range ordering. The work presented herein will show the synthesis of MII thiocyanate complexes and their reaction with TCNE radical anion to yield M(TCNE)[C4(CN)8]1/2, which is obtained through ligand substitution between TCNE and thiocyanate. The development of new MII thiocyanate complexes through MII(NCMe)x(BF4)2 (x = 4, 6) in acetone, acetonitrile, and tetrahydrofuran will be the focus of Chapter 2. Also, in Chapter 2, structural and magnetic characterization will be discussed. Few of the metal thiocyanate complexes exhibit antiferromagnetic ordering at

  4. Exploring the limit of dislocation based plasticity in nanostructured metals.

    PubMed

    Hughes, D A; Hansen, N

    2014-04-01

    A twofold decrease to an unexplored scale of 5 nm was produced in Cu by applying a large sliding load in liquid nitrogen. Statistical and universal scaling analyses of deformation induced high angle boundaries, dislocation boundaries, and individual dislocations observed by high resolution electron microscopy reveal that dislocation processes still dominate. Dislocation based plasticity continues far below the transition suggested by experiment and molecular dynamics simulations, with a limit below 5 nm. Very high strength metals may emerge based on this enhanced structural refinement. PMID:24745438

  5. Optically Transparent Microwave Polarizer Based On Quasi-Metallic Graphene

    PubMed Central

    Grande, Marco; Bianco, Giuseppe Valerio; Vincenti, Maria Antonietta; de Ceglia, Domenico; Capezzuto, Pio; Scalora, Michael; D’Orazio, Antonella; Bruno, Giovanni

    2015-01-01

    In this paper, we report on the engineering and the realization of optically transparent graphene-based microwave devices using Chemical Vapour Deposition (CVD) graphene whose sheet resistance may be tailored down to values below 30 Ω/sq. In particular, we show that the process was successfully used to realize and characterize a simple, optically transparent graphene-based wire-grid polarizer at microwave frequencies (X band). The availability of graphene operating in a quasi-metallic region may allow the integration of graphene layers in several microwave components, thus leading to the realization of fully transparent (and flexible) microwave devices. PMID:26603112

  6. Optically Transparent Microwave Polarizer Based On Quasi-Metallic Graphene.

    PubMed

    Grande, Marco; Bianco, Giuseppe Valerio; Vincenti, Maria Antonietta; de Ceglia, Domenico; Capezzuto, Pio; Scalora, Michael; D'Orazio, Antonella; Bruno, Giovanni

    2015-01-01

    In this paper, we report on the engineering and the realization of optically transparent graphene-based microwave devices using Chemical Vapour Deposition (CVD) graphene whose sheet resistance may be tailored down to values below 30 Ω/sq. In particular, we show that the process was successfully used to realize and characterize a simple, optically transparent graphene-based wire-grid polarizer at microwave frequencies (X band). The availability of graphene operating in a quasi-metallic region may allow the integration of graphene layers in several microwave components, thus leading to the realization of fully transparent (and flexible) microwave devices. PMID:26603112

  7. High pressure die casting of Fe-based metallic glass

    NASA Astrophysics Data System (ADS)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  8. High pressure die casting of Fe-based metallic glass

    PubMed Central

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-01-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications. PMID:27725780

  9. Infrared transparent frequency selective surface based on metallic meshes

    SciTech Connect

    Yu, Miao; Xu, Nianxi; Liu, Hai; Gao, Jinsong

    2014-02-15

    This paper presents an infrared transparent frequency selective surface (ITFSS) based on metallic meshes. In this ITFSS structure, periodic cross-slot units are integrated on square metallic meshes empowered by coating and UV-lithography. A matching condition is proposed to avoid the distortion of units. Experimental results show that this ITFSS possesses a good transmittance of 80% in the infrared band of 3–5 μm, and also a stable band-pass behavior at the resonance frequency of 36.4 GHz with transmittance of −0.56 dB. Theoretical simulations about the ITFSS diffractive characteristics and frequency responses are also investigated. The novel ITFSS will attract renewed interest and be exploited for applications in various fields.

  10. Multiferroic materials based on organic transition-metal molecular nanowires.

    PubMed

    Wu, Menghao; Burton, J D; Tsymbal, Evgeny Y; Zeng, Xiao Cheng; Jena, Puru

    2012-09-01

    We report on the density functional theory aided design of a variety of organic ferroelectric and multiferroic materials by functionalizing crystallized transition-metal molecular sandwich nanowires with chemical groups such as -F, -Cl, -CN, -NO(2), ═O, and -OH. Such functionalized polar wires exhibit molecular reorientation in response to an electric field. Ferroelectric polarizations as large as 23.0 μC/cm(2) are predicted in crystals based on fully hydroxylized sandwich nanowires. Furthermore, we find that organic nanowires formed by sandwiching transition-metal atoms in croconic and rhodizonic acids, dihydroxybenzoquinone, dichloro-dihydroxy-p-benzoquinone, or benzene decorated by -COOH groups exhibit ordered magnetic moments, leading to a multiferroic organometallic crystal. When crystallized through hydrogen bonds, the microscopic molecular reorientation translates into a switchable polarization through proton transfer. A giant interface magnetoelectric response that is orders of magnitude greater than previously reported for conventional oxide heterostructure interfaces is predicted. PMID:22881120

  11. Terahertz Modulator based on Metamaterials integrated with Metal-Semiconductor-Metal Varactors

    NASA Astrophysics Data System (ADS)

    Nouman, Muhammad Tayyab; Kim, Hyun-Woong; Woo, Jeong Min; Hwang, Ji Hyun; Kim, Dongju; Jang, Jae-Hyung

    2016-05-01

    The terahertz (THz) band of the electromagnetic spectrum, with frequencies ranging from 300 GHz to 3 THz, has attracted wide interest in recent years owing to its potential applications in numerous areas. Significant progress has been made toward the development of devices capable of actively controlling terahertz waves; nonetheless, further advances in device functionality are necessary for employment of these devices in practical terahertz systems. Here, we demonstrate a low voltage, sharp switching terahertz modulator device based on metamaterials integrated with metal semiconductor metal (MSM) varactors, fabricated on an AlGaAs/InGaAs based heterostructure. By varying the applied voltage to the MSM-varactor located at the center of split ring resonator (SRR), the resonance frequency of the SRR-based metamaterial is altered. Upon varying the bias voltage from 0 V to 3 V, the resonance frequency exhibits a transition from 0.52 THz to 0.56 THz, resulting in a modulation depth of 45 percent with an insertion loss of 4.3 dB at 0.58 THz. This work demonstrates a new approach for realizing active terahertz devices with improved functionalities.

  12. Terahertz Modulator based on Metamaterials integrated with Metal-Semiconductor-Metal Varactors.

    PubMed

    Nouman, Muhammad Tayyab; Kim, Hyun-Woong; Woo, Jeong Min; Hwang, Ji Hyun; Kim, Dongju; Jang, Jae-Hyung

    2016-01-01

    The terahertz (THz) band of the electromagnetic spectrum, with frequencies ranging from 300 GHz to 3 THz, has attracted wide interest in recent years owing to its potential applications in numerous areas. Significant progress has been made toward the development of devices capable of actively controlling terahertz waves; nonetheless, further advances in device functionality are necessary for employment of these devices in practical terahertz systems. Here, we demonstrate a low voltage, sharp switching terahertz modulator device based on metamaterials integrated with metal semiconductor metal (MSM) varactors, fabricated on an AlGaAs/InGaAs based heterostructure. By varying the applied voltage to the MSM-varactor located at the center of split ring resonator (SRR), the resonance frequency of the SRR-based metamaterial is altered. Upon varying the bias voltage from 0 V to 3 V, the resonance frequency exhibits a transition from 0.52 THz to 0.56 THz, resulting in a modulation depth of 45 percent with an insertion loss of 4.3 dB at 0.58 THz. This work demonstrates a new approach for realizing active terahertz devices with improved functionalities. PMID:27194128

  13. Terahertz Modulator based on Metamaterials integrated with Metal-Semiconductor-Metal Varactors

    PubMed Central

    Nouman, Muhammad Tayyab; Kim, Hyun-Woong; Woo, Jeong Min; Hwang, Ji Hyun; Kim, Dongju; Jang, Jae-Hyung

    2016-01-01

    The terahertz (THz) band of the electromagnetic spectrum, with frequencies ranging from 300 GHz to 3 THz, has attracted wide interest in recent years owing to its potential applications in numerous areas. Significant progress has been made toward the development of devices capable of actively controlling terahertz waves; nonetheless, further advances in device functionality are necessary for employment of these devices in practical terahertz systems. Here, we demonstrate a low voltage, sharp switching terahertz modulator device based on metamaterials integrated with metal semiconductor metal (MSM) varactors, fabricated on an AlGaAs/InGaAs based heterostructure. By varying the applied voltage to the MSM-varactor located at the center of split ring resonator (SRR), the resonance frequency of the SRR-based metamaterial is altered. Upon varying the bias voltage from 0 V to 3 V, the resonance frequency exhibits a transition from 0.52 THz to 0.56 THz, resulting in a modulation depth of 45 percent with an insertion loss of 4.3 dB at 0.58 THz. This work demonstrates a new approach for realizing active terahertz devices with improved functionalities. PMID:27194128

  14. Leachability of metals from sludge-based artificial lightweight aggregate.

    PubMed

    Chang, Fang-Chih; Lo, Shang-Lien; Lee, Ming-Yu; Ko, Chun-Han; Lin, Jyh-Dong; Huang, Su-Chen; Wang, Chu-Fang

    2007-07-19

    Metal sludge from industrial wastewater treatment plants was mixed with mining residues to be recycled into lightweight aggregate (LWA) through sintering at different temperatures. The physical properties of the LWA thus obtained were examined by scanning electron microscopy analyzer (SEM) coupled with an energy dispersive X-ray analyzer (EDX). The sequential extraction method combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) was employed to determine the concentration and distribution of hazardous toxic elements in the metal sludge-based artificial LWA. The results show that the leaching concentrations of Cd, Cr, Cu, and Pb present in the non-sintered raw aggregate pellets reached 7.4, 68.0, 96.0, and 61.4 mg/l, respectively, far exceeding the regulatory threshold. Sintering at 1150 degrees C for 15 min results in stronger chemical bonds being formed between the elements. Hence, after the first three steps of sequential extraction, the concentrations of Cr, Cu, and Pb reached 2.69, 1.50, and 1.88 mg/l at 1150 degrees C, while the final residues had total concentrations of 96.1, 88.4, and 60.6 mg/kg, respectively, with Cd undetected in both phases. The concentration levels fell within the regulatory threshold, indicating that the LWA fabricated from recycled metal sludge contains elements that are toxic and hazardous but not leached. Having no harmful effect on the environment, the metal sludge-based artificial LWA is not only safe but also practical with good physical properties. PMID:17222508

  15. [The bonding mechanisms of base metals for metal-ceramic crown microstructure analysis of bonding agent and gold bond between porcelain and base metals].

    PubMed

    Wang, C C; Hsu, C S

    1996-06-01

    The use of base metal alloys for porcelain fused to a metal crown and bridges has increased recently because of lower price, high hardness, high tensile strength and high elastic modulus. The addition of beryllium to base metal alloys increased fluidity and improved casting fitness. Beryllium also controlled surface oxidation and bonding strength. The bonding agent and gold bonding agent also affected the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys were studied (two alloys contained beryllium element, another two did not). The purpose of this investigation was to study the microstructure between porcelain matrix, bonding agent and alloy matrix interfaces. A scanning electron micro-probe analyzer and energy dispersive X-ray spectroscopy (EDXS) were used to study the distribution of elements (Ni, Cr, Mo, Cu, O, Si, Sn, Al) in four base alloys. The following results were obtained: 1. The thickness of the oxidized layer of Rexillium III alloy and Unitbond alloy (contained beryllium) was thinner than Unibond alloy and Wiron 88 alloy (no beryllium). 2. The thickness of the oxidized layer of alloys in air (10 minutes and 30 minutes) was thinner in Unitbond (2.45 microns and 3.80 microns) and thicker in Wiron 88 (4.39 microns and 5.96 microns). 3. The thickness of the oxidized layer occurring for a duration of ten minutes (in vaccum) showed that the Rexillium III alloy was the thinnest (1.93 microns), and Wiron 88 alloy was the thickest (2.30 microns). But in thirty minutes (vacuum), Unitbond alloy was the thinnest (3.37 microns), and Wiron 88 alloy was the thickest (5.51 microns). 4. The intensity of Cr elements was increased obviously near the interface between Unitbond alloy, Wiron 88 alloy (no beryllium) and oxidized layer, but the intensity of Ni and Mo elements was slightly increased. The intensity of Cr element was not increased markedly between Rexillium III alloy, Unitbond alloy (beryllium) and oxidized

  16. Real-time PCR based analysis of metal resistance genes in metal resistant Pseudomonas aeruginosa strain J007.

    PubMed

    Choudhary, Sangeeta; Sar, Pinaki

    2016-07-01

    A uranium (U)-resistant and -accumulating Pseudomonas aeruginosa strain was characterized to assess the response of toxic metals toward its growth and expression of metal resistance determinants. The bacterium showed MIC (minimum inhibitory concentration) values of 6, 3, and 2 mM for Zn, Cu, and Cd, respectively; with resistance phenotype conferred by periplasmic Cu sequestering copA and RND type heavy metal efflux czcA genes. Real-time PCR-based expression analysis revealed significant upregulation of both these genes upon exposure to low concentrations of metals for short duration, whereas the global stress response gene sodA encoding superoxide dismutase enzyme was upregulated only at higher metal concentrations or longer exposure time. It could also be inferred that copA and czcA are involved in providing resistance only at low metal concentrations, whereas involvement of "global stress response" phenomenon (expression of sodA) at higher metal concentration or increased exposure was evident. This study provides significant understanding of the adaptive response of bacteria surviving in metal and radionuclide contaminated environments along with the development of real-time PCR-based quantification method of using metal resistance genes as biomarker for monitoring relevant bacteria in such habitats. PMID:26662317

  17. Hydrate-based heavy metal separation from aqueous solution

    NASA Astrophysics Data System (ADS)

    Song, Yongchen; Dong, Hongsheng; Yang, Lei; Yang, Mingjun; Li, Yanghui; Ling, Zheng; Zhao, Jiafei

    2016-02-01

    A novel hydrate-based method is proposed for separating heavy metal ions from aqueous solution. We report the first batch of experiments and removal characteristics in this paper, the effectiveness and feasibility of which are verified by Raman spectroscopy analysis and cross-experiment. 88.01-90.82% of removal efficiencies for Cr3+, Cu2+, Ni2+, and Zn2+ were obtained. Further study showed that higher R141b-effluent volume ratio contributed to higher enrichment factor and yield of dissociated water, while lower R141b-effluent volume ratio resulted in higher removal efficiency. This study provides insights into low-energy, intensive treatment of wastewater.

  18. Methods of Fabricating a Layer of Metallic Glass-Based Material Using Immersion and Pouring Techniques

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas (Inventor)

    2015-01-01

    Systems and methods in accordance with embodiments of the invention implement layers of metallic glass-based materials. In one embodiment, a method of fabricating a layer of metallic glass includes: applying a coating layer of liquid phase metallic glass to an object, the coating layer being applied in a sufficient quantity such that the surface tension of the liquid phase metallic glass causes the coating layer to have a smooth surface; where the metallic glass has a critical cooling rate less than 1000 K/s; and cooling the coating layer of liquid phase metallic glass to form a layer of solid phase metallic glass.

  19. Dual wavelength demultiplexer based on metal-insulator-metal plasmonic circular ring resonators

    NASA Astrophysics Data System (ADS)

    Rakhshani, Mohammad Reza; Mansouri-Birjandi, Mohammad Ali

    2016-06-01

    In this paper, we investigated a plasmonic demultiplexer structure based on Metal-Insulator-Metal (MIM) waveguides and circular ring resonators. In order to achieve the structure of demultiplexer, two improved ring resonators have been used, which input and outputs MIM waveguides coupled by the ring resonators. To improve the transmission efficiency, a reflector was introduced at the right end of the input and output waveguides. By substituting the ring core with dielectric, the possibility of tuning the resonance wavelength of the proposed structure is illustrated, and the effect of various parameters such as radius and refractive index in transmission efficiency is studied in detail. This is useful for the design of integrated circuits in which it is not possible to extend the dimension of the ring resonator to attain a longer resonance wavelength. Transmission efficiency and quality factor of the single ring are 84% and 110, respectively. The simulation results using finite difference time domain method shows that in the proposed demultiplexer, which is composed of two rings with different core refractive indexes, the average power efficiency, bandwidth for each output channel, and the mean value of crosstalk are estimated 80%, 17 nm, and -26.95 dB, respectively. It is revealed that the significant features of the device are high transmission efficiency, low crosstalk, high-quality factor, and tunability for desired wavelengths. Therefore, the proposed structure has the potential to be applied in plasmonic integrated circuits.

  20. Transition-metal dichalcogenide-based dipolariton optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Kolmakov, German; Byrnes, Tim; He, Andy; Kezerashvili, Roman Ya.

    Using computational modeling, we simulate the dynamics of dipolaritons in an optical microcavity, which encompasses the transition-metal dichalcogenide double-layer structure. We demonstrate that dipolaritons, a three-way superposition of photons, direct excitons and indirect excitons, are guided by a pattern deposited on the microcavity and can be driven by an external electric field or voltage applied to the structure. Focusing on a normal dipolariton gas in Y- and Psi-shaped patterns, we isolate conditions when the dipolariton flow can be switched between the channel branches of the pattern by the electric field. We also studied the superfluid dynamics of dipolariton Bose-Einstein condensates in patterned substrates at low temperatures, showing that the condensate in the channels can be accelerated and then directed by the electric field. We compare the obtained results with those for GaAs-based microcavities and demonstrate that dipolaritons in transition-metal dichalcogenide-based microcavities can be utilized for the design of optical switches and transistors for optoelectronic integrated circuits.

  1. Carbon-Based Metal-Free Catalysts for Electrocatalysis beyond the ORR.

    PubMed

    Hu, Chuangang; Dai, Liming

    2016-09-19

    Besides their use in fuel cells for energy conversion through the oxygen reduction reaction (ORR), carbon-based metal-free catalysts have also been demonstrated to be promising alternatives to noble-metal/metal oxide catalysts for the oxygen evolution reaction (OER) in metal-air batteries for energy storage and for the splitting of water to produce hydrogen fuels through the hydrogen evolution reaction (HER). This Review focuses on recent progress in the development of carbon-based metal-free catalysts for the OER and HER, along with challenges and perspectives in the emerging field of metal-free electrocatalysis. PMID:27460826

  2. Carbon-Based Metal-Free Catalysts for Electrocatalysis beyond the ORR.

    PubMed

    Hu, Chuangang; Dai, Liming

    2016-09-19

    Besides their use in fuel cells for energy conversion through the oxygen reduction reaction (ORR), carbon-based metal-free catalysts have also been demonstrated to be promising alternatives to noble-metal/metal oxide catalysts for the oxygen evolution reaction (OER) in metal-air batteries for energy storage and for the splitting of water to produce hydrogen fuels through the hydrogen evolution reaction (HER). This Review focuses on recent progress in the development of carbon-based metal-free catalysts for the OER and HER, along with challenges and perspectives in the emerging field of metal-free electrocatalysis.

  3. Process Windows for Sheet Metal Parts based on Metamodels

    NASA Astrophysics Data System (ADS)

    Harsch, D.; Heingärtner, J.; Hortig, D.; Hora, P.

    2016-08-01

    Achieving robust production of deep drawn sheet metal parts is challenging. The fluctuations of process and material properties often lead to robustness problems. Numerical simulations are used to validate the feasibility and to detect critical regions of a part. To enhance the consistency with the real process conditions, the measured material data and the force distribution are taken into account. The simulation metamodel contains the virtual knowledge of a particular forming process, which is determined based on a series of finite element simulations with variable input parameters. Based on the metamodels, process windows can be evaluated for different parameter configurations. This helps improving the operating point search, to adjust process settings if the process becomes unstable and to visualize the influence of arbitrary parameters on the process window.

  4. Stepwise Assembly of Coordination-Based Metal-Organic Networks

    SciTech Connect

    R Kaminker; L Motiei; A Gulino; I Fragala; L Shimon; G Evmenenko; P Dutta; M Iron; M van der Boom

    2011-12-31

    Metal-organic networks (MONs) were created by a stepwise solution deposition approach from vinylpyridine-based building blocks and PdCl{sub 2}. The combined experimental and computational study demonstrates the formation of saturated, structurally organized systems on solid supports. The rigid nature and geometry of the components are well-suited to form honeycomb and parallelogram structures, as predicted by a computational study. Detailed structural information of the new MONs was obtained by optical (UV/vis) spectroscopy, ellipsometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and synchrotron X-ray reflectivity (XRR). Notably, the XPS elemental composition indicates the formation of a palladium coordination-based network.

  5. SVM-based base-metal prospectivity modeling of the Aravalli Orogen, Northwestern India

    NASA Astrophysics Data System (ADS)

    Porwal, Alok; Yu, Le

    2010-05-01

    The Proterozoic Aravalli orogen in the state of Rajasthan, northwestern India, constitutes the most important metallogenic province for base-metal deposits in India and hosts the entire economically viable lead-zinc resource-base of the country. The orogen evolved through near-orderly Wilson cycles of repeated extensional and compressional tectonics resulting in sequential opening and closing of intracratonic rifts and amalgamation of crustal domains during a circa 1.0-Ga geological history from 2.2 Ga to 1.0 Ga. This study develops a conceptual tectonostratigraphic model of the orogen based on a synthesis of the available geological, geophysical and geochronological data followed by deep-seismic-reflectivity-constrained 2-D forward gravity modeling, and links it to the Proterozoic base-metal metallogeny in the orogen in order to identify key geological controls on the base-metal mineralization. These controls are translated into exploration criteria for base-metal deposits, validated using empirical spatial analysis, and used to derive input spatial variables for model-based base-metal prospectivity mapping of the orogen. A support vector machine (SVM) algorithm augmented by incorporating a feature selection procedure is used in a GIS environment to implement the prospectivity mapping. A comparison of the SVM-derived prospectivity map with the ones derived using other established models such as neural-networks, logistic regression, and Bayesian weights-of-evidence indicates that the SVM outperforms other models, which is attributed to the capability of the SVM to return robust classification based on small training datasets.

  6. A handy liquid metal based electroosmotic flow pump.

    PubMed

    Gao, Meng; Gui, Lin

    2014-06-01

    A room temperature liquid metal based electroosmotic flow (EOF) pump has been proposed in this work. This low-cost EOF pump is convenient for both fabrication and integration. It utilizes polydimethylsiloxane (PDMS) microchannels filled with the liquid-metal as non-contact pump electrodes. The electrode channels are fabricated symmetrically to both sides of the pumping channel, having no contact with the pumping channel. To test the pumping performance of the EOF pump, the mean flow velocities of the fluid (DI water) in the EOF pumps were experimentally measured by tracing the fluorescent microparticles in the flow. To provide guidance for designing a low voltage EOF pump, parametric studies on dimensions of the electrode and pumping channels were performed in this work. According to the experimental results, the pumping speed can reach 5.93 μm s(-1) at a driving voltage of only 1.6 V, when the gap between the electrode and the pumping channel is 20 μm. Injecting a room temperature liquid metal into microchannels can provide a simple, rapid, low-cost but accurately self-aligned way to fabricate microelectrodes for EOF pumps, which is a promising method to achieve the miniaturization and integration of the EOF pump in microfluidic systems. The non-contact liquid electrodes have no influence on the fluid in the pumping channel when pumping, reducing Joule heat generation and preventing gas bubble formation at the surface of electrodes. The pump has great potential to drive a wide range of fluids, such as drug reagents, cell suspensions and biological macromolecule solutions.

  7. A handy liquid metal based electroosmotic flow pump.

    PubMed

    Gao, Meng; Gui, Lin

    2014-06-01

    A room temperature liquid metal based electroosmotic flow (EOF) pump has been proposed in this work. This low-cost EOF pump is convenient for both fabrication and integration. It utilizes polydimethylsiloxane (PDMS) microchannels filled with the liquid-metal as non-contact pump electrodes. The electrode channels are fabricated symmetrically to both sides of the pumping channel, having no contact with the pumping channel. To test the pumping performance of the EOF pump, the mean flow velocities of the fluid (DI water) in the EOF pumps were experimentally measured by tracing the fluorescent microparticles in the flow. To provide guidance for designing a low voltage EOF pump, parametric studies on dimensions of the electrode and pumping channels were performed in this work. According to the experimental results, the pumping speed can reach 5.93 μm s(-1) at a driving voltage of only 1.6 V, when the gap between the electrode and the pumping channel is 20 μm. Injecting a room temperature liquid metal into microchannels can provide a simple, rapid, low-cost but accurately self-aligned way to fabricate microelectrodes for EOF pumps, which is a promising method to achieve the miniaturization and integration of the EOF pump in microfluidic systems. The non-contact liquid electrodes have no influence on the fluid in the pumping channel when pumping, reducing Joule heat generation and preventing gas bubble formation at the surface of electrodes. The pump has great potential to drive a wide range of fluids, such as drug reagents, cell suspensions and biological macromolecule solutions. PMID:24706096

  8. Feasibility Study on 3-D Printing of Metallic Structural Materials with Robotized Laser-Based Metal Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Ding, Yaoyu; Kovacevic, Radovan

    2016-07-01

    Metallic structural materials continue to open new avenues in achieving exotic mechanical properties that are naturally unavailable. They hold great potential in developing novel products in diverse industries such as the automotive, aerospace, biomedical, oil and gas, and defense. Currently, the use of metallic structural materials in industry is still limited because of difficulties in their manufacturing. This article studied the feasibility of printing metallic structural materials with robotized laser-based metal additive manufacturing (RLMAM). In this study, two metallic structural materials characterized by an enlarged positive Poisson's ratio and a negative Poisson's ratio were designed and simulated, respectively. An RLMAM system developed at the Research Center for Advanced Manufacturing of Southern Methodist University was used to print them. The results of the tensile tests indicated that the printed samples successfully achieved the corresponding mechanical properties.

  9. Hydrate-based heavy metal separation from aqueous solution

    PubMed Central

    Song, Yongchen; Dong, Hongsheng; Yang, Lei; Yang, Mingjun; Li, Yanghui; Ling, Zheng; Zhao, Jiafei

    2016-01-01

    A novel hydrate-based method is proposed for separating heavy metal ions from aqueous solution. We report the first batch of experiments and removal characteristics in this paper, the effectiveness and feasibility of which are verified by Raman spectroscopy analysis and cross-experiment. 88.01–90.82% of removal efficiencies for Cr3+, Cu2+, Ni2+, and Zn2+ were obtained. Further study showed that higher R141b–effluent volume ratio contributed to higher enrichment factor and yield of dissociated water, while lower R141b–effluent volume ratio resulted in higher removal efficiency. This study provides insights into low-energy, intensive treatment of wastewater. PMID:26887357

  10. Semiconductor metal oxide compounds based gas sensors: A literature review

    NASA Astrophysics Data System (ADS)

    Patil, Sunil Jagannath; Patil, Arun Vithal; Dighavkar, Chandrakant Govindrao; Thakare, Kashinath Shravan; Borase, Ratan Yadav; Nandre, Sachin Jayaram; Deshpande, Nishad Gopal; Ahire, Rajendra Ramdas

    2015-03-01

    This paper gives a statistical view about important contributions and advances on semiconductor metal oxide (SMO) compounds based gas sensors developed to detect the air pollutants such as liquefied petroleum gas (LPG), H2S, NH3, CO2, acetone, ethanol, other volatile compounds and hazardous gases. Moreover, it is revealed that the alloy/composite made up of SMO gas sensors show better gas response than their counterpart single component gas sensors, i.e., they are found to enhance the 4S characteristics namely speed, sensitivity, selectivity and stability. Improvement of such types of sensors used for detection of various air pollutants, which are reported in last two decades, is highlighted herein.

  11. Metallic glass nanofibers in future hydrogel-based scaffolds.

    PubMed

    Sadeghian, Ramin Banan; Ahadian, Samad; Yaginuma, Shin; Ramón-Azcón, Javier; Liang, Xiaobin; Nakajima, Ken; Shiku, Hitoshi; Matsue, Tomokazu; Nakayama, Koji S; Khademhosseini, Ali

    2014-01-01

    Electrically conductive reinforced hydrogels offer a wide range of applications as three-dimensional scaffolds in tissue engineering. We report electrical and mechanical characterization of methacrylated gelatin (GelMA) hydrogel, containing palladium-based metallic glass nanofibers (MGNF). Also we show that the fibers are biocompatible and C2C12 myoblasts in particular, planted into the hybrid hydrogel, tend to attach to and elongate along the fibers. The MGNFs in this work were created by gas atomization. Ravel of fibers were embedded in the GelMA prepolymer in two different concentrations (0.5 and 1.0 mg/ml), and then the ensemble was cured under UV light, forming the hybrid hydrogel. The conductivity of the hybrid hydrogel was proportional to the fiber concentration.

  12. Static Behavior of Chalcogenide Based Programmable Metallization Cells

    NASA Astrophysics Data System (ADS)

    Rajabi, Saba

    Nonvolatile memory (NVM) technologies have been an integral part of electronic systems for the past 30 years. The ideal non-volatile memory have minimal physical size, energy usage, and cost while having maximal speed, capacity, retention time, and radiation hardness. A promising candidate for next-generation memory is ion-conducting bridging RAM which is referred to as programmable metallization cell (PMC), conductive bridge RAM (CBRAM), or electrochemical metallization memory (ECM), which is likely to surpass flash memory in all the ideal memory characteristics. A comprehensive physics-based model is needed to completely understand PMC operation and assist in design optimization. To advance the PMC modeling effort, this thesis presents a precise physical model parameterizing materials associated with both ion-rich and ion-poor layers of the PMC's solid electrolyte, so that captures the static electrical behavior of the PMC in both its low-resistance on-state (LRS) and high resistance off-state (HRS). The experimental data is measured from a chalcogenide glass PMC designed and manufactured at ASU. The static on- and off-state resistance of a PMC device composed of a layered (Ag-rich/Ag-poor) Ge30Se70 ChG film is characterized and modeled using three dimensional simulation code written in Silvaco Atlas finite element analysis software. Calibrating the model to experimental data enables the extraction of device parameters such as material bandgaps, workfunctions, density of states, carrier mobilities, dielectric constants, and affinities. The sensitivity of our modeled PMC to the variation of its prominent achieved material parameters is examined on the HRS and LRS impedance behavior. The obtained accurate set of material parameters for both Ag-rich and Ag-poor ChG systems and process variation verification on electrical characteristics enables greater fidelity in PMC device simulation, which significantly enhances our ability to understand the underlying physics of

  13. Commercial Implementation of Model-Based Manufacturing of Nanostructured Metals

    SciTech Connect

    Lowe, Terry C.

    2012-07-24

    Computational modeling is an essential tool for commercial production of nanostructured metals. Strength is limited by imperfections at the high strength levels that are achievable in nanostructured metals. Processing to achieve homogeneity at the micro- and nano-scales is critical. Manufacturing of nanostructured metals is intrinsically a multi-scale problem. Manufacturing of nanostructured metal products requires computer control, monitoring and modeling. Large scale manufacturing of bulk nanostructured metals by Severe Plastic Deformation is a multi-scale problem. Computational modeling at all scales is essential. Multiple scales of modeling must be integrated to predict and control nanostructural, microstructural, macrostructural product characteristics and production processes.

  14. A New Sheet Metal Forming System Based on Incremental Punching

    NASA Astrophysics Data System (ADS)

    Luo, Yuanxin

    Stamping is one of the most commonly used manufacturing processes. Everyday, millions of parts are formed by this process. The conventional stamping is to form a part in one or several operations with a press machine and a set/sets of dies. It is very efficient but is not cost effective for small batch production parts and prototypes as the dies are expensive and time consuming to make. Recently, with the increasing demands for low-volume and customer-made products, a die-less forming method, Incremental Sheet Metal Forming (ISMF), has become one of the leading R&D topics in the industry. ISMF uses a small generic tool to apply a sequence of operations along the given path to deform the sheet incrementally. These small deformations accumulate to form the final shape of the part. As a result, different parts can be made by the same setup. Despite of some 30 years of research and development, however, ISMF technology is still premature for industrial applications due to the following reasons: The accuracy of the part is limited; the surface roughness is poor; and the productivity is low. This motivates the presented research. In this research, a new incremental forming system based on incremental punching is designed and built. The system consists of a 3-axes CNC platform, a high speed hydraulic cylinder with a hemispherical forming tool, and a PC-based CNC control system. The hydraulic system provides the forming force to deform the sheet metal with constant stokes, while the CNC system positions the part. When forming a part, the forming tool punches the sheet metal along the given contour of the part punch by punch; when one layer of the part is completed, the forming tool moves down to the next layer; and the process is finished till all layers are completed. The CNC control system works with standard NC code, and hence, is easy to use. In order to ensure the desirable performance of the machine, dynamic analysis of the machine is necessary. The analysis is

  15. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

    2016-02-01

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system.

  16. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries.

    PubMed

    Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

    2016-02-16

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system.

  17. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries

    PubMed Central

    Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

    2016-01-01

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system. PMID:26878890

  18. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries.

    PubMed

    Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

    2016-01-01

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system. PMID:26878890

  19. Methods of capturing and immobilizing radioactive nuclei with metal fluorite-based inorganic materials

    DOEpatents

    Wang, Yifeng; Miller, Andy; Bryan, Charles R.; Kruichak, Jessica Nicole

    2015-11-17

    Methods of capturing and immobilizing radioactive nuclei with metal fluorite-based inorganic materials are described. For example, a method of capturing and immobilizing radioactive nuclei includes flowing a gas stream through an exhaust apparatus. The exhaust apparatus includes a metal fluorite-based inorganic material. The gas stream includes a radioactive species. The radioactive species is removed from the gas stream by adsorbing the radioactive species to the metal fluorite-based inorganic material of the exhaust apparatus.

  20. Methods of capturing and immobilizing radioactive nuclei with metal fluorite-based inorganic materials

    SciTech Connect

    Wang, Yifeng; Miller, Andy; Bryan, Charles R; Kruichar, Jessica Nicole

    2015-04-07

    Methods of capturing and immobilizing radioactive nuclei with metal fluorite-based inorganic materials are described. For example, a method of capturing and immobilizing radioactive nuclei includes flowing a gas stream through an exhaust apparatus. The exhaust apparatus includes a metal fluorite-based inorganic material. The gas stream includes a radioactive species. The radioactive species is removed from the gas stream by adsorbing the radioactive species to the metal fluorite-based inorganic material of the exhaust apparatus.

  1. Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

    PubMed Central

    TANOUE, Naomi; MATSUDA, Yasuhiro; YANAGIDA, Hiroaki; MATSUMURA, Hideo; SAWASE, Takashi

    2013-01-01

    Objective The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated. Material and Methods Disk specimens (diameter 10 mm and thickness 2.5 mm) were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1) air-abraded with 50-70-µm grain alumina (CON); 2) 1) + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA); 3) 1) + conditioned with a primer including a diphosphate monomer (MDP); 4) treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles. Results The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05) greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy. Conclusion Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used. PMID:24037070

  2. High performance supercapacitor electrodes based on metal/metal-oxide core/shell nano-heterostructures

    NASA Astrophysics Data System (ADS)

    Singh, Ashutosh Kumar; Mandal, Kalyan

    2015-06-01

    This study demonstrates the fabrication technique of novel nano-heterostructures (NHs) and their comparative study of electrochemical performance as supercapacitor electrodes. The fabricated Ni/NiO core/shell and Co-Ni/Co3O4-NiO core/shell nano-heterostructures supercapacitor electrodes offer the desired properties of macroporosity to allow facile electrolyte flow, thereby reducing device resistance and nanoporosity with large surface area to allow faster reaction kinetics. In three electrode configuration, Ni/NiO core/shell and Co-Ni/Co3O4-NiO core/shell nano-heterostructures supercapacitor electrodes exhibited specific capacitance values (731 and 2013 F g-1, respectively, at a constant current density of 2.5 A g-1), high energy (36.5 and 44.7 Wh kg-1, respectively), power density (7.5 and 5.6 kW kg-1, respectively), good capacitance retention and long cyclicality. The remarkable electrochemical property of the large surface area nano-heterostructures is demonstrated based on the effective nano-architectural design of the electrode with the coexistence of the highly redox active materials at the surface supported by highly conducting metal channel at the core for faster charge transport.

  3. Direct micro/nano metal patterning based on two-step transfer printing of ionic metal nano-ink.

    PubMed

    Kim, Sanghyeok; Lee, Won Seok; Lee, Jihye; Park, Inkyu

    2012-07-20

    We present a direct metal patterning method by a two-step transfer printing process of non-particle, ionic metal nano-ink solution. This fabrication method allows a simple direct patterning of various micro/nanoscale metallic structures. Complex structures such as multilayer line arrays, patterns along non-flat topologies, and micro/nanoscale hybrid patterns can be achieved by using this process. Also, the low temperature and pressure process conditions are compatible with the fabrication of electronic structures and devices on flexible substrates such as polyimide film and photographic papers. As an application of this process, we fabricated ZnO nanowire-based flexible UV sensors, where metal electrodes were fabricated by two-step transfer printing. In the case of ZnO nanowire sensors, highly sensitive and fast responding performances to UV illumination and good mechanical robustness against repeated bending conditions could be verified.

  4. A base-metal conductor system for silicon solar cells

    NASA Technical Reports Server (NTRS)

    Coleman, M. G.; Pryor, R. A.; Sparks, T. G.

    1980-01-01

    Solder, copper, and silver are evaluated as conductor layer metals for silicon solar cell metallization on the basis of metal price stability and reliability under operating conditions. Due to its properties and cost, copper becomes an attractive candidate for the conductor layer. It is shown that nickel operates as an excellent diffusion barrier between copper and silicon while simultaneously serving as an electrical contact and mechanical contact to silicon. The nickel-copper system may be applied to the silicon by plating techniques utilizing a variety of plating bath compositions. Solar cells having excellent current-voltage characteristics are fabricated to demonstrate the nickel-copper metallization system.

  5. Influence of Deuterium Treatments on the Polysilicon-Based Metal-Semiconductor-Metal Photodetector.

    PubMed

    Lee, Jae-Sung

    2016-06-01

    The electrical behavior of metal-semiconductor-metal (MSM) Schottky barrier photodetector structure, depending on deuterium treatment, is analyzed by means of the dark current and the photocurrent measurements. Al/Ti bilayer was used as Schottky metal. The deuterium incorporation into the absorption layer, undoped polysilicon, was achieved with annealing process and with ion implantation process, respectively. In the photocurrent-to-dark current ratio measurement, deuterium-ion-implanted photodetector shows over hundred higher than the control device. It means that the heightening of the Schottky barrier and the passivation of grain boundary trap were achieved effectively through the deuterium ion implantation process. PMID:27427689

  6. Influence of Deuterium Treatments on the Polysilicon-Based Metal-Semiconductor-Metal Photodetector.

    PubMed

    Lee, Jae-Sung

    2016-06-01

    The electrical behavior of metal-semiconductor-metal (MSM) Schottky barrier photodetector structure, depending on deuterium treatment, is analyzed by means of the dark current and the photocurrent measurements. Al/Ti bilayer was used as Schottky metal. The deuterium incorporation into the absorption layer, undoped polysilicon, was achieved with annealing process and with ion implantation process, respectively. In the photocurrent-to-dark current ratio measurement, deuterium-ion-implanted photodetector shows over hundred higher than the control device. It means that the heightening of the Schottky barrier and the passivation of grain boundary trap were achieved effectively through the deuterium ion implantation process.

  7. The mineral base and productive capacities of metals and non-metals of Kosovo

    SciTech Connect

    Rizaj, M.; Beqiri, E.; McBow, I.; O'Brien, E.Z.; Kongoli, F.

    2008-08-15

    All historical periods of Kosovo - Ilirik, Roman, Medieval, Turkish, and former Yugoslavian - are linked with the intensive development of mining and metallurgy. This activity influenced and still is influencing the overall position of Kosovo as a country. For example, according to a 2006 World Bank report as well as other studies, Kosovo has potential lignite resources (geological reserves) of about 1.5 billion tonnes, which are ranked fifth in the world in importance. Other significant Kosovan mineral resources include lead, zinc, gold, silver, bauxite, and uranium, and rare metals accompanying those minerals, including indium, cadmium, thallium, gallium, and bismuth. These rare metals are of particular importance in developing advanced industrial technologies. Kosovo also has reserves of high-quality non-metals, including magnesite, quartz grit, bentonite, argil, talc, and asbestos. No database exists for these non-metal reserves, and further research and studies are needed.

  8. Tunneling-enabled spectrally selective thermal emitter based on flat metallic films

    SciTech Connect

    Wang, Zhu; Luk, Ting S.; Tan, Yixuan; Ji, Dengxin; Zhou, Ming; Gan, Qiaoqiang; Yu, Zongfu

    2015-03-11

    Infrared thermal emission from metals has important energy applications in thermophotovoltaics, radiative cooling, and lighting. The emissivity of flat metal films is close to zero because the screening effect prevents metals' fluctuating currents from emitting to the far field. As a result, metal films are often used as reflecting mirrors instead of thermal emitters. Recently, nanostructured metals, such as metamaterials, have emerged as an interesting way to enhance and to spectrally control thermal emission based on plasmonic resonant effects. However, they require sophisticated lithography. Here, we proposed and experimentally demonstrated a completely different mechanism to achieve spectrally selective metallic emitters based on atunneling effect. Furthermore, this effect allows a simple flat metal film to achieve a near-unity emissivity with controlled spectral selectivity for efficient heat-to-light energy conversion.

  9. Tunneling-enabled spectrally selective thermal emitter based on flat metallic films

    SciTech Connect

    Wang, Zhu; Tan, Yixuan; Zhou, Ming; Yu, Zongfu; Luk, Ting Shan; Ji, Dengxin; Gan, Qiaoqiang

    2015-03-09

    Infrared thermal emission from metals has important energy applications in thermophotovoltaics, radiative cooling, and lighting. Unfortunately, the emissivity of flat metal films is close to zero because the screening effect prevents metals' fluctuating currents from emitting to the far field. As a result, metal films are often used as reflecting mirrors instead of thermal emitters. Recently, nanostructured metals, such as metamaterials, have emerged as an interesting way to enhance and to spectrally control thermal emission based on plasmonic resonant effects. However, they require sophisticated lithography. Here, we proposed and experimentally demonstrated a completely different mechanism to achieve spectrally selective metallic emitters based on a tunneling effect. This effect allows a simple flat metal film to achieve a near-unity emissivity with controlled spectral selectivity for efficient heat-to-light energy conversion.

  10. Electrically conductive polycrystalline diamond and particulate metal based electrodes

    DOEpatents

    Swain, Greg M.; Wang, Jian

    2005-04-26

    An electrically conducting and dimensionally stable diamond (12, 14) and metal particle (13) electrode produced by electrodepositing the metal on the diamond is described. The electrode is particularly useful in harsh chemical environments and at high current densities and potentials. The electrode is particularly useful for generating hydrogen, and for reducing oxygen and oxidizing methanol in reactions which are of importance in fuel cells.

  11. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  12. Control of metal dusting corrosion in Ni-base alloys.

    SciTech Connect

    Zeng, Z.; Natesan, K.; Energy Technology

    2007-11-01

    Metal dusting is a major issue in plants used in the production of hydrogen-and methanol-reformer systems, and syngas (H{sub 2}/CO mixtures) systems that are pertinent to the chemical and petrochemical industries. Usually, metal dusting corrosion has two stages: incubation and growth resulting in propagation of metal dusting pits. The two stages were studied by scanning electron microscopy and profile mapping to evaluate the scale of the surface oxide in the initiation and propagation of metal dusting attack. The initiation occurs because of the presence of defects, and the propagation is determined by the diffusion of carbon into the alloy. The carbon diffusion pathways can be blocked by periodically oxidizing alloy surface at moderate temperatures in controlled atmospheres. It was concluded that metal dusting degradation can be mitigated by selecting an alloy with a long incubation time and subjecting it to intermediate oxidation.

  13. Metal-Based Nanoparticles and the Immune System: Activation, Inflammation, and Potential Applications

    PubMed Central

    Luo, Yueh-Hsia; Chang, Louis W.; Lin, Pinpin

    2015-01-01

    Nanomaterials, including metal-based nanoparticles, are used for various biological and medical applications. However, metals affect immune functions in many animal species including humans. Different physical and chemical properties induce different cellular responses, such as cellular uptake and intracellular biodistribution, leading to the different immune responses. The goals of this review are to summarize and discuss the innate and adaptive immune responses triggered by metal-based nanoparticles in a variety of immune system models. PMID:26125021

  14. Thermodynamical properties of Zr-based bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Gaur, Jitendra; Mishra, R. K.

    2015-11-01

    The temperature dependence of Gibb's free energy difference (ΔG), entropy difference (ΔS) and enthalpy difference (ΔH) between the undercooled melt and the corresponding equilibrium solid phases of bulk metallic glass (BMG) forming melts has been proved to be very useful in the study of their thermodynamical behavior. The present study is made by calculating ΔG, ΔS and ΔH in the entire temperature range Tm (melting temperature) to Tg (glass transition temperature) for three Zr-based samples of BMGs: Zr57Cu15.4Ni12.6Al10Nb5, Zr41.2Ti13.8Ni10Cu12.5Be22.5 and Zr58.5Cu15.6Ni12.8Al10.3Nb2.8. The study is made on the basis of Taylor's series expansion and a comparative study is also performed between the present result and the result obtained in the framework of expansions proposed by earlier workers, and also with the experimental results. An attempt has also been made to study the glass forming ability for BMGs.

  15. Superconductivity in transition metal subsituted iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Kirshenbaum, Kevin

    I report on superconductivity in undoped SrFe2As 2 and find that it is caused by lattice strain in the as-grown crystals that can be removed or returned with annealing or pressure, respectively. To study the magnetic/structural transition I measure the evolution of these transitions in solid solutions of the [Ca, Sr, Ba]Fe2As2 series and determine that the Neel temperature is independent of the size of the antiferromagnetically ordered moment. I present the first reported phase diagrams for Ni- and Pt-substitution in SrFe2As2, showing that the simple charge-counting picture of chemical substitution cannot completely describe the onset and offset of the superconducting phase. Finally, I use the transport scattering rate to explain the variation in Tc seen in transition metal substituted 122s. I will show that pair breaking can explain the variation in the optimum transition temperature, and that the rate of suppression of Tc with scattering will show that the pairing symmetry of the iron-based superconductors is a sign-changing, multiband s-wave order parameter that must include both inter- and intraband scattering.

  16. Friction and wear of some ferrous-base metallic glasses

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1983-01-01

    Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminum oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

  17. Ultrafast response sensor to formaldehyde gas based on metal oxide.

    PubMed

    Choi, N-J; Lee, H-K; Moon, S E; Kim, J; Yang, W S

    2014-08-01

    Thick film semiconductor gas sensors based on indium oxide were fabricated on Si substrate. The sensing materials on Si substrate were characterized using optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and so on. They were very fine and uniform and we found out that particle sizes were about 20~30 nm through XRD analysis. Gas responses of fabricated sensors were measured in a chamber where gas flow was controlled by mass flow controller (MFC). Their resistance changes were monitored in real time by using data acquisition board and personal computer. Gas response characteristics were examined for formaldehyde (HCHO) gas which was known as the cause of sick building syndrome. Particularly, the sensors showed responses to formaldehyde gas at sub ppm (cf, standard of natural environment in building is about 80 ppb by ministry of environment in Korea), as a function of operating temperatures and gas concentrations. Also, we investigated sensitivity, repetition, selectivity, response speed and reproducibility of the sensors. The lowest detection limit is HCHO 25 ppb and sensitivity at 800 ppb is over 25% at 350 °C operating temperature. The response time (8 s) and recovery time (15 s) to HCHO gas at 200 ppb were very fast compared to other commercial products in flow type measurement condition. Repetition measurement was very good with ±3% in full measurement range. The fabricated metal oxide gas sensor showed good performance to HCHO gas and proved that it could be adaptable to indoor environment in building. PMID:25936006

  18. Porous silicon based anode material formed using metal reduction

    SciTech Connect

    Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

    2015-09-22

    A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

  19. Friction and wear of some ferrous-base metallic glasses

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1984-01-01

    Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminium oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

  20. Optical hydrogen sensors based on metal-hydrides

    NASA Astrophysics Data System (ADS)

    Slaman, M.; Westerwaal, R.; Schreuders, H.; Dam, B.

    2012-06-01

    For many hydrogen related applications it is preferred to use optical hydrogen sensors above electrical systems. Optical sensors reduce the risk of ignition by spark formation and are less sensitive to electrical interference. Currently palladium and palladium alloys are used for most hydrogen sensors since they are well known for their hydrogen dissociation and absorption properties at relatively low temperatures. The disadvantages of palladium in sensors are the low optical response upon hydrogen loading, the cross sensitivity for oxygen and carbon, the limited detection range and the formation of micro-cracks after some hydrogen absorption/desorption cycles. In contrast to Pd, we find that the use of magnesium or rear earth bases metal-hydrides in optical hydrogen sensors allow tuning of the detection levels over a broad pressure range, while maintaining a high optical response. We demonstrate a stable detection layer for detecting hydrogen below 10% of the lower explosion limit in an oxygen rich environment. This detection layer is deposited at the bare end of a glass fiber as a micro-mirror and is covered with a thin layer of palladium. The palladium layer promotes the hydrogen uptake at room temperature and acts as a hydrogen selective membrane. To protect the sensor for a long time in air a final layer of a hydrophobic fluorine based coating is applied. Such a sensor can be used for example as safety detector in automotive applications. We find that this type of fiber optic hydrogen sensor is also suitable for hydrogen detection in liquids. As example we demonstrate a sensor for detecting a broad range of concentrations in transformer oil. Such a sensor can signal a warning when sparks inside a high voltage power transformer decompose the transformer oil over a long period.

  1. Plasmonic Bragg reflectors based on metal-embedded MIM structure

    NASA Astrophysics Data System (ADS)

    Tian, Ming; Lu, Ping; Chen, Li; Liu, Deming; Peyghambarian, Nasser

    2012-11-01

    We propose and investigate a metalembedded metal-insulator-metal (MIM) structure plasmonic Bragg reflector (PBR) using the finite-difference time-domain (FDTD) method with PMLs (perfectly matched layers) boundary conditions. It improves the performance of conventional step profile MIM PBRs to some extent. Our numerical study reveals that the metal-embedded PBRs exhibit lower insertion loss, narrower bandgap, and reduced rippling in the transmission spectrum when compared with the step PBRs at the same normalized index contrast and transmission levels. The defect mode of the metal-embedded PBRs also exhibits higher transmission. To suppress the sidelobes in the transmission spectrum, we further smooth the end of the embedded metal, which demonstrates a better performance. Then, we find with respect to the Bragg wavelength, the longer wavelengths have a tendency to spread in the wider regions of the insulator layer; however, the shorter wavelengths have a tendency to spread in the embedded metal regions. The apodized PBRs with the embedded metal length decreasing (increasing) efficaciously suppress the ripples at the right (left) band edges. Then, we use the impedance theoretical model to explain this phenomenon. Finally, we realize a flat-top transmission band filter by connecting two apodized PBRs, and the band and center wavelength can be adjusted.

  2. Boron carbon nitride based metal-insulator-metal UV detectors for harsh environment applications.

    PubMed

    Prakash, Adithya; Nehate, Shraddha D; Sundaram, Kalpathy B

    2016-09-15

    A metal-insulator-metal (MIM) structure using boron carbon nitride (BCN) was tested for its UV detection capability. Since BCN is one of the hardest and chemically robust materials, it is expected to be a potential choice for a UV detector in extreme and harsh conditions. The BCN thin films were deposited using a dual target RF magnetron sputtering process. The optoelectronic performance of the BCN MIM devices were examined through UV photocurrent measurements. A UV photocurrent of two orders of magnitude higher with respect to dark current was achieved in the range of -3 to 3 V. PMID:27628369

  3. A Refractive Index Sensor Based on a Metal-Insulator-Metal Waveguide-Coupled Ring Resonator

    PubMed Central

    Yan, Shu-Bin; Luo, Liang; Xue, Chen-Yang; Zhang, Zhi-Dong

    2015-01-01

    A refractive index sensor composed of two straight metal-insulator-metal waveguides and a ring resonator is presented. One end of each straight waveguide is sealed and the other end acts as port. The transmission spectrum and magnetic field distribution of this sensor structure are simulated using finite-difference time-domain method (FDTD). The results show that an asymmetric line shape is observed in the transmission spectrum, and that the transmission spectrum shows a filter-like behavior. The quality factor and sensitivity are taken to characterize its sensing performance and filter properties. How structural parameters affect the sensing performance and filter properties is also studied. PMID:26610491

  4. Mechanochemical synthesis of an yttrium based metal-organic framework.

    PubMed

    Singh, Niraj K; Hardi, Meenakshi; Balema, Viktor P

    2013-02-01

    For the first time a metal hydride has been used for the preparation of a metal-organic framework. MIL-78 has been synthesized by the solid-state mechanochemical reaction between yttrium hydride and trimesic acid. The process does not involve solvents and does not generate liquid by-products, thus proving the viability of the solid-state approach to the synthesis of MOFs.

  5. Nano-structured noble metal catalysts based on hexametallate architecture for the reforming of hydrocarbon fuels

    DOEpatents

    Gardner, Todd H.

    2015-09-15

    Nano-structured noble metal catalysts based on hexametallate lattices, of a spinel block type, and which are resistant to carbon deposition and metal sulfide formation are provided. The catalysts are designed for the reforming of hydrocarbon fuels to synthesis gas. The hexametallate lattices are doped with noble metals (Au, Pt, Rh, Ru) which are atomically dispersed as isolated sites throughout the lattice and take the place of hexametallate metal ions such as Cr, Ga, In, and/or Nb. Mirror cations in the crystal lattice are selected from alkali metals, alkaline earth metals, and the lanthanide metals, so as to reduce the acidity of the catalyst crystal lattice and enhance the desorption of carbon deposit forming moieties such as aromatics. The catalysts can be used at temperatures as high as 1000.degree. C. and pressures up to 30 atmospheres. A method for producing these catalysts and applications of their use also is provided.

  6. A Model Based Approach to Increase the Part Accuracy in Robot Based Incremental Sheet Metal Forming

    SciTech Connect

    Meier, Horst; Laurischkat, Roman; Zhu Junhong

    2011-01-17

    One main influence on the dimensional accuracy in robot based incremental sheet metal forming results from the compliance of the involved robot structures. Compared to conventional machine tools the low stiffness of the robot's kinematic results in a significant deviation of the planned tool path and therefore in a shape of insufficient quality. To predict and compensate these deviations offline, a model based approach, consisting of a finite element approach, to simulate the sheet forming, and a multi body system, modeling the compliant robot structure, has been developed. This paper describes the implementation and experimental verification of the multi body system model and its included compensation method.

  7. Phase diagrams of microemulsions containing reducing agents and metal salts as bases for the synthesis of metallic nanoparticles.

    PubMed

    Najjar, Reza; Stubenrauch, Cosima

    2009-03-01

    We studied the phase diagrams of microemulsions with a view to using these systems for the synthesis of metallic Pt, Pb, and Bi nanoparticles as well as of intermetallic Pt/Pb and Pt/Bi nanoparticles. The microemulsions consisted of H(2)O/salt-n-decane-SDS-1-butanol. The salt was either one metal precursor (H(2)PtCl(6) x 6 H(2)O, Pb(NO(3))(2), or Bi(NO(3))(3) x 5 H(2)O), a mixture of two metal precursors (H(2)PtCl(6) x 6 H(2)O + Pb(NO(3))(2) or H(2)PtCl(6) x 6 H(2)O + Bi(NO(3))(3) x 5 H(2)O), or the reducing agent (NaBH(4)). In addition, other salts needed to be added in order to solubilize the metal precursors, to stabilize the reducing agent, and to adjust the ionic strength. Combining the microemulsion (mu e1) that contains the metal precursor(s) with the microemulsion (mu e2) that contains the reducing agent leads to metallic nanoparticles. To study systematically how the shape and size of the synthesized metallic nanoparticles depend on the size and shape of the respective microemulsion droplets, first of all one has to find those conditions under which mu e1 and mu e2 have the same structure. For that purpose we determined the water emulsification failure boundary (wefb) of each microemulsion as it is at the wefb where the water droplets are known to be spherical. We found that the ionic strength (I) of the aqueous phase as well as the hard acid and hard base properties of the ions are the key tuning parameters for the location of the wefb.

  8. Metallated porphyrin based porous organic polymers as efficient electrocatalysts

    NASA Astrophysics Data System (ADS)

    Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

    2015-10-01

    Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm-2) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm-2). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e- pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system.Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(ii) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ~100% constant ORR current over 50 000 s in both

  9. Metallated porphyrin based porous organic polymers as efficient electrocatalysts.

    PubMed

    Lu, Guolong; Zhu, Youlong; Xu, Kongliang; Jin, Yinghua; Ren, Zhiyong Jason; Liu, Zhenning; Zhang, Wei

    2015-11-21

    Developing efficient, stable and low-cost catalysts for Oxygen Reduction Reaction (ORR) is of great significance to many emerging technologies including fuel cells and metal-air batteries. Herein, we report the development of a cobalt(II) porphyrin based porous organic polymer (CoPOP) and its pyrolyzed derivatives as highly active ORR catalysts. The as-synthesized CoPOP exhibits high porosity and excellent catalytic performance stability, retaining ∼100% constant ORR current over 50,000 s in both alkaline and acidic media. Pyrolysis of CoPOP at various temperatures (600 °C, 800 °C, and 1000 °C) yields the materials consisting of graphitic carbon layers and cobalt nanoparticles, which show greatly enhanced catalytic activity compared to the as-synthesized CoPOP. Among them, CoPOP-800/C pyrolyzed at 800 °C shows the highest specific surface area and ORR activity, displaying the most positive half-wave potential (0.825 V vs. RHE) and the largest limited diffusion current density (5.35 mA cm(-2)) in an alkaline medium, which are comparable to those of commercial Pt/C (20 wt%) (half-wave potential 0.829 V vs. RHE, limited diffusion current density 5.10 mA cm(-2)). RDE and RRDE experiments indicate that CoPOP-800/C directly reduces molecular oxygen to water through a 4-e(-) pathway in both alkaline and acidic media. More importantly, CoPOP-800/C exhibits excellent durability and methanol-tolerance under acidic and alkaline conditions, which surpass the Pt/C (20 wt%) system. PMID:26486413

  10. Pulse based sensor networking using mechanical waves through metal substrates

    NASA Astrophysics Data System (ADS)

    Lorenz, S.; Dong, B.; Huo, Q.; Tomlinson, W. J.; Biswas, S.

    2013-05-01

    This paper presents a novel wireless sensor networking technique using ultrasonic signal as the carrier wave for binary data exchange. Using the properties of lamb wave propagation through metal substrates, the proposed network structure can be used for runtime transport of structural fault information to ultrasound access points. Primary applications of the proposed sensor networking technique will include conveying fault information on an aircraft wing or on a bridge to an ultrasonic access point using ultrasonic wave through the structure itself (i.e. wing or bridge). Once a fault event has been detected, a mechanical pulse is forwarded to the access node using shortest path multi-hop ultrasonic pulse routing. The advantages of mechanical waves over traditional radio transmission using pulses are the following: First, unlike radio frequency, surface acoustic waves are not detectable outside the medium, which increases the inherent security for sensitive environments in respect to tapping. Second, event detection can be represented by the injection of a single mechanical pulse at a specific temporal position, whereas radio messages usually take several bits. The contributions of this paper are: 1) Development of a transceiver for transmitting/receiving ultrasound pulses with a pulse loss rate below 2·10-5 and false positive rate with an upper bound of 2·10-4. 2) A novel one-hop distance estimation based on the properties of lamb wave propagation with an accuracy of above 80%. 3) Implementation of a wireless sensor network using mechanical wave propagation for event detection on a 2024 aluminum alloy commonly used for aircraft skin construction.

  11. Pattern-based detection of toxic metals in surface water with DNA polyfluorophores.

    PubMed

    Yuen, Lik Hang; Franzini, Raphael M; Wang, Shenliang; Crisalli, Pete; Singh, Vijay; Jiang, Wei; Kool, Eric T

    2014-05-19

    Heavy metal contamination of water can be toxic to humans and wildlife; thus the development of methods to detect this contamination is of high importance. Here we describe the design and application of DNA-based fluorescent chemosensors on microbeads to differentiate eight toxic metal ions in water. We developed and synthesized four fluorescent 2'-deoxyribosides of metal-binding ligands. A tetramer-length oligodeoxy-fluoroside (ODF) library of 6561 members was constructed and screened for sequences responsive to metal ions, of which seven sequences were selected. Statistical analysis of the response patterns showed successful differentiation of the analytes at concentrations as low as 100 nM. Sensors were able to classify water samples from 13 varied sites and quantify metal contamination in unknown specimens. The results demonstrate the practical potential of bead-based ODF chemosensors to analyze heavy metal contamination in water samples by a simple and inexpensive optical method.

  12. Proteomic Approaches in Understanding Action Mechanisms of Metal-Based Anticancer Drugs

    PubMed Central

    Wang, Ying; Chiu, Jen-Fu

    2008-01-01

    Medicinal inorganic chemistry has been stimulating largely by the success of the anticancer drug, cisplatin. Various metal complexes are currently used as therapeutic agents (e.g., Pt, Au, and Ru) in the treatment of malignant diseases, including several types of cancers. Understanding the mechanism of action of these metal-based drugs is for the design of more effective drugs. Proteomic approaches combined with other biochemical methods can provide comprehensive understanding of responses that are involved in metal-based anticancer drugs-induced cell death, including insights into cytotoxic effects of metal-based anticancer drugs, correlation of protein alterations to drug targets, and prediction of drug resistance and toxicity. This information, when coupled with clinical data, can provide rational basses for the future design and modification of present used metal-based anticancer drugs. PMID:18670610

  13. An evaluation of metallized propellants based on vehicle performance

    NASA Technical Reports Server (NTRS)

    Zurawski, Robert L.; Green, James M.

    1987-01-01

    An analytical study was conducted to determine the improvements in vehicle performance possible by burning metals with conventional liquid bipropellants. These metallized propellants theoretically offer higher specific impulse, increased propellant density and improved vehicle performance compared with conventional liquid bipropellants. Metals considered were beryllium, lithium, aluminum and iron. Liquid bipropellants were H2/O2, N2H4/N2O4, RP-1/O2 and H2/F2. A mission with a delta V = 4267.2 m/sec (14,000 ft/sec) and vehicle with propellant volume fixed at 56.63 cu m (2000 cu ft) and dry mass fixed at 2761.6 kg (6000 lb) was used, roughly representing the transfer of a chemically propelled upper-stage vehicle from a low-Earth orbit to a geosynchronous orbit. The results of thermochemical calculations and mission analysis calculations for bipropellants metallized with beryllium, lithium, aluminum and iron are presented. Technology issues pertinent to metallized propellants are discussed.

  14. A Review of Thermal Spray Metallization of Polymer-Based Structures

    NASA Astrophysics Data System (ADS)

    Gonzalez, R.; Ashrafizadeh, H.; Lopera, A.; Mertiny, P.; McDonald, A.

    2016-06-01

    A literature review on the thermal spray deposition of metals onto polymer-based structures is presented. The deposition of metals onto polymer-based structures has been developed to enhance the thermal and electrical properties of the resulting metal-polymer material system. First, the description of the thermal spray metallization processes and technologies for polymer-based materials are outlined. Then, polymer surface preparation methods and the deposition of metal bond-coats are explored. Moreover, the thermal spray process parameters that affect the properties of metal deposits on polymers are described, followed by studies on the temperature distribution within the polymer substrate during the thermal spray process. The objective of this review is devoted to testing and potential applications of thermal-sprayed metal coatings deposited onto polymer-based substrates. This review aims to summarize the state-of-the-art contributions to research on the thermal spray metallization of polymer-based materials, which has gained recent attention for potential and novel applications.

  15. Mn in misch-metal based superlattice metal hydride alloy - Part 1 structural, hydrogen storage and electrochemical properties

    NASA Astrophysics Data System (ADS)

    Young, K.; Wong, D. F.; Wang, L.; Nei, J.; Ouchi, T.; Yasuoka, S.

    2015-03-01

    The structural, gaseous phase hydrogen storage, and electrochemical properties of a series of Mn-modified misch-metal based superlattice metal hydride alloys were investigated in part one of this two-part series of papers. X-ray diffraction analysis showed that these alloys are all multi-phased compositions with different abundances of AB2, AB3, A2B7, AB4, and AB5 phases. Substitution of Ni in the B-site by Mn promotes AB5 phase formation and decreases both gaseous phase and electrochemical capacities due to the reduction in the abundance of main hexagonal A2B7 phase. AC impedance and magnetic susceptibility measurement were employed to characterize the surface of Mn-free and Mn-modified alloys and show deterioration in surface catalytic ability as the Mn-content increases. Mn-modification adversely affected misch-metal based superlattice metal hydride alloy properties such as phase homogeneity, capacity, cycle stability, high-rate performance, and surface reaction.

  16. Prominent β-relaxations in yttrium based metallic glasses

    SciTech Connect

    Luo, P.; Lu, Z.; Zhu, Z. G.; Li, Y. Z.; Bai, H. Y.; Wang, W. H.

    2015-01-19

    Most metallic glasses (MGs) exhibit weak slow β-relaxation. We report the prominent β-relaxation in YNiAl metallic glass with a wide composition range. Compared with other MGs, the MGs show a pronounced β-relaxation peak and high β-relaxation peak temperature, and the β-relaxation behavior varies significantly with the changes of the constituent elements, which is attributed to the fluctuations of chemical interactions between the components. We demonstrate the correlation between the β-relaxation and the activation of flow units for mechanical behaviors of the MG and show that the MG is model system for studying some controversial issues in glasses.

  17. Tunable optical antennas based on metallic nanoshells with nanoknobs.

    PubMed

    Denisyuk, Andrey I; Tinskaya, Maria A; Petrov, Mikhail I; Shelaev, Artem V; Dorozhkin, Pavel S

    2012-11-01

    We investigate optical properties of a new complex plasmonic nanostructure, which consists of a spherical metallic nanoshell and a small metallic nanoparticle ("nanoknob") situated on its surface. The plasmon resonance wavelength of the entire structure is guided by the geometrical and material properties of the nanoshell whereas the electromagnetic field of the incident light is localized and enhanced near the "nanoknob". The idea is supported with electromagnetic modeling and near-field optical microscopy imaging. In addition, we proposed and demonstrated a new method of nanoparticle precise manipulation under electron beam, which could be used in fabrication of such plasmonic structures and other nanosized elements. PMID:23421259

  18. Ancient concept of metal pharmacology based on Ayurvedic literature

    PubMed Central

    Sarkar, Prasanta Kumar; Das, Sanjita; Prajapati, P. K.

    2010-01-01

    Metals have had a long history in Ayurvedic system of medicine. Mercury (Parada), gold (Swarna), silver (Rajata), copper (Tamra), iron (Lauha), tin (Vanga), lead (Naga), and zinc (Yasada) are used in therapeutics in an incinerated (Bhasma) form. The pharmacological actions, therapeutic indications, adverse effects and management of adverse effects of these metals are described and emphasis has been given to the proper preparation, rational dose and duration during clinical practice in the classics of Ayurveda. Most important observation is, there are no contraindications of these Bhasmas, indicating universal applicability to all age levels with suitable adjuvant, proper dose and duration. PMID:22557360

  19. Ancient concept of metal pharmacology based on Ayurvedic literature.

    PubMed

    Sarkar, Prasanta Kumar; Das, Sanjita; Prajapati, P K

    2010-04-01

    Metals have had a long history in Ayurvedic system of medicine. Mercury (Parada), gold (Swarna), silver (Rajata), copper (Tamra), iron (Lauha), tin (Vanga), lead (Naga), and zinc (Yasada) are used in therapeutics in an incinerated (Bhasma) form. The pharmacological actions, therapeutic indications, adverse effects and management of adverse effects of these metals are described and emphasis has been given to the proper preparation, rational dose and duration during clinical practice in the classics of Ayurveda. Most important observation is, there are no contraindications of these Bhasmas, indicating universal applicability to all age levels with suitable adjuvant, proper dose and duration.

  20. Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole

    NASA Astrophysics Data System (ADS)

    Kalanithi, M.; Rajarajan, M.; Tharmaraj, P.; Sheela, C. D.

    2012-02-01

    Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol( HL1), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol( HL2), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol( HL3). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry.

  1. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    SciTech Connect

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF[sub 2], ThO[sub 2], YDT(0.85ThO[sub 2]-0.15YO[sub 1.5]), and LDT(0.85ThO[sub 2]- 0.15LaO[sub 1.5]) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  2. The strong reactions of Lewis-base noble-metals with vanadium and other acidic transition metals

    SciTech Connect

    Ebbinghaus, B.B.

    1991-05-01

    The noble metals often thought of as unreactive solids,react strongly with nearly 40% of the elements in the periodictable: group IIIB-VB transition metals, lanthanides, theactinides, and group IIIA-IVA non-transition metals. These strong reactions arise from increased bonding/electron transfer fromnonbonding electrons d electron pairs on the noble metal tovacant orbitals on V, etc. This effect is a generalized Lewis acid-base interaction. The partial Gibbs energy of V in the noblemetals has been measured as a function of concentration at a temperature near 1000C. Thermodynamics of the intermetallics are determined by ternary oxide equilibria, ternary carbide equilibria, and the high-temperature galvanic cell technique. These experimental methods use equilibrated solid composite mixtures in which grains of V oxides or of V carbides are interspersed with grains of V-NM(noble-metal) alloys. In equilibrium the activity of V in the oxide or the carbide equals the activity in the alloy. Consequently, the thermodynamics available in the literature for the V oxides and V carbides are reviewed. Test runs on the galvanic cell were attempted. The V oxide electrode reacts with CaF{sub 2}, ThO{sub 2}, YDT(0.85ThO{sub 2}-0.15YO{sub 1.5}), and LDT(0.85ThO{sub 2}- 0.15LaO{sub 1.5}) to interfere with the measured data observed toward the beginning of a galvanic cell experiment are the most accurate. The interaction of vanadium at infinite dilution in the noble-metals was determined.

  3. Recognition- and reactivity-based fluorescent probes for studying transition metal signaling in living systems.

    PubMed

    Aron, Allegra T; Ramos-Torres, Karla M; Cotruvo, Joseph A; Chang, Christopher J

    2015-08-18

    Metals are essential for life, playing critical roles in all aspects of the central dogma of biology (e.g., the transcription and translation of nucleic acids and synthesis of proteins). Redox-inactive alkali, alkaline earth, and transition metals such as sodium, potassium, calcium, and zinc are widely recognized as dynamic signals, whereas redox-active transition metals such as copper and iron are traditionally thought of as sequestered by protein ligands, including as static enzyme cofactors, in part because of their potential to trigger oxidative stress and damage via Fenton chemistry. Metals in biology can be broadly categorized into two pools: static and labile. In the former, proteins and other macromolecules tightly bind metals; in the latter, metals are bound relatively weakly to cellular ligands, including proteins and low molecular weight ligands. Fluorescent probes can be useful tools for studying the roles of transition metals in their labile forms. Probes for imaging transition metal dynamics in living systems must meet several stringent criteria. In addition to exhibiting desirable photophysical properties and biocompatibility, they must be selective and show a fluorescence turn-on response to the metal of interest. To meet this challenge, we have pursued two general strategies for metal detection, termed "recognition" and "reactivity". Our design of transition metal probes makes use of a recognition-based approach for copper and nickel and a reactivity-based approach for cobalt and iron. This Account summarizes progress in our laboratory on both the development and application of fluorescent probes to identify and study the signaling roles of transition metals in biology. In conjunction with complementary methods for direct metal detection and genetic and/or pharmacological manipulations, fluorescent probes for transition metals have helped reveal a number of principles underlying transition metal dynamics. In this Account, we give three recent

  4. SINGLE-PARTICLE ICPMS FOR CHARACTERIZING METAL-BASED NANOPARTICLES IN THE ENVIRONMENT - ADVANCES AND CHALLENGES

    EPA Science Inventory

    As engineered metal-based nanomaterials become widely used in consumer and industrial products, the amount of these materials introduced into the environment by a variety of paths will increase. The concentration of metal associated with these engineered nanoparticles will be s...

  5. REDUCTION OF COAL-BASED METAL EMISSIONS BY FURNACE SORBENT INJECTION

    EPA Science Inventory

    The ability of sorbent injection technology to reduce the potential for trace metal emissions from coal combustion was researched. Pilot scale tests of high-temperature furnace sorbent injection were accompanied by stack sampling for coal-based, metallic air toxics. Tested sorben...

  6. Electrochromic artificial muscles based on nanoporous metal-polymer composites

    NASA Astrophysics Data System (ADS)

    Detsi, E.; Onck, P. R.; De Hosson, J. T. M.

    2013-11-01

    This work shows that a nano-coating of electrochromic polymer grown onto the ligaments of nanoporous gold causes reversible dimensional and color changes during electrochemical actuation. This combination of electromechanical and optical properties opens additional avenues for the applications of artificial muscles, i.e., a metallic muscle exhibits its progress during work by changing color that can be detected by optical means.

  7. Photogalvanic and photovoltaic effects in systems based on metal complexes of Schiff bases

    NASA Astrophysics Data System (ADS)

    Smirnova, E. A.; Besedina, M. A.; Karushev, M. P.; Vasil'ev, V. V.; Timonov, A. M.

    2016-05-01

    The nature of the processes that occur when electrodes modified with complexes [M(Schiff)] (M = Ni, Pd, Pt; Schiff denotes four-dentate Schiff base ligands) are irradiated with visible light for the potential use of these electrodes in photoelectrochemical energy conversion devices is considered. The factors responsible for shifts in the electrode potential upon photoexcitation, i.e., the nature of the metal site, the nature of the substituents in the sensitizer, and the oxygen concentration are discussed. Tentative mechanisms of the photovoltaic effects observed for conventional and semiconductor electrodes modified with [M(Schiff)] complexes are determined.

  8. Case studies for heavy metals removal using a granular, magnesium-based adsorbent

    SciTech Connect

    Walter, M.D.; Witkowski, J.T.; Reyes, A.

    1994-12-31

    Environmental regulations have become increasingly severe regarding the types and amounts of pollutants that may be released into the environment. In particular, metal finishers are commonly restricted to the metal concentrations and pH of waste water that may be discharged into natural waterways, municipal sewers, etc. This paper details a granular Magnesium-based Adsorbent (FloMag{trademark} G) which has been used to remove various metals from surface finishing waste water streams. The metals treated in this study include copper, nickel, and zinc. Effluent concentrations of the treated metals are typically less than 0.5 mg/L. Three case studies are presented detailing the performance of FloMag{trademark} G as well as information about how FloMag{trademark} G removes metals from solution.

  9. Metal artifacts reduction in x-ray CT based on segmentation and forward-projection.

    PubMed

    Nawaz, Shoukat; Fu, Jian; Fan, Dekai

    2014-01-01

    X-ray computed tomography (CT) is a powerful clinical diagnosis tool and has been used widely in many clinical and biological settings. Metal artifacts, caused by high density implants, are commonly encountered in clinical CT applications, thereby affecting the detection of abnormal structures and undermining CT's diagnostic value. In this paper, we developed a metal artifact reduction approach based on image segmentation and forward-projection. We further demonstrate the usefulness of our approach by using a biomedical specimen consisting of muscles, bones and metals. Our aim is to remove the inaccurate metal artifact pixels in the original CT slices and exactly reconstruct the soft-tissue using the forward projections with no metal information. During the reconstruction, artifacts are reduced by replacing the metal projection using the forward projection. The presented work is of interest for CT biomedical applications.

  10. Deformation Behaviors of Zr-BASED Bulk Metallic Glass Under Impact Indentation

    NASA Astrophysics Data System (ADS)

    Shin, Hyung-Seop; Chang, Soon-Nam; Kim, Do Kyung

    Metallic glasses are amorphous meta-stable solids and are now being processed in bulk form suitable for structural applications under impact loading. Bulk metallic glasses have many unique mechanical properties such as high yield strength and fracture toughness, good corrosion and wear resistance that distinguish them from crystalline metals and alloys. However, only a few studies could be found mentioning the dynamic response and damage of metallic glasses under impact or shock loading. In this study, we employed a small explosive detonator for the dynamic indentation to a Zr-based bulk amorphous metal in order to evaluate the damage behavior of bulk amorphous metal under impact or shock loading conditions. Results were compared with those of spherical indentation under quasi-static and impact loading and were discussed. The interface bonded specimen method was adopted in order to observe the subsurface damage, especially the formation of shear bands induced during indentation under different loading conditions.

  11. Preparation and magnetic properties of phthalocyanine-based carbon materials containing transition metals

    NASA Astrophysics Data System (ADS)

    Honda, Z.; Sato, S.; Hagiwara, M.; Kida, T.; Sakai, M.; Fukuda, T.; Kamata, N.

    2016-07-01

    A simple method for the preparation of bulk quantities of magnetic carbon materials, which contain uniformly dispersed transition metals (M = Fe, Co, Ni, and Cu) as the magnetic components, is presented. By using highly chlorinated metal phthalocyanine as the building block and potassium as the coupling reagent, phthalocyanine-based carbon materials (PBCMs) containing transition metals were obtained. Our experiments demonstrate the structure of these PBCMs consists of transition metals embedded in graphitic carbon that includes a square planar MN4 magnetic core and the Fe and Co-PBCM possess spontaneous magnetization at room temperature. In addition, carbon-coated transition metal particles were obtained by the Wurtz-type reaction with excess amount of potassium coupling agent. The large transition metal surface area and magnetization of these M-PBCMs are useful for spintronic and catalytic applications.

  12. Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide-semiconductor-compatible silicon nanowires

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Jun; Agarwal, Ajay; Buddharaju, Kavitha D.; Singh, Navab; Gao, Zhiqiang

    2007-06-01

    Highly sensitive sensors for alkali metal ions based on complementary-metal-oxide- semiconductor-compatible silicon nanowires (SiNWs) with crown ethers covalently immobilized on their surface are presented. A densely packed organic monolayer terminated with amine groups is introduced to the SiNW surface via hydrosilylation. Amine-modified crown ethers, acting as sensing elements, are then immobilized onto the SiNWs through a cross-linking reaction with the monolayer. The crown ether-functionalized SiNWs recognize Na+ and K+ according to their complexation ability to the crown ethers. The SiNW sensors are highly selective and capable of achieving an ultralow detection limit down to 50nM, over three orders of magnitude lower than that of conventional crown ether-based ion-selective electrodes.

  13. Fano Resonance Based on Metal-Insulator-Metal Waveguide-Coupled Double Rectangular Cavities for Plasmonic Nanosensors

    PubMed Central

    Zhang, Zhidong; Luo, Liang; Xue, Chenyang; Zhang, Wendong; Yan, Shubin

    2016-01-01

    A refractive index sensor based on metal-insulator-metal (MIM) waveguides coupled double rectangular cavities is proposed and investigated numerically using the finite element method (FEM). The transmission properties and refractive index sensitivity of various configurations of the sensor are systematically investigated. An asymmetric Fano resonance lineshape is observed in the transmission spectra of the sensor, which is induced by the interference between a broad resonance mode in one rectangular and a narrow one in the other. The effect of various structural parameters on the Fano resonance and the refractive index sensitivity of the system based on Fano resonance is investigated. The proposed plasmonic refractive index sensor shows a maximum sensitivity of 596 nm/RIU. PMID:27164101

  14. Carbon based secondary compounds do not provide protection against heavy metal road pollutants in epiphytic macrolichens.

    PubMed

    Gauslaa, Yngvar; Yemets, Olena A; Asplund, Johan; Solhaug, Knut Asbjørn

    2016-01-15

    Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to search for relationships between concentrations of heavy metals and CBSCs along a gradient in heavy metal pollutants. Viability parameters and concentrations of 21 elements including nutrients and heavy metals in these lichen samples were reported in a separate paper. Medullary CBSCs in fruticose lichens (Ramalina farinacea, Usnea dasypoga) were reduced in the most polluted sites, but not in foliose ones (Parmelia sulcata, Lobaria pulmonaria), whereas cortical CBSC did not change with distance from the road in any species. Strong positive correlations only occurred between the major medullary compound stictic acid present in L. pulmonaria and most heavy metals, consistent with a chelating role of stictic acid, but not of other studied CBSCs or in other species. However, heavy metal chelating did not protect L. pulmonaria against damage because this species experienced the strongest reduction in viability in the polluted sites. CBSCs with an accumulation potential for heavy metals should be quantified in lichen biomonitoring studies of heavy metals because they, like stictic acid, could overshadow pollutant inputs in some species rendering biomonitoring data less useful. In the two fruticose lichen species, CBSCs decreased with increasing heavy metal concentration, probably because heavy metal exposure impaired secondary metabolism. Thus, we found no support for a heavy metal protection role of any CBSCs in studied epiphytic lichens. No intraspecific relationships occurred between CBSCs versus N or C/N-ratio. Interspecifically, medullary CBSCs decreased and cortical CBSCs increased with increasing C/N-ratio.

  15. Noninvasive Evaluation of Heavy Metal Uptake and Storage in Micoralgae Using a Fluorescence Resonance Energy Transfer-Based Heavy Metal Biosensor1[C][W][OPEN

    PubMed Central

    Rajamani, Sathish; Torres, Moacir; Falcao, Vanessa; Ewalt Gray, Jaime; Coury, Daniel A.; Colepicolo, Pio; Sayre, Richard

    2014-01-01

    We have developed a fluorescence resonance energy transfer (FRET)-based heavy metal biosensor for the quantification of bioavailable free heavy metals in the cytoplasm of the microalga Chlamydomonas reinhardtii. The biosensor is composed of an end-to-end fusion of cyan fluorescent protein (CFP), chicken metallothionein II (MT-II), and yellow fluorescent protein (YFP). In vitro measurements of YFP/CFP fluorescence emission ratios indicated that the addition of metals to the purified biosensor enhanced FRET between CFP and YFP, consistent with heavy metal-induced folding of MT-II. A maximum YFP/CFP FRET ratio of 2.8 was observed in the presence of saturating concentrations of heavy metals. The sensitivity of the biosensor was greatest for Hg2+ followed by Cd2+ ≈ Pb2+ > Zn2+ > Cu2+. The heavy metal biosensor was unresponsive to metals that do not bind to MT-II (Na+ and Mg2+). When expressed in C. reinhardtii, we observed a differential metal-dependent response to saturating external concentrations (1.6 mm) of heavy metals (Pb2+ > Cd2+) that was unlike that observed for the isolated biosensor (in vitro). Significantly, analysis of metal uptake kinetics indicated that equilibration of the cytoplasm with externally applied heavy metals occurred within seconds. Our results also indicated that algae have substantial buffering capacity for free heavy metals in their cytosol, even at high external metal concentrations. PMID:24368336

  16. Noninvasive evaluation of heavy metal uptake and storage in micoralgae using a fluorescence resonance energy transfer-based heavy metal biosensor.

    PubMed

    Rajamani, Sathish; Torres, Moacir; Falcao, Vanessa; Ewalt Gray, Jaime; Coury, Daniel A; Colepicolo, Pio; Sayre, Richard

    2014-02-01

    We have developed a fluorescence resonance energy transfer (FRET)-based heavy metal biosensor for the quantification of bioavailable free heavy metals in the cytoplasm of the microalga Chlamydomonas reinhardtii. The biosensor is composed of an end-to-end fusion of cyan fluorescent protein (CFP), chicken metallothionein II (MT-II), and yellow fluorescent protein (YFP). In vitro measurements of YFP/CFP fluorescence emission ratios indicated that the addition of metals to the purified biosensor enhanced FRET between CFP and YFP, consistent with heavy metal-induced folding of MT-II. A maximum YFP/CFP FRET ratio of 2.8 was observed in the presence of saturating concentrations of heavy metals. The sensitivity of the biosensor was greatest for Hg2+ followed by Cd2+≈Pb2+>Zn2+>Cu2+. The heavy metal biosensor was unresponsive to metals that do not bind to MT-II (Na+ and Mg2+). When expressed in C. reinhardtii, we observed a differential metal-dependent response to saturating external concentrations (1.6 mm) of heavy metals (Pb2+>Cd2+) that was unlike that observed for the isolated biosensor (in vitro). Significantly, analysis of metal uptake kinetics indicated that equilibration of the cytoplasm with externally applied heavy metals occurred within seconds. Our results also indicated that algae have substantial buffering capacity for free heavy metals in their cytosol, even at high external metal concentrations.

  17. Corrosion and wear resistance of titanium- and aluminum-based metal matrix composites fabricated by direct metal laser deposition

    NASA Astrophysics Data System (ADS)

    Waldera, Benjamin L.

    Titanium- and Aluminum-based metal matrix composites (MMC) have shown favorable properties for aerospace applications such as airframes, reinforcement materials and joining elements. In this research, such coatings were developed by direct metal laser deposition with a powder-fed fiber coupled diode laser. The MMC formulations consisted of pure titanium and aluminum matrices with reinforcing powder blends of chromium carbide and tungsten carbide nickel alloy. Two powder formulations were investigated for each matrix material (Ti1, Ti2, Al1 and Al2). Titanium based composites were deposited onto a Ti6Al4V plate while aluminum composites were deposited onto AA 7075 and AA 5083 for Al1 and Al2, respectively. Microstructures of the MMCs were studied by optical and scanning electron microscopy. The hardness and reduced Young's modulus (Er) were assessed through depth-sensing instrumented nanoindentation. microhardness (Vickers) was also analyzed for each composite. The corrosion resistance of the MMCs were compared by monitoring open circuit potential (OCP), polarization resistance (Rp) and potentiodynamic polarization in 0.5 M NaCl to simulate exposure to seawater. The Ti-MMCs demonstrated improvements in hardness between 205% and 350% over Ti6Al4V. Al-MMCs showed improvements between 47% and 79% over AA 7075 and AA 5083. The MMCs showed an increase in anodic current density indicating the formation of a less protective surface oxide than the base metals.

  18. Electrical active defects in HfO2 based metal/oxide/metal devices

    NASA Astrophysics Data System (ADS)

    El Kamel, F.

    2016-01-01

    Dielectric as well as thermally stimulated current measurements were performed on metal/HfO2/Pt capacitors in order to study the electrical active defects in hafnia thin films. Two thermally activated relaxation processes have been carried out from both measurements. At low temperatures, the relaxation process can be ascribed to the shallow traps level localized at 0.65 eV and generally evidenced by the second ionization of oxygen vacancies. At high temperatures, the relaxation process arises from the diffusion of positively charged oxygen vacancies by overcoming an energetic barrier of about 1 eV.

  19. Metal exposure influences the melanin and carotenoid-based colorations in great tits.

    PubMed

    Giraudeau, M; Mateos-Gonzalez, F; Cotín, J; Pagani-Nuñez, E; Torné-Noguera, A; Senar, J C

    2015-11-01

    Metals are naturally found in the environment but are also emitted through anthropogenic activities, raising some concerns about the potential deleterious effects of these elements on wildlife. The potential effects of metals on bird coloration have been the focus of several recent studies since animal colored-signals often reflect the physiology of their bearers and are thus used by animals to assess the quality of another individual as a mate or competitor. These studies have shown that the melanin pigmentation seems to be positively associated and the carotenoid-based coloration negatively associated with metal exposure in wild birds. Although these studies have been very useful to show the associations between metal exposure and coloration, only few of them have actually quantified the levels of metal exposure at the individual level; always focusing on one or two of them. Here, we measured the concentrations of eight metals in great tits' feathers and then assessed how these levels of metals were associated with the carotenoid and melanin-based colorations. We found that the melanin pigmentation was positively associated with the copper concentration and negatively correlated with the chromium concentration in feathers. In addition, we have shown that the carotenoid-based coloration was negatively associated with the feather's mercury concentration. This study is the first one to identify some metals that might affect positively and negatively the deposition of melanin and carotenoid into the plumage of wild birds.

  20. Solution structure of a DNA double helix with consecutive metal-mediated base pairs.

    PubMed

    Johannsen, Silke; Megger, Nicole; Böhme, Dominik; Sigel, Roland K O; Müller, Jens

    2010-03-01

    Metal-mediated base pairs represent a powerful tool for the site-specific functionalization of nucleic acids with metal ions. The development of applications of the metal-modified nucleic acids will depend on the availability of structural information on these double helices. We present here the NMR solution structure of a self-complementary DNA oligonucleotide with three consecutive imidazole nucleotides in its centre. In the absence of transition-metal ions, a hairpin structure is adopted with the artificial nucleotides forming the loop. In the presence of Ag(i) ions, a duplex comprising three imidazole-Ag(+)-imidazole base pairs is formed. Direct proof for the formation of metal-mediated base pairs was obtained from ¹J(¹⁵N,¹⁰⁷/¹⁰⁹Ag) couplings upon incorporation of ¹⁵N-labelled imidazole. The duplex adopts a B-type conformation with only minor deviations in the region of the artificial bases. This work represents the first structural characterization of a metal-modified nucleic acid with a continuous stretch of metal-mediated base pairs. PMID:21124482

  1. The Metal Abundances across Cosmic Time (MACT) Survey. II. Evolution of the Mass–metallicity Relation over 8 Billion Years, Using [OIII]4363AA-based Metallicities

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malkan, Matthew A.; Rigby, Jane R.; Nagao, Tohru

    2016-09-01

    We present the first results from MMT and Keck spectroscopy for a large sample of 0.1≤slant z≤slant 1 emission-line galaxies selected from our narrowband imaging in the Subaru Deep Field. We measured the weak [O iii] λ4363 emission line for 164 galaxies (66 with at least 3σ detections, and 98 with significant upper limits). The strength of this line is set by the electron temperature for the ionized gas. Because the gas temperature is regulated by the metal content, the gas-phase oxygen abundance is inversely correlated with [O iii] λ4363 line strength. Our temperature-based metallicity study is the first to span ≈ 8 Gyr of cosmic time and ≈ 3 dex in stellar mass for low-mass galaxies, {log}({M}\\star /{M}ȯ )≈ 6.0–9.0. Using extensive multi-wavelength photometry, we measure the evolution of the stellar mass–gas metallicity relation and its dependence on dust-corrected star formation rate (SFR). The latter is obtained from high signal-to-noise Balmer emission-line measurements. Our mass–metallicity relation is consistent with Andrews & Martini at z≤slant 0.3, and evolves toward lower abundances at a given stellar mass, {log}{({{O/H}})\\propto (1+z)}-{2.32-0.26+0.52}. We find that galaxies with lower metallicities have higher SFRs at a given stellar mass and redshift, although the scatter is large (≈ 0.3 dex) and the trend is weaker than seen in local studies. We also compare our mass–metallicity relation against predictions from high-resolution galaxy formation simulations, and find good agreement with models that adopt energy- and momentum-driven stellar feedback. We identified 16 extremely metal-poor galaxies with abundances of less than a tenth of solar; our most metal-poor galaxy at z≈ 0.84 is similar to I Zw 18.

  2. The Metal Abundances across Cosmic Time (MACT) Survey. II. Evolution of the Mass-metallicity Relation over 8 Billion Years, Using [OIII]4363AA-based Metallicities

    NASA Astrophysics Data System (ADS)

    Ly, Chun; Malkan, Matthew A.; Rigby, Jane R.; Nagao, Tohru

    2016-09-01

    We present the first results from MMT and Keck spectroscopy for a large sample of 0.1≤slant z≤slant 1 emission-line galaxies selected from our narrowband imaging in the Subaru Deep Field. We measured the weak [O iii] λ4363 emission line for 164 galaxies (66 with at least 3σ detections, and 98 with significant upper limits). The strength of this line is set by the electron temperature for the ionized gas. Because the gas temperature is regulated by the metal content, the gas-phase oxygen abundance is inversely correlated with [O iii] λ4363 line strength. Our temperature-based metallicity study is the first to span ≈ 8 Gyr of cosmic time and ≈ 3 dex in stellar mass for low-mass galaxies, {log}({M}\\star /{M}⊙ )≈ 6.0-9.0. Using extensive multi-wavelength photometry, we measure the evolution of the stellar mass-gas metallicity relation and its dependence on dust-corrected star formation rate (SFR). The latter is obtained from high signal-to-noise Balmer emission-line measurements. Our mass-metallicity relation is consistent with Andrews & Martini at z≤slant 0.3, and evolves toward lower abundances at a given stellar mass, {log}{({{O/H}})\\propto (1+z)}-{2.32-0.26+0.52}. We find that galaxies with lower metallicities have higher SFRs at a given stellar mass and redshift, although the scatter is large (≈ 0.3 dex) and the trend is weaker than seen in local studies. We also compare our mass-metallicity relation against predictions from high-resolution galaxy formation simulations, and find good agreement with models that adopt energy- and momentum-driven stellar feedback. We identified 16 extremely metal-poor galaxies with abundances of less than a tenth of solar; our most metal-poor galaxy at z≈ 0.84 is similar to I Zw 18.

  3. Exploring Mg-Zn-Ca-Based Bulk Metallic Glasses for Biomedical Applications Based on Thermodynamic Approach

    NASA Astrophysics Data System (ADS)

    Ramya, M.; Sarwat, Syed Ghazi; Udhayabanu, V.; Raj, Baldev; Ravi, K. R.

    2015-12-01

    Magnesium (Mg)-based metallic glasses are considered as possible candidates in orthopedic implant applications. This paper aims to theoretically predict the glass-forming ability (GFA) in Mg-Zn-Ca alloy using a newly proposed thermodynamic model ( P HHS), and the consistency of this model is verified through experimental analysis. P HHS is based on thermodynamic parameters such as enthalpy of chemical mixing, elastic enthalpy, and configurational entropy, thus incorporating the pivotal effects, i.e., electron transfer effects, effect of atomic size mismatch, and effect of randomness, which aid to high GFA. In essence, P HHS can be visualized as the energy barrier that exists between the transformations of random atomic structure of glass to ordered crystalline structure. When the P HHS value is more negative, the energy barrier will be high, supporting easy glass formation. Various Mg-Zn-Ca metallic glass compositions displayed almost an expected and supporting trend, where the critical diameter of the metallic glass rod increased with a more negative P HHS value. Among the predicted Mg-Zn-Ca systems, the Mg60Zn35Ca5 composition shows deviation from the expected trend. This discrepancy has been clearly elucidated using a eutectic phase diagram. In addition to the consistency of the P HHS parameter to verifying the GFA of various compositions, the unique ability of this model is to predict unexplored Mg-Zn-Ca glass-forming compositions using contour development. Thus, proving P HHS parameter to be used as an efficient tool in predicting new glass-forming compositions.

  4. Creep deformation and rupture behavior of 2.25Cr-1Mo steel weldments and its constituents (base metal, weld metal and simulated heat affected zones)

    SciTech Connect

    Laha, K.; Chandravathi, K.S.; Rao, K.B.S.; Mannan, S.L.

    1995-12-31

    Microstructure across a weldment base metal through transformed heat-affected zone (HAZ) to cast weld metal. HAZ of 2.25Cr-1Mo weldment consists of coarse-grain bainite, fine-grain bainite and intercritical region. These HAZ microstructures were simulated by isothermal heat-treatments. Creep tests were carried out on base metal, weld metal, weldment and the simulated HAZ structures. Creep deformation and fracture behavior of 2.25Cr-1Mo weldments has been assessed based on the properties of its constituents. Coarse-grain bainite with low ductility and intercritical structure with low strength are the critical components of HAZ determining performance of the weldments.

  5. A Novel Methodology for Metal Ion Separation Based on Molecularly Imprinting

    SciTech Connect

    Zuo, Xiaobin; Mosha, Donnati; Hassan, Mansour M.; Givens, Richard S.; Busch, Daryle H.

    2004-03-31

    The siderophore-based extraction of iron from the soil by bacteria is proposed as a model for a new separation methodology labeled the soil poutice, a molecular device that would selectively retrieve the complex of a targeted metal ion. In this report we described the synthesis and characterization of molecularly imprinted polymers and their application in the specific recognition of macrocyclic metal complexes. The imprinting is based on non-covalent interactions such as hydrogen bonding, electrostatic attractions and minor metal-ligand coordination. Good rebinding capacity for the imprinting metal complex was observed in acetonitrile as well as in water. The polymers are resistant to strong acids and oxidizing agents and showed an increase of rebinding capacity during cycles of reuse. The imprinting procedure, combined with the previously known selective chelation of macrocyclic ligands, supports the feasibility of a new methodology that can be used to extract waste metal ions effectively and selectively from soils and ground water.

  6. A fluorometric paper-based sensor array for the discrimination of heavy-metal ions.

    PubMed

    Feng, Liang; Li, Hui; Niu, Li-Ya; Guan, Ying-Shi; Duan, Chun-Feng; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-04-15

    A fluorometric paper-based sensor array has been developed for the sensitive and convenient determination of seven heavy-metal ions at their wastewater discharge standard concentrations. Combining with nine cross-reactive BODIPY fluorescent indicators and array technologies-based pattern-recognition, we have obtained the discrimination capability of seven different heavy-metal ions at their wastewater discharge standard concentrations. After the immobilization of indicators and the enrichment of analytes, identification of the heavy-metal ions was readily acquired using a standard chemometric approach. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative estimation of the heavy-metal ion concentration was obtained by comparing color changes with a set of known concentrations. The sensor array was tentatively investigated in spiked tap water and sea water, and showed possible feasibility for real sample testing.

  7. A fluorometric paper-based sensor array for the discrimination of heavy-metal ions.

    PubMed

    Feng, Liang; Li, Hui; Niu, Li-Ya; Guan, Ying-Shi; Duan, Chun-Feng; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-04-15

    A fluorometric paper-based sensor array has been developed for the sensitive and convenient determination of seven heavy-metal ions at their wastewater discharge standard concentrations. Combining with nine cross-reactive BODIPY fluorescent indicators and array technologies-based pattern-recognition, we have obtained the discrimination capability of seven different heavy-metal ions at their wastewater discharge standard concentrations. After the immobilization of indicators and the enrichment of analytes, identification of the heavy-metal ions was readily acquired using a standard chemometric approach. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative estimation of the heavy-metal ion concentration was obtained by comparing color changes with a set of known concentrations. The sensor array was tentatively investigated in spiked tap water and sea water, and showed possible feasibility for real sample testing. PMID:23601876

  8. Reliability Modeling Development and Its Applications for Ceramic Capacitors with Base-Metal Electrodes (BMEs)

    NASA Technical Reports Server (NTRS)

    Liu, Donhang

    2014-01-01

    This presentation includes a summary of NEPP-funded deliverables for the Base-Metal Electrodes (BMEs) capacitor task, development of a general reliability model for BME capacitors, and a summary and future work.

  9. Transition-metal-free atropo-selective synthesis of biaryl compounds based on arynes.

    PubMed

    Leroux, Frédéric R; Berthelot, Anaïs; Bonnafoux, Laurence; Panossian, Armen; Colobert, Françoise

    2012-11-01

    A modular way towards biaryls: Highly enantioenriched biphenyls can be prepared based on a transition-metal-free aryl-aryl coupling followed by efficient desymmetrization or deracemization and chemoselective functionalization (see scheme).

  10. A Bioanalytical Chemistry Experiment for Undergraduate Students: Biosensors Based on Metal Nanoparticles

    ERIC Educational Resources Information Center

    Niagi, John; Warner, John; Andreesco, Silvana

    2007-01-01

    The study describes the development of new biosensors based on metal nanoparticles because of its high surface area and large binding ability. The adopted procedure is extremely simple and versatile and can be used in various applications of electrochemistry.

  11. First examples of hybrids based on polyoxometalates, metal halide clusters and organic ligands

    SciTech Connect

    Wang Lamei; Fan Yong; Wang Yan; Xiao Lina; Hu Yangyang; Peng Yu; Wang Tiegang; Gao Zhongmin; Zheng Dafang; Cui Xiaobing; Xu Jiqing

    2012-07-15

    Two new organic-inorganic compounds based on polyoxometalates, metal halide clusters and organic ligands: [BW{sub 12}O{sub 40}]{sub 2}[Cu{sub 2}(Phen){sub 4}Cl](H{sub 2}4, 4 Prime -bpy){sub 4}{center_dot}H{sub 3}O{center_dot}5H{sub 2}O (1) and [HPW{sub 12}O{sub 40}][Cd{sub 2}(Phen){sub 4}Cl{sub 2}](4, 4 Prime -bpy) (2) (Phen=1, 10-phenanthroline, bpy=bipyridine), have been prepared and characterized by IR, UV-vis, XPS, XRD and single crystal X-ray diffraction analyses. Crystal structure analyses reveal that compound 1 is constructed from [BW{sub 12}O{sub 40}]{sup 5-}, metal halide clusters [Cu{sub 2}(Phen){sub 4}Cl]{sup +}and 4, 4 Prime -bpy ligands, while compound 2 is constructed from [PW{sub 12}O{sub 40}]{sup 3-}, metal halide cluster [Cd{sub 2}(Phen){sub 4}Cl{sub 2}]{sup 2+} and 4, 4 Prime -bpy ligands. Compound 1 and compound 2 are not common hybrids based on polyoxometalates and metal halide clusters, they also contain dissociated organic ligands, therefore, compound 1 and 2 are the first examples of hybrids based on polyoxometalates, metal halide clusters and organic ligands. - Graphical Abstract: Two new compounds have been synthesized and characterized. Structure analyses revealed that the two compounds are the first examples of hybrids based on polyoxometalates, metal halide clusters and organic ligands. Highlights: Black-Right-Pointing-Pointer First examples of hybrids based on polyoxometalates, metal halide clusters and organic ligands. Black-Right-Pointing-Pointer Two different kinds of metal halide clusters. Black-Right-Pointing-Pointer Supramolecular structures based on polyoxometalates, metal halide clusters and organic ligands. Black-Right-Pointing-Pointer Hybridization of three different of building blocks.

  12. Permutation entropy based speckle analysis in metal cutting

    NASA Astrophysics Data System (ADS)

    Nair, Usha; Krishna, Bindu M.; Namboothiri, V. N. N.; Nampoori, V. P. N.

    2008-08-01

    Machine tool chatter is an unfavorable phenomenon during metal cutting, which results in heavy vibration of cutting tool. With increase in depth of cut the cutting regime changes from chatter- free cutting to one with chatter. In this paper, we propose the use of permutation entropy (PE), a conceptually simple and computationally fast measure to detect the onset of chatter from the time series generated using laser speckle pattern recorded using Charge Couple Device (CCD) camera. Laser speckle is an interference pattern produced by light reflected or scattered from different parts of the illuminated surface. It is the superposition of many wave fronts with random phases, scattered from different parts of the rough surface. If a speckle pattern is produced by coherent light incident on a rough surface, then surely the speckle pattern, or at least the statistics of the speckle pattern, must depend upon the detailed surface properties. Therefore we propose PE as an ideal measure, which can efficiently distinguish regular and complex nature of any signal, to extract information about the roughness of the reflecting surface. In the present study two work pieces, one taper cut and one step cut are machined to form cylindrical pieces, by continuously varying the depth of cut. As the depth of cut increases the surface finish is expected to deteriorate, mainly due to the onset of chatter vibrations. To analyze the surface texture characteristics, the speckle pattern is obtained by illuminating this curved surface using a collimated laser beam (5mW Diode Laser at 676nm wavelength.). The laser beam is made to incident obliquely to the curved surface of the work piece, and the speckle pattern is recorded using a CCD camera. The beam is scanned along the axis of the work-piece and the speckle pattern is recorded at different regions at constant intervals. A time series is generated from the speckle data and analyzed using PE. Permutation entropy is a complexity measure suitable

  13. Photocatalytic water reduction with copper-based photosensitizers: a noble-metal-free system.

    PubMed

    Luo, Shu-Ping; Mejía, Esteban; Friedrich, Aleksej; Pazidis, Alexandra; Junge, Henrik; Surkus, Annette-Enrica; Jackstell, Ralf; Denurra, Stefania; Gladiali, Serafino; Lochbrunner, Stefan; Beller, Matthias

    2013-01-01

    Of noble descent: a fully noble-metal-free system for the photocatalytic reduction of water at room temperature has been developed. This system consists of Cu(I) complexes as photosensitizers and [Fe(3)(CO)(12)] as the water-reduction catalyst. The novel Cu-based photosensitizers are relatively inexpensive, readily available from commercial sources, and stable to ambient conditions, thus making them an attractive alternative to the widely used noble-metal based systems. PMID:23047871

  14. Technological applications arising from the interactions of DNA bases with metal ions.

    PubMed

    Park, Ki Soo; Park, Hyun Gyu

    2014-08-01

    An intense interest has grown in the unique interactions of nucleic acids with metal ions, which lead to the formation of metal-base pairs and the generation of fluorescent nanomaterials. In this review, different types of metal-base pairs, especially those formed from naturally occurring nucleosides, are described with emphasis also being given to recent advances made in employing these complexes to govern enzymatic reactions. The review also contains a comprehensive description of DNA-templated inorganic nanomaterials such as silver nanoclusters which possess excellent fluorescence properties. Finally, a summary is given about how these materials have led to recent advances in the field of nanobiotechnology.

  15. Technological applications arising from the interactions of DNA bases with metal ions.

    PubMed

    Park, Ki Soo; Park, Hyun Gyu

    2014-08-01

    An intense interest has grown in the unique interactions of nucleic acids with metal ions, which lead to the formation of metal-base pairs and the generation of fluorescent nanomaterials. In this review, different types of metal-base pairs, especially those formed from naturally occurring nucleosides, are described with emphasis also being given to recent advances made in employing these complexes to govern enzymatic reactions. The review also contains a comprehensive description of DNA-templated inorganic nanomaterials such as silver nanoclusters which possess excellent fluorescence properties. Finally, a summary is given about how these materials have led to recent advances in the field of nanobiotechnology. PMID:24832070

  16. Metal patterning using maskless vacuum evaporation process based on selective deposition of photochromic diarylethene

    SciTech Connect

    Takagi, Rie; Masui, Kyoko; Tsujioka, Tsuyoshi; Nakamura, Shinichiro

    2008-11-24

    We developed an electrode/wiring patterning method that does not employ evaporation shadow masks; this method is based on selective metal deposition of photochromic diarylethene (DAE). In the selective Mg deposition based on the photoisomerization of DAE, Mg vapor atoms are deposited only on colored DAE film obtained upon UV irradiation, but not on uncolored film. We demonstrated fine metal Mg patterning with a minimum width of 3 {mu}m and the preparation of a patterned cathode. The selective metal deposition method has significant potential for preparing fine electrodes/wiring for various organic electronic devices.

  17. Atmospheric deposition of heavy metals in Wuxi, China: estimation based on native moss analysis.

    PubMed

    Yan, Yun; Zhang, Qiang; Wang, G Geoff; Fang, Yan-Ming

    2016-06-01

    We studied atmospheric deposition of heavy metals in Wuxi, China, using moss (Haplocladium microphyllum and H. angustifolium) as a biomonitoring agent. Moss samples were collected from 49 sites determined by a systematic sampling method. The top layer of soil on each site was also sampled. No significant correlation (P < 0.05) was observed between the moss and soil concentrations for any of the six heavy metal elements (Cd, Cr, Cu, Ni, Pb, and Zn), indicating that the soil substrate had little effect on the heavy metal concentrations in the moss materials. The metal enrichment capacity of the moss material, characterized by the concentration ratio between the moss and soil samples for each heavy metal, was topped by Cd and then followed by Zn, Pb, Cu, Cr, and Ni, respectively. Significant (P < 0.05) correlations were found among the six elements in mosses, suggesting potential anthropogenic inputs of these heavy metal pollutants. Based on concentrations of the heavy metals in mosses and the calculated contamination factors, we evaluated the contamination level of each heavy metal on the 49 sampling sites. Spatial distribution maps of heavy metal deposition for each element were interpolated using ArcGIS 9.0. A total pollution coefficient was calculated for each sampling site to identify the seriously polluted areas in the region.

  18. Atmospheric deposition of heavy metals in Wuxi, China: estimation based on native moss analysis.

    PubMed

    Yan, Yun; Zhang, Qiang; Wang, G Geoff; Fang, Yan-Ming

    2016-06-01

    We studied atmospheric deposition of heavy metals in Wuxi, China, using moss (Haplocladium microphyllum and H. angustifolium) as a biomonitoring agent. Moss samples were collected from 49 sites determined by a systematic sampling method. The top layer of soil on each site was also sampled. No significant correlation (P < 0.05) was observed between the moss and soil concentrations for any of the six heavy metal elements (Cd, Cr, Cu, Ni, Pb, and Zn), indicating that the soil substrate had little effect on the heavy metal concentrations in the moss materials. The metal enrichment capacity of the moss material, characterized by the concentration ratio between the moss and soil samples for each heavy metal, was topped by Cd and then followed by Zn, Pb, Cu, Cr, and Ni, respectively. Significant (P < 0.05) correlations were found among the six elements in mosses, suggesting potential anthropogenic inputs of these heavy metal pollutants. Based on concentrations of the heavy metals in mosses and the calculated contamination factors, we evaluated the contamination level of each heavy metal on the 49 sampling sites. Spatial distribution maps of heavy metal deposition for each element were interpolated using ArcGIS 9.0. A total pollution coefficient was calculated for each sampling site to identify the seriously polluted areas in the region. PMID:27207630

  19. Solution-based deposition of ultrathin metal oxide films on metal and superconductor surfaces

    NASA Astrophysics Data System (ADS)

    Westwood, Glenn

    Solution chemical methods were used to deposit ultrathin metal oxide films on metal and superconductor surfaces. Platinum-molybdenum oxide films were deposited by spontaneous adsorption and electrodeposition of hexamolybdoplatinate, PtMO6O248-. Spectroscopic characterization by 17O and 195Pt NMR showed that the PtMo6O248- anion is stable in aqueous solution below pH 4. The interaction of this solution stable anion with Au and Ag was characterized by in situ scanning tunneling microscopy, x-ray photoelectron spectroscopy, and cyclic voltammetry. The anion was partially reduced upon adsorption on Ag, but spontaneously adsorbed on Au to form an amorphous surface phase. The electrodeposition of hexamolybdoplatinate on Au electrodes resulted in an electrode surface that was different from the spontaneously adsorbed species, in terms of composition, voltammetry, and reactivity. Cyclic voltammetry was also used to compare the reactivity of these materials for the electrooxidation of methanol. Ultrathin zirconia films were deposited on YBa2Cu3O 7-delta by alternating exposures to tetra n-propyl zirconate, Zr4(OPrn)16, and H2O in n-propanol. Physical and chemical characterization of these films was done by x-ray photoelectron spectroscopy, atomic force microscopy, and cross-section transmission electron microscopy. The zirconia films were determined to be ultrathin (<10 nm) and highly conformal to the surface of YBa2Cu3O7-delta. Metal-insulator-superconductor tunnel junctions fabricated in this fashion were characterized by current-voltage and conductivity-voltage measurements. Solution deposition from Zr4(OPrn) 16 was also used to deposit ultrathin zirconia films on gold, silver, and aluminum surfaces. X-ray photoelectron spectroscopy and atomic force microscopy were used to compare the physical properties of these films. Electrical measurements showed that zirconia films on Ag and Au are not insulating, but aluminum-zirconia-aluminum capacitors fabricated by this method

  20. Comparison of metals extractability from Al/Fe-based drinking water treatment residuals.

    PubMed

    Wang, Changhui; Bai, Leilei; Pei, Yuansheng; Wendling, Laura A

    2014-12-01

    Recycling of drinking water treatment residuals (WTRs) as environment amendments has attracted substantial interest due to their productive reuse concomitant with waste minimization. In the present study, the extractability of metals within six Al/Fe-hydroxide-comprised WTRs collected throughout China was investigated using fractionation, in vitro digestion and the toxicity characteristic leaching procedure (TCLP). The results suggested that the major components and structure of the WTRs investigated were similar. The WTRs were enriched in Al, Fe, Ca, and Mg, also contained varying quantities of As, Ba, Be, Cd, Co, Cr, Cu, K, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn, but Ag, Hg, Sb, and Se were not detected. Most of the metals within the WTRs were largely non-extractable using the European Community Bureau of Reference (BCR) procedure, but many metals exhibited high bioaccessibility based on in vitro digestion. However, the WTRs could be classified as non-hazardous according to the TCLP assessment method used by the US Environmental Protection Agency (USEPA). Further analysis showed the communication factor, which is calculated as the ratio of total extractable metal by BCR procedure to the total metal, for most metals in the six WTRs, was similar, whereas the factor for Ba, Mn, Sr, and Zn varied substantially. Moreover, metals in the WTRs investigated had different risk assessment code. In summary, recycling of WTRs is subject to regulation based on assessment of risk due to metals prior to practical application.

  1. Comparison of metals extractability from Al/Fe-based drinking water treatment residuals.

    PubMed

    Wang, Changhui; Bai, Leilei; Pei, Yuansheng; Wendling, Laura A

    2014-12-01

    Recycling of drinking water treatment residuals (WTRs) as environment amendments has attracted substantial interest due to their productive reuse concomitant with waste minimization. In the present study, the extractability of metals within six Al/Fe-hydroxide-comprised WTRs collected throughout China was investigated using fractionation, in vitro digestion and the toxicity characteristic leaching procedure (TCLP). The results suggested that the major components and structure of the WTRs investigated were similar. The WTRs were enriched in Al, Fe, Ca, and Mg, also contained varying quantities of As, Ba, Be, Cd, Co, Cr, Cu, K, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn, but Ag, Hg, Sb, and Se were not detected. Most of the metals within the WTRs were largely non-extractable using the European Community Bureau of Reference (BCR) procedure, but many metals exhibited high bioaccessibility based on in vitro digestion. However, the WTRs could be classified as non-hazardous according to the TCLP assessment method used by the US Environmental Protection Agency (USEPA). Further analysis showed the communication factor, which is calculated as the ratio of total extractable metal by BCR procedure to the total metal, for most metals in the six WTRs, was similar, whereas the factor for Ba, Mn, Sr, and Zn varied substantially. Moreover, metals in the WTRs investigated had different risk assessment code. In summary, recycling of WTRs is subject to regulation based on assessment of risk due to metals prior to practical application. PMID:25023656

  2. High responsivity A-plane GaN-based metal-semiconductor-metal photodetectors for polarization-sensitive applications

    SciTech Connect

    Navarro, A.; Rivera, C.; Pereiro, J.; Munoz, E.; Imer, B.; DenBaars, S. P.; Speck, J. S.

    2009-05-25

    The fabrication and characterization of metal-semiconductor-metal polarization-sensitive photodetectors based on A-plane GaN grown on R-plane sapphire substrates is reported. These photodetectors take advantage of the in-plane crystal anisotropy, which results in linear dichroism near the band gap energy. The high resistivity of the A-plane GaN material leads to extremely low dark currents. For an optimized finger spacing of 1 {mu}m, dark current density and responsivity at 30 V are 0.3 nA/mm{sup 2} and 2 A/W, respectively. A maximum polarization sensitivity ratio of 1.8 was determined. In a differential configuration, the full width at half maximum of the polarization-sensitive region is 8.5 nm.

  3. Bivalent metal-based MIL-53 analogues: Synthesis, properties and application

    SciTech Connect

    Liu, Yongxin; Liu, Dan; Wang, Cheng

    2015-03-15

    Trivalent metal-based MIL-53 (Al{sup 3+}, Cr{sup 3+}, Fe{sup 3+}, In{sup 3+}) compounds are interesting metal–organic frameworks (MOFs) with breathing effect and are promising gas sorption materials. Replacing bridging μ{sub 2}-OH group by neutral ligands such as pyridine N-oxide and its derivatives (PNOs), the trivalent metal-based MIL-53 analogous structures could be extended to bivalent metal systems. The introduction of PNOs and bivalent metal elements endows the frameworks with new structural features and physical and chemical properties. This minireview summarizes the recent development of bivalent metal-based MIL-53 analogues (Mn{sup 2+}, Co{sup 2+}, Ni{sup 2+}), typically, focusing on the synthetic strategies and potential applications based on our own works and literatures. We present the synthetic strategy to achieve structures evolution from single-ligand-walled to double-ligand-walled channel. Properties and application of these new materials in a wide range of potential areas are discussed including thermal stability, gas adsorption, magnetism and liquid-phase separation. Promising directions of this research field are also highlighted. - Graphical abstract: The recent development of bivalent metal-based MIL-53 analogues (Mn{sup 2+}, Co{sup 2+}, Ni{sup 2+}) on their synthetic strategies, properties and potential applications was reviewed. - Highlights: • Structure features of bivalent metal-based MIL-53 analogues are illustrated. • Important properties and application are presented. • Host–guest interactions are main impetus for liquid-phase separation. • Promising directions of bivalent metal-based MIL-53 analogues are highlighted.

  4. Operational strategy for metal bioleaching based on pH measurements

    SciTech Connect

    Du, Y.G.; Tyagi, R.D.; Sreekrishnan, T.R.

    1995-07-01

    An advanced operational strategy was developed in this study for a batch microbial leaching process, employing sulfur oxidation for heavy metal removal from sewage sludge, to terminate the batch operation at its best moment. Due to the practical difficulties associated with on-line measurement of soluble metal concentrations during the leaching operation, the present methodology is based on pH measurements in the reacting system. To monitor the metal solubilization, the bioleaching process model was developed, corresponding with the activity of the less-acidophilic bacteria and the acidophilic bacteria. An advanced online predicting system was then implemented; it employed the techniques of extended Kalman filtering and the neural net-based model that was based on a large amount of experimental observations in the laboratory to predict concentrations of six heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in the bioleaching system`s liquid phase. Finally, a case study illustrating the application is presented.

  5. Ni-based Metal Matrix Composite Functionally Graded Coatings

    NASA Astrophysics Data System (ADS)

    Amado, J. M.; Montero, J.; Tobar, M. J.; Yáñez, A.

    Functional graded materials (FGMs) are a class of composites that have a continuous variation of material properties. One of the aims of such variation is to relieve the stress concentrations that appear in laminated materials. Coating techniques using powder as filler material can be adapted for the manufacture of composition gradients by means of a mixing unit in a powder feed system which is the basis of the laser cladding technology. The aim of this paper is to get coats with layers of the highest possible ceramic concentration on a metal matrix composite (MMC) with the help of the FGM methodology.

  6. Effect of metal base layer on the absorptance and emittance of sputtered graded metal-carbon selective absorbing surfaces

    NASA Astrophysics Data System (ADS)

    Harding, G. L.; Craig, S.

    1981-08-01

    Solar absorptance and temperature-dependent emittance is measured for graded metal-carbon films deposited onto smooth aluminum, copper, nickel, and stainless steel base layers, sputter-deposited onto glass tubes at relatively low argon pressure (approximately 0.5 Pa), and deposited onto textured copper using argon pressures 3 to 40 Pa. Absorptance measurements are made on surfaces deposited onto small plane glass slides attached to a glass tube in the coating system, and emittance measurements are made on coated tubes, assembled into glass envelopes. Both the small planar specimens of selective surface and coated tubes were inserted in continuously evacuated glass envelopes and annealed at 500 C for approximately 1 hr. It is shown that solar absorptance varies by only 1-2% for the different base layers, whereas the emittance of surfaces based on nickel and stainless steel is considerably higher than for surfaces based on copper and aluminum. Small changes occur in absorptances and emittances after annealing. It is concluded that the optimum selective surface for evacuated collectors used with mirrors of low concentrations consists of graded metal-carbon overlaid with smooth copper.

  7. Photodynamic Therapy and the Development of Metal-Based Photosensitisers

    PubMed Central

    Josefsen, Leanne B.; Boyle, Ross W.

    2008-01-01

    Photodynamic therapy (PDT) is a treatment modality that has been used in the successful treatment of a number of diseases and disorders, including age-related macular degeneration (AMD), psoriasis, and certain cancers. PDT uses a combination of a selectively localised light-sensitive drug (known as a photosensitiser) and light of an appropriate wavelength. The light-activated form of the drug reacts with molecular oxygen to produce reactive oxygen species (ROS) and radicals; in a biological environment these toxic species can interact with cellular constituents causing biochemical disruption to the cell. If the homeostasis of the cell is altered significantly then the cell enters the process of cell death. The first photosensitiser to gain regulatory approval for clinical PDT was Photofrin. Unfortunately, Photofrin has a number of associated disadvantages, particularly pro-longed patient photosensitivity. To try and overcome these disadvantages second and third generation photosensitisers have been developed and investigated. This Review highlights the key photosensitisers investigated, with particular attention paid to the metallated and non-metallated cyclic tetrapyrrolic derivatives that have been studied in vitro and in vivo; those which have entered clinical trials; and those that are currently in use in the clinic for PDT. PMID:18815617

  8. Adaptive Engineering of Phytochelatin-based Heavy Metal Tolerance*

    PubMed Central

    Cahoon, Rebecca E.; Lutke, W. Kevin; Cameron, Jeffrey C.; Chen, Sixue; Lee, Soon Goo; Rivard, Rebecca S.; Rea, Philip A.; Jez, Joseph M.

    2015-01-01

    Metabolic engineering approaches are increasingly employed for environmental applications. Because phytochelatins (PC) protect plants from heavy metal toxicity, strategies directed at manipulating the biosynthesis of these peptides hold promise for the remediation of soils and groundwaters contaminated with heavy metals. Directed evolution of Arabidopsis thaliana phytochelatin synthase (AtPCS1) yields mutants that confer levels of cadmium tolerance and accumulation greater than expression of the wild-type enzyme in Saccharomyces cerevisiae, Arabidopsis, or Brassica juncea. Surprisingly, the AtPCS1 mutants that enhance cadmium tolerance and accumulation are catalytically less efficient than wild-type enzyme. Metabolite analyses indicate that transformation with AtPCS1, but not with the mutant variants, decreases the levels of the PC precursors, glutathione and γ-glutamylcysteine, upon exposure to cadmium. Selection of AtPCS1 variants with diminished catalytic activity alleviates depletion of these metabolites, which maintains redox homeostasis while supporting PC synthesis during cadmium exposure. These results emphasize the importance of metabolic context for pathway engineering and broaden the range of tools available for environmental remediation. PMID:26018077

  9. Adaptive Engineering of Phytochelatin-based Heavy Metal Tolerance.

    PubMed

    Cahoon, Rebecca E; Lutke, W Kevin; Cameron, Jeffrey C; Chen, Sixue; Lee, Soon Goo; Rivard, Rebecca S; Rea, Philip A; Jez, Joseph M

    2015-07-10

    Metabolic engineering approaches are increasingly employed for environmental applications. Because phytochelatins (PC) protect plants from heavy metal toxicity, strategies directed at manipulating the biosynthesis of these peptides hold promise for the remediation of soils and groundwaters contaminated with heavy metals. Directed evolution of Arabidopsis thaliana phytochelatin synthase (AtPCS1) yields mutants that confer levels of cadmium tolerance and accumulation greater than expression of the wild-type enzyme in Saccharomyces cerevisiae, Arabidopsis, or Brassica juncea. Surprisingly, the AtPCS1 mutants that enhance cadmium tolerance and accumulation are catalytically less efficient than wild-type enzyme. Metabolite analyses indicate that transformation with AtPCS1, but not with the mutant variants, decreases the levels of the PC precursors, glutathione and γ-glutamylcysteine, upon exposure to cadmium. Selection of AtPCS1 variants with diminished catalytic activity alleviates depletion of these metabolites, which maintains redox homeostasis while supporting PC synthesis during cadmium exposure. These results emphasize the importance of metabolic context for pathway engineering and broaden the range of tools available for environmental remediation. PMID:26018077

  10. Adaptive Engineering of Phytochelatin-based Heavy Metal Tolerance.

    PubMed

    Cahoon, Rebecca E; Lutke, W Kevin; Cameron, Jeffrey C; Chen, Sixue; Lee, Soon Goo; Rivard, Rebecca S; Rea, Philip A; Jez, Joseph M

    2015-07-10

    Metabolic engineering approaches are increasingly employed for environmental applications. Because phytochelatins (PC) protect plants from heavy metal toxicity, strategies directed at manipulating the biosynthesis of these peptides hold promise for the remediation of soils and groundwaters contaminated with heavy metals. Directed evolution of Arabidopsis thaliana phytochelatin synthase (AtPCS1) yields mutants that confer levels of cadmium tolerance and accumulation greater than expression of the wild-type enzyme in Saccharomyces cerevisiae, Arabidopsis, or Brassica juncea. Surprisingly, the AtPCS1 mutants that enhance cadmium tolerance and accumulation are catalytically less efficient than wild-type enzyme. Metabolite analyses indicate that transformation with AtPCS1, but not with the mutant variants, decreases the levels of the PC precursors, glutathione and γ-glutamylcysteine, upon exposure to cadmium. Selection of AtPCS1 variants with diminished catalytic activity alleviates depletion of these metabolites, which maintains redox homeostasis while supporting PC synthesis during cadmium exposure. These results emphasize the importance of metabolic context for pathway engineering and broaden the range of tools available for environmental remediation.

  11. Metal amides as the simplest acid/base catalysts for stereoselective carbon-carbon bond-forming reactions.

    PubMed

    Yamashita, Yasuhiro; Kobayashi, Shū

    2013-07-15

    In this paper, new possibilities for metal amides are described. Although typical metal amides are recognized as strong stoichiometric bases for deprotonation of inert or less acidic hydrogen atoms, transition-metal amides, namely silver and copper amides, show interesting abilities as one of the simplest acid/base catalysts in stereoselective carbon-carbon bond-forming reactions.

  12. Design and fabrication of a high-density multilayer metal-insulator-metal capacitor based on selective etching

    SciTech Connect

    Tseng, VFG; Xie, H

    2013-02-06

    This paper presents a novel and cost-effective method for fabricating high-density multilayer metal-insulator-metal (MIM) integrated capacitors. To eliminate the usage of numerous photolithography steps when parallel stacking multiple capacitors layers, a unique process has been developed based on depositing the MIM layers onto a substrate with two protruding pillars, polishing down the pillars to expose the multilayer cross sections and then selectively etching the metal layers on each pillar to form the alternating capacitor plate electrodes. For demonstration purpose, only capacitors with two dielectric layers were fabricated, and the measurement results were verified by a compact analytical model together with finite element simulations. With 200 nm thick silicon nitride/oxide dielectric layers, a capacitance density of 0.6 fF mu m(-2) was achieved, which can be easily increased by scaling down the layer thicknesses and/or stacking more layers. A low equivalent series resistance (ESR) of 300-700 m Omega was measured, and the self-resonance frequency was above measurement limits (> 100 MHz). Further design optimization shows that the ESR can be reduced to below 80 m Omega, while the operation frequency extended to above 2.6 GHz.

  13. A dislocation-based, strain–gradient–plasticity strengthening model for deformation processed metal-metal composites

    SciTech Connect

    Tian, Liang; Russell, Alan; Anderson, Iver

    2014-01-03

    Deformation processed metal–metal composites (DMMCs) are high-strength, high-electrical conductivity composites developed by severe plastic deformation of two ductile metal phases. The extraordinarily high strength of DMMCs is underestimated using the rule of mixture (or volumetric weighted average) of conventionally work-hardened metals. In this article, a dislocation-density-based, strain–gradient–plasticity model is proposed to relate the strain-gradient effect with the geometrically necessary dislocations emanating from the interface to better predict the strength of DMMCs. The model prediction was compared with the experimental findings of Cu–Nb, Cu–Ta, and Al–Ti DMMC systems to verify the applicability of the new model. The results show that this model predicts the strength of DMMCs better than the rule-of-mixture model. The strain-gradient effect, responsible for the exceptionally high strength of heavily cold worked DMMCs, is dominant at large deformation strain since its characteristic microstructure length is comparable with the intrinsic material length.

  14. Mobilization and attenuation of metals downstream from a base-metal mining site in the Matra Mountains, northeastern Hungary

    USGS Publications Warehouse

    Odor, L.; Wanty, R.B.; Horvath, I.; Fugedi, U.; ,

    1999-01-01

    Regional geochemical baseline values have been established for Hungary by the use of low-density stream-sediment surveys of flood-plain deposits of large drainage basins and of the fine fraction of stream sediments. The baseline values and anomaly thresholds thus produced helped to evaluate the importance of high toxic element concentrations found in soils in a valley downstream of a polymetallic vein-type base-metal mine. Erosion of the mine dumps and flotation dump, losses of metals during filtering, storage and transportation, human neglects, and operational breakdowns, have all contributed to the contamination of a small catchment basin in a procession of releases of solid waste. The sulfide-rich waste material weathers to a yellow color; this layer of 'yellow sand' blankets a narrow strip of the floodplain of Toka Creek in the valley near the town of Gyongyosoroszi. Contamination was spread out in the valley by floods. Metals present in the yellow sand include Pb, As, Cd, Cu, Zn, and Sb. Exposure of the local population to these metals may occur through inhalation of airborne particulates or by ingestion of these metals that are taken up by crops grown in the valley. To evaluate the areal extent and depth of the contamination, active stream sediment, flood-plain deposits, lake or reservoir sediments, soils, and surface water were sampled along the erosion pathways downstream of the mine and dumps. The flood-plain profile was sampled in detail to see the vertical distribution of elements and to relate the metal concentrations to the sedimentation and contamination histories of the flood plain. Downward migration of mobile Zn and Cd from the contaminated upper layers under supergene conditions is observed, while vertical migration of Pb, As, Hg and Sb appears to be insignificant. Soil profiles of 137Cs which originated from above-ground atomic bomb tests and the Chernobyl accident, provide good evidence that the upper 30-40 cm of the flood-plain sections, which

  15. β-Galactosidase-based colorimetric paper sensor for determination of heavy metals.

    PubMed

    Hossain, S M Zakir; Brennan, John D

    2011-11-15

    We demonstrate a novel approach for rapid, selective, and sensitive detection of heavy metals using a solid-phase bioactive lab-on-paper sensor that is inkjet printed with sol-gel entrapped reagents to allow colorimetric visualization of the enzymatic activity of β-galactosidase (B-GAL). The bioactive paper assay is able to detect a range of heavy metals, either alone or as mixtures, in as little as 10 min, with detection limits as follows: Hg(II) = 0.001 ppm; Ag(I) = 0.002 ppm, Cu(II) = 0.020 ppm; Cd(II) = 0.020 ppm; Pb(II) = 0.140 ppm; Cr(VI) = 0.150 ppm; Ni(II) = 0.230 ppm. The paper-based assay was immune to interferences from nontoxic metal ions such as Na(+) or K(+), could be used to detect heavy metals that were spiked into tap water or lake water, and provided quantitative data that was in agreement with values obtained by atomic absorption. With the incorporation of standard chromogenic metal sensing reagents into a multiplexed bioactive paper sensor, it was possible to identify specific metals in mixtures, albeit with much lower detection limits than were obtained with the enzymatic assay. The paper-based sensor should be valuable for rapid, on-site screening of trace levels of heavy metals in resource limited areas and developing countries.

  16. Fe-based bulk metallic glasses used for magnetic shielding

    NASA Astrophysics Data System (ADS)

    Şerban, Va; Codrean, C.; Uţu, D.; Ercuţa, A.

    2009-01-01

    The casting in complex shapes (tubullar) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small adittion of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  17. Focus tunable device actuator based on ionic polymer metal composite

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Wei; Su, Guo-Dung J.

    2015-09-01

    IPMC (Ionic Polymer Metallic Composite) is a kind of electroactive polymer (EAP) which is used as an actuator because of its low driving voltage and small size. The mechanism of IPMC actuator is due to the ionic diffusion when the voltage gradient is applied. In this paper, the complex IPMC fabrication such as Ag-IPMC be further developed in this paper. The comparison of response time and tip bending displacement of Pt-IPMC and Ag-IPMC will also be presented. We also use the optimized IPMC as the lens actuator integrated with curvilinear microlens array, and use the 3D printer to make a simple module and spring stable system. We also used modeling software, ANSYS Workbench, to confirm the effect of spring system. Finally, we successfully drive the lens system in 200μm stroke under 2.5V driving voltage within 1 seconds, and the resonant frequency is approximately 500 Hz.

  18. Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source

    SciTech Connect

    Thorn, A.; Ritter, E.; Zschornack, G.; Ullmann, F.; Pilz, W.; Bischoff, L.

    2012-02-15

    We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au{sup 60+}. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

  19. Influence of S. mutans on base-metal dental casting alloy toxicity.

    PubMed

    McGinley, E L; Dowling, A H; Moran, G P; Fleming, G J P

    2013-01-01

    We have highlighted that exposure of base-metal dental casting alloys to the acidogenic bacterium Streptococcus mutans significantly increases cellular toxicity following exposure to immortalized human TR146 oral keratinocytes. With Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), S. mutans-treated nickel-based (Ni-based) and cobalt-chromium-based (Co-Cr-based) dental casting alloys were shown to leach elevated levels of metal ions compared with untreated dental casting alloys. We targeted several biological parameters: cell morphology, viable cell counts, cell metabolic activity, cell toxicity, and inflammatory cytokine expression. S. mutans-treated dental casting alloys disrupted cell morphology, elicited significantly decreased viable cell counts (p < 0.0001) and cell metabolic activity (p < 0.0001), and significantly increased cell toxicity (p < 0.0001) and inflammatory cytokine expression (p < 0.0001). S. mutans-treated Ni-based dental casting alloys induced elevated levels of cellular toxicity compared with S. mutans-treated Co-Cr-based dental casting alloys. While our findings indicated that the exacerbated release of metal ions from S. mutans-treated base-metal dental casting alloys was the likely result of the pH reduction during S. mutans growth, the exact nature of mechanisms leading to accelerated dissolution of alloy-discs is not yet fully understood. Given the predominance of S. mutans oral carriage and the exacerbated cytotoxicity observed in TR146 cells following exposure to S. mutans-treated base-metal dental casting alloys, the implications for the long-term stability of base-metal dental restorations in the oral cavity are a cause for concern.

  20. A new metal detection method based on balanced coil for mobile phone wireless charging system

    NASA Astrophysics Data System (ADS)

    Zhou, B.; Liu, Z. Z.; Chen, H. X.; Zeng, H.; Hei, T.

    2016-08-01

    The wireless charging time of mobile phone will increase greatly if the metal objects mix in the magnetic field coupling area. In addition, the fire may be caused as for the high temperature of metal objects. The paper proposed an improved detecting method based on balance coil for mobile phone wireless charging system according to comparing the advantages and disadvantages of traditional metal detection methods. The circuit model was established, and hardware and software were optimized. At last, experimental results verified the theoretical analysis.

  1. All-metal structural color printing based on aluminum plasmonic metasurfaces.

    PubMed

    Li, Zhigang; Wang, Wei; Rosenmann, Daniel; Czaplewski, David A; Yang, Xiaodong; Gao, Jie

    2016-09-01

    An all-metal structural color printing platform based on aluminum plasmonic metasurfaces is proposed and demonstrated with high color performance using only a one-step etching process on aluminum surface. A wide visible color range is realized with the designed metallic square-shaped disk arrays by simply adjusting the geometrical parameters of the disk etching depth, disk width and unit cell period. The demonstrated all-metal microscale structural color printing on aluminum surface offers great potential for many practical color related applications. PMID:27607652

  2. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

    NASA Astrophysics Data System (ADS)

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-02-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  3. LaNi{sub 5}-based metal hydride electrode in Ni-MH rechargeable cells

    DOEpatents

    Bugga, R.V.; Fultz, B.; Bowman, R.; Surampudi, S.R.; Witham, C.K.; Hightower, A.

    1999-03-30

    An at least ternary metal alloy of the formula AB{sub (Z-Y)}X{sub (Y)} is disclosed. In this formula, A is selected from the rare earth elements, B is selected from the elements of Groups 8, 9, and 10 of the Periodic Table of the Elements, and X includes at least one of the following: antimony, arsenic, germanium, tin or bismuth. Z is greater than or equal to 4.8 and less than or equal to 6.0. Y is greater than 0 and less than 1. Ternary or higher-order substitutions to the base AB{sub 5} alloys that form strong kinetic interactions with the predominant metals in the base metal hydride are used to form metal alloys with high structural integrity after multiple cycles of hydrogen sorption. 16 figs.

  4. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

    PubMed

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-01-01

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  5. Highly selectively monitoring heavy and transition metal ions by a fluorescent sensor based on dipeptide.

    PubMed

    Neupane, Lok Nath; Thirupathi, Ponnaboina; Jang, Sujung; Jang, Min Jung; Kim, Jung Hwa; Lee, Keun-Hyeung

    2011-09-15

    Fluorescent sensor (DMH) based on dipeptide was efficiently synthesized in solid phase synthesis. The dipeptide sensor shows sensitive response to Ag(I), Hg(II), and Cu(II) among 14 metal ions in 100% aqueous solution. The fluorescent sensor differentiates three heavy metal ions by response type; turn on response to Ag(I), ratiometric response to Hg(II), and turn off detection of Cu(II). The detection limits of the sensor for Ag(I) and Cu(II) were much lower than the EPA's drinking water maximum contaminant levels (MCL). Specially, DMH penetrated live cells and detected intracellular Ag(+) by turn on response. We described the fluorescent change, binding affinity, detection limit for the metal ions. The study of a heavy metal-responsive sensor based on dipeptide demonstrates its potential utility in the environment field.

  6. Metal substrate based electrodes for flexible dye-sensitized solar cells: fabrication methods, progress and challenges.

    PubMed

    Balasingam, Suresh Kannan; Kang, Man Gu; Jun, Yongseok

    2013-12-21

    A step towards commercialization of dye-sensitized solar cells (DSSCs) requires more attention to engineering aspects, such as flexibility, the roll to roll fabrication process, the use of cost effective materials, etc. In this aspect, advantages of flexible DSSCs attracted many researchers to contemplate the transparent conducting oxide coated flexible plastic substrates and the thin metallic foils. In this feature article, the pros and cons of these two kinds of substrates are compared. The flexible dye-sensitized solar cells fabricated using metal substrates are briefly discussed. The working electrodes of DSSCs fabricated on various metal substrates, their fabrication methods, the effect of high temperature calcination and drawbacks of back illumination are reviewed in detail. A few reports on the flexible metal substrate based counter electrodes that could be combined with the plastic substrate based working electrodes are also covered at the end. PMID:24196211

  7. Thermal conductivity studies of metal dispersed multiwalled carbon nanotubes in water and ethylene glycol based nanofluids

    SciTech Connect

    Jha, Neetu; Ramaprabhu, S.

    2009-10-15

    High thermal conducting metal nanoparticles have been dispersed on the multiwalled carbon nanotubes (MWNTs) outer surface. Structural and morphological characterizations of metal dispersed MWNTs have been carried out using x-ray diffraction analysis, high resolution transmission electron microscopy, energy dispersive x-ray analysis, and Fourier transform infrared spectroscopy. Nanofluids have been synthesized using metal-MWNTs in de-ionized water (DI water) and ethylene glycol (EG) base fluids. It has been observed that nanofluids maintain the same sequence of thermal conductivity as that of metal nanoparticles Ag-MWNTs>Au-MWNTs>Pd-MWNTs. A maximum enhancement of 37.3% and 11.3% in thermal conductivity has been obtained in Ag-MWNTs nanofluid with DI water and EG as base fluids, respectively, at a volume fraction of 0.03%. Temperature dependence study also shows enhancement of thermal conductivity with temperature.

  8. Mechanical Properties and Microstructure of Plasma Sprayed Ni-Based Metallic Glass Coating

    NASA Astrophysics Data System (ADS)

    Kobayashi, Akira; Kuroda, Toshio; Kimura, Hisamichi; Inoue, Akihisa

    2010-10-01

    Various developmental research works on the metallic glass have been conducted in order to broaden its application field. Thermal spraying method is one of the potential techniques to enhance the excellent properties such as high toughness and corrosion resistance of the metallic glass material. The gas tunnel type plasma spraying is useful to obtain high quality ceramic coatings such as Al2O3 and ZrO2 coatings. In this study, the Ni-based metallic glass coatings were produced by the gas tunnel type plasma spraying under various experimental conditions, and their microstructure and mechanical properties were investigated. At the plasma current of 200-300 A, the Ni-based metallic glass coatings of more than 200 μm in thickness were formed densely with Vickers hardness of about Hv = 600.

  9. A Comprehensive Review of Glucose Biosensors Based on Nanostructured Metal-Oxides

    PubMed Central

    Rahman, Md. Mahbubur; Saleh Ahammad, A. J.; Jin, Joon-Hyung; Ahn, Sang Jung; Lee, Jae-Joon

    2010-01-01

    Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation. This article concentrates mainly on the development of different nanostructured metal-oxide [such as ZnO, Cu(I)/(II) oxides, MnO2, TiO2, CeO2, SiO2, ZrO2, and other metal-oxides] based glucose biosensors. Additionally, we devote our attention to the operating principles (i.e., potentiometric, amperometric, impedimetric and conductometric) of these nanostructured metal-oxide based glucose sensors. Finally, this review concludes with a personal prospective and some challenges of these nanoscaled sensors. PMID:22399911

  10. Electro-active Polymer Actuator Based on Sulfonated Polyimide with Highly Conductive Silver Electrodes Via Self-metallization.

    PubMed

    Song, Jiangxuan; Jeon, Jin-Han; Oh, Il-Kwon; Park, K C

    2011-10-01

    We report here a facile synthesis of high performance electro-active polymer actuator based on a sulfonated polyimide with well-defined silver electrodes via self-metallization. The proposed method greatly reduces fabrication time and cost, and obviates a cation exchange process required in the fabrication of ionic polymer-metal composite actuators. Also, the self-metallized silver electrodes exhibit outstanding metal-polymer adhesion with high conductivity, resulting in substantially larger tip displacements compared with Nafion-based actuators.

  11. Selective cancer-killing ability of metal-based nanoparticles: implications for cancer therapy.

    PubMed

    Akhtar, Mohd Javed; Alhadlaq, Hisham A; Kumar, Sudhir; Alrokayan, Salman A; Ahamed, Maqusood

    2015-11-01

    There has been little focus on the promising ability of metal-based nanoparticles (NPs) to kill cancer cells while sparing normal cells. Many in vitro and in vivo reports suggest that certain metal-based NPs are able to induce apoptosis and autophagy in cancer cells at specific concentrations that are not significantly toxic to non-cancerous cells. Those NPs are thought to exploit the oxidative stress conditions that prevail in cancer cells, which are largely exhausted of antioxidant ability. This review considers the induction of reactive oxygen species (ROS) by metal-based NPs as a mechanism for the specific killing of cancer cells. The article concomitantly provides a comprehensive description of the important pathways and molecules leading to programmed cell death (PCD), which occurs mainly via apoptosis, autophagy, and necroptosis. The PCD pathways are followed as ROS-burdened cancer cells succumb to ROS-generating metal-based NPs. Exploration of nanotechnology interventions in anticancer therapy demands further research into the mechanism of intracellular induction of ROS by metal-based NPs. Furthermore, the induction of ROS by NPs should be strictly controlled if ROS-based therapy is to become a paradigm in cancer therapy.

  12. Fixed-base recycling of contaminated metals in the commercial market

    SciTech Connect

    Loiselle, V. )

    1993-01-01

    Since the establishment of the first fixed-base commercial decontamination facility in 1982, commercial processors have cleaned and recycled more than 120 million lb of metals for productive reuse. This represents enough metal to duplicate the Eiffel Tower eight times. This paper examines the economic conditions that led to the foundation of this industry and the types of decontamination technology that have been successfully employed by the processors.

  13. Shape assisted fabrication of fluorescent cages of squarate based metal-organic coordination frameworks.

    PubMed

    Jayaramulu, Kolleboyina; Krishna, Katla Sai; George, Subi J; Eswaramoorthy, Muthuswamy; Maji, Tapas Kumar

    2013-05-11

    Micronic cage structures of squarate based metal-organic coordination frameworks (MOCFs) have been fabricated for the first time by specific anion selective etching of metal squarate cubes. Time and stoichiometry dependent synthesis and the corresponding microscopic studies have provided mechanistic insight into the cage formation. Furthermore, a non-covalent post-synthetic strategy has been adopted to functionalize the micronic cubes or cages with chromophores rendering the resulting hybrids green fluorescent.

  14. FINDSITE-metal: Integrating evolutionary information and machine learning for structure-based metal binding site prediction at the proteome level

    PubMed Central

    Brylinski, Michal; Skolnick, Jeffrey

    2010-01-01

    The rapid accumulation of gene sequences, many of which are hypothetical proteins with unknown function, has stimulated the development of accurate computational tools for protein function prediction with evolution/structure-based approaches showing considerable promise. In this paper, we present FINDSITE-metal, a new threading-based method designed specifically to detect metal binding sites in modeled protein structures. Comprehensive benchmarks using different quality protein structures show that weakly homologous protein models provide sufficient structural information for quite accurate annotation by FINDSITE-metal. Combining structure/evolutionary information with machine learning results in highly accurate metal binding annotations; for protein models constructed by TASSER, whose average Cα RMSD from the native structure is 8.9 Å, 59.5% (71.9%) of the best of top five predicted metal locations are within 4 Å (8 Å) from a bound metal in the crystal structure. For most of the targets, multiple metal binding sites are detected with the best predicted binding site at rank 1 and within the top 2 ranks in 65.6% and 83.1% of the cases, respectively. Furthermore, for iron, copper, zinc, calcium and magnesium ions, the binding metal can be predicted with high, typically 70-90%, accuracy. FINDSITE-metal also provides a set of confidence indexes that help assess the reliability of predictions. Finally, we describe the proteome-wide application of FINDSITE-metal that quantifies the metal binding complement of the human proteome. FINDSITE-metal is freely available to the academic community at http://cssb.biology.gatech.edu/findsite-metal/. PMID:21287609

  15. PROCESS OF COATING METALS WITH BISMUTH OR BISMUTH-BASE ALLOYS

    DOEpatents

    Beach, J.G.

    1958-01-28

    A method is described for producing coatings of bismuth or bismuth alloys on a metal base. This is accomplished by electrodepositing the bismuth from an aqueous solution of BiCl/sub 3/, and by making the metal base alternately the cathode and the anode, the cathode periods being twice as long as the anode periods. In one embodiment a nickel coating is first electrodeposited in a known way, and this nickel plated piece is tae base upon which tae bismuth is deposited by the process of this patent. The coated piece is then heat treated to produce a homogeneous Ni--Bi alloy by diffusion.

  16. Novel Metal Ion Based Estrogen Mimics for Molecular Imaging

    SciTech Connect

    Rajagopalan, Raghavan

    2006-01-30

    The overall objective of the SBIR Phase I proposal is to prepare and evaluate a new class of {sup 99m}Tc or {sup 94m}Tc containing estrogen-like small molecules ('estrogen mimics') for SPECT or PET molecular imaging of estrogen receptor positive (ER+) tumors. In this approach, the metal ion is integrated into the estrone skeleton by isosteric substitution of a carbon atom in the steroidal structure to give new class of mimics that are topologically similar to the native estrogen (Fig. 1). Although both N{sub 2}S{sub 2} and N{sub 3}S mimics 1 and 2 were considered as target structures, molecular modeling study revealed that the presence of the acetyl group at position-15 in the N{sub 3}S mimic 2 causes steric hinderance toward binding of 2 to SHBG. Therefore, initial efforts were directed at the synthesis and evaluation of the N{sub 2}S{sub 2} mimic 1.

  17. Metallic photonic crystals based on solution-processible gold nanoparticles.

    PubMed

    Zhang, Xinping; Sun, Baoquan; Friend, Richard H; Guo, Hongcang; Nau, Dietmar; Giessen, Harald

    2006-04-01

    We demonstrate the fabrication of metallic photonic crystals, in the form of a periodic array of gold nanowires on a waveguide, by spin-coating a colloidal gold suspension onto a photoresist mask and subsequent annealing. The photoresist mask with a period below 500 nm is manufactured by interference lithography on an indium tin oxide (ITO) glass substrate, where the ITO layer has a thickness around 210 nm and acts as the waveguide. The width of the nanowires can be controlled from 100 to 300 nm by changing the duty cycle of the mask. During evaporation of solvent, the gold nanoparticles are drawn to the grooves of the grating with apparently complete dewetting off the photoresist for channels less than 2 microm in width, which therefore form nanowires after the annealing process. Strong coupling between the waveguide mode and the plasmon resonance of the nanowires, which is dependent on the polarization and incidence angle of the light wave, is demonstrated by optical extinction measurements. Continuity of the nanowires is confirmed by conductivity properties. Simplicity, high processing speed, and low cost are the main advantages of this method, which may have a plethora of applications in telecommunication, all-optical switching, sensors, and semiconductor devices.

  18. Strain Engineering for Transition Metal Dichalcogenides Based Field Effect Transistors.

    PubMed

    Shen, Tingting; Penumatcha, Ashish V; Appenzeller, Joerg

    2016-04-26

    Using electrical characteristics from three-terminal field-effect transistors (FETs), we demonstrate substantial strain induced band gap tunability in transition metal dichalcogenides (TMDs) in line with theoretical predictions and optical experiments. Devices were fabricated on flexible substrates, and a cantilever sample holder was used to apply uniaxial tensile strain to the various multilayer TMD FETs. Analyzing in particular transfer characteristics, we argue that the modified device characteristics under strain are clear evidence of a band gap reduction of 100 meV in WSe2 under 1.35% uniaxial tensile strain at room temperature. Furthermore, the obtained device characteristics imply that the band gap does not shrink uniformly under strain relative to a reference potential defined by the source/drain contacts. Instead, the band gap change is only related to a change of the conduction band edge of WSe2, resulting in a decrease in the Schottky barrier (SB) for electrons without any change for hole injection into the valence band. Simulations of SB device characteristics are employed to explain this point and to quantify our findings. Last, our experimental results are compared with DFT calculations under strain showing excellent agreement between theoretical predictions and the experimental data presented here. PMID:27043387

  19. Polymer waveguide couplers based on metal nanoparticle-polymer nanocomposites.

    PubMed

    Signoretto, M; Suárez, I; Chirvony, V S; Abargues, R; Rodríguez-Cantó, P J; Martínez-Pastor, J

    2015-11-27

    In this work Au nanoparticles (AuNPs) are incorporated into poly(methyl methacrylate) (PMMA) waveguides to develop optical couplers that are compatible with planar organic polymer photonics. A method for growing AuNPs (of 10 to 100 nm in size) inside the commercially available Novolak resist is proposed with the intention of tuning the plasmon resonance and the absorption/scattering efficiencies inside the patterned structures. The refractive index of the MNP-Novolak nanocomposite (MNPs: noble metal nanoparticles) is carefully analysed both experimentally and numerically in order to find the appropriate fabrication conditions (filling factor and growth time) to optimize the scattering cross section at a desired wavelength. Then the nanocomposite is patterned inside a PMMA waveguide to exploit its scattering properties to couple and guide a normal incident laser light beam along the polymer. In this way, light coupling is experimentally demonstrated in a broad wavelength range (404-780 nm). Due to the elliptical shape of the MNPs the nanocomposite demonstrates a birefringence, which enhances the coupling to the TE mode up to efficiencies of around 1%. PMID:26526708

  20. Advanced Metal-Hydrides-Based Thermal Battery: A New Generation of High Density Thermal Battery Based on Advanced Metal Hydrides

    SciTech Connect

    2011-12-01

    HEATS Project: The University of Utah is developing a compact hot-and-cold thermal battery using advanced metal hydrides that could offer efficient climate control system for EVs. The team’s innovative designs of heating and cooling systems for EVs with high energy density, low-cost thermal batteries could significantly reduce the weight and eliminate the space constraint in automobiles. The thermal battery can be charged by plugging it into an electrical outlet while charging the electric battery and it produces heat and cold through a heat exchanger when discharging. The ultimate goal of the project is a climate-controlling thermal battery that can last up to 5,000 charge and discharge cycles while substantially increasing the driving range of EVs, thus reducing the drain on electric batteries.

  1. Bond strength: a comparison between chemical coated and mechanical interlock bases of ceramic and metal brackets.

    PubMed

    Wang, W N; Meng, C L; Tarng, T H

    1997-04-01

    Two types of chemically coated bases, two types of mechanical interlock base polycrystalline ceramic brackets, as well as one type of mechanical interlock base metal bracket were selected for bonding with Concise orthodontic resin on 60 extracted premolars. Bond strength was measured with an Instron testing machine and the debonded interface and enamel detachment were examined with scanning electron microscope and energy dispersive x-ray spectrometer. The results showed the greater bond strength with a chemically coated base of ceramic brackets had a greater debonded interface between enamel and resin, and the weaker bond strength of mechanical interlock base of ceramic and metal brackets had a greater debonded interfaces between bracket and resin. There was no significant statistical difference in bond strengths with mechanically interlock bases between ceramic and metal brackets. The enamel detachment was found on only the stronger bond strength in which there was a chemically coated base on the ceramic bracket. Ceramic bracket fractures were not found during debonding in this specially designed specimen with 1 mm/min speed of crosshead. The mechanical interlock base of the ceramic bracket combines the strength, durability and retention of a metal bracket along with an aesthetic advantage and no enamel detachment after debonding. PMID:9109582

  2. H+-induced irradiation damage resistance in Fe- and Ni-based metallic glass

    NASA Astrophysics Data System (ADS)

    Zhang, Hongran; Mei, Xianxiu; Zhang, Xiaonan; Li, Xiaona; Wang, Yingmin; Sun, Jianrong; Wang, Younian

    2016-05-01

    In this study, use of 40-keV H+ ion for irradiating metallic glass Fe80Si7.43B12.57 and Ni62Ta38 as well as metallic tungsten (W) at fluences of 1 × 1018 and 3 × 1018 ions/cm2, respectively, was investigated. At the fluence of 1 × 1018 ions/cm2, a crystalline layer appeared in metallic glass Fe80Si7.43B12.57, with α-Fe as the major crystalline phase, coupled with a little Fe2B, Fe3B, and metastable β-Mn-type phase. Fe80Si7.43B12.57 exhibited good soft magnetic properties after irradiation. At the fluence of 3 × 1018 ions/cm2, Ni62Ta38 was found to be amorphous-based, with a little μ-NiTa and Ni3Ta phases. No significant irradiation damage phenomenon appeared in metallic glasses Fe80Si7.43B12.57 and Ni62Ta38. Blistering, flaking, and other damage occurred on the surface of metallic W, and the root-mean-square (RMS) roughness increased with the increase of fluence. Metallic glass Ni62Ta38 exhibited better resistance to H+ irradiation than Fe80Si7.43B12.57, both of which were superior to the metallic W.

  3. Printable Ultrathin Metal Oxide Semiconductor-Based Conformal Biosensors.

    PubMed

    Rim, You Seung; Bae, Sang-Hoon; Chen, Huajun; Yang, Jonathan L; Kim, Jaemyung; Andrews, Anne M; Weiss, Paul S; Yang, Yang; Tseng, Hsian-Rong

    2015-12-22

    Conformal bioelectronics enable wearable, noninvasive, and health-monitoring platforms. We demonstrate a simple and straightforward method for producing thin, sensitive In2O3-based conformal biosensors based on field-effect transistors using facile solution-based processing. One-step coating via aqueous In2O3 solution resulted in ultrathin (3.5 nm), high-density, uniform films over large areas. Conformal In2O3-based biosensors on ultrathin polyimide films displayed good device performance, low mechanical stress, and highly conformal contact determined using polydimethylsiloxane artificial skin having complex curvilinear surfaces or an artificial eye. Immobilized In2O3 field-effect transistors with self-assembled monolayers of NH2-terminated silanes functioned as pH sensors. Functionalization with glucose oxidase enabled d-glucose detection at physiologically relevant levels. The conformal ultrathin field-effect transistor biosensors developed here offer new opportunities for future wearable human technologies. PMID:26498319

  4. Printable Ultrathin Metal Oxide Semiconductor-Based Conformal Biosensors.

    PubMed

    Rim, You Seung; Bae, Sang-Hoon; Chen, Huajun; Yang, Jonathan L; Kim, Jaemyung; Andrews, Anne M; Weiss, Paul S; Yang, Yang; Tseng, Hsian-Rong

    2015-12-22

    Conformal bioelectronics enable wearable, noninvasive, and health-monitoring platforms. We demonstrate a simple and straightforward method for producing thin, sensitive In2O3-based conformal biosensors based on field-effect transistors using facile solution-based processing. One-step coating via aqueous In2O3 solution resulted in ultrathin (3.5 nm), high-density, uniform films over large areas. Conformal In2O3-based biosensors on ultrathin polyimide films displayed good device performance, low mechanical stress, and highly conformal contact determined using polydimethylsiloxane artificial skin having complex curvilinear surfaces or an artificial eye. Immobilized In2O3 field-effect transistors with self-assembled monolayers of NH2-terminated silanes functioned as pH sensors. Functionalization with glucose oxidase enabled d-glucose detection at physiologically relevant levels. The conformal ultrathin field-effect transistor biosensors developed here offer new opportunities for future wearable human technologies.

  5. Fabrication methods and applications of microstructured gallium based liquid metal alloys

    NASA Astrophysics Data System (ADS)

    Khondoker, M. A. H.; Sameoto, D.

    2016-09-01

    This review contains a comparative study of reported fabrication techniques of gallium based liquid metal alloys embedded in elastomers such as polydimethylsiloxane or other rubbers as well as the primary challenges associated with their use. The eutectic gallium–indium binary alloy (EGaIn) and gallium–indium–tin ternary alloy (galinstan) are the most common non-toxic liquid metals in use today. Due to their deformability, non-toxicity and superior electrical conductivity, these alloys have become very popular among researchers for flexible and reconfigurable electronics applications. All the available manufacturing techniques have been grouped into four major classes. Among them, casting by needle injection is the most widely used technique as it is capable of producing features as small as 150 nm width by high-pressure infiltration. One particular fabrication challenge with gallium based liquid metals is that an oxide skin is rapidly formed on the entire exposed surface. This oxide skin increases wettability on many surfaces, which is excellent for keeping patterned metal in position, but is a drawback in applications like reconfigurable circuits, where the position of liquid metal needs to be altered and controlled accurately. The major challenges involved in many applications of liquid metal alloys have also been discussed thoroughly in this article.

  6. Fabrication methods and applications of microstructured gallium based liquid metal alloys

    NASA Astrophysics Data System (ADS)

    Khondoker, M. A. H.; Sameoto, D.

    2016-09-01

    This review contains a comparative study of reported fabrication techniques of gallium based liquid metal alloys embedded in elastomers such as polydimethylsiloxane or other rubbers as well as the primary challenges associated with their use. The eutectic gallium-indium binary alloy (EGaIn) and gallium-indium-tin ternary alloy (galinstan) are the most common non-toxic liquid metals in use today. Due to their deformability, non-toxicity and superior electrical conductivity, these alloys have become very popular among researchers for flexible and reconfigurable electronics applications. All the available manufacturing techniques have been grouped into four major classes. Among them, casting by needle injection is the most widely used technique as it is capable of producing features as small as 150 nm width by high-pressure infiltration. One particular fabrication challenge with gallium based liquid metals is that an oxide skin is rapidly formed on the entire exposed surface. This oxide skin increases wettability on many surfaces, which is excellent for keeping patterned metal in position, but is a drawback in applications like reconfigurable circuits, where the position of liquid metal needs to be altered and controlled accurately. The major challenges involved in many applications of liquid metal alloys have also been discussed thoroughly in this article.

  7. Structuralization of Ca(2+)-Based Metal-Organic Frameworks Prepared via Coordination Replication of Calcium Carbonate.

    PubMed

    Sumida, Kenji; Hu, Ming; Furukawa, Shuhei; Kitagawa, Susumu

    2016-04-01

    The emergence of metal-organic frameworks (MOFs) as potential candidates to supplant existing adsorbent types in real-world applications has led to an explosive growth in the number of compounds available to researchers, as well as in the diversity of the metal salts and organic linkers from which they are derived. In this context, the use of carbonate-based precursors as metal sources is of interest due to their abundance in mineral deposits and their reaction chemistry with acids, resulting in just water and carbon dioxide as side products. Here, we have explored the use of calcium carbonate as a metal source and demonstrate its versatility as a precursor to several known frameworks, as well as a new flexible compound based on the 2,5-dihydroxybenzoquinone (H2dhbq) linker, Ca(dhbq)(H2O)2. Furthermore, inspired by the ubiquity and unique structures of biomineralized forms of calcium carbonate, we also present examples of the preparation of superstructures of Ca-based MOFs via the coordination replication technique. In all, the results confirm the suitability of carbonate-based metal sources for the preparation of MOFs and further expand upon the growing scope of coordination replication as a convenient strategy for the preparation of structuralized materials. PMID:27002690

  8. Spectroscopic characterization of metal complexes of novel Schiff base. Synthesis, thermal and biological activity studies

    NASA Astrophysics Data System (ADS)

    Omar, M. M.; Mohamed, Gehad G.; Ibrahim, Amr A.

    2009-07-01

    Novel Schiff base (HL) ligand is prepared via condensation of 4-aminoantipyrine and 2-aminobenzoic acid. The ligand is characterized based on elemental analysis, mass, IR and 1H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA, DrTGA and DTA). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine N, amino N and deprotonated caroxylic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia Coli, Pseudomonas aeruginosa, Staphylococcus Pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.

  9. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-07-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis.

  10. An ammonium soal solution based method for the preparation of ceramic/copper metal microcomposites

    SciTech Connect

    Walker, R.J.; Robinson, D.A.

    1995-12-01

    Robinson and Maginnis have developed a process for the preparation of metal ceramic composites using an ammonium soap solution based route. This current work is an extension of their patent application. Their work focused on preparing silver/YBa{sub 2}Cu{sub 3}O{sub 7-x}. We have extended their work to prepare copper ceramic microcomposites. In this method, an ammonium soap of 2-ethylhexanoate is used to prepare a metallorganic in solution that is rapidly jelled or precipitated around a suspended and dispersed ceramic. This step is followed by a low temperature heat treatment in hydrogen to produce the desired composite. Depending on the heat treatment, the composite can be varied from metal coated ceramic grains to finely dispersed metal in a ceramic matrix. System specific schemes for the preparation of copper metal/ceramics will be presented along with X-ray Diffraction data, SEM and Optical micrographs.

  11. Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases.

    PubMed

    Perim, Eric; Lee, Dongwoo; Liu, Yanhui; Toher, Cormac; Gong, Pan; Li, Yanglin; Simmons, W Neal; Levy, Ohad; Vlassak, Joost J; Schroers, Jan; Curtarolo, Stefano

    2016-01-01

    Metallic glasses attract considerable interest due to their unique combination of superb properties and processability. Predicting their formation from known alloy parameters remains the major hindrance to the discovery of new systems. Here, we propose a descriptor based on the heuristics that structural and energetic 'confusion' obstructs crystalline growth, and demonstrate its validity by experiments on two well-known glass-forming alloy systems. We then develop a robust model for predicting glass formation ability based on the geometrical and energetic features of crystalline phases calculated ab initio in the AFLOW framework. Our findings indicate that the formation of metallic glass phases could be much more common than currently thought, with more than 17% of binary alloy systems potential glass formers. Our approach pinpoints favourable compositions and demonstrates that smart descriptors, based solely on alloy properties available in online repositories, offer the sought-after key for accelerated discovery of metallic glasses. PMID:27480126

  12. 2D Transition-Metal-Dichalcogenide-Nanosheet-Based Composites for Photocatalytic and Electrocatalytic Hydrogen Evolution Reactions.

    PubMed

    Lu, Qipeng; Yu, Yifu; Ma, Qinglang; Chen, Bo; Zhang, Hua

    2016-03-01

    Hydrogen (H2) is one of the most important clean and renewable energy sources for future energy sustainability. Nowadays, photocatalytic and electrocatalytic hydrogen evolution reactions (HERs) from water splitting are considered as two of the most efficient methods to convert sustainable energy to the clean energy carrier, H2. Catalysts based on transition metal dichalcogenides (TMDs) are recognized as greatly promising substitutes for noble-metal-based catalysts for HER. The photocatalytic and electrocatalytic activities of TMD nanosheets for the HER can be further improved after hybridization with many kinds of nanomaterials, such as metals, oxides, sulfides, and carbon materials, through different methods including the in situ reduction method, the hot-injection method, the heating-up method, the hydro(solvo)thermal method, chemical vapor deposition (CVD), and thermal annealing. Here, recent progress in photocatalytic and electrocatalytic HERs using 2D TMD-based composites as catalysts is discussed.

  13. Study of Glass Forming Ability Parameters of Mg-Ni-Pr-BASED Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Prajapati, Sonal R.; Patel, Ashmi T.; Pratap, Arun

    Knowledge of Glass forming Ability (GFA) of metallic glasses is of great importance as it gives an insight of a better Glass former. Number of GFA parameters like Gibb’s free energy difference ∆G, ∆S, ∆H, η, γ, γm, Q, Trg (=Tg/Tl) etc. are calculated and compared for Mg-Ni-Pr-based metallic glass forming alloys to predict which parameter describes the best GFA criterion. On the basis of these parameters the excellent glass forming composition is identified. Also the GFA parameters of Mg-Ni-Pr-based alloys are studied in air and argon atmosphere. Present work suggests that ∆G is the best GFA criterion and Mg-Ni-Pr-based metallic glassy alloys can be successfully fabricated in air due to its high oxidation resistance ability.

  14. Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases

    NASA Astrophysics Data System (ADS)

    Perim, Eric; Lee, Dongwoo; Liu, Yanhui; Toher, Cormac; Gong, Pan; Li, Yanglin; Simmons, W. Neal; Levy, Ohad; Vlassak, Joost J.; Schroers, Jan; Curtarolo, Stefano

    2016-08-01

    Metallic glasses attract considerable interest due to their unique combination of superb properties and processability. Predicting their formation from known alloy parameters remains the major hindrance to the discovery of new systems. Here, we propose a descriptor based on the heuristics that structural and energetic `confusion' obstructs crystalline growth, and demonstrate its validity by experiments on two well-known glass-forming alloy systems. We then develop a robust model for predicting glass formation ability based on the geometrical and energetic features of crystalline phases calculated ab initio in the AFLOW framework. Our findings indicate that the formation of metallic glass phases could be much more common than currently thought, with more than 17% of binary alloy systems potential glass formers. Our approach pinpoints favourable compositions and demonstrates that smart descriptors, based solely on alloy properties available in online repositories, offer the sought-after key for accelerated discovery of metallic glasses.

  15. Spectral descriptors for bulk metallic glasses based on the thermodynamics of competing crystalline phases

    PubMed Central

    Perim, Eric; Lee, Dongwoo; Liu, Yanhui; Toher, Cormac; Gong, Pan; Li, Yanglin; Simmons, W. Neal; Levy, Ohad; Vlassak, Joost J.; Schroers, Jan; Curtarolo, Stefano

    2016-01-01

    Metallic glasses attract considerable interest due to their unique combination of superb properties and processability. Predicting their formation from known alloy parameters remains the major hindrance to the discovery of new systems. Here, we propose a descriptor based on the heuristics that structural and energetic ‘confusion' obstructs crystalline growth, and demonstrate its validity by experiments on two well-known glass-forming alloy systems. We then develop a robust model for predicting glass formation ability based on the geometrical and energetic features of crystalline phases calculated ab initio in the AFLOW framework. Our findings indicate that the formation of metallic glass phases could be much more common than currently thought, with more than 17% of binary alloy systems potential glass formers. Our approach pinpoints favourable compositions and demonstrates that smart descriptors, based solely on alloy properties available in online repositories, offer the sought-after key for accelerated discovery of metallic glasses. PMID:27480126

  16. [Mapping Critical Loads of Heavy Metals for Soil Based on Different Environmental Effects].

    PubMed

    Shi, Ya-xing; Wu, Shao-hua; Zhou, Sheng-lu; Wang, Chun-hui; Chen, Hao

    2015-12-01

    China's rapid development of industrialization and urbanization causes the growing problem of heavy metal pollution of soil, threatening environment and human health. Therefore, prevention and management of heavy metal pollution become particularly important. Critical loads of heavy metals are an important management tool that can be utilized to prevent the occurrence of heavy metal pollution. Our study was based on three cases: status balance, water environmental effects and health risks. We used the steady-state mass balance equation to calculate the critical loads of Cd, Cu, Pb, Zn at different effect levels and analyze the values and spatial variation of critical loads. In addition, we used the annual input fluxes of heavy metals of the agro-ecosystem in the Yangtze River delta and China to estimate the proportion of area with exceedance of critical loads. The results demonstrated that the critical load value of Cd was the minimum, and the values of Cu and Zn were lager. There were spatial differences among the critical loads of four elements in the study area, lower critical loads areas mainly occurred in woodland and high value areas distributed in the east and southwest of the study area, while median values and the medium high areas mainly occurred in farmland. Comparing the input fluxes of heavy metals, we found that Pb and Zn in more than 90% of the area exceeded the critical loads under different environmental effects in the study area. The critical load exceedance of Cd mainly occurred under the status balance and the water environmental effect, while Cu under the status balance and water environmental effect with a higher proportion of exceeded areas. Critical loads of heavy metals at different effect levels in this study could serve as a reference from effective control of the emissions of heavy metals and to prevent the occurrence of heavy metal pollution. PMID:27011999

  17. [Mapping Critical Loads of Heavy Metals for Soil Based on Different Environmental Effects].

    PubMed

    Shi, Ya-xing; Wu, Shao-hua; Zhou, Sheng-lu; Wang, Chun-hui; Chen, Hao

    2015-12-01

    China's rapid development of industrialization and urbanization causes the growing problem of heavy metal pollution of soil, threatening environment and human health. Therefore, prevention and management of heavy metal pollution become particularly important. Critical loads of heavy metals are an important management tool that can be utilized to prevent the occurrence of heavy metal pollution. Our study was based on three cases: status balance, water environmental effects and health risks. We used the steady-state mass balance equation to calculate the critical loads of Cd, Cu, Pb, Zn at different effect levels and analyze the values and spatial variation of critical loads. In addition, we used the annual input fluxes of heavy metals of the agro-ecosystem in the Yangtze River delta and China to estimate the proportion of area with exceedance of critical loads. The results demonstrated that the critical load value of Cd was the minimum, and the values of Cu and Zn were lager. There were spatial differences among the critical loads of four elements in the study area, lower critical loads areas mainly occurred in woodland and high value areas distributed in the east and southwest of the study area, while median values and the medium high areas mainly occurred in farmland. Comparing the input fluxes of heavy metals, we found that Pb and Zn in more than 90% of the area exceeded the critical loads under different environmental effects in the study area. The critical load exceedance of Cd mainly occurred under the status balance and the water environmental effect, while Cu under the status balance and water environmental effect with a higher proportion of exceeded areas. Critical loads of heavy metals at different effect levels in this study could serve as a reference from effective control of the emissions of heavy metals and to prevent the occurrence of heavy metal pollution.

  18. Isothermal fatigue mechanisms in Ti-based metal matrix composites

    NASA Technical Reports Server (NTRS)

    Majumdar, Bhaskar S.; Newaz, Golam M.

    1993-01-01

    Stress-controlled isothermal fatigue experiments were performed at room temperature (RT) and 548 C (in argon) on (0)8 SCS6/Ti 15-3 metal matrix composites (MMC's) with 15 and 41 volume percent SCS6 (SiC) fibers. The primary objectives were to evaluate the mechanical responses, and to obtain a clear understanding of the damage mechanisms leading to failure of the MMC's. The mechanical data indicated that strain ranges attained fairly constant values in the stress-controlled experiments at both RT and 538 C, and remained so for more than 85 percent of life. The fatigue data for MMC's with different volume fraction fibers showed that MMC life was controlled by the imposed strain range rather than the stress range. At RT, and at low and intermediate strain ranges, the dominant fatigue mechanism was matrix fatigue, and this was confirmed metallurgically from fractographic evidence as well as from observations of channel type dislocation structures in the matrix of fatigued MMC specimens. Reaction-zone cracks acted as important crack initiating sites at RT, with their role being to facilitate slip band formation and consequent matrix crack initiation through classical fatigue mechanisms. MMC life agreed with matrix life at the lower strain ranges, but was smaller than matrix life at higher strain ranges. Unlike the case of monotonic deformation, debonding damage was another major damage mechanism during fatigue at RT, and it increased for higher strain ranges. At high strain ranges at RT, fractography and metallography showed an absence of matrix cracks, but long lengths of debonds in the outer layers of the SCS6 fibers. Such debonding and consequent rubbing during fatigue is believed to have caused fiber damage and their failure at high strain ranges. Thus, whereas life was matrix dominated at low and intermediate strain ranges, it was fiber dominated at high strain ranges. At 538 C, the mean stain constantly increased (ratchetting) with the number of cycles. At high

  19. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    ERIC Educational Resources Information Center

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and…

  20. Base metal alloys with self-healing native conductive oxides for electrical contact materials

    NASA Astrophysics Data System (ADS)

    Aindow, M.; Alpay, S. P.; Liu, Y.; Mantese, J. V.; Senturk, B. S.

    2010-10-01

    Base metals for electrical contacts exhibit high bulk conductivities but form low-conductivity native oxide scales in air, leading to unacceptably high contact resistances. Here we show that alloying base metals can lead to higher conductivity native scales by: doping to enhance carrier concentration; inducing mixed oxidation states to give electron/polaron hopping; and/or phase separation for conducting pathways. Data from Cu-La, Fe-V, and Ni-Ru alloys demonstrate the viability of these approaches, yielding contact resistances up to 106 times lower than that for oxidized Cu.

  1. Extraordinary transmission-based super-resolved axial imaging using subwavelength metallic nanoaperture arrays

    NASA Astrophysics Data System (ADS)

    Lee, Wonju; Oh, Youngjin; Choi, Jong-ryul; Kim, Kyujung; Kim, Donghyun

    2015-03-01

    A super-resolved axial imaging technique was investigated based on extraordinary transmission (EOT) of light using metallic gradient nanoaperture arrays. Light through subwavelength nanoapertures at thick metal film can be transmitted and amplified by several orders of magnitude due to plasmonic coupling. Here, the feasibility of EOT-based axial imaging with super resolution is explored. Since light penetration of EOT is much deeper than that of evanescent waves, the axial range to obtain the distance information of fluorescence signals can be extended by EOT. The axial distribution of ganglioside in mouse macrophage cells was measured with sub-diffraction-limited resolution after reconstruction using differential fluorescence excitation on gradient aperture arrays.

  2. Gingival pigmentation by Ni-Cr-based metal ceramic crowns: A clinical report.

    PubMed

    Tian, Min; Ma, Sai; Niu, Lina; Chen, Jihua

    2016-01-01

    This clinical report describes treatment of a patient with gingival pigmentation after the restoration of the right maxillary canine and first premolar with Ni-Cr-based metal ceramic crowns and investigation of mechanisms of gingival discoloration. Histopathological observation and energy dispersive x-ray spectroscopy analysis of the retrieved pigmented gingiva revealed brown deposits both in the epithelial cells and along the basement membranes but no trace of Ni or Cr elements in the pigmented particles, indicating that the gingival pigmentation adjacent to the Ni-Cr-based metal ceramic prosthesis may not be caused by direct deposition of the released ions. PMID:26548874

  3. Energy requirements for metals production: comparison between ocean nodules and land-based resources. Final report

    SciTech Connect

    Not Available

    1980-09-01

    A methodology was developed to compare the energy requirements of technologies for production of metals from ocean nodules with production of same metals from land based ores using conventional processes. The energy requirements for production of copper, nickel, cobalt, and manganese from ocean nodules are based on an ocean mining operation of 3 million tons per year of dry nodules. A linear relationship exists between the amount of nodules processed and the total energy so that the energy can be easily converted to other processing rates if desired.

  4. Nonlinear Metal-Insulator-Metal (MIM) Nanoplasmonic Waveguides Based on Electron Tunneling for Optical Rectification and Frequency Generation

    NASA Astrophysics Data System (ADS)

    Lei, Xiaoqin

    Metal-Insulator-Metal (MIM) electron tunneling diodes have recently emerged as an attractive alternative to semiconductor photodiodes for THz and optical detection due to their fast response time and relative ease of fabrication. However, current antenna-coupled MIM diode detectors are still limited by poor responsivity and low detection bandwidth due to impedance mismatch between the diode and antenna, large RC time constant of lumped MIM junctions, and narrow bandwidth of traditional antenna designs. In this thesis we address these issues by considering traveling-wave MIM detector designs which exhibit enhanced responsivity and low impedance that can be more easily matched to planar antennas. We also propose new antenna geometries based on surface modification of traditional bowtie antennas that are capable of receiving ultra-wideband THz signals. The concept of traveling-wave MIM detectors is then extended to the investigation of nonlinear MIM nanoplasmonic waveguides for on-chip single-cycle THz pulse generation, frequency conversion, as well as plasmonic switching and modulation.

  5. Design of a compact and high sensitive refractive index sensor base on metal-insulator-metal plasmonic Bragg grating.

    PubMed

    Binfeng, Yun; Guohua, Hu; Ruohu, Zhang; Yiping, Cui

    2014-11-17

    A nanometric and high sensitive refractive index sensor based on the metal-insulator-metal plasmonic Bragg grating is proposed. The wavelength encoded sensing characteristics of the refractive index sensor were investigated by analyzing its transmission spectrum. The numerical results show that a good linear relationship between the Bragg wavelength and the refractive index of the sensing material can be obtained, which is in accordance with the analytical results very well. A high refractive index sensitivity of 1,488 nm/RIU around Bragg resonance wavelength of 1,550 nm was obtained. Besides, the simulation results show that the sensitivity is depended on the Bragg resonance wavelength and the longer the Bragg resonance wavelength, the higher sensitivity can be obtained. Furthermore, the figure of merit of the refractive index sensor can be greatly increased by introducing a nano-cavity in the proposed plasmonic Bragg grating structure. This work pave the way for high sensitive nanometric refractive index sensor design and application.

  6. Diverse structures of metal-organic frameworks based on different metal ions: luminescence and gas adsorption properties.

    PubMed

    Zhang, Chuan-Lei; Qin, Ling; Shi, Zhen-Zhen; Zheng, He-Gen

    2015-03-01

    Four coordination polymers with different metal ions have been synthesized based on a rigid linear pyridine and a flexible V-shaped dicarboxylate ligand (L = 4,4'-(2,5-dimethoxy-1,4-phenylene)dipyridine; H2OBA = 4,4'-oxydibenzoic acid): {[Co(L)(OBA)]·2H2O}n (1), [Zn(L)(OBA)·2H2O]n (2), {[Ni(L)(OBA)]·DMF·H2O}n (3), [Cd(L)(OBA)]·DMF·H2O}n (4). The reaction conditions are similar except for the metal ions for complexes 1-4. Complexes 1 and 2 present a 3D unprecedented hxg-d-4-Cccm net, but 3 and 4 are 4-connected sql nets with a point symbol {4(4)·6(2)}. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. The UV-visible spectra, fluorescence, and gas adsorption properties of the compounds were also explored. PMID:25631059

  7. Design of a compact and high sensitive refractive index sensor base on metal-insulator-metal plasmonic Bragg grating.

    PubMed

    Binfeng, Yun; Guohua, Hu; Ruohu, Zhang; Yiping, Cui

    2014-11-17

    A nanometric and high sensitive refractive index sensor based on the metal-insulator-metal plasmonic Bragg grating is proposed. The wavelength encoded sensing characteristics of the refractive index sensor were investigated by analyzing its transmission spectrum. The numerical results show that a good linear relationship between the Bragg wavelength and the refractive index of the sensing material can be obtained, which is in accordance with the analytical results very well. A high refractive index sensitivity of 1,488 nm/RIU around Bragg resonance wavelength of 1,550 nm was obtained. Besides, the simulation results show that the sensitivity is depended on the Bragg resonance wavelength and the longer the Bragg resonance wavelength, the higher sensitivity can be obtained. Furthermore, the figure of merit of the refractive index sensor can be greatly increased by introducing a nano-cavity in the proposed plasmonic Bragg grating structure. This work pave the way for high sensitive nanometric refractive index sensor design and application. PMID:25402107

  8. A mini-review on functional nucleic acids-based heavy metal ion detection.

    PubMed

    Zhan, Shenshan; Wu, Yuangen; Wang, Lumei; Zhan, Xuejia; Zhou, Pei

    2016-12-15

    Recent years have witnessed great progress in developing functional nucleic acids (FNAs)-based sensors for the detection of heavy metal ion. In this review, four types of the FNAs that most widely-used in heavy metal ions detection were briefly introduced and a dozen of recently published review articles which summarized those FNAs-based sensors were introduced. Particularly, according to the degree of automation and system integration, those FNAs-based sensors which belong to the lab-on-a-chip (LOC) category were reviewed in more detail by classifying them into six types such as microfluidic LOC system, microchip, lateral flow dipstick, personal glucose meter, microfluidic paper-based analytical devices (μPADs) and disc-based analytical platform. After gave a brief description of the sensing strategies, properties, advantages or disadvantages of these FNAs-based sensors, existing problems and future perspectives were also discussed. PMID:27395020

  9. A mini-review on functional nucleic acids-based heavy metal ion detection.

    PubMed

    Zhan, Shenshan; Wu, Yuangen; Wang, Lumei; Zhan, Xuejia; Zhou, Pei

    2016-12-15

    Recent years have witnessed great progress in developing functional nucleic acids (FNAs)-based sensors for the detection of heavy metal ion. In this review, four types of the FNAs that most widely-used in heavy metal ions detection were briefly introduced and a dozen of recently published review articles which summarized those FNAs-based sensors were introduced. Particularly, according to the degree of automation and system integration, those FNAs-based sensors which belong to the lab-on-a-chip (LOC) category were reviewed in more detail by classifying them into six types such as microfluidic LOC system, microchip, lateral flow dipstick, personal glucose meter, microfluidic paper-based analytical devices (μPADs) and disc-based analytical platform. After gave a brief description of the sensing strategies, properties, advantages or disadvantages of these FNAs-based sensors, existing problems and future perspectives were also discussed.

  10. Ultrafast degradation of azo dyes catalyzed by cobalt-based metallic glass

    NASA Astrophysics Data System (ADS)

    Qin, X. D.; Zhu, Z. W.; Liu, G.; Fu, H. M.; Zhang, H. W.; Wang, A. M.; Li, H.; Zhang, H. F.

    2015-12-01

    Reactivity and mass loss are considered mutually exclusive in conventional zero-valent metal (ZVM) technology to treat environmental contaminants. Here, we report the outstanding performance of Co-based metallic glass (MG) in degrading an aqueous solution of azo dye, thus eliminating this trade-off. Ball-milled Co-based MG powders completely degrade Acid Orange II at an ultrafast rate. The surface-area-normalized rate constant of Co-based MG powders was one order of magnitude higher than that of Co-based crystalline counterparts and three orders of magnitude higher than that of the widely studied Fe0 powders. The coordinatively unsaturated local structure in Co-based MG responds to the catalysis for degradation, resulting in very low mass loss. Wide applicability and good reusability were also present. Co-based MG is the most efficient material for azo dye degradation reported thus far, and will promote the practical application of MGs as functional materials.

  11. Metal based synthetic routes to heavy alkaline earth aryloxo complexes involving ligands of moderate steric bulk.

    PubMed

    Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Guino-o, Marites; Ruhlandt-Senge, Karin

    2009-07-01

    Treatment of an alkaline earth metal (Ca, Sr, Ba) with 2,4,6-trimethylphenol (HOmes) at elevated temperatures in the presence of mercury under solvent-free conditions, followed by extraction of the reaction mixture with 1,2-dimethoxyethane (dme), afforded dinuclear alkaline earth aryloxo complexes [Ae2(Omes)4(dme)4] (Ae = Ca 1, Sr 3, Ba 6). Extraction of the Ca metal and HOmes reaction mixture with thf afforded [Ca3(Omes)6(thf)] 2. In contrast, redox transmetallation ligand exchange reactions between an alkaline earth metal, diphenylmercury and HOmes in dme yielded solely 1 for Ca metal, a mixture of 3 and the methoxide bridged cage [Sr5(Omes)5(OMe)5(dme)4] x 2dme 4 for Sr metal, and solely [Ba5(Omes)5(OMe)5(dme)4] x dme 7 for Ba metal. The methoxide ligands originate from the C-O activation of the dme solvent. Treatment of liquid ammonia activated Sr or Ba metal with HOmes in thf afforded the linear species [Ae3(Omes)6(thf)6] (Ae = Sr 5, Ba 8), and 8 was also obtained from barium metal and HOmes in refluxing thf. The structures of 1 and 3, determined by X-ray crystallography, consist of two six coordinate Ae metal atoms, to each of which is bound a terminal aryloxide ligand, two bridging aryloxide ligands, and chelating and unidentate dme ligands. The structures of 4 and 7 contain five Ae metal atoms arranged on the vertices of a distorted square based pyramid. The Ae atoms are linked by four mu3-OMe ligands and a mu4-OMe ligand. Four bridging aryloxide ligands and four chelating dme ligands complete the coordination spheres of the four seven coordinate Ae atoms at the base of the pyramid, and a terminal aryloxide ligand is bound to the five coordinate apical Ae atom. The structures of 5 and 8 consist of a trinuclear linear array of Ae metal atoms, and contain solely bridging aryloxide ligands. Three thf ligands are bound to each terminal Ae atom, giving all Ae atoms a coordination number of six. PMID:19662279

  12. Development a Cu-based Metal Powder for Selective Laser Micro Sintering

    NASA Astrophysics Data System (ADS)

    Dai, C.; Zhu, H. H.; Ke, L. D.; Lei, W. J.; Chen, B. J.

    2011-02-01

    A Cu-based metal powder which consists of Cu and Cu-P alloy for selective micro laser sintering has been developed based on the theoretical analysis of the characteristics of the laser micro sintering metal powder. The characteristics of the wetting, capillary force and viscosity have been considered. The preliminary experimental investigation on the selective laser micro sintering Cu-based metal powder has been performed. A 50W CW Nd:YAG laser was employed to sinter the developed metal powder mixture. The sintering mechanism and the effect of the process parameters on the characteristics of the sintering samples have been preliminary investigated. The results show that the mechanism of laser micro sintering this developed metal powder is liquid-phase sintering and Cu-P alloy powder plays an effectively binder in the sintering process. The process parameter has significant effects on the characteristics of the sintering parts. From the SEM image, two different microstructures of samples with different scan spacing parameters were compared and a better binding effect was obtained at a parameter of 0.05mm scan spacing.

  13. Metal Complexes of Macrocyclic Schiff-Base Ligand: Preparation, Characterisation, and Biological Activity

    PubMed Central

    Ahmed, Riyadh M.; Yousif, Enaam I.; Hasan, Hasan A.; Al-Jeboori, Mohamad J.

    2013-01-01

    A new macrocyclic multidentate Schiff-base ligand Na4L consisting of two submacrocyclic units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12]tetracosa-1(23),2,6,8,10,12(24),13,17,19,21,-decaene-23,24-disodium) and its tetranuclear metal complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) are reported. Na4L was prepared via a template approach, which is based on the condensation reaction of sodium 2,4,6-triformyl phenolate with ethylenediamine in mole ratios of 2 : 3. The tetranuclear macrocyclic-based complexes were prepared from the reaction of the corresponding metal chloride with the ligand. The mode of bonding and overall geometry of the compounds were determined through physicochemical and spectroscopic methods. These studies revealed tetrahedral geometries about Mn, Co, and Zn atoms. However, square planar geometries have been suggested for NiII and CuII complexes. Biological activity of the ligand and its metal complexes against Gram positive bacterial strain Staphylococcus aureus and Gram negative bacteria Escherichia coli revealed that the metal complexes become more potentially resistive to the microbial activities as compared to the free ligand. However, these metal complexes do not exhibit any effects on the activity of Pseudomonas aeruginosa bacteria. There is therefore no inhibition zone. PMID:23935414

  14. Assessment of diffuse trace metal inputs into surface waters - Combining empirical estimates with process based simulations

    NASA Astrophysics Data System (ADS)

    Schindewolf, Marcus; Steinz, André; Schmidt, Jürgen

    2015-04-01

    As a result of mining activities since the 13th century, surface waters of the German Mulde catchment suffer from deleterious dissolved and sediment attached lead (Pb) and zinc (Zn) inputs. The leaching rate of trace metals with drainage water is a significant criterion for assessing trace metal concentrations of soils and associated risks of ground water pollution. However, the vertical transport rates of trace metals in soils are difficult to quantify. Monitoring is restricted to small lysimeter plots, which limits the transferability of results. Additionally the solid-liquid-transfer conditions in soils are highly variable, primarily due to the fluctuating retention time of percolating soil water. In contrast, lateral sediment attached trace metal inputs are mostly associated with soil erosion and resulting sediment inputs into surface waters. Since soil erosion by water is related to rare single events, monitoring and empirical estimates reveal visible shortcomings. This gap in knowledge can only be closed by process based model calculations. Concerning these calculations it has to be considered, that Pb and Zn are predominantly attached to the fine-grained soil particles (<0.063 mm). The selective nature of soil erosion causes a preferential transport of these fine particles, while less contaminated larger particles remain on site. Consequently trace metals are enriched in the eroded sediment compared to the origin soil. This paper aims to introduce both, a new method that allows the assessment of trace metal leaching rates from contaminated top soils for standardised transfer conditions and a process based modelling approach for sediment attached trace metal inputs into surface waters. Pb and Zn leaching rates amounts to 20 Mg ha-1 yr-1 resp. 114 Mg ha-1 yr-1. Deviations to observed dissolved trace metal yields at the Bad Düben gauging station are caused by plant uptake and subsoil retention. Sediment attached Pb and Zn input rates amounts to 114 Mg ha-1 yr

  15. The electron-transfer based interaction between transition metal ions and photoluminescent graphene quantum dots (GQDs): a platform for metal ion sensing.

    PubMed

    Huang, Hongduan; Liao, Lei; Xu, Xiao; Zou, Mingjian; Liu, Feng; Li, Na

    2013-12-15

    The electron-transfer based quenching effect of commonly encountered transition metal ions on the photoluminescence of grapheme quantum dots (GQDs) was for the first time investigated, and was found to be associated with electron configuration of the individual metal ion. Ethylene diamine tetraacetic acid (EDTA), the metal ion chelator, can competitively interact with metal ions to recover the quenched photoluminescence of GQDs. Basically, metal ions with empty or completely filled d orbits could not quench the photoluminescence of GQDs, but this quenching effect was observed for the metal ions with partly filled d orbits. Based on the quenching-recovering strategy, a simple optical metal sensing platform was established by taking Ni(2+) as an example. Using the nickel ion-specific chelating reagent, dimethylglyoxime (DMG), to replace EDTA, a detection limit of 4.1 μM was obtained in standard solution. This proposed strategy does not need further functionalization of GQDs, facilitating the application for simple, fast and cost-effective screening of metal ions.

  16. Controllable synthesis and property of graphene-based magnetic metal nanostructures

    NASA Astrophysics Data System (ADS)

    Wu, Kong-Lin; Li, Xiang-Zi; Wei, Xian-Wen; Ding, Ting-Hui; Jiang, Miao; Zhang, Wen-Juan; Ye, Yin

    2014-12-01

    A facile and effective solution phase reduction method was developed to synthesize graphene-based magnetic metal nanocomposites. Metals (Co, and Ni) or alloys (Fe51Co49, Fe48Ni52, Ni49Co51, Co51Cu49, and Ni52Cu48)/reduced graphene oxide (RGO) nanocomposites were successfully prepared by reduction of the corresponding aqueous metal ions and ethylenediamine (EDA)-graphene oxide (GO) with hydrazine hydrate at 353 K for 1 h under N2 atmosphere. The effects of synthetic parameters such as metal ions concentration, adding sequence of NaOH and N2H4·H2O, linkage agent and reaction time on the formation of nanocomposites were investigated. The experimental results showed that using ethylenediamine and adding sequence played critical roles in the formation of metals or alloys/RGO nanocomposites. Magnetic hysteresis measurements revealed that the as-synthesized metals or alloys in nanocomposites showed excellent soft magnetic behavior with enhanced saturation magnetization, and could have promising applications in biotechnology, catalysis, and magnetic storage devices.

  17. BODIPY-based fluorometric sensor array for the highly sensitive identification of heavy-metal ions.

    PubMed

    Niu, Li-Ya; Li, Hui; Feng, Liang; Guan, Ying-Shi; Chen, Yu-Zhe; Duan, Chun-Feng; Wu, Li-Zhu; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-05-01

    A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library.

  18. BODIPY-based fluorometric sensor array for the highly sensitive identification of heavy-metal ions.

    PubMed

    Niu, Li-Ya; Li, Hui; Feng, Liang; Guan, Ying-Shi; Chen, Yu-Zhe; Duan, Chun-Feng; Wu, Li-Zhu; Guan, Ya-Feng; Tung, Chen-Ho; Yang, Qing-Zheng

    2013-05-01

    A BODIPY(4,4-difluoro-4-bora-3a,4a-diaza-s-indacene)-based fluorometric sensor array has been developed for the highly sensitive detection of eight heavy-metal ions at micromolar concentration. The di-2-picolyamine (DPA) derivatives combine high affinities for a variety of heavy-metal ions with the capacity to perturb the fluorescence properties of BODIPY, making them perfectly suitable for the design of fluorometric sensor arrays for heavy-metal ions. 12 cross-reactive BODIPY fluorescent indicators provide facile identification of the heavy-metal ions using a standard chemometric approach (hierarchical clustering analysis); no misclassifications were found over 45 trials. Clear differentiation among heavy-metal ions as a function of concentration was also achieved, even down to 10(-7)M. A semi-quantitative interpolation of the heavy-metal concentration is obtained by comparing the total Euclidean distance of the measurement with a set of known concentrations in the library. PMID:23601979

  19. Rapid detection of transition metals in welding fumes using paper-based analytical devices.

    PubMed

    Cate, David M; Nanthasurasak, Pavisara; Riwkulkajorn, Pornpak; L'Orange, Christian; Henry, Charles S; Volckens, John

    2014-05-01

    Metals in particulate matter (PM) are considered a driving factor for many pathologies. Despite the hazards associated with particulate metals, personal exposures for at-risk workers are rarely assessed due to the cost and effort associated with monitoring. As a result, routine exposure assessments are performed for only a small fraction of the exposed workforce. The objective of this research was to evaluate a relatively new technology, microfluidic paper-based analytical devices (µPADs), for measuring the metals content in welding fumes. Fumes from three common welding techniques (shielded metal arc, metal inert gas, and tungsten inert gas welding) were sampled in two welding shops. Concentrations of acid-extractable Fe, Cu, Ni, and Cr were measured and independently verified using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results from the µPAD sensors agreed well with ICP-OES analysis; the two methods gave statistically similar results in >80% of the samples analyzed. Analytical costs for the µPAD technique were ~50 times lower than market-rate costs with ICP-OES. Further, the µPAD method was capable of providing same-day results (as opposed several weeks for ICP laboratory analysis). Results of this work suggest that µPAD sensors are a viable, yet inexpensive alternative to traditional analytic methods for transition metals in welding fume PM. These sensors have potential to enable substantially higher levels of hazard surveillance for a given resource cost, especially in resource-limited environments. PMID:24515892

  20. Rapid detection of transition metals in welding fumes using paper-based analytical devices.

    PubMed

    Cate, David M; Nanthasurasak, Pavisara; Riwkulkajorn, Pornpak; L'Orange, Christian; Henry, Charles S; Volckens, John

    2014-05-01

    Metals in particulate matter (PM) are considered a driving factor for many pathologies. Despite the hazards associated with particulate metals, personal exposures for at-risk workers are rarely assessed due to the cost and effort associated with monitoring. As a result, routine exposure assessments are performed for only a small fraction of the exposed workforce. The objective of this research was to evaluate a relatively new technology, microfluidic paper-based analytical devices (µPADs), for measuring the metals content in welding fumes. Fumes from three common welding techniques (shielded metal arc, metal inert gas, and tungsten inert gas welding) were sampled in two welding shops. Concentrations of acid-extractable Fe, Cu, Ni, and Cr were measured and independently verified using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results from the µPAD sensors agreed well with ICP-OES analysis; the two methods gave statistically similar results in >80% of the samples analyzed. Analytical costs for the µPAD technique were ~50 times lower than market-rate costs with ICP-OES. Further, the µPAD method was capable of providing same-day results (as opposed several weeks for ICP laboratory analysis). Results of this work suggest that µPAD sensors are a viable, yet inexpensive alternative to traditional analytic methods for transition metals in welding fume PM. These sensors have potential to enable substantially higher levels of hazard surveillance for a given resource cost, especially in resource-limited environments.

  1. Rapid Detection of Transition Metals in Welding Fumes Using Paper-Based Analytical Devices

    PubMed Central

    Volckens, John

    2014-01-01

    Metals in particulate matter (PM) are considered a driving factor for many pathologies. Despite the hazards associated with particulate metals, personal exposures for at-risk workers are rarely assessed due to the cost and effort associated with monitoring. As a result, routine exposure assessments are performed for only a small fraction of the exposed workforce. The objective of this research was to evaluate a relatively new technology, microfluidic paper-based analytical devices (µPADs), for measuring the metals content in welding fumes. Fumes from three common welding techniques (shielded metal arc, metal inert gas, and tungsten inert gas welding) were sampled in two welding shops. Concentrations of acid-extractable Fe, Cu, Ni, and Cr were measured and independently verified using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results from the µPAD sensors agreed well with ICP-OES analysis; the two methods gave statistically similar results in >80% of the samples analyzed. Analytical costs for the µPAD technique were ~50 times lower than market-rate costs with ICP-OES. Further, the µPAD method was capable of providing same-day results (as opposed several weeks for ICP laboratory analysis). Results of this work suggest that µPAD sensors are a viable, yet inexpensive alternative to traditional analytic methods for transition metals in welding fume PM. These sensors have potential to enable substantially higher levels of hazard surveillance for a given resource cost, especially in resource-limited environments. PMID:24515892

  2. Laser brazing of inconel 718 alloy with a silver based filler metal

    NASA Astrophysics Data System (ADS)

    Khorram, A.; Ghoreishi, M.; Torkamany, M. J.; Bali, M. M.

    2014-03-01

    In the presented study laser brazing of an inconel 718 alloy with silver based filler metal using 400 W pulsed Nd:YAG laser is investigated. Laser brazing was performed with varying laser frequency, pulse width, process speed and gap distance. The effect of preheating on wetting and spreading also was studied. Brazing geometrical images were observed using an optical microscope. The composition analysis and microstructure of the filler metal and brazed joints were examined using X-ray diffraction analyzer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Micro-hardness and tensile test were performed for investigation of mechanical properties. The experimental observations show that filler metal consist of α-Ag solid solution, ά-Cu solid solution surround by the α-Ag solid solution and eutectic structure. Phases of the brazed joint are similar to the filler metal. The results indicate that the filler metal has adequate wetting and spreading on inconel 718 and the wetting angle depends on the heat input significantly. Interdiffusion occurs in laser brazing and the average thickness of reaction layer is approximately 2.5 μm. Whenever the gap is big, it is needed to use longer pulse width in order to have a better melting flow. Preheating has significant influence on wetting and spreading of the filler metal.

  3. Creep properties of PWC-11 base metal and weldments as affected by heat treatment

    SciTech Connect

    Titran, R.H.; Moore, T.J.; Grobstein, T.L.

    1994-09-01

    In a preliminary study using single specimens for each condition, PWC-11 (a niobium-base alloy with a nominal composition of Nb-1%Zr-0.1%C) was creep tested at 1350 K and 40 MPa. Base metal specimens and specimens with transverse electrode beam welds were tested with and without a 1000 hr, 1350 K aging treatment prior to testing. In the annealed condition (1 hr at 1755 K + 2 hr at 1475 K), the base metal exhibited superior creep strength compared to the aged condition, reaching 1 percent strain in 3480 hr. A 1000 hr, 1350 K aging treatment prior to creep testing had a severe detrimental effect on creep strength of the base metal and transverse electron beam weldments, reducing the time to attain 1 percent strain by an order of magnitude. Extrapolated temperature compensated creep rates indicate that the present heat of PWC-11 may be four times as creep resistance as similarly tested Nb-1%Zr. The extrapolated stress to achieve 1 percent creep strain in 7 yr at 1350 K is 0.6 MPa for annealed Nb-1%Zr and 2.8 MPa for annealed and aged PWC-11 base metal with and without a transverse electron beam weld.

  4. Creep properties of PWC-11 base metal and weldments as affected by heat treatment

    NASA Technical Reports Server (NTRS)

    Titran, R. H.; Moore, T. J.; Grobstein, T. L.

    1986-01-01

    In a preliminary study using single specimens for each condition, PWC-11 (a niobium-base alloy with a nominal composition of Nb-1%Zr-0.1%C) was creep tested at 1350 K and 40 MPa. Base metal specimens and specimens with transverse electron beam welds were tested with and without a 1000 hr, 1350 K aging treatment prior to testing. In the annealed condition (1 hr at 1755 K + 2 hr at 1475 K), the base metal exhibited superior creep strength compared to the nonaged condition, reaching 1 percent strain in 3480 hr. A 1000 hr, 1350 K aging treatment prior to creep testing had a severe detrimental effect on creep strength of the base metal and transverse electron beam weldments, reducing the time to attain 1 percent strain by an order of magnitude. Extrapolated temperature compensated creep rates indicate that the present heat of PWC-11 may be four times as creep resistant as similarly tested Nb-1%Zr. The extrapolated stress to achieve 1 percent creep strain in 7 yr at 1350 K is 2.7 MPa for annealed Nb-1%Zr and 12 MPa for annealed and aged PWC-11 base metal with and without a transverse electron beam weld.

  5. The electronic structure of metal oxide/organo metal halide perovskite junctions in perovskite based solar cells

    PubMed Central

    Dymshits, Alex; Henning, Alex; Segev, Gideon; Rosenwaks, Yossi; Etgar, Lioz

    2015-01-01

    Cross-sections of a hole-conductor-free CH3NH3PbI3 perovskite solar cell were characterized with Kelvin probe force microscopy. A depletion region width of about 45 nm was determined from the measured potential profiles at the interface between CH3NH3PbI3 and nanocrystalline TiO2, whereas a negligible depletion was measured at the CH3NH3PbI3/Al2O3 interface. A complete solar cell can be realized with the CH3NH3PbI3 that functions both as light harvester and hole conductor in combination with a metal oxide. The band diagrams were estimated from the measured potential profile at the interfaces, and are critical findings for a better understanding and further improvement of perovskite based solar cells. PMID:25731963

  6. Low beryllium content Zr-based bulk metallic glass composite with plasticity and work hardenability

    SciTech Connect

    Zheng, Q. E-mail: dujuan@nimte.ac.cn; Du, J. E-mail: dujuan@nimte.ac.cn

    2014-01-28

    A modified Zr-based bulk metallic glass matrix composite Zr{sub 47.67}Cu{sub 40}Ti{sub 3.66}Ni{sub 2.66}Be{sub 6} has been produced by increasing the contents of elements of Zr and Cu with higher Poisson ratio and reducing the contents of Ti, Ni, and Be elements with lower Poisson ratio based on famous metallic glass former Vitreloy 1. A compressive yielding strength of 1804 MPa, fracture strength of 1938 MPa and 3.5% plastic strain was obtained for obtained metallic glass composite. Also, work-hardening behavior was observed during compressive experiment which was ascribed to the interaction of the in situ precipitated CuZr phase and shear bands.

  7. Graphene circular polarization analyzer based on spiral metal triangle antennas arrays.

    PubMed

    Zhu, Bofeng; Ren, Guobin; Gao, Yixiao; Wu, Beilei; Wan, Chenglong; Jian, Shuisheng

    2015-09-21

    In this paper we propose a circular polarization analyzer based on spiral metal triangle antenna arrays deposited on graphene. Via the dipole antenna resonances, plasmons are excited on graphene surface and the wavefront can be tailed by arranging metal antennas into linetype, circular or spiral arrays. Especially, for spiral antenna arrays, the geometric phase effect can be cancelled by or superposed on the chirality carried within circular polarization incidence, producing spatially separated solid dot or donut shape fields at the center. Such a phenomenon enables the graphene based spiral metal triangle antennas arrays to achieve functionality as a circular polarization analyzer. Extinction ratio over 550 can be achieved and the working wavelength can be tuned by adjusting graphene Fermi level dynamically. The proposed analyzer may find applications in analyzing chiral molecules using different circularly polarized waves.

  8. Metal Iodate-Based Energetic Composites and Their Combustion and Biocidal Performance.

    PubMed

    Wang, H; Jian, G; Zhou, W; DeLisio, J B; Lee, V T; Zachariah, M R

    2015-08-12

    The biological agents that can be weaponized, such as Bacillus anthracis, pose a considerable potential public threat. Bacterial spores, in particular, are highly stress resistant and cannot be completely neutralized by common bactericides. This paper reports on synthesis of metal iodate-based aluminized electrospray-assembled nanocomposites which neutralize spores through a combined thermal and chemical mechanism. Here metal iodates (Bi(IO3)3, Cu(IO3)2, and Fe(IO3)3) act as a strong oxidizer to nanoaluminum to yield a very exothermic and violent reaction, and simultaneously generate iodine as a long-lived bactericide. These microparticle-assembled nanocomposites when characterized in terms of reaction times and temporal pressure release show significantly improved reactivity. Furthermore, sporicidal performance superior to conventional metal-oxide-based thermites clearly shows the advantages of combining both a thermal and biocidal mechanism in spore neutralization.

  9. Low beryllium content Zr-based bulk metallic glass composite with plasticity and work hardenability

    NASA Astrophysics Data System (ADS)

    Zheng, Q.; Du, J.

    2014-01-01

    A modified Zr-based bulk metallic glass matrix composite Zr47.67Cu40Ti3.66Ni2.66Be6 has been produced by increasing the contents of elements of Zr and Cu with higher Poisson ratio and reducing the contents of Ti, Ni, and Be elements with lower Poisson ratio based on famous metallic glass former Vitreloy 1. A compressive yielding strength of 1804 MPa, fracture strength of 1938 MPa and 3.5% plastic strain was obtained for obtained metallic glass composite. Also, work-hardening behavior was observed during compressive experiment which was ascribed to the interaction of the in situ precipitated CuZr phase and shear bands.

  10. Docking of ethanamine Schiff base imines & metal (II) complexes, cytotoxicity & DNA interaction studies

    NASA Astrophysics Data System (ADS)

    Sujarani, S.; Ramu, A.

    2015-01-01

    The present study deals with a series of biologically and stereo chemically important novel transition metal (II) Schiff base chelates. The Cu (II), Co (II), Mn (II) and Ni (II) ions containing complexes were synthesized by using diphenylethanamine and 2-hydroxy/2, 4-dihydroxy/2-hydroxy-4-methoxybenzaldehydes. The synthesized complexes were characterized using micro analytical, IR, NMR, ESI-Mass, UV-Visible, cyclic voltammetry and the EPR spectroscopic techniques. The spectral data evidenced the action of ligands as a neutral bidentate Schiff bases, coordinating through azomethine nitrogen and oxygen atom of hydroxyl group. The interaction studies revealed the groove binding nature of complexes with CT-DNA. The ligand and synthesized metal complexes showed cytotoxicity against cancerous cells. The strong binding affinity of the imine and metal complexes was also confirmed by molecular docking studies.

  11. Laser-induced breakdown spectroscopy detection of heavy metal in water based on graphite conch method

    NASA Astrophysics Data System (ADS)

    Wang, Chunlong; Liu, Jianguo; Zhao, Nanjing; Shi, Huan; Liu, Lituo; Ma, Mingjun; Zhang, Wei; Chen, Dong; Liu, Jing; Zhang, Yujun; Liu, Wenqing

    2012-10-01

    The laser-induced breakdown spectroscopy emission characteristics of trace heavy metal lead in water is studied based on graphite conch method, with a 1064nm wavelength Nd: YAG laser as excitation source, the echelle spectrometer and ICCD detector are used for spectral separation and high sensitive detection with high resolution and wide spectral range. The delay time 900ns and gate time 1600ns are determined in the experiment. The calibration curve of Pb is plotted based on the different concentration measurement results, and a limit of detection of 0.0138mg / L is obtained for Pb in water. Graphite conch method effectively overcomes the current problems on laser-induced breakdown spectroscopy detection of heavy metal in water. The detection limits and stability are improved. The reference data is provided for further study on the fast measurement of trace heavy metals in water by laser induced breakdown spectroscopy technique.

  12. Ab initio investigation on hydrogen adsorption capability in Zn and Cu-based metal organic frameworks

    NASA Astrophysics Data System (ADS)

    Tanuwijaya, V. V.; Hidayat, N. N.; Agusta, M. K.; Dipojono, H. K.

    2015-09-01

    One of the biggest challenge in material technology for hydrogen storage application is to increase hydrogen uptake in room temperature and pressure. As a class of highly porous material, Metal-Organic Frameworks (MOF) holds great potential with its tunable structure. However, little is known about the effect of metal cluster to its hydrogen storage capability. Investigation on this matter has been carried out carefully on small cluster of Zn and Cu-based MOF using first principles method. The calculation of two distinct building units of MOFs, namely octahedral and paddle-wheel models, have been done with B3LYP density functional method using 6-31G(d,p) and LANL2DZ basis sets. From geometry optimization of Zn-based MOF linked by benzene-dicarboxylate (MOF-5), it is found that hydrogen tends to keep distance from metal cluster group and stays above benzene ring. In the other hand, hydrogen molecule prefers to stay atop of the exposed Cu atom in Cu-based MOF system linked by the same linker group (Cu-bdc). Calculated hydrogen binding enthalpies for Zn and Cu octahedral cages at ZnO3 sites are 1.64kJ/mol and 2.73kJ/mol respectively, while hydrogen binding enthalpies for Zn and Cu paddle-wheel cages calculated on top of metal atoms are found to be at 6.05kJ/mol and 6.10kJ/mol respectively. Major difference between Zn-MOF-5 and Cu-bdc hydrogen uptake performance might be caused by unsaturated metal sites present in Cu-bdc system and the influence of their geometric structures, although a small difference on binding energy in the type of transition metal used is also observed. The comparison between Zn and Cu-based MOF may contribute to a comprehensive understanding of metal clusters and the importance of selecting best transition metal for design and synthesis of metal-organic frameworks.

  13. Ab initio investigation on hydrogen adsorption capability in Zn and Cu-based metal organic frameworks

    SciTech Connect

    Tanuwijaya, V. V.; Hidayat, N. N. Agusta, M. K. Dipojono, H. K.

    2015-09-30

    One of the biggest challenge in material technology for hydrogen storage application is to increase hydrogen uptake in room temperature and pressure. As a class of highly porous material, Metal-Organic Frameworks (MOF) holds great potential with its tunable structure. However, little is known about the effect of metal cluster to its hydrogen storage capability. Investigation on this matter has been carried out carefully on small cluster of Zn and Cu-based MOF using first principles method. The calculation of two distinct building units of MOFs, namely octahedral and paddle-wheel models, have been done with B3LYP density functional method using 6-31G(d,p) and LANL2DZ basis sets. From geometry optimization of Zn-based MOF linked by benzene-dicarboxylate (MOF-5), it is found that hydrogen tends to keep distance from metal cluster group and stays above benzene ring. In the other hand, hydrogen molecule prefers to stay atop of the exposed Cu atom in Cu-based MOF system linked by the same linker group (Cu-bdc). Calculated hydrogen binding enthalpies for Zn and Cu octahedral cages at ZnO{sub 3} sites are 1.64kJ/mol and 2.73kJ/mol respectively, while hydrogen binding enthalpies for Zn and Cu paddle-wheel cages calculated on top of metal atoms are found to be at 6.05kJ/mol and 6.10kJ/mol respectively. Major difference between Zn-MOF-5 and Cu-bdc hydrogen uptake performance might be caused by unsaturated metal sites present in Cu-bdc system and the influence of their geometric structures, although a small difference on binding energy in the type of transition metal used is also observed. The comparison between Zn and Cu-based MOF may contribute to a comprehensive understanding of metal clusters and the importance of selecting best transition metal for design and synthesis of metal-organic frameworks.

  14. Transition Metal Ion Complexes of Schiff-bases. Synthesis, Characterization and Antibacterial Properties

    PubMed Central

    Munawar, Asifa; Supuran, Claudiu T.

    2001-01-01

    Some novel transition metal [Co(II), Cu(II), Ni(II) and Zn(II)] complexes of substituted pyridine Schiff-bases have been prepared and characterized by physical, spectral and analytical data. The synthesized Schiff-bases act as deprotonated tridentate for the complexation reaction with Co(II), Ni(II) and Zn(II) ions. The new compounds, possessing the general formula [M(L)2] where [M=Co(II), Cu(II), Ni(II) and Zn(II) and HL=HL1, HL2, HL3 and HL4] show an octahedral geometry. In order to evaluate the effect of metal ions upon chelation, the Schiff bases and their complexes have been screened for antibacterial activity against the strains such as Escherichia coli,Staphylococcus aureus, and Pseudomonas aeruginosa. The complexed Schiff bases have shown to be more antibacterial against one more bacterial species as compared to uncomplexed Schiff-bases. PMID:18475987

  15. Transient nucleation and local structure in zirconium-based metallic glasses

    NASA Astrophysics Data System (ADS)

    Shen, Youtao

    Over the past decade, there has been increasing attention in metallic glasses due to their scientific and engineering significance. One particular interest in metallic glasses is the frequent nanocrystallization upon devitrification. However, the full understanding of such nanostructure formation during devitrification remains incomplete. In this thesis, nanocrystallization upon annealing is studied in Zr-based metallic glasses. Quantitative transient nucleation rate data during glass crystallization to an icosahedral quasicrystal phase (i-phase) were obtained for the first time by measuring the crystal density following two-step annealing treatments by transmission electron microscopy. The data fit well to the classical theory of nucleation. The extremely small interfacial free energy (sigma = 0.006 J/m2) between the i-phase and the glass obtained from fits to the nucleation data indicates a significant icosahedral order in the glass. Taken together with high energy X-ray diffraction studies of the glass, these data provide the strongest evidence to date of the significant icosahedral order in metallic glasses. The addition of a few atomic percent of elements can change the glass formation and crystallization behavior significantly in these glasses. We report the discovery of Zr65Cu27Ti8 bulk metallic glasses with diameters up to 1 mm produced by suction casting. The effects of structural relaxation on the glass transition and crystallization kinetics, investigated by differential scanning calorimetry, are discussed. The effects of the addition of small amounts of Ti on the local order in Zr-based metallic glasses were investigated by high energy synchrotron X-ray diffraction and fluctuation electron microscopy. An increasing icosahedral order with increasing Ti content explains the bulk metallic glass formation in the Zr-Cu-Ti alloys. However, this is not true in a related, but more complex, Zr-Ti-Cu-Ni-Al alloy.

  16. Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.

    PubMed

    Doi, H; Harrori, M; Hasegawa, K; Yoshinari, M; Kawada, E; Oda, Y

    2001-02-01

    The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases. PMID:11484793

  17. Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.

    PubMed

    Doi, H; Harrori, M; Hasegawa, K; Yoshinari, M; Kawada, E; Oda, Y

    2001-02-01

    The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases.

  18. Synthesis and Structural Characterization of Carboxylate-Based Metal-Organic Frameworks and Coordination Networks

    NASA Astrophysics Data System (ADS)

    Calderone, Paul

    Coordination networks (CNs) and metal-organic frameworks (MOFs) are crystalline materials composed of metal ions linked by multifunctional organic ligands. From these connections, infinite arrays of one-, two-, or three-dimensional networks can be formed. Exploratory synthesis and research of novel CNs and MOFs is of current interest because of their many possible industrial applications including gas storage, catalysis, magnetism, and luminescence. A variety of metal centers and organic ligands can be used to synthesize MOFs and CNs under a range of reaction conditions, leading to extraordinary structural diversity. The characteristics of the metals and linkers, such as properties and coordination preferences, play the biggest role in determining the structure and properties of the resulting network. Thus, the choice of metal and linker is dictated by the desired traits of the target network. The pervasive use of transition metal centers in MOF synthesis stems from their well-known coordination behavior with carboxylate-based linkers, thus facilitating design strategies. Conversely, CNs and MOFs based on s-block and lanthanide metals are less studied because each group presents unique challenges to structure prediction. Lanthanide metals have variable coordination spheres capable of accommodating up to twelve atoms, while the bonding in s-block metals takes on a mainly ionic character. In spite of these obstacles, lanthanide and s-block CNs are worthwhile synthetic targets because of their unique properties. Interesting photoluminescent and sensing materials can be developed using lanthanide metals, whereas low atomic weight s-block metals may afford an advantage in gravimetric advantages for gas storage applications. The aim of this research was to expand the current understanding of carboxylate-based CN and MOF synthesis by varying the metals, solvents, and temperatures used. To this end

  19. MoM-based topology optimization method for planar metallic antenna design

    NASA Astrophysics Data System (ADS)

    Liu, Shutian; Wang, Qi; Gao, Renjing

    2016-09-01

    The metallic antenna design problem can be treated as a problem to find the optimal distribution of conductive material in a certain domain. Although this problem is well suited for topology optimization method, the volumetric distribution of conductive material based on 3D finite element method (FEM) has been known to cause numerical bottlenecks such as the skin depth issue, meshed "air regions" and other numerical problems. In this paper a topology optimization method based on the method of moments (MoM) for configuration design of planar metallic antenna was proposed. The candidate structure of the planar metallic antenna was approximately considered as a resistance sheet with position-dependent impedance. In this way, the electromagnetic property of the antenna can be analyzed easily by using the MoM to solve the radiation problem of the resistance sheet in a finite domain. The topology of the antenna was depicted with the distribution of the impedance related to the design parameters or relative densities. The conductive material (metal) was assumed to have zero impedance, whereas the non-conductive material was simulated as a material with a finite but large enough impedance. The interpolation function of the impedance between conductive material and non-conductive material was taken as a tangential function. The design of planar metallic antenna was optimized for maximizing the efficiency at the target frequency. The results illustrated the effectiveness of the method.

  20. Association constants of Pb2+ with binding sites of fungal biomass using metal-based titrations.

    PubMed

    Naja, G; Mustin, C; Volesky, B; Berthelin, J

    2006-01-01

    Biosorption is perceived as an alternative method for toxic heavy metal removal/recovery from aqueous effluents. This work focused on derivation of some key quantitative physico-chemical characteristics of a representative biosorbent material required for its further effective exploitation. The newly developed acid-base and metal-based titrator allowed the characterization of the chemisorption active sites of Rhizopus arrhizus biomass and the study of their metal affinity. This experimental approach, combined with an analytical method consisting of transforming the initial data enabled the calculation of the number and capacity of the reactive sites (Qads) and the metal affinity constants (Km) for lead sorption by R. arrhizus biomass. The pKm values for Rhizopus biomass varied between -3 and -6 for sites releasing no protons, -1 and 1 for sites releasing one proton, and > 8 for sites releasing two protons - combined with the Pb precipitation phenomenon. At low temperatures, the active binding site number was lower at lower lead concentrations whereas the precipitation was promoted at higher lead concentration values. Lead adsorption contributed modestly (11%) to its overall uptake and occurred at low lead concentrations onto strong and medium affinity binding sites. Micro-precipitation quickly commenced around active binding sites distinguished by their weak affinity whenever the solution lead concentrations reached 10(-6) or 10(-5) M and represented more than 85% of the total sorbed metal quantity. The work also demonstrated the usefulnes of the methodology reported here for characterizing complex biosorbent materials.

  1. Metallomics insights into the programmed cell death induced by metal-based anticancer compounds.

    PubMed

    Tan, Cai-Ping; Lu, Yi-Ying; Ji, Liang-Nian; Mao, Zong-Wan

    2014-05-01

    Since the discovery of cisplatin more than 40 years ago, enormous research efforts have been dedicated to developing metal-based anticancer agents and to elucidating the mechanisms involved in the action of these compounds. Abnormal metabolism and the evasion of apoptosis are important hallmarks of malignant transformation, and the induction of apoptotic cell death has been considered to be a main pathway by which cytotoxic metal complexes combat cancer. However, many cancers have cellular defects involving the apoptotic machinery, which results in an acquired resistance to apoptotic cell death and therefore reduced chemotherapeutic effectiveness. Over the past decade, it has been revealed that a growing number of cell death pathways induced by metal complexes are not dependent on apoptosis. Metal complexes specifically triggering these alternative cell death pathways have been identified and explored as novel cancer treatment options. In this review, we discuss recent examples of metallomics studies on the different types of cell death induced by metal-based anticancer drugs, especially on the three major forms of programmed cell death (PCD) in mammalian cells: apoptosis, autophagy and regulated necrosis, also called necroptosis.

  2. Personal exposure assessment to particulate metals using a paper-based analytical device

    NASA Astrophysics Data System (ADS)

    Cate, David; Volckens, John; Henry, Charles

    2013-03-01

    The development of a paper-based analytical device (PAD) for assessing personal exposure to particulate metals will be presented. Human exposure to metal aerosols, such as those that occur in the mining, construction, and manufacturing industries, has a significant impact on the health of our workforce, costing an estimated $10B in the U.S and causing approximately 425,000 premature deaths world-wide each year. Occupational exposure to particulate metals affects millions of individuals in manufacturing, construction (welding, cutting, blasting), and transportation (combustion, utility maintenance, and repair services) industries. Despite these effects, individual workers are rarely assessed for their exposure to particulate metals, due mainly to the high cost and effort associated with personal exposure measurement. Current exposure assessment methods for particulate metals call for an 8-hour filter sample, after which time, the filter sample is transported to a laboratory and analyzed by inductively-coupled plasma (ICP). The time from sample collection to reporting is typically weeks and costs several hundred dollars per sample. To exacerbate the issue, method detection limits suffer because of sample dilution during digestion. The lack of sensitivity hampers task-based exposure assessment, for which sampling times may be tens of minutes. To address these problems, and as a first step towards using microfluidics for personal exposure assessment, we have developed PADs for measurement of Pb, Cd, Cr, Fe, Ni, and Cu in aerosolized particulate matter.

  3. Stress corrosion cracking in canistered waste package containers: Welds and base metals

    SciTech Connect

    Huang, J.S.

    1998-03-01

    The current design of waste package containers include outer barrier using corrosion allowable material (CAM) such as A516 carbon steel and inner barrier of corrosion resistant material (CRM) such as alloy 625 and C22. There is concern whether stress corrosion cracking would occur at welds or base metals. The current memo documents the results of our analysis on this topic.

  4. Substrate Effects on the High Temperature Oxidation Behavior of a Gold-Based Braze Filler Metal

    SciTech Connect

    Weil, K. Scott; Rice, Joseph P.

    2005-06-30

    Oxidation testing was conducted on a commercial gold-based braze alloy, Gold ABA, and on zirconia and stainless steel joining couples prepared using this braze filler metal. Preliminary results reveal that both substrates play a significant role in determining the overall oxidation resistance of the brazed joint.

  5. Substrate Effects on the High Temperature Oxidation Behavior of a Gold-Based Braze Filler Metal

    SciTech Connect

    Weil, K. Scott; Rice, Joseph P.

    2005-06-01

    Oxidation testing was conducted on a commercial gold-based braze alloy, Gold ABA®, and on zirconia/stainless steel couples joined using this filler metal. Preliminary results reveal that both substrates play a significant role in determining the overall oxidation behavior of the brazed joint.

  6. Microwave-assisted solvothermal synthesis of zirconium oxide based metal-organic frameworks.

    PubMed

    Liang, Weibin; D'Alessandro, Deanna M

    2013-05-01

    Zirconium oxide based Metal-Organic Frameworks were synthesised using a rapid and efficient microwave-assisted solvothermal method that produced purer phases and higher quality crystalline products in significantly (>95%) less time than the conventional heating method. A new amino-functionalised analogue has been synthesised exclusively using this microwave-assisted methodology.

  7. Molecular magnets based on metal complexes with spin-labeled imidazoles

    NASA Astrophysics Data System (ADS)

    Fursova, E.; Romanenko, G.; Ikorskii, V.; Ovcharenko, V.

    2004-04-01

    New heterospin systems based on Cu(II) and Mn(II) complexes with spin-labeled imidazol-4-yl derivatives were synthesized. Magneto-structural correlations inherent in their nature were investigated. Key words. Nitroxides metal complexes structure magnetic properties.

  8. Characterizing Metal-Based Nanoparticles in Surface Water by Single-Particle ICPMS

    EPA Science Inventory

    Engineered metal-based nanomaterials are being used in increasing quantities in consumer and industrial products. These materials may be introduced into surface waters by a variety of paths depending on usage, and will be superimposed on concentrations of other particles containi...

  9. Single Particle ICPMS for Characterizing Metal-based Nanoparticles and Monitoring Transformation Processes in Surface Water

    EPA Science Inventory

    Engineered metal-based nanomaterials will likely be used in increasing quantities in consumer and industrial products. These may be introduced into surface waters by a variety of paths depending on usage. Other naturally occurring and anthropogenic particles containing these met...

  10. Compatibility studies of metallic materials with lithium-based oxides

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Dienst, W.

    1988-07-01

    The compatibility of Li 2O, Li 4SiO 4 and Li 2SiO 3 with the cladding materials AISI 316, 1.4914, Hastelloy X and Inconel 625 was investigated at 800-1000°C for annealing times up to 1000 h. A controlled oxygen reactivity was established by adding 1 mol% NiO per mole Li 2O to the Li-based oxides. In addition, some compatibility tests were performed at 600-900°C on Be, which is of interest as a neutron multiplier material, with Li 2SiO 3 as well as AISI 316. Li 2O accounted for the strongest cladding attack, followed by Li 4SiO 4 and Li 2SiO 3. In the absence of NiO, Li 2SiO 3 caused no chemical interactions at all. With respect to the cladding materials, there was no considerable difference in the reaction rates of AISI 316, Hastelloy X and Inconel 625. However, the steel 1.4914 was clearly more heavily attacked at and above 800°C. The compatibility of Be with Li 2SiO 3 or AISI 316 seems to be tolerable up to about 650°C. At higher temperatures a liquid Li suicide phase is formed which results in strong local attack and penetration into Li 2SiO 3.

  11. Economizer Based Data Center Liquid Cooling with Advanced Metal Interfaces

    SciTech Connect

    Timothy Chainer

    2012-11-30

    A new chiller-less data center liquid cooling system utilizing the outside air environment has been shown to achieve up to 90% reduction in cooling energy compared to traditional chiller based data center cooling systems. The system removes heat from Volume servers inside a Sealed Rack and transports the heat using a liquid loop to an Outdoor Heat Exchanger which rejects the heat to the outdoor ambient environment. The servers in the rack are cooled using a hybrid cooling system by removing the majority of the heat generated by the processors and memory by direct thermal conduction using coldplates and the heat generated by the remaining components using forced air convection to an air- to- liquid heat exchanger inside the Sealed Rack. The anticipated benefits of such energy-centric configurations are significant energy savings at the data center level. When compared to a traditional 10 MW data center, which typically uses 25% of its total data center energy consumption for cooling this technology could potentially enable a cost savings of up to $800,000-$2,200,000/year (assuming electricity costs of 4 to 11 cents per kilowatt-hour) through the reduction in electrical energy usage.

  12. Performance of Alumina-Forming Austenitic Steels, Fe-base and Ni-base alloys exposed to metal dusting environments

    SciTech Connect

    Vande Put Ep Rouaix, Aurelie; Unocic, Kinga A; Pint, Bruce A; Brady, Michael P

    2011-01-01

    A series of conventional Fe- and Ni- base, chromia- and alumina- forming alloys, and a newly developed creep-resistant, alumina-forming austenitic steel were developed and its performance relative to conventional Fe- and Ni-based chromia-forming alloys was evaluated in metal dusting environments with a range of water vapor contents. Five 500h experiments have been performed at 650 C with different water vapor contents and total pressures. Without water vapor, the Ni-base alloys showed greater resistance to metal dusting than the Fe-base alloys, including AFA. However, with 10-28% water vapor, more protective behavior was observed with the higher-alloyed materials and only small mass changes were observed. Longer exposure times are in progress to further differentiate performance.

  13. Metal-based biologically active azoles and β-lactams derived from sulfa drugs.

    PubMed

    Ebrahimi, Hossein Pasha; Hadi, Jabbar S; Almayah, Abdulelah A; Bolandnazar, Zeinab; Swadi, Ali G; Ebrahimi, Amirpasha

    2016-03-01

    Metal complexes of Schiff bases derived from sulfamethoxazole (SMZ) and sulfathiazole (STZ), converted to their β-lactam derivatives have been synthesized and experimentally characterized by elemental analysis, spectral (IR, (1)H NMR, (13)C NMR, and EI-mass), molar conductance measurements and thermal analysis techniques. The structural and electronic properties of the studied molecules were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The spectral and thermal analysis reveals that the Schiff bases act as bidentate ligands via the coordination of azomethine nitrogen to metal ions as well as the proton displacement from the phenolic group through the metal ions; therefore, Cu complexes can attain the square planner arrangement and Zn complexes have a distorted tetrahedral structure. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps. In addition, the antibacterial activities of synthesized compounds have been screened in vitro against various pathogenic bacterial species. Inspection of the results revealed that all newly synthesized complexes individually exhibit varying degrees of inhibitory effects on the growth of the tested bacterial species, therefore, they may be considered as drug candidates for bacterial pathogens. The free Schiff base ligands (1-2) exhibited a broad spectrum antibacterial activity against Gram negative Escherichia coli, Pseudomonas aeruginosa, and Proteus spp., and Gram positive Staphylococcus aureus bacterial strains. The results also indicated that the β-lactam derivatives (3-4) have high antibacterial activities on Gram positive bacteria as well as the metal complexes (5-8), particularly Zn complexes, have a significant activity against all Gram negative bacterial strains. It has been shown that the metal complexes have significantly higher activity than corresponding

  14. Metal based nanoparticles as cancer antigen delivery vehicles for macrophage based antitumor vaccine.

    PubMed

    Chattopadhyay, Sourav; Dash, Sandeep Kumar; Mandal, Debasis; Das, Balaram; Tripathy, Satyajit; Dey, Aditi; Pramanik, Panchanan; Roy, Somenath

    2016-02-10

    In the present study, we would like to evaluate the efficacy of modified metal oxide nanoparticles (NPs) as cancer antigen delivery vehicles for macrophage (MФs) based antitumor vaccine. The cobalt oxide nanoparticles (CoO NPs) were promising tools for delivery of antigens to antigen presenting cells and have induced an antitumor immune response. Synthesized CoO NPs were modified by N-phosphonomethyliminodiacetic acid (PMIDA), facilitated the conjugation of lysate antigen, i.e. cancer antigen derived from lysis of cancer cells. The cancer cell lysate antigen conjugated PMIDA-CoO NPs (Ag-PMIDA-CoO NPs) successfully activated macrophage (MФ) evident by the increasing the serum IFN-γ and TNF-α level. Immunization of mice with the Ag-PMIDA-CoO NPs constructed an efficient immunological adjuvant induced anticancer IgG responses, and increased the antibody dependent cellular cytotoxicity (ADCC) response than only lysate antigen treated group to combat the cancer cell. The nanocomplexes enhanced the anticancer CD4(+)T cell response in mice. The result showed that Ag-PMIDA-CoO NPs can stimulate the immune responses over only lysate antigens, which are the most important findings in this study. These NP-mediated Ag deliveries may significantly improve the anticancer immune response by activating MФs and may act as adjuvant and will balance the pro-inflammatory and anti-inflammatory immunoresponse. The crosstalk between the activated MФ with other immune competent cells will be monitored by measuring the cytokines which illustrate the total immunological network setups.

  15. Band-overlap metallization of BaS, BaSe and BaTe

    NASA Technical Reports Server (NTRS)

    Carlsson, A. E.; Wilkins, J. W.

    1983-01-01

    The insulator-metal transition volumes for BaS, BaSe, and BaTe are calculated for the first time, using the self-consistent augmented spherical wave technique. The metallized transition volumes are smaller than those corresponding to the NaCl yields CsCl structural transitions, but, 10 to 15% larger than those obtained by the Herzfeld dielectric theory. The calculated equilibrium energy gaps in the NaCl structure underestimate the measured ones by 50 to 60%.

  16. Friction and surface chemistry of some ferrous-base metallic glasses

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The friction properties of some ferrous-base metallic glasses were measured both in argon and in vacuum to a temperature of 350 C. The alloy surfaces were also analyzed with X-ray photoelectron spectroscopy to identify the compounds and elements present on the surface. The results of the investigation indicate that even when the surfaces of the amorphous alloys, or metallic glasses, are atomically clean, bulk contaminants such as boric oxide and silicon dioxide diffuse to the surfaces. Friction measurements in both argon and vacuum indicate that the alloys exhibit higher coefficients of friction in the crystalline state than they do in the amorphous state.

  17. Design of mid-infrared ultra-wideband metallic absorber based on circuit theory

    NASA Astrophysics Data System (ADS)

    Arik, Kamalodin; Abdollahramezani, Sajjad; Farajollahi, Saeed; Khavasi, Amin; Rejaei, Behzad

    2016-12-01

    An ultra-broadband absorber of light is proposed by using periodic array of ultra-thin metallic ribbons on top of a lossless quarter-wavelength dielectric spacer placed on a metallic reflector. We propose a fully analytical circuit model for the structure, and then the absorber is duly designed based on the impedance matching concept. As a result, normalized bandwidth of 99.5% is realized by the proposed absorbing structure in mid-infrared regime. Performing a numerical optimization algorithm, we could also reach to normalized bandwidth of 103%.

  18. Development of dithizone based fibre optic evanescent wave sensor for heavy metal ion detection in aqueous environments

    NASA Astrophysics Data System (ADS)

    Bhavsar, K.; Prabhu, R.; Pollard, P.

    2013-06-01

    Detection of highly toxic heavy metal ions requires rapid, simple, sensitive and selective detection methods in the environment. Optical fibre based sensing facilitates the remote, continuous and in-situ detection approaches in the environment. Herein, we report the development of a dithizone based fibre optic sensor with a simple procedure to detect heavy metal ions in the aqueous environment using an evanescent wave sensing approach. The chromogenic ligand dithizone and its spectral specificity with metal ions has been elaborated in this work.

  19. Synthesis, characterization and biological activity of ferrocene-based Schiff base ligands and their metal (II) complexes

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Ting; Lian, Gui-Dan; Yin, Da-Wei; Su, Bao-Jun

    Metal (II) complexes derived from S-benzyl-N-(1-ferrocenyl-3-(4-methylbenzene)acrylketone) dithiocarbazate; HL1, S-benzyl-N-(1-ferrocenyl-3-(4-chlorobenzene)acrylketone)dithiocarbazate; HL2, all the compounds were characterized using various spectroscopic techniques. The molar conductance data revealed that the chelates were non-electrolytes. IR spectra showed that the Schiff bases were coordinated to the metal ions in a bidentate manner with N, S donor sites. The ligands and their metal complexes have been screened for in vitro antibacterial, antifungal properties. The result of these studies have revealed that zinc (II) complexes 6 and 13 of both the ligands and copper (II) complexes 9 of the HL2 were observed to be the most active against all bacterial strains, antifungal activity was overall enhanced after complexation of the ligands.

  20. Synthesis, characterization and biological activity of ferrocene-based Schiff base ligands and their metal (II) complexes.

    PubMed

    Liu, Yu-Ting; Lian, Gui-Dan; Yin, Da-Wei; Su, Bao-Jun

    2013-01-01

    Metal (II) complexes derived from S-benzyl-N-(1-ferrocenyl-3-(4-methylbenzene)acrylketone) dithiocarbazate; HL(1), S-benzyl-N-(1-ferrocenyl-3-(4-chlorobenzene)acrylketone)dithiocarbazate; HL(2), all the compounds were characterized using various spectroscopic techniques. The molar conductance data revealed that the chelates were non-electrolytes. IR spectra showed that the Schiff bases were coordinated to the metal ions in a bidentate manner with N, S donor sites. The ligands and their metal complexes have been screened for in vitro antibacterial, antifungal properties. The result of these studies have revealed that zinc (II) complexes 6 and 13 of both the ligands and copper (II) complexes 9 of the HL(2) were observed to be the most active against all bacterial strains, antifungal activity was overall enhanced after complexation of the ligands.

  1. Wavelength-Tunable Microlasers Based on the Encapsulation of Organic Dye in Metal-Organic Frameworks.

    PubMed

    Wei, Yanhui; Dong, Haiyun; Wei, Cong; Zhang, Wei; Yan, Yongli; Zhao, Yong Sheng

    2016-09-01

    A wavelength-tunable microlaser is realized based on the controlled intramolecular charge transfer (ICT) process in dye-encapsulated metal-organic framework (MOF) material. The confinement effect of the MOFs is beneficial for low-threshold lasing. By effectively controlling the polarity of the MOF pores, the population distribution between the locally excited and ICT states is continuously modulated, thus achieving broadband tunable MOF-based microlasers. PMID:27314453

  2. Wavelength-Tunable Microlasers Based on the Encapsulation of Organic Dye in Metal-Organic Frameworks.

    PubMed

    Wei, Yanhui; Dong, Haiyun; Wei, Cong; Zhang, Wei; Yan, Yongli; Zhao, Yong Sheng

    2016-09-01

    A wavelength-tunable microlaser is realized based on the controlled intramolecular charge transfer (ICT) process in dye-encapsulated metal-organic framework (MOF) material. The confinement effect of the MOFs is beneficial for low-threshold lasing. By effectively controlling the polarity of the MOF pores, the population distribution between the locally excited and ICT states is continuously modulated, thus achieving broadband tunable MOF-based microlasers.

  3. A Naphthalenediimide-Based Metal-Organic Framework and Thin Film Exhibiting Photochromic and Electrochromic Properties.

    PubMed

    Xie, Yi-Xin; Zhao, Wen-Na; Li, Guo-Chang; Liu, Peng-Fei; Han, Lei

    2016-01-19

    A multifunctional metal-organic framework, NBU-3, has been explored as a 2D three-connected network based on a naphthalenediimide-based ligand. The NBU-3 crystals display photochromic properties, and NBU-3 thin films on FTO substrates exhibit electrochromic properties. NBU-3 is the first example of MOF materials containing both photochromic and electrochromic properties, which can be desirable for thin film devices. PMID:26713454

  4. Theoretical investigation of all-metal-based mushroom plasmonic metamaterial absorbers at infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Kimata, Masafumi

    2015-12-01

    High-performance wavelength-selective infrared (IR) sensors require small pixel structures, a low-thermal mass, and operation in the middle-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) regions for multicolor IR imaging. All-metal-based mushroom plasmonic metamaterial absorbers (MPMAs) were investigated theoretically and were designed to enhance the performance of wavelength-selective uncooled IR sensors. All components of the MPMAs are based on thin layers of metals such as Au without oxide insulators for increased absorption. The absorption properties of the MPMAs were investigated by rigorous coupled-wave analysis. Strong wavelength-selective absorption is realized over a wide range of MWIR and LWIR wavelengths by the plasmonic resonance of the micropatch and the narrow-gap resonance, without disturbance from the intrinsic absorption of oxide insulators. The absorption wavelength is defined mainly by the micropatch size and is longer than its period. The metal post width has less impact on the absorption properties and can maintain single-mode operation. Through-holes can be formed on the plate area to reduce the thermal mass. A small pixel size with reduced thermal mass and wideband single-mode operation can be realized using all-metal-based MPMAs.

  5. Redox activation of metal-based prodrugs as a strategy for drug delivery

    PubMed Central

    Graf, Nora

    2012-01-01

    This review provides an overview of metal-based anticancer drugs and drug candidates. In particular, we focus on metal complexes that can be activated in the reducing environment of cancer cells, thus serving as prodrugs. There are many reports of Pt and Ru complexes as redox-activatable drug candidates, but other d-block elements with variable oxidation states have a similar potential to serve as prodrugs in this manner. In this context are compounds based on Fe, Co, or Cu chemistry, which are also covered. A trend in the field of medicinal inorganic chemistry has been toward molecularly targeted, metal-based drugs obtained by functionalizing complexes with biologically active ligands. Another recent activity is the use of nanomaterials for drug delivery, exploiting passive targeting of tumors with nanosized constructs made from Au, Fe, carbon, or organic polymers. Although complexes of all of the above mentioned metals will be described, this review focuses primarily on Pt compounds, including constructs containing nanomaterials. PMID:22289471

  6. A prior-based metal artifact reduction algorithm for x-ray CT.

    PubMed

    Li, Ming; Zheng, Jian; Zhang, Tao; Guan, Yihui; Xu, Pin; Sun, Mingshan

    2015-01-01

    In computed tomography (CT), metal objects in the scanning filed are accompanied by physical phenomenon that causes projections to be inconsistent. These inconsistencies produce bright and dark shadows or streaks in analytically reconstructed images. Interpolation-based metal artifact reduction (MAR) algorithms usually replace the inconsistent projection data by estimating surrogate data based on the surrounding uncorrupted projections. In such cases, secondary artifacts will be generated when the data estimates are inaccurate. Therefore, better projection estimation is critical. This paper proposes an image post-processing strategy to create an intermediate image, named the prior image and better estimates of the surrogate data by forward projecting this prior image. The proposed method consists of three steps based on the forward projection MAR framework. First, metallic implants in the uncorrected images are segmented using a Markov random field model (MRF). Then a prior image is generated via an edge-preserving filter and a recovery procedure of the adjacent anatomical structures. Finally, the projection is completed via forward projecting this prior image and the corrected image is reconstructed by the filtered backprojection (FBP) method. Studies on both phantom and clinical data are carried out to verify the performance of the proposed method. The comparisons with other previous MAR algorithms demonstrate that the proposed MAR method performs better in metal artifact suppression and anatomical structure preservation. PMID:25882733

  7. Removing Endotoxin from Metallic Biomaterials with Compressed Carbon Dioxide-Based Mixtures

    PubMed Central

    Tarafa, Pedro J.; Williams, Eve; Panvelker, Samir; Zhang, Jian; Matthews, Michael A.

    2010-01-01

    Bacterial endotoxins have strong affinity for metallic biomaterials because of surface energy effects. Conventional depyrogenation methods may not eradicate endotoxins and may compromise biological properties and functionality of metallic instruments and implants. We evaluated the solubilization and removal of E. coli endotoxin from smooth and porous titanium (Ti) surfaces and stainless steel lumens using compressed CO2-based mixtures having water and/or surfactant Ls-54. The CO2/water/Ls-54 ternary mixture in the liquid CO2 region (25 °C and 27.6 MPa) with strong mixing removed endotoxin below detection levels. This suggests that the ternary mixture penetrates and dissolves endotoxins from all the tested substrates. The successful removal of endotoxins from metallic biomaterials with compressed CO2 is a promising cleaning technology for biomaterials and reusable medical devices. PMID:21499532

  8. Enhancing Skin Permeation of Biphenylacetic Acid (BPA) Using Salt Formation with Organic and Alkali Metal Bases.

    PubMed

    Pawar, Vijay; Naik, Prashant; Giridhar, Rajani; Yadav, Mange Ram

    2015-01-01

    In the present study, a series of organic and alkali metal salts of biphenylacetic acid (BPA) have been prepared and evaluated in vitro for percutaneous drug delivery. The physicochemical properties of BPA salts were determined using solubility measurements, DSC, and IR. The DSC thermogram and FTIR spectra confirmed the salt formation with organic and alkali metal bases. Among the series, salts with organic amines (ethanolamine, diethanolamine, triethanolamine, and diethylamine) had lowered melting points while the alkali metal salt (sodium) had a higher melting point than BPA. The in vitro study showed that salt formation improves the physicochemical properties of BPA, leading to improved permeability through the skin. Amongst all the prepared salts, ethanolamine salt (1b) showed 7.2- and 5.4-fold higher skin permeation than the parent drug at pH 7.4 and 5.0, respectively, using rat skin.

  9. Core shell hybrids based on noble metal nanoparticles and conjugated polymers: synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Fratoddi, Ilaria; Venditti, Iole; Battocchio, Chiara; Polzonetti, Giovanni; Cametti, Cesare; Russo, Maria Vittoria

    2011-12-01

    Noble metal nanoparticles of different sizes and shapes combined with conjugated functional polymers give rise to advanced core shell hybrids with interesting physical characteristics and potential applications in sensors or cancer therapy. In this paper, a versatile and facile synthesis of core shell systems based on noble metal nanoparticles (AuNPs, AgNPs, PtNPs), coated by copolymers belonging to the class of substituted polyacetylenes has been developed. The polymeric shells containing functionalities such as phenyl, ammonium, or thiol pending groups have been chosen in order to tune hydrophilic and hydrophobic properties and solubility of the target core shell hybrids. The Au, Ag, or Pt nanoparticles coated by poly(dimethylpropargylamonium chloride), or poly(phenylacetylene-co-allylmercaptan). The chemical structure of polymeric shell, size and size distribution and optical properties of hybrids have been assessed. The mean diameter of the metal core has been measured (about 10-30 nm) with polymeric shell of about 2 nm.

  10. Fatigue Strength Prediction of Drilling Materials Based on the Maximum Non-metallic Inclusion Size

    NASA Astrophysics Data System (ADS)

    Zeng, Dezhi; Tian, Gang; Liu, Fei; Shi, Taihe; Zhang, Zhi; Hu, Junying; Liu, Wanying; Ouyang, Zhiying

    2015-12-01

    In this paper, the statistics of the size distribution of non-metallic inclusions in five drilling materials were performed. Based on the maximum non-metallic inclusion size, the fatigue strength of the drilling material was predicted. The sizes of non-metallic inclusions in drilling materials were observed to follow the inclusion size distribution rule. Then the maximum inclusion size in the fatigue specimens was deduced. According to the prediction equation of the maximum inclusion size and fatigue strength proposed by Murakami, fatigue strength of drilling materials was obtained. Moreover, fatigue strength was also measured through rotating bending tests. The predicted fatigue strength was significantly lower than the measured one. Therefore, according to the comparison results, the coefficients in the prediction equation were revised. The revised equation allowed the satisfactory prediction results of fatigue strength of drilling materials at the fatigue life of 107 rotations and could be used in the fast prediction of fatigue strength of drilling materials.

  11. Ruthenium based metals using atomic vapor deposition for gate electrode applications

    NASA Astrophysics Data System (ADS)

    Choi, Changhwan; Ando, Takashi; Narayanan, Vijay

    2011-02-01

    The impacts of ruthenium-based metal gate electrodes (Ru,RuOx,RuSiOx) with atomic vapor deposition (AVD) on flatband voltage (VFB) and equivalent oxide thickness (EOT) are demonstrated using a low temperature (<400 °C) process. Increasing thickness of Ru and RuOx exhibits higher VFB, attributed to filling oxygen vacancies [Vo] in high-k gate dielectric with oxygen supplied from AVD metal gate electrodes upon annealing. Ru is efficient to attain a higher work-function and thinner EOT compared to RuOx and RuSiOx. Subsequent physical-vapor-deposition (PVD) TiN capping on AVD metals blocks oxygen out-diffusion, leading to higher VFB than PVD W or AVD TiN capping.

  12. Chromophore-Based Luminescent Metal-Organic Frameworks as Lighting Phosphors.

    PubMed

    Lustig, William P; Wang, Fangming; Teat, Simon J; Hu, Zhichao; Gong, Qihan; Li, Jing

    2016-08-01

    Energy-efficient solid-state-lighting (SSL) technologies are rapidly developing, but the lack of stable, high-performance rare-earth free phosphors may impede the growth of the SSL market. One possible alternative is organic phosphor materials, but these can suffer from lower quantum yields and thermal instability compared to rare-earth phosphors. However, if luminescent organic chromophores can be built into a rigid metal-organic framework, their quantum yields and thermal stability can be greatly improved. This Forum Article discusses the design of a group of such chromophore-based luminescent metal-organic frameworks with exceptionally high performance and rational control of the important parameters that influence their emission properties, including electronic structures of chromophore, coligands, metal ions, and guest molecules. PMID:27244591

  13. The preparation of ceramic nickel metal microcompostes using an ammonium soap solution-based method

    SciTech Connect

    Clark, N.A.; Robinson, D.A.

    1995-12-01

    Robinson and Maginnis have developed a process for the preparation of metal ceramic composites using an ammonium soap solution-based route. Their work focused on the preparation of silver/YBa{sub 2}Cu{sub 3}O{sub 7-x} composites. We have extended their work to prepare nickel ceramic microcomposites. In this method, an ammonium soap of 2-ethylhexanoate is used to prepare a nickel metallorganic in solution that is rapidly gelled or precipitated around a suspended and dispersed ceramic. This is followed by a low-temperature heat treatment in hydrogen to produce the desired composite. By varying the heat treatment, the composite can be altered from metal-coated ceramic grains to finely dispersed metal in a ceramic matrix. The experimental preparation of this material will be presented along with optical micrographs and spectroscopic data.

  14. Change of immitance during electroforming and resistive switching in the metal-insulator-metal memristive structures based on SiO x

    NASA Astrophysics Data System (ADS)

    Tikhov, S. V.; Gorshkov, O. N.; Antonov, I. N.; Kasatkin, A. P.; Korolev, D. S.; Belov, A. I.; Mikhaylov, A. N.; Tetel'baum, D. I.

    2016-05-01

    The change of the immitance of the metal-insulator-metal memristive structures based on SiOx, which is observed during electroforming and resistive switching, confirms the formation of conducting channels (filaments) in the insulator during forming and their rupture upon a transition of the structure to a highresistance state. The observed switching of the differential capacitance and conductivity synchronously with the switching of current (resistance) can substantially extend the functional applications of memristive devices of this type.

  15. Synthesis and structures of transition metal pacman complexes of heteroditopic Schiff-base pyrrole macrocycles.

    PubMed

    Leeland, James W; Finn, Colin; Escuyer, Bérengère; Kawaguchi, Hiroyuki; Nichol, Gary S; Slawin, Alexandra M Z; Love, Jason B

    2012-12-01

    A series of polydentate dual-compartment, Schiff-base pyrrole macrocycles has been prepared through the straightforward Lewis acid catalysed [1 + 1] condensation reactions between ONO or O(5)-linked aryldiamines and dipyrromethane dialdehydes. These macrocycles display hydrogen-bond acceptor and donor properties and provide distinct N(4) and O(5)/ONO donor sets for metallation reactions, so forming alkali, alkaline earth, and transition metal complexes that were characterised spectroscopically and crystallographically. While the conformationally flexible O(5) donor set allows the formation of helical potassium salt structures, the transition metal complexes of all variants of these macrocycles invariably adopt wedged, Pacman-shaped structures in which the metal is bound in the pyrrole-imine N(4) donor set, so leaving the ONO/O(5) donor set pendant and apical. In some cases (V, Cr, and Co), this proximate combination of Lewis acid binding site and hydrogen bond acceptor facilitates the coordination of water within the molecular cleft; alternatively, direct interaction between the pendant arm and the metal is seen (e.g. Ti). Higher order [2 + 2] macrocycles were also prepared as minor, inseparable by-products of cyclisation, and Fe(2), Mn(2), and Co(2) complexes of these larger macrocycles were found to adopt binuclear helical structures by X-ray crystallography.

  16. Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes.

    PubMed

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-29

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation. PMID:27168177

  17. Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes.

    PubMed

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-29

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation.

  18. Structure vs chemistry: friction and wear of Pt-based metallic surfaces.

    PubMed

    Caron, A; Louzguine-Luzguin, D V; Bennewitz, R

    2013-11-13

    In comparison of a Pt57.5Cu14.7Ni5.3P22.5 metallic glass with a Pt(111) single crystal we find that wearless friction is determined by chemistry through bond formation alloying, while wear is determined by structure through plasticity mechanisms. In the wearless regime, friction is affected by the chemical composition of the counter body and involves the formation of a liquid-like neck and interfacial alloying. The wear behavior of Pt-based metallic surfaces is determined by their structural properties and corresponding mechanisms for plastic deformation. In the case of Pt(111) wear occurs by dislocation-mediated homogeneous plastic deformation. In contrast the wear of Pt57.5Cu14.7Ni5.3P22.5 metallic glass occurs through localized plastic deformation in shear bands that merge together in a single shear zone above a critical load and corresponds to the shear softening of metallic glasses. These results open a new route in the control of friction and wear of metals and are relevant for the development of self-lubricated and wear-resistant mechanical devices.

  19. Resistance to sulfur poisoning of Ni-based alloy with coinage (IB) metals

    NASA Astrophysics Data System (ADS)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2015-12-01

    The poisoning effects of S atom on the (1 0 0), (1 1 0) and (1 1 1) metal surfaces of pure Ni and Ni-based alloy with IB (coinage) metals (Cu, Ag, Au) are systematically studied. The effects of IB metal dopants on the S poisoning features are analyzed combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that introducing IB doping metals into Ni surface can shift the d-band center downward from the Fermi level and weaken the adsorption of S on the (1 0 0) and (1 1 0) surfaces, and the S tolerance ability increases in the order of Ni, Cu/Ni, Ag/Ni and Au/Ni. Nevertheless, on the (1 1 1) surface, the S tolerance ability increases in the order of Ag/Ni (or Cu/Ni), Ni, and Au/Ni. When we increase the coverage of the IB metal dopants, we found that not only Au, but Cu and Ag can increase its S tolerance. We therefore propose that alloying can increase its S tolerance and alloying with Au would be a better way to increase the resistance to sulfur poisoning of the Ni anode as compared with the pure Ni and the Ag- or, Cu-doped Ni materials.

  20. Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions.

    PubMed

    Yang, Shengyuan; Wu, Chao; Tan, Hui; Wu, Yan; Liao, Shuzhen; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2013-01-01

    In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors. PMID:23214408

  1. Bioaccessibility of metals in dust from the indoor environment: application of a physiologically based extraction test.

    PubMed

    Turner, Andrew; Ip, Ka-Hei

    2007-11-15

    A physiologically based extraction test, simulating sequential digestion in the stomach and intestine, has been applied to dust samples collected from various domestic and working settings to define bioaccessible concentrations of metals (Al, Ca, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, U, Zn) in the indoor environment. With the exception of Ca, Cd, and Zn in the stomach phase, mean bioaccessibilities (relative to respective total metal concentrations) were less than 50%. For a given metal, bioaccessibility in either phase was variable among samples but, in many cases, displayed an inverse dependence on total concentration. This suggests that, to a good approximation, variations in both metal contamination and accessibility in the indoor environment arise from variable proportions of metal-rich particulates of low digestibility. Compared with accessibility in the stomach, accessibility in the more alkaline, carbonate-rich intestine was either lower (Al, Ca, Cd, Mn, Ni, Sn, Pb, Zn), similar (Co, Cu, Fe) or greater (Cr, U). We attribute these observations to precipitation and/or readsorption in the intestine, stabilization by complexation, or anion-like adsorption of negatively charged, polyatomic species, respectively.

  2. 76 FR 7558 - GBC Metals LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-10

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission GBC Metals LLC; Supplemental Notice That Initial Market-Based Rate Filing...-referenced proceeding of GBC Metals LLC's application for market-based rate authority, with an...

  3. Powder-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2016-05-03

    A powder-based adsorbent and a related method of manufacture are provided. The powder-based adsorbent includes polymer powder with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the powder-based adsorbent includes irradiating polymer powder, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Powder-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  4. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  5. In vivo evaluation of a Ti-based bulk metallic glass alloy bar.

    PubMed

    Kokubun, Ryo; Wang, Wei; Zhu, Shengli; Xie, Guoqiang; Ichinose, Shizuko; Itoh, Soichiro; Takakuda, Kazuo

    2015-01-01

    Ti-based bulk metallic glasses are reported with high strength, low Young modulus and high corrosion resistance, suggesting their potentials in biomedical applications. However a thorough in vivo evaluation of its biocompatibilities has not been conducted yet. In this study, we implanted bars of Ti-based bulk metallic glass in the femoral bone of rats, followed up local tissue reaction as well as its component ions' diffusion in local area and whole body. The Ti-based BMG (Ti40Zr10Cu34Pd14Sn2) alloy exhibited favorable features of both high strength and high elasticity. In vivo implant evaluation showed that it has a good tissue compatibility, equivalent bone integration and bonding ability with Ti sample. No component ion diffusion was detected up to 3 months post implantation. The possibility and efficacy of its use for bone implant is confirmed. Thus further long term implant study is recommended.

  6. 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.

  7. Graphene-Based Microbots for Toxic Heavy Metal Removal and Recovery from Water.

    PubMed

    Vilela, Diana; Parmar, Jemish; Zeng, Yongfei; Zhao, Yanli; Sánchez, Samuel

    2016-04-13

    Heavy metal contamination in water is a serious risk to the public health and other life forms on earth. Current research in nanotechnology is developing new nanosystems and nanomaterials for the fast and efficient removal of pollutants and heavy metals from water. Here, we report graphene oxide-based microbots (GOx-microbots) as active self-propelled systems for the capture, transfer, and removal of a heavy metal (i.e., lead) and its subsequent recovery for recycling purposes. Microbots' structure consists of nanosized multilayers of graphene oxide, nickel, and platinum, providing different functionalities. The outer layer of graphene oxide captures lead on the surface, and the inner layer of platinum functions as the engine decomposing hydrogen peroxide fuel for self-propulsion, while the middle layer of nickel enables external magnetic control of the microbots. Mobile GOx-microbots remove lead 10 times more efficiently than nonmotile GOx-microbots, cleaning water from 1000 ppb down to below 50 ppb in 60 min. Furthermore, after chemical detachment of lead from the surface of GOx-microbots, the microbots can be reused. Finally, we demonstrate the magnetic control of the GOx-microbots inside a microfluidic system as a proof-of-concept for automatic microbots-based system to remove and recover heavy metals.

  8. Flexible transparent metal/polymer composite materials based on optical resonant laminate structures.

    PubMed

    Narayanan, Sudarshan; Choi, Jihoon; Porter, Lisa; Bockstaller, Michael R

    2013-05-22

    Suitable design of periodic metal/polymer composite materials is shown to facilitate resonant tunneling of light at absorbing wavelengths and to provide a means to significantly reduce optical absorption losses in polymer-based metallodielectric composite structures. The conditions for resonant tunneling are established based on the concept of "photonic band edge alignment" in 1D-periodic systems. For the particular case of a four-layer gold/polystyrene laminate structure, it is shown that the matching of the lower band edge of the 1D-periodic structure with the plasma frequency of the metal component facilitates the increase of optical transmission by about 500% as compared to monolithic film structures of equal total thickness. The effect of sheet thickness on the optical properties of thin metal films is determined and shown to be an important prerequisite for the reliable prediction of resonant metallodielectric structures. The resonant 1D-periodic metal/polymer heterostructures are shown to retain the flexural stability of the polymer matrix and thus could find application as flexible transparent conductors in areas such as "plastic electronics".

  9. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases

    NASA Astrophysics Data System (ADS)

    Hanif, Muhammad; Chohan, Zahid H.

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L1-L3 have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

  10. A highly efficient degradation mechanism of methyl orange using Fe-based metallic glass powders

    PubMed Central

    Xie, Shenghui; Huang, Ping; Kruzic, Jamie J.; Zeng, Xierong; Qian, Haixia

    2016-01-01

    A new Fe-based metallic glass with composition Fe76B12Si9Y3 (at. %) is found to have extraordinary degradation efficiency towards methyl orange (MO, C14H14N3SO3) in strong acidic and near neutral environments compared to crystalline zero-valent iron (ZVI) powders and other Fe-based metallic glasses. The influence of temperature (294–328 K) on the degradation reaction rate was measured using ball-milled metallic glass powders revealing a low thermal activation energy barrier of 22.6 kJ/mol. The excellent properties are mainly attributed to the heterogeneous structure consisting of local Fe-rich and Fe-poor atomic clusters, rather than the large specific surface and strong residual stress in the powders. The metallic glass powders can sustain almost unchanged degradation efficiency after 13 cycles at room temperature, while a drop in degradation efficiency with further cycles is attributed to visible surface oxidation. Triple quadrupole mass spectrometry analysis conducted during the reaction was used to elucidate the underlying degradation mechanism. The present findings may provide a new, highly efficient and low cost commercial method for azo dye wastewater treatment. PMID:26902824

  11. Photolithography-Based Patterning of Liquid Metal Interconnects for Monolithically Integrated Stretchable Circuits.

    PubMed

    Park, Chan Woo; Moon, Yu Gyeong; Seong, Hyejeong; Jung, Soon Won; Oh, Ji-Young; Na, Bock Soon; Park, Nae-Man; Lee, Sang Seok; Im, Sung Gap; Koo, Jae Bon

    2016-06-22

    We demonstrate a new patterning technique for gallium-based liquid metals on flat substrates, which can provide both high pattern resolution (∼20 μm) and alignment precision as required for highly integrated circuits. In a very similar manner as in the patterning of solid metal films by photolithography and lift-off processes, the liquid metal layer painted over the whole substrate area can be selectively removed by dissolving the underlying photoresist layer, leaving behind robust liquid patterns as defined by the photolithography. This quick and simple method makes it possible to integrate fine-scale interconnects with preformed devices precisely, which is indispensable for realizing monolithically integrated stretchable circuits. As a way for constructing stretchable integrated circuits, we propose a hybrid configuration composed of rigid device regions and liquid interconnects, which is constructed on a rigid substrate first but highly stretchable after being transferred onto an elastomeric substrate. This new method can be useful in various applications requiring both high-resolution and precisely aligned patterning of gallium-based liquid metals. PMID:27250997

  12. Photolithography-Based Patterning of Liquid Metal Interconnects for Monolithically Integrated Stretchable Circuits.

    PubMed

    Park, Chan Woo; Moon, Yu Gyeong; Seong, Hyejeong; Jung, Soon Won; Oh, Ji-Young; Na, Bock Soon; Park, Nae-Man; Lee, Sang Seok; Im, Sung Gap; Koo, Jae Bon

    2016-06-22

    We demonstrate a new patterning technique for gallium-based liquid metals on flat substrates, which can provide both high pattern resolution (∼20 μm) and alignment precision as required for highly integrated circuits. In a very similar manner as in the patterning of solid metal films by photolithography and lift-off processes, the liquid metal layer painted over the whole substrate area can be selectively removed by dissolving the underlying photoresist layer, leaving behind robust liquid patterns as defined by the photolithography. This quick and simple method makes it possible to integrate fine-scale interconnects with preformed devices precisely, which is indispensable for realizing monolithically integrated stretchable circuits. As a way for constructing stretchable integrated circuits, we propose a hybrid configuration composed of rigid device regions and liquid interconnects, which is constructed on a rigid substrate first but highly stretchable after being transferred onto an elastomeric substrate. This new method can be useful in various applications requiring both high-resolution and precisely aligned patterning of gallium-based liquid metals.

  13. Tailoring the optical properties of wide-bandgap based microcavities via metal films

    SciTech Connect

    Sebald, K. Rahman, SK. S.; Cornelius, M.; Gutowski, J.; Klein, T.; Klembt, S.; Kruse, C.; Hommel, D.

    2015-08-10

    We report on the tuning of the optical properties of II-VI-material-based microcavity samples, which is achieved by depositing Ag films on top of the structures. The micro-reflectivity spectra show a spectral shift of the sample resonance dependent on the metal layer thickness. By comparison of the experimental findings with the theoretical calculations applying the transfer matrix method on a metal-dielectric mirror structure, the influence of the metal layer particularly with regard to its partial oxidation was explored. Tamm plasmon modes are created at the interface between an open cavity with three ZnSe quantum wells and a metal layer on top. When tuning the excitonic emission relative to the mode by changing the sample temperature, an anticrossing of the resonances was observed. This is a clear indication that the strong coupling regime has been achieved in that sample configuration yielding a Rabi splitting of 18.5 meV. These results are promising for the realization of polariton-based optical devices with a rather simple sample configuration.

  14. A highly efficient degradation mechanism of methyl orange using Fe-based metallic glass powders

    NASA Astrophysics Data System (ADS)

    Xie, Shenghui; Huang, Ping; Kruzic, Jamie J.; Zeng, Xierong; Qian, Haixia

    2016-02-01

    A new Fe-based metallic glass with composition Fe76B12Si9Y3 (at. %) is found to have extraordinary degradation efficiency towards methyl orange (MO, C14H14N3SO3) in strong acidic and near neutral environments compared to crystalline zero-valent iron (ZVI) powders and other Fe-based metallic glasses. The influence of temperature (294–328 K) on the degradation reaction rate was measured using ball-milled metallic glass powders revealing a low thermal activation energy barrier of 22.6 kJ/mol. The excellent properties are mainly attributed to the heterogeneous structure consisting of local Fe-rich and Fe-poor atomic clusters, rather than the large specific surface and strong residual stress in the powders. The metallic glass powders can sustain almost unchanged degradation efficiency after 13 cycles at room temperature, while a drop in degradation efficiency with further cycles is attributed to visible surface oxidation. Triple quadrupole mass spectrometry analysis conducted during the reaction was used to elucidate the underlying degradation mechanism. The present findings may provide a new, highly efficient and low cost commercial method for azo dye wastewater treatment.

  15. Graphene-Based Microbots for Toxic Heavy Metal Removal and Recovery from Water

    PubMed Central

    2016-01-01

    Heavy metal contamination in water is a serious risk to the public health and other life forms on earth. Current research in nanotechnology is developing new nanosystems and nanomaterials for the fast and efficient removal of pollutants and heavy metals from water. Here, we report graphene oxide-based microbots (GOx-microbots) as active self-propelled systems for the capture, transfer, and removal of a heavy metal (i.e., lead) and its subsequent recovery for recycling purposes. Microbots’ structure consists of nanosized multilayers of graphene oxide, nickel, and platinum, providing different functionalities. The outer layer of graphene oxide captures lead on the surface, and the inner layer of platinum functions as the engine decomposing hydrogen peroxide fuel for self-propulsion, while the middle layer of nickel enables external magnetic control of the microbots. Mobile GOx-microbots remove lead 10 times more efficiently than nonmotile GOx-microbots, cleaning water from 1000 ppb down to below 50 ppb in 60 min. Furthermore, after chemical detachment of lead from the surface of GOx-microbots, the microbots can be reused. Finally, we demonstrate the magnetic control of the GOx-microbots inside a microfluidic system as a proof-of-concept for automatic microbots-based system to remove and recover heavy metals. PMID:26998896

  16. Simultaneous detection of multiple DNA targets based on encoding metal ions.

    PubMed

    Zheng, Lichun; Li, Xiaoyan; Liu, Panpan; Wu, Guofan; Lu, Xiaoquan; Liu, Xiuhui

    2014-02-15

    We present a novel strategy for simultaneous electrochemical detection of multiple DNA targets based on the use of different encoding metal ions as tags. The principle of this scheme is that metal ions bound to metallothionein (MT) molecules can be released down after hybridization with DNA targets and then be detected by stripping voltammetry. The novel detection probes, ssDNA/MT conjugates, covered with different metal ions were synthesized for the first time, then three encoding metal ions (Zn(2+), Cd(2+), and Pb(2+)) were used to differentiate the signals of three virus DNA due to their well-defined anodic stripping peaks at -1.13 V (Zn), -0.78 V (Cd), and -0.52 V (Pb) at BiFE, respectively. The anodic peak currents increased linearly with the concentrations of DNA targets in the range from 0.1 nM to 10nM with a detection limit of 33 pM. In addition, the one-base mismatched target was effectively discriminated from the complementary target. The described results demonstrated that this method possesses high sensitivity and selectivity for multi-target DNA assay and has great potential in applications for detection of even more targets in biological assays, particularly immunoassays.

  17. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases.

    PubMed

    Hanif, Muhammad; Chohan, Zahid H

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L(1)-L(3) have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination. PMID:23277183

  18. Graphene-Based Microbots for Toxic Heavy Metal Removal and Recovery from Water.

    PubMed

    Vilela, Diana; Parmar, Jemish; Zeng, Yongfei; Zhao, Yanli; Sánchez, Samuel

    2016-04-13

    Heavy metal contamination in water is a serious risk to the public health and other life forms on earth. Current research in nanotechnology is developing new nanosystems and nanomaterials for the fast and efficient removal of pollutants and heavy metals from water. Here, we report graphene oxide-based microbots (GOx-microbots) as active self-propelled systems for the capture, transfer, and removal of a heavy metal (i.e., lead) and its subsequent recovery for recycling purposes. Microbots' structure consists of nanosized multilayers of graphene oxide, nickel, and platinum, providing different functionalities. The outer layer of graphene oxide captures lead on the surface, and the inner layer of platinum functions as the engine decomposing hydrogen peroxide fuel for self-propulsion, while the middle layer of nickel enables external magnetic control of the microbots. Mobile GOx-microbots remove lead 10 times more efficiently than nonmotile GOx-microbots, cleaning water from 1000 ppb down to below 50 ppb in 60 min. Furthermore, after chemical detachment of lead from the surface of GOx-microbots, the microbots can be reused. Finally, we demonstrate the magnetic control of the GOx-microbots inside a microfluidic system as a proof-of-concept for automatic microbots-based system to remove and recover heavy metals. PMID:26998896

  19. A 1-dodecanethiol-based phase transfer protocol for the highly efficient extraction of noble metal ions from aqueous phase.

    PubMed

    Chen, Dong; Cui, Penglei; Cao, Hongbin; Yang, Jun

    2015-03-01

    A 1-dodecanethiol-based phase-transfer protocol is developed for the extraction of noble metal ions from aqueous solution to a hydrocarbon phase, which calls for first mixing the aqueous metal ion solution with an ethanolic solution of 1-dodecanethiol, and then extracting the coordination compounds formed between noble metal ions and 1-dodecanethiol into a non-polar organic solvent. A number of characterization techniques, including inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis demonstrate that this protocol could be applied to extract a wide variety of noble metal ions from water to dichloromethane with an efficiency of >96%, and has high selectivity for the separation of the noble metal ions from other transition metals. It is therefore an attractive alternative for the extraction of noble metals from water, soil, or waste printed circuit boards.

  20. Graphene oxide-based hydrogels to make metal nanoparticle-containing reduced graphene oxide-based functional hybrid hydrogels.

    PubMed

    Adhikari, Bimalendu; Biswas, Abhijit; Banerjee, Arindam

    2012-10-24

    In this study, stable supramolecular hydrogels have been obtained from the assembly of graphene oxide (GO) in presence of polyamines including tris(aminoethyl)amine, spermine, and spermidine [biologically active molecule]. One of these hydrogels has been well characterized by various techniques including field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD) study, and Raman spectroscopy. TEM and AFM studies of one of these hydrogels have revealed the presence of a network structure of cross-linked nanosheets. This suggests the supramolecular assembly of GO in the presence of polyamines using the acid-base type electrostatic interaction. In presence of a mild reducing agent (vitamin C), one of these GO hydrogels has been transformed into a reduced graphene oxide (RGO)-based hydrogel by a simple in situ reduction of GO sheets within the hydrogel matrix. Moreover, noble metal nanoparticle containing RGO based hybrid hydrogels have been obtained using in situ and simultaneous co-reduction of GO and noble metal precursors within the GO gel matrix. The elegance of this method is in situ, "green chemical" and simultaneous reduction of GO and metal salts within the hydrogel matrix to form RGO-based hybrid gel and concomitant stabilization of metal nanoparticles (MNPs) within the gel system. The nascently formed MNPs are homogeneously and uniformly distributed on the surface of the RGO nanosheets within the hybrid gel. Interestingly, this MNP containing RGO-based hybrid hydrogel matrix acts as a potential catalyst for the reduction of aromatic nitro to amino group. The catalyst (hybrid gel matrix) can be separated easily after the reaction and reused several times. PMID:22970805

  1. Multiplexed Paper Analytical Device for Quantification of Metals using Distance-Based Detection

    PubMed Central

    Cate, David M.; Noblitt, Scott D.; Volckens, John; Henry, Charles S.

    2015-01-01

    Exposure to metal-containing aerosols has been linked with adverse health outcomes for almost every organ in the human body. Commercially available techniques for quantifying particulate metals are time-intensive, laborious, and expensive; often sample analysis exceeds $100. We report a simple technique, based upon a distance-based detection motif, for quantifying metal concentrations of Ni, Cu, and Fe in airborne particulate matter using microfluidic paper-based analytical devices. Paper substrates are used to create sensors that are self-contained, self-timing, and require only a drop of sample for operation. Unlike other colorimetric approaches in paper microfluidics that rely on optical instrumentation for analysis, with distance-based detection, analyte is quantified visually based on the distance of a colorimetric reaction, similar to reading temperature on a thermometer. To demonstrate the effectiveness of this approach, Ni, Cu, and Fe were measured individually in single-channel devices; detection limits as low as 0.1, 0.1, and 0.05 µg were reported for Ni, Cu, and Fe. Multiplexed analysis of all three metals was achieved with detection limits of 1, 5, and 1 µg for Ni, Cu, and Fe. We also extended the dynamic range for multi-analyte detection by printing concentration gradients of colorimetric reagents using an off the shelf inkjet printer. Analyte selectivity was demonstrated for common interferences. To demonstrate utility of the method, Ni, Cu, and Fe were measured from samples of certified welding fume; levels measured with paper sensors matched known values determined gravimetrically. PMID:26009988

  2. Impact Ignition and Combustion Behavior of Amorphous Metal-Based Reactive Composites

    NASA Astrophysics Data System (ADS)

    Mason, Benjamin; Groven, Lori; Son, Steven

    2013-06-01

    Recently published molecular dynamic simulations have shown that metal-based reactive powder composites consisting of at least one amorphous component could lead to improved reaction performance due to amorphous materials having a zero heat of fusion, in addition to having high energy densities and potential uses such as structural energetic materials and enhanced blast materials. In order to investigate the feasibility of these systems, thermochemical equilibrium calculations were performed on various amorphous metal/metalloid based reactive systems with an emphasis on commercially available or easily manufactured amorphous metals, such as Zr and Ti based amorphous alloys in combination with carbon, boron, and aluminum. Based on the calculations and material availability material combinations were chosen. Initial materials were either mixed via a Resodyn mixer or mechanically activated using high energy ball milling where the microstructure of the milled material was characterized using x-ray diffraction, optical microscopy and scanning electron microscopy. The mechanical impact response and combustion behavior of select reactive systems was characterized using the Asay shear impact experiment where impact ignition thresholds, ignition delays, combustion velocities, and temperatures were quantified, and reported. Funding from the Defense Threat Reduction Agency (DTRA), Grant Number HDTRA1-10-1-0119. Counter-WMD basic research program, Dr. Suhithi M. Peiris, program director is gratefully acknowledged.

  3. Microstructural characterization of Mg-based bulk metallic glass and nanocomposite

    SciTech Connect

    Babilas, Rafał; Nowosielski, Ryszard; Pawlyta, Mirosława; Fitch, Andy; Burian, Andrzej

    2015-04-15

    New magnesium-based bulk metallic glasses Mg{sub 60}Cu{sub 30}Y{sub 10} have been prepared by pressure casting. Glassy alloys were successfully annealed to become nanocomposite containing 200 nm crystallites in an amorphous matrix. The microstructure of bulk glassy alloy and nanocomposite obtained during heat treatment was examined by X-ray diffraction and scanning and high-resolution electron microscopy. Metallic glass has been also studied to explain the structural characteristics by the reverse Monte Carlo (RMC) modeling based on the diffraction data. The HRTEM images allow to indicate some medium-range order (MRO) regions about 2–3 nm in size and formation of local atomic clusters. The RMC modeling results confirmed some kinds of short range order (SRO) structures. It was found that the structure of bulk metallic glass formed by the pressure casting is homogeneous. The composite material contained very small particles in the amorphous matrix. Homogeneous glassy alloy had better corrosion resistance than a composite containing nanocrystalline particles in a glassy matrix. - Highlights: • RMC modeling demonstrates some kinds of SRO structures in Mg-based BMGs. • HRTEM indicated MRO regions about 2–3 nm and SRO regions about 0.5 nm in size. • Mg-based glassy alloys were successfully annealed to become nanocomposite material. • Crystalline particles have spherical morphology with an average diameter of 200 nm. • Glassy alloy had higher corrosion resistance than a nanocomposite sample.

  4. Simultaneous and integrated neutron-based techniques for material analysis of a metallic ancient flute

    NASA Astrophysics Data System (ADS)

    Festa, G.; Pietropaolo, A.; Grazzi, F.; Sutton, L. F.; Scherillo, A.; Bognetti, L.; Bini, A.; Barzagli, E.; Schooneveld, E.; Andreani, C.

    2013-09-01

    A metallic 19th century flute was studied by means of integrated and simultaneous neutron-based techniques: neutron diffraction, neutron radiative capture analysis and neutron radiography. This experiment follows benchmark measurements devoted to assessing the effectiveness of a multitask beamline concept for neutron-based investigation on materials. The aim of this study is to show the potential application of the approach using multiple and integrated neutron-based techniques for musical instruments. Such samples, in the broad scenario of cultural heritage, represent an exciting research field. They may represent an interesting link between different disciplines such as nuclear physics, metallurgy and acoustics.

  5. Recent advances in porous polyoxometalate-based metal-organic framework materials.

    PubMed

    Du, Dong-Ying; Qin, Jun-Sheng; Li, Shun-Li; Su, Zhong-Min; Lan, Ya-Qian

    2014-07-01

    Polyoxometalate (POM)-based metal-organic framework (MOF) materials contain POM units and generally generate MOF materials with open networks. POM-based MOF materials, which utilize the advantages of both POMs and MOFs, have received increasing attention, and much effort has been devoted to their preparation and relevant applications over the past few decades. They have good prospects in catalysis owing to the electronic and physical properties of POMs that are tunable by varying constituent elements. In this review, we present recent developments in porous POM-based MOF materials, including their classification, synthesis strategies, and applications, especially in the field of catalysis. PMID:24676127

  6. Effect of embedded metal nanocrystals on the resistive switching characteristics in NiN-based resistive random access memory cells

    SciTech Connect

    Yun, Min Ju; Kim, Hee-Dong; Man Hong, Seok; Hyun Park, Ju; Su Jeon, Dong; Geun Kim, Tae

    2014-03-07

    The metal nanocrystals (NCs) embedded-NiN-based resistive random access memory cells are demonstrated using several metal NCs (i.e., Pt, Ni, and Ti) with different physical parameters in order to investigate the metal NC's dependence on resistive switching (RS) characteristics. First, depending on the electronegativity of metal, the size of metal NCs is determined and this affects the operating current of memory cells. If metal NCs with high electronegativity are incorporated, the size of the NCs is reduced; hence, the operating current is reduced owing to the reduced density of the electric field around the metal NCs. Second, the potential wells are formed by the difference of work function between the metal NCs and active layer, and the barrier height of the potential wells affects the level of operating voltage as well as the conduction mechanism of metal NCs embedded memory cells. Therefore, by understanding these correlations between the active layer and embedded metal NCs, we can optimize the RS properties of metal NCs embedded memory cells as well as predict their conduction mechanisms.

  7. Normal metal tunnel junction-based superconducting quantum interference proximity transistor

    SciTech Connect

    D'Ambrosio, Sophie Meissner, Martin; Blanc, Christophe; Ronzani, Alberto; Giazotto, Francesco

    2015-09-14

    We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current via the application of an external magnetic field. This results into a drastic suppression of power dissipation which can be as low as a few ∼10{sup −17} W. In this context, the interferometer allows an improvement of up to four orders of magnitude with respect to earlier SQUIPT designs and makes it ideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has been recently predicted to be the enabling candidate for the implementation of coherent caloritronic devices based on proximity effect.

  8. Metal-based drugs for malaria, trypanosomiasis and leishmaniasis: recent achievements and perspectives.

    PubMed

    Navarro, Maribel; Gabbiani, Chiara; Messori, Luigi; Gambino, Dinorah

    2010-12-01

    Tropical diseases today constitute a major health problem and a big challenge for drug discovery. Because of the limited arsenal of effective antiparasitic agents and the frequent appearance of chemoresistance, there is an urgent and continuous need to develop new drugs against these ailments. Metal compounds still offer excellent opportunities to find new 'leads' against the major protozoan diseases such as malaria, leishmaniasis and trypanosomiasis. A few metal-based drugs are already available in this therapeutic area, and others are currently being developed. Recent progress in parasite genomics and the identification of a few biomolecular targets hold great promise for the discovery of new 'mechanism-based' antiparasitic metallodrugs. The trends and perspectives for this exciting research field are outlined here.

  9. Effects of metal contacts and dopants on the performance of ZnO-based memristive devices

    NASA Astrophysics Data System (ADS)

    Qiu, Julia; Shih, Andy; Zhou, Wendi; Mi, Zetian; Shih, Ishiang

    2011-07-01

    We have performed a detailed investigation of the fabrication and switching characteristics of ZnO-based memristive devices. The effects of doping and various metal contacts have been studied. It is observed that, with the use of Al metal contacts and ZnO:Al layers, relatively high ROFF/RON ratios of 200 can be achieved. Much improved device stability and reproducibility, on the other hand, can be realized by using either nominally undoped or Mg-doped ZnO memristive layers. The experimental results may be well explained by an oxygen vacancy formation and migration model. The present work represents an important step in realizing high performance ZnO-based memristive devices for future nonvolatile memory applications.

  10. Recent progress in studies of metallic nickel and nickel-based nanoparticles' genotoxicity and carcinogenicity.

    PubMed

    Magaye, Ruth; Zhao, Jinshun

    2012-11-01

    Recently, nanoparticles have been the focus of many research and innovation. Metallic nickel and nickel-based nanoparticles are among those being exploited. Nickel fine particles are known to be genotoxic and carcinogenic. It has been discovered that many properties of nano sized elements and materials are not present in their bulk states. The nano size of these particles renders them the ability to be easily transported into biological systems, thus raising the question of their effects on the susceptible system. Therefore scientific research on the effects of nickel nanoparticles is important. This mini-review intends to summarize the current knowledge on the genotoxicity and carcinogenicity potential of metallic nickel and nickel-based nanoparticles implicated in in vitro and in vivo mammalian studies. PMID:23000472

  11. Recent advances in transition-metal dichalcogenide based nanomaterials for water splitting

    NASA Astrophysics Data System (ADS)

    Wang, Fengmei; Shifa, Tofik Ahmed; Zhan, Xueying; Huang, Yun; Liu, Kaili; Cheng, Zhongzhou; Jiang, Chao; He, Jun

    2015-11-01

    The desire for sustainable and clean energy future continues to be the concern of the scientific community. Researchers are incessantly targeting the development of scalable and abundant electro- or photo-catalysts for water splitting. Owing to their suitable band-gap and excellent stability, an enormous amount of transition-metal dichalcogenides (TMDs) with hierarchical nanostructures have been extensively explored. Herein, we present an overview of the recent research progresses in the design, characterization and applications of the TMD-based electro- or photo-catalysts for hydrogen and oxygen evolution. Emphasis is given to the layered and pyrite-phase structured TMDs encompassing semiconducting and metallic nanomaterials. Illustrative results and the future prospects are pointed out. This review will provide the readers with insight into the state-of-the-art research progresses in TMD based nanomaterials for water splitting.

  12. Lead zirconate titanate on base metal foils: An approach for embedded high-K passive components

    SciTech Connect

    Maria, J.-P.; Cheek, K.; Streiffer, S. K.; Kim, S.-H.; Dunn, G.; Kingon, A. I.

    2000-01-26

    An approach for embedding high-K dielectric thin films into polymer packages has been developed. Pb{sub 0.85}La{sub 0.15}(Zr{sub 0.52}Ti{sub 0.48}){sub 0.96}O{sub 3} thin films were prepared by chemical solution deposition on 50 {micro}m thick Ni-coated Cu foils. Sputter deposited Ni top electrodes completed the all base-metal capacitor stack. After high temperature N{sub 2} crystallization anneals, the PLZT composition showed reduction resistance while the base-metal foils remained flexible. Capacitance density and Loss tangent values range between 300 and 400 nF/cm{sup 2} and 0.01 and 0.02 from 1 to 1,000 kHz respectively. These properties represent a 2 to 3 order of magnitude improvement over available embedded capacitor technologies for polymeric packages.

  13. Coordination properties of hydralazine Schiff base. Synthesis and equilibrium studies of some metal ion complexes

    NASA Astrophysics Data System (ADS)

    Shoukry, Azza A.; Shoukry, Mohamed M.

    2008-08-01

    In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and 1H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies.

  14. Copper-phthalocyanine based metal-organic interfaces: the effect of fluorination, the substrate, and its symmetry.

    PubMed

    de Oteyza, D G; El-Sayed, A; Garcia-Lastra, J M; Goiri, E; Krauss, T N; Turak, A; Barrena, E; Dosch, H; Zegenhagen, J; Rubio, A; Wakayama, Y; Ortega, J E

    2010-12-01

    Metal-organic interfaces based on copper-phthalocyanine monolayers are studied in dependence of the metal substrate (Au versus Cu), of its symmetry [hexagonal (111) surfaces versus fourfold (100) surfaces], as well as of the donor or acceptor semiconducting character associated with the nonfluorinated or perfluorinated molecules, respectively. Comparison of the properties of these systematically varied metal-organic interfaces provides new insight into the effect of each of the previously mentioned parameters on the molecule-substrate interactions.

  15. Plasmonic Enhancement of Raman Signal using Complex Metallic Nanostructures based on DNA Origami

    NASA Astrophysics Data System (ADS)

    Finkelstein, Gleb

    2015-03-01

    DNA-based nanostructures, such as ``DNA origami,'' have recently emerged as one of the leading techniques for precise positioning of nanoscale materials in fields ranging from computer science to biomedical engineering. The origami is composed of a single scaffold DNA strand to which smaller ``staple`` strands are attached through DNA complementarity. The staples help to fold the scaffold strand into the designed structure of a predetermined shape. The resulting templates are highly addressable and have proven to be versatile tools for site-specific placement of various nanocomponents, such as metallic nanoparticles, quantum dots, fluorophores, etc. Building upon massively paralleled assembly mechanism of the origami and its ability to position nanocomponents, one may hope to utilize it for biosensing purposes. One attractive goal is the Raman spectroscopy, which provides a highly specific chemical fingerprint. Unfortunately, the Raman scattering cross section is small; Surface Enhanced Raman Spectroscopy (SERS) enhances the otherwise weak Raman signal by trapping the analyte molecules in the regions of intense electric field produced near rough metallic surfaces. These ``hot spots`` can be understood as resulting from localized surface plasmon modes resonantly exited by the incident laser excitation. We have earlier shown that metallic nanoparticles controllably attached to DNA origami can be further enlarged via an in-solution metallization; this technique allowed us to build metallic structures of complex topology. Recently, we have performed Raman spectroscopy of molecules attached to these metallic assemblies. Specifically, DNA origami is first used to organize the metallic structures, followed by a covalent attachment of Raman-active molecules to the metal. We found that the substrates with four nanoparticles per origami produce a strongly enhanced Raman signal compared to the control samples with only one nanoparticle per origami for the same particle

  16. Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair

    SciTech Connect

    Wang, Ping; Guliaev, Anton B.; Hang, Bo

    2006-02-28

    Cadmium (Cd{sup 2+}), nickel (Ni{sup 2+}) and cobalt (Co{sup 2+}) are human and/or animal carcinogens. Zinc (Zn{sup 2+}) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (var epsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1000 {micro}M, both Cd{sup 2+} and Zn{sup 2+} showed metal-dependent inhibition of the MPG catalytic activity. Ni{sup 2+} also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co{sup 2+} and Mg{sup 2+} did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the var epsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd{sup 2+}, Zn{sup 2+}, and Ni{sup 2+} at concentrations that show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn{sup 2+} showed that the MPG active site has a potential binding site for Zn{sup 2+}, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.

  17. A novel Schiff base: Synthesis, structural characterisation and comparative sensor studies for metal ion detections.

    PubMed

    Köse, Muhammet; Purtas, Savas; Güngör, Seyit Ali; Ceyhan, Gökhan; Akgün, Eyup; McKee, Vickie

    2015-02-01

    A novel Schiff base ligand was synthesized by the condensation reaction of 2,6-diformylpyridine and 4-aminoantipyrine in MeOH and characterised by its melting point, elemental analysis, FT-IR, (1)H, (13)C NMR and mass spectroscopic studies. Molecular structure of the ligand was determined by single crystal X-ray diffraction technique. The electrochemical properties of the Schiff base ligand were studied in different solvents at various scan rates. Sensor ability of the Schiff base ligand was investigated by colorimetric and fluorometric methods. Visual colour change of the ligand was investigated in MeOH solvent in presence of various metal ions Na(+), Mg(2+), Al(3+), K(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+). Upon addition of Al(3+) ion into a MeOH solution of the ligand, an orange colour developed which is detectable by naked eye. Fluorescence emission studies showed that the ligand showed single emission band at 630-665nm upon excitation at 560nm. Addition of metal ions Na(+), Mg(2+), K(+), Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+) (1:1M ratio) cause fluorescence quenching, however addition of Al(+3) resulted in an increase in fluorescence intensity. No significant variation was observed in the fluorescence intensity caused by Al(3+) in presence of other metal ions. Therefore, the Schiff base ligand can be used for selective detection of Al(3+) ions in the presence of the other metal ions studied.

  18. Flexible perovskite solar cells based on the metal-insulator-semiconductor structure.

    PubMed

    Wei, Jing; Li, Heng; Zhao, Yicheng; Zhou, Wenke; Fu, Rui; Pan, Huiyue; Zhao, Qing

    2016-09-14

    The metal-insulator-semiconductor (MIS) structure is applied to perovskite solar cells, in which the traditional compact layer TiO2 is replaced by Al2O3 as the hole blocking material to realize an all-low-temperature process. Flexible devices based on this structure are also realized with excellent flexibility, which hold 85% of their initial efficiency after bending 100 times. PMID:27524362

  19. Assessment of Metal Media Filters for Advanced Coal-Based Power Generation Applications

    SciTech Connect

    Alvin, M.A.

    2002-09-19

    Advanced coal and biomass-based gas turbine power generation technologies (IGCC, PFBC, PCFBC, and Hipps) are currently under development and demonstration. Efforts at Siemens Westinghouse Power Corporation (SWPC) have been focused on the development and demonstration of hot gas filter systems as an enabling technology for power generation. This paper reviews SWPC's material and component assessment efforts, identifying the performance, stability, and life of porous metal, advanced alloy, and intermetallic filters under simulated, pressurized fluidized-bed combustion conditions.

  20. Retinal Stimulation on Rabbit Using Complementary Metal Oxide Semiconductor Based Multichip Flexible Stimulator toward Retinal Prosthesis

    NASA Astrophysics Data System (ADS)

    Tokuda, Takashi; Asano, Ryosuke; Sugitani, Sachie; Taniyama, Mari; Terasawa, Yasuo; Nunoshita, Masahiro; Nakauchi, Kazuaki; Fujikado, Takashi; Tano, Yasuo; Ohta, Jun

    2008-04-01

    The Functionality of a complementary metal oxide semiconductor (CMOS) LSI-based, multichip flexible retinal stimulator was demonstrated in retinal stimulation experiments on rabbits. A 1×4-configured multichip stimulator was fabricated for application to experiments on animals. An experimental procedure including surgical operations was developed, and retinal stimulation was performed with the fabricated multichip stimulator. Neural responses on the visual cortex were successfully evoked by the fabricated stimulator. The stimulator is confirmed to be applicable to acute animal experiments.

  1. A novel Schiff base: Synthesis, structural characterisation and comparative sensor studies for metal ion detections

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Purtas, Savas; Güngör, Seyit Ali; Ceyhan, Gökhan; Akgün, Eyup; McKee, Vickie

    2015-02-01

    A novel Schiff base ligand was synthesized by the condensation reaction of 2,6-diformylpyridine and 4-aminoantipyrine in MeOH and characterised by its melting point, elemental analysis, FT-IR, 1H, 13C NMR and mass spectroscopic studies. Molecular structure of the ligand was determined by single crystal X-ray diffraction technique. The electrochemical properties of the Schiff base ligand were studied in different solvents at various scan rates. Sensor ability of the Schiff base ligand was investigated by colorimetric and fluorometric methods. Visual colour change of the ligand was investigated in MeOH solvent in presence of various metal ions Na+, Mg2+, Al3+, K+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+. Upon addition of Al3+ ion into a MeOH solution of the ligand, an orange colour developed which is detectable by naked eye. Fluorescence emission studies showed that the ligand showed single emission band at 630-665 nm upon excitation at 560 nm. Addition of metal ions Na+, Mg2+, K+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ (1:1 M ratio) cause fluorescence quenching, however addition of Al+3 resulted in an increase in fluorescence intensity. No significant variation was observed in the fluorescence intensity caused by Al3+ in presence of other metal ions. Therefore, the Schiff base ligand can be used for selective detection of Al3+ ions in the presence of the other metal ions studied.

  2. Focusing capability of a phononic crystal based on a hollow metallic structure.

    PubMed

    Hladky-Hennion, Anne-Christine; Croenne, Charles; Vasseur, Jerome; Haumesser, Lionel; Norris, Andrew

    2014-08-01

    The dispersion curves of a phononic crystal (PC) based on a hollow metallic structure are presented. They exhibit a negative refraction dispersion branch and perfect refractive index matching with the surrounding water, leading to focusing capability. Numerical and experimental results are reported for a flat PC lens. The characteristics of the focal spot (intensity, dimensions, etc.) are numerically and experimentally investigated with the goal of finding the frequency of the optimal imaging performance. PMID:25073139

  3. Recent progress in BEDT-TTF (bis(ethylenedithio)-tetratiofulvalene) based synthetic metals

    SciTech Connect

    Wang, H.H.; Allen, T.J.; Schlueter, J.A.; Hallenbeck, S.L.; Stupka, D.L.; Chen, M.Y.; Despotes, A.M.; Kao, H-C.I.; Carlson, K.D.; Geiser, U.

    1987-01-01

    BEDT-TTF based organic metals with tetrahedral and linear anions are reviewed. New (ET)/sub 2/MX/sub 4/ complexes, their electrical and ESR properties are reported (M = Ga, In, Tl, and X is halides). A novel solid state phase transformation from semiconducting ..cap alpha.. to superconducting ..beta..-(ET)/sub 2/IBr/sub 2/ is presented. 40 refs., 5 figs., 2 tabs.

  4. Photoswitchable Adsorption in Metal-Organic Frameworks Based on Polar Guest-Host Interactions.

    PubMed

    Wang, Zhengbang; Grosjean, Sylvain; Bräse, Stefan; Heinke, Lars

    2015-12-21

    Reversible remote-controlled switching of the properties of nanoporous metal-organic frameworks (MOFs) is enabled by incorporating photoswitchable azobenzene. The interaction of the host material with different guest molecules, which is crucial for all applications, is precisely studied using thin MOF films of the type Cu2 (BDC)2 (AzoBipyB). A molecule-specific effect of the photoswitching, based on dipole-dipole interactions, is found.

  5. Microstructural Characterization of Base Metal Alloys with Conductive Native Oxides for Electrical Contact Applications

    NASA Astrophysics Data System (ADS)

    Senturk, Bilge Seda

    Metallic contacts are a ubiquitous method of connecting electrical and electronic components/systems. These contacts are usually fabricated from base metals because they are inexpensive, have high bulk electrical conductivities and exhibit excellent formability. Unfortunately, such base metals oxidize in air under ambient conditions, and the characteristics of the native oxide scales leads to contact resistances orders of magnitude higher than those for mating bare metal surface. This is a critical technological issue since the development of unacceptably high contact resistances over time is now by far the most common cause of failure in electrical/electronic devices and systems. To overcome these problems, several distinct approaches are developed for alloying base metals to promote the formation of self-healing inherently conductive native oxide scales. The objective of this dissertation study is to demonstrate the viability of these approaches through analyzing the data from Cu-9La (at%) and Fe-V binary alloy systems. The Cu-9 La alloy structure consists of eutectic colonies tens of microns in diameter wherein a rod-like Cu phase lies within a Cu6La matrix phase. The thin oxide scale formed on the Cu phase was found to be Cu2O as expected while the thicker oxide scale formed on the Cu6La phase was found to be a polycrystalline La-rich Cu2O. The enhanced electrical conductivity in the native oxide scale of the Cu-9La alloy arises from heavy n-type doping of the Cu2O lattice by La3+. The Fe-V alloy structures consist of a mixture of large elongated and equiaxed grains. A thin polycrystalline Fe3O4 oxide scale formed on all of the Fe-V alloys. The electrical conductivities of the oxide scales formed on the Fe-V alloys are higher than that formed on pure Fe. It is inferred that this enhanced conductivity arises from doping of the magnetite with V+4 which promotes electron-polaron hopping. Thus, it has been demonstrated that even in simple binary alloy systems one

  6. Synthesis, characterization and biological approach of metal chelates of some first row transition metal ions with halogenated bidentate coumarin Schiff bases containing N and O donor atoms.

    PubMed

    Prabhakara, Chetan T; Patil, Sangamesh A; Toragalmath, Shivakumar S; Kinnal, Shivashankar M; Badami, Prema S

    2016-04-01

    The impregnation of halogen atoms in a molecule is an emerging trend in pharmaceutical chemistry. The presence of halogens (Cl, Br, I and F) increases the lipophilic nature of molecule and improves the penetration of lipid membrane. The presence of electronegative halogen atoms increases the bio- activity of core moiety. In the present study, Co(II), Ni(II) and Cu(II) complexes are synthesised using Schiff bases (HL(I) and HL(II)), derived from 8-formyl-7-hydroxy-4-methylcoumarin/3-chloro-8-formyl-7-hydroxy-4-methylcoumarin with 2,4-difluoroaniline/o-toluidine respectively. The synthesized compounds were characterized by spectral (IR, NMR, UV-visible, Mass, ESI-MS, ESR), thermal, fluorescence and molar conductivity studies. All the synthesized metal complexes are completely soluble in DMF and DMSO. The non-electrolytic nature of the metal complexes was confirmed by molar conductance studies. Elemental analysis study suggest [ML2(H2O)2] stoichiometry, here M=Co(II), Ni(II) and Cu(II), L=deprotonated ligand. The obtained IR data supports the binding of metal ion to Schiff base. Thermal study suggests the presence of coordinated water molecules. Electronic spectral results reveal six coordinated geometry for the synthesized metal complexes. The Schiff bases and their metal complexes were evaluated for antibacterial (Pseudomonas aureginosa and Proteus mirabilis), antifungal (Aspergillus niger and Rhizopus oryzae), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activities. PMID:26874303

  7. Synthesis, characterization and biological approach of metal chelates of some first row transition metal ions with halogenated bidentate coumarin Schiff bases containing N and O donor atoms.

    PubMed

    Prabhakara, Chetan T; Patil, Sangamesh A; Toragalmath, Shivakumar S; Kinnal, Shivashankar M; Badami, Prema S

    2016-04-01

    The impregnation of halogen atoms in a molecule is an emerging trend in pharmaceutical chemistry. The presence of halogens (Cl, Br, I and F) increases the lipophilic nature of molecule and improves the penetration of lipid membrane. The presence of electronegative halogen atoms increases the bio- activity of core moiety. In the present study, Co(II), Ni(II) and Cu(II) complexes are synthesised using Schiff bases (HL(I) and HL(II)), derived from 8-formyl-7-hydroxy-4-methylcoumarin/3-chloro-8-formyl-7-hydroxy-4-methylcoumarin with 2,4-difluoroaniline/o-toluidine respectively. The synthesized compounds were characterized by spectral (IR, NMR, UV-visible, Mass, ESI-MS, ESR), thermal, fluorescence and molar conductivity studies. All the synthesized metal complexes are completely soluble in DMF and DMSO. The non-electrolytic nature of the metal complexes was confirmed by molar conductance studies. Elemental analysis study suggest [ML2(H2O)2] stoichiometry, here M=Co(II), Ni(II) and Cu(II), L=deprotonated ligand. The obtained IR data supports the binding of metal ion to Schiff base. Thermal study suggests the presence of coordinated water molecules. Electronic spectral results reveal six coordinated geometry for the synthesized metal complexes. The Schiff bases and their metal complexes were evaluated for antibacterial (Pseudomonas aureginosa and Proteus mirabilis), antifungal (Aspergillus niger and Rhizopus oryzae), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activities.

  8. Transition metal cation separations with a resorcinarene-based amino acid stationary phase.

    PubMed

    Li, Na; Allen, Lee J; Harrison, Roger G; Lamb, John D

    2013-03-01

    A resorcinarene-based macrocyclic ligand functionalized with alanine and undecyl groups (AUA) was synthesized and applied to ion chromatographic separations. The selectivity and separation of transition metal ions on a column packed with AUA adsorbed onto 55% cross-linked styrene-divinylbenzene resin are presented. The upper and lower rims of the resorcinarene were modified with amino acids and -C(11)H(23) alkyl chains, respectively. The four carboxylic acid groups on the upper rim act as cation-exchangers while the four -C(11)H(23) alkyl chains serve to anchor the ligand to the resin surface by the hydrophobic effect. A systematic study of the effect of different eluent components including non-metal-chelating (HNO(3)) and chelating acids (oxalic acid, succinic acid, dipicolinic acid, and citric acid) on the retention of transition metal ions was investigated. Six metal ions (Mn(2+), Co(2+), Ni(2+), Cd(2+), Cu(2+), and Zn(2+)) were separated on the AUA column within a reasonable time with a single eluent gradient using oxalic acid. The separation is compared to that obtained using a commercial column containing carboxylic acid functional groups. The AUA column containing four preorganized carboxylic acid groups showed selectivity for Cu(2+) when no chelating eluent was present, a selectivity which was not observed with the comparison column.

  9. Biocompatibility evaluation of sputtered zirconium-based thin film metallic glass-coated steels

    PubMed Central

    Subramanian, Balasubramanian; Maruthamuthu, Sundaram; Rajan, Senthilperumal Thanka

    2015-01-01

    Thin film metallic glasses comprised of Zr48Cu36Al8Ag8 (at.%) of approximately 1.5 μm and 3 μm in thickness were prepared using magnetron sputtering onto medical grade 316L stainless steel. Their structural and mechanical properties, in vitro corrosion, and antimicrobial activity were analyzed. The amorphous thin film metallic glasses consisted of a single glassy phase, with an absence of any detectable peaks corresponding to crystalline phases. Elemental composition close to the target alloy was noted from EDAX analysis of the thin film. The surface morphology of the film showed a smooth surface on scanning electron microscopy and atomic force microscopy. In vitro electrochemical corrosion studies indicated that the zirconium-based metallic glass could withstand body fluid, showing superior resistance to corrosion and electrochemical stability. Interactions between the coated surface and bacteria were investigated by agar diffusion, solution suspension, and wet interfacial contact methods. The results indicated a clear zone of inhibition against the growth of microorganisms such as Escherichia coli and Staphylococcus aureus, confirming the antimicrobial activity of the thin film metallic glasses. Cytotoxicity studies using L929 fibroblast cells showed these coatings to be noncytotoxic in nature. PMID:26491304

  10. Piezoelectric sensor for sensitive determination of metal ions based on the phosphate-modified dendrimer

    NASA Astrophysics Data System (ADS)

    Wang, S. H.; Shen, C. Y.; Lin, Y. M.; Du, J. C.

    2016-08-01

    Heavy metal ions arising from human activities are retained strongly in water; therefore public water supplies must be monitored regularly to ensure the timely detection of potential problems. A phosphate-modified dendrimer film was investigated on a quartz crystal microbalance (QCM) for sensing metal ions in water at room temperature in this study. The chemical structures and sensing properties were characterized by Fourier transform infrared spectroscopy and QCM measurement, respectively. This phosphate-modified dendrimer sensor can directly detect metal ions in aqueous solutions. This novel sensor was evaluated for its capacity to sense various metal ions. The sensor exhibited a higher sensitivity level and shorter response time to copper(II) ions than other sensors. The linear detection range of the prepared QCM based on the phosphate-modified dendrimer was 0.0001 ∼ 1 μM Cu(II) ions (R2 = 0.98). The detection properties, including sensitivity, response time, selectivity, reusability, maximum adsorption capacity, and adsorption equilibrium constants, were also investigated.

  11. Organometallic Probe for the Electronics of Base-Stabilized Group 11 Metal Cations.

    PubMed

    Braunschweig, Holger; Ewing, William C; Kramer, Thomas; Mattock, James D; Vargas, Alfredo; Werner, Christine

    2015-08-24

    A number of trimetalloborides have been synthesized through the reactions of base-stabilized coinage metal chlorides with a dimanganaborylene lithium salt in the hope of using this organometallic platform to compare and evaluate the electronics of these popular coinage metal fragments. The adducts of Cu(I), Ag(I), and Au(I) ions, stabilized by tricyclohexylphosphine (PCy3), N-1,3-bis(4-methylphenyl)imidazol-2-ylidene (ITol), or 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene (CAAC), with [{Cp(CO)2Mn}2B](-) were studied spectroscopically, structurally, and computationally. The geometries of the adducts fall into two classes, one symmetric and one asymmetric, each relying on the combined characteristics of both the metal and ligand. The energetic factors proposed as the causes of the structural differences were investigated by ETS-NOCV (extended transition state-natural orbitals for chemical valence) analysis, which showed the final geometry to be controlled by the competition between the tendency of the coinage metal to adopt a higher or lower coordination number and the willingness of the cationic fragment to participate in back-bonding interactions. PMID:26178571

  12. Hydrogen Sensors Using Nitride-Based Semiconductor Diodes: The Role of Metal/Semiconductor Interfaces

    PubMed Central

    Irokawa, Yoshihiro

    2011-01-01

    In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C–V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C–V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C–V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I–V) characterization, suggesting that low-frequency C–V method would be effective in detecting very low hydrogen concentrations. PMID:22346597

  13. Gas Sensors Based on One Dimensional Nanostructured Metal-Oxides: A Review

    PubMed Central

    Arafat, M. M.; Dinan, B.; Akbar, Sheikh A.; Haseeb, A. S. M. A.

    2012-01-01

    Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO2, TiO2, In2O3, WOx, AgVO3, CdO, MoO3, CuO, TeO2 and Fe2O3. Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research. PMID:22969344

  14. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting

    PubMed Central

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-01-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis. PMID:27404510

  15. Transmission enhancement based on strong interference in metal-semiconductor layered film for energy harvesting.

    PubMed

    Li, Qiang; Du, Kaikai; Mao, Kening; Fang, Xu; Zhao, Ding; Ye, Hui; Qiu, Min

    2016-01-01

    A fundamental strategy to enhance optical transmission through a continuous metallic film based on strong interference dominated by interface phase shift is developed. In a metallic film coated with a thin semiconductor film, both transmission and absorption are simultaneously enhanced as a result of dramatically reduced reflection. For a 50-nm-thick Ag film, experimental transmission enhancement factors of 4.5 and 9.5 are realized by exploiting Ag/Si non-symmetric and Si/Ag/Si symmetric geometries, respectively. These planar layered films for transmission enhancement feature ultrathin thickness, broadband and wide-angle operation, and reduced resistance. Considering one of their potential applications as transparent metal electrodes in solar cells, a calculated 182% enhancement in the total transmission efficiency relative to a single metallic film is expected. This strategy relies on no patterned nanostructures and thereby may power up a wide spectrum of energy-harvesting applications such as thin-film photovoltaics and surface photocatalysis. PMID:27404510

  16. Bioinspired nanoreactors for the biomineralisation of metallic-based nanoparticles for nanomedicine.

    PubMed

    Bain, Jennifer; Staniland, Sarah S

    2015-06-28

    This review explores the synthesis of inorganic metallic-based nanoparticles (MBNPs) (metals, alloys, metal oxides) using biological and biologically inspired nanoreactors for precipitation/crystallisation. Such nanoparticles exhibit a range of nanoscale properties such as surface plasmon resonance (nobel metals e.g. Au), fluorescence (semiconductor quantum dots e.g. CdSe) and nanomagnetism (magnetic alloys e.g. CoPt and iron oxides e.g. magnetite), which are currently the subject of intensive research for their applicability in diagnostic and therapeutic nanomedicine. For such applications, MBNPs are required to be biocompatible, of a precise size and shape for a consistent signal or output and be easily modified with biomolecules for applications. Ideally the MBNPs would be obtained via an environmentally-friendly synthetic route. A biological or biologically inspired nanoreactor synthesis of MBNPs is shown to address these issues. Biological nanoreactors for crystallizing MBNPs within cells (magnetosomes), protein cages (ferritin) and virus capsids (cowpea chlorotic mottle, cowpea mosaic and tobacco mosaic viruses), are discussed along with how these have been modified for applications and for the next generation of new materials. Biomimetic liposome, polymersome and even designed self-assembled proteinosome nanoreactors are also reviewed for MBNP crystallisation and further modification for applications. With the advent of synthetic biology, the research and understanding in this field is growing, with the goal of realising nanoreactor synthesis of MBNPs for biomedical applications within our grasp in the near future.

  17. Spatial Pattern Analysis of Heavy Metals in Beijing Agricultural Soils Based on Spatial Autocorrelation Statistics

    PubMed Central

    Huo, Xiao-Ni; Zhang, Wei-Wei; Sun, Dan-Feng; Li, Hong; Zhou, Lian-Di; Li, Bao-Guo

    2011-01-01

    This study explored the spatial pattern of heavy metals in Beijing agricultural soils using Moran’s I statistic of spatial autocorrelation. The global Moran’s I result showed that the spatial dependence of Cr, Ni, Zn, and Hg changed with different spatial weight matrixes, and they had significant and positive global spatial correlations based on distance weight. The spatial dependence of the four metals was scale-dependent on distance, but these scale effects existed within a threshold distance of 13 km, 32 km, 50 km, and 29 km, respectively for Cr, Ni, Zn, and Hg. The maximal spatial positive correlation range was 57 km, 70 km, 57 km, and 55 km for Cr, Ni, Zn, and Hg, respectively and these were not affected by sampling density. Local spatial autocorrelation analysis detected the locations of spatial clusters and spatial outliers and revealed that the pollution of these four metals occurred in significant High-high spatial clusters, Low-high, or even High-low spatial outliers. Thus, three major areas were identified and should be receiving more attention: the first was the northeast region of Beijing, where Cr, Zn, Ni, and Hg had significant increases. The second was the southeast region of Beijing where wastewater irrigation had strongly changed the content of metals, particularly of Cr and Zn, in soils. The third area was the urban fringe around city, where Hg showed a significant increase. PMID:21776217

  18. Interfacial shear bond strength between different base metal alloys and five low fusing feldspathic ceramic systems.

    PubMed

    Sipahi, Cumhur; Ozcan, Mutlu

    2012-01-01

    This study compared the bond strength between metal alloys and 5 ceramic systems. Ceramic systems (Vita VMK68, Ivoclar IPSd. SIGN, Ceramco II, Matchmaker and Finesse) were fired onto either Ni-Cr or Co-Cr base metal alloy. Metal-ceramic interfaces were subjected to shear loading until failure. The ceramic type significantly affected the bond strength results (p<0.05). For Ni-Cr alloy, the results ranged between 15.4-25.3 MPa and for Co-Cr alloy between 13.3-19.0 MPa. The highest mean bond strength value was obtained with the combination of Ni-Cr alloy-Ceramco II (25.3 MPa), the lowest bond strength was received from the combination of Co-Cr alloy-Ivoclar IPS d.SIGN ceramic (13.3 MPa). Adhesive failures between metal and ceramic were significantly more frequent with Ni-Cr alloy (31 out of 50) than with Co-Cr (20 out of 50) (p<0.05). Ceramco II presented the highest bond strength with both Ni-Cr and Co-Cr being significantly different from one another.

  19. Robust Design of Sheet Metal Forming Process Based on Kriging Metamodel

    NASA Astrophysics Data System (ADS)

    Xie, Yanmin

    2011-08-01

    Nowadays, sheet metal forming processes design is not a trivial task due to the complex issues to be taken into account (conflicting design goals, complex shapes forming and so on). Optimization methods have also been widely applied in sheet metal forming. Therefore, proper design methods to reduce time and costs have to be developed mostly based on computer aided procedures. At the same time, the existence of variations during manufacturing processes significantly may influence final product quality, rendering non-robust optimal solutions. In this paper, a small size of design of experiments is conducted to investigate how a stochastic behavior of noise factors affects drawing quality. The finite element software (LS_DYNA) is used to simulate the complex sheet metal stamping processes. The Kriging metamodel is adopted to map the relation between input process parameters and part quality. Robust design models for sheet metal forming process integrate adaptive importance sampling with Kriging model, in order to minimize impact of the variations and achieve reliable process parameters. In the adaptive sample, an improved criterion is used to provide direction in which additional training samples can be added to better the Kriging model. Nonlinear functions as test functions and a square stamping example (NUMISHEET'93) are employed to verify the proposed method. Final results indicate application feasibility of the aforesaid method proposed for multi-response robust design.

  20. Compact metal probes: a solution for atomic force microscopy based tip-enhanced Raman spectroscopy.

    PubMed

    Rodriguez, R D; Sheremet, E; Müller, S; Gordan, O D; Villabona, A; Schulze, S; Hietschold, M; Zahn, D R T

    2012-12-01

    There are many challenges in accomplishing tip-enhanced Raman spectroscopy (TERS) and obtaining a proper tip is probably the greatest one. Since tip size, composition, and geometry are the ultimate parameters that determine enhancement of intensity and lateral resolution, the tip becomes the most critical component in a TERS experiment. However, since the discovery of TERS the cantilevers used in atomic force microscopy (AFM) have remained basically the same: commercial silicon (or silicon nitride) tips covered by a metallic coating. The main issues of using metal-coated silicon cantilevers, such as wearing off of the metal layer or increased tip radius, can be completely overcome by using all-metal cantilevers. Until now in TERS experiments such probes have only been used in a scanning tunneling microscope or in a tuning fork-based shear force microscope but not in AFM. In this work for the first time, we show the use of compact silver cantilevers that are fully compatible with contact and tapping modes in AFM demonstrating their superb performance in TERS experiments.

  1. Compact metal probes: A solution for atomic force microscopy based tip-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodriguez, R. D.; Sheremet, E.; Müller, S.; Gordan, O. D.; Villabona, A.; Schulze, S.; Hietschold, M.; Zahn, D. R. T.

    2012-12-01

    There are many challenges in accomplishing tip-enhanced Raman spectroscopy (TERS) and obtaining a proper tip is probably the greatest one. Since tip size, composition, and geometry are the ultimate parameters that determine enhancement of intensity and lateral resolution, the tip becomes the most critical component in a TERS experiment. However, since the discovery of TERS the cantilevers used in atomic force microscopy (AFM) have remained basically the same: commercial silicon (or silicon nitride) tips covered by a metallic coating. The main issues of using metal-coated silicon cantilevers, such as wearing off of the metal layer or increased tip radius, can be completely overcome by using all-metal cantilevers. Until now in TERS experiments such probes have only been used in a scanning tunneling microscope or in a tuning fork-based shear force microscope but not in AFM. In this work for the first time, we show the use of compact silver cantilevers that are fully compatible with contact and tapping modes in AFM demonstrating their superb performance in TERS experiments.

  2. Hydrogen sensors using nitride-based semiconductor diodes: the role of metal/semiconductor interfaces.

    PubMed

    Irokawa, Yoshihiro

    2011-01-01

    In this paper, I review my recent results in investigating hydrogen sensors using nitride-based semiconductor diodes, focusing on the interaction mechanism of hydrogen with the devices. Firstly, effects of interfacial modification in the devices on hydrogen detection sensitivity are discussed. Surface defects of GaN under Schottky electrodes do not play a critical role in hydrogen sensing characteristics. However, dielectric layers inserted in metal/semiconductor interfaces are found to cause dramatic changes in hydrogen sensing performance, implying that chemical selectivity to hydrogen could be realized. The capacitance-voltage (C-V) characteristics reveal that the work function change in the Schottky metal is not responsible mechanism for hydrogen sensitivity. The interface between the metal and the semiconductor plays a critical role in the interaction of hydrogen with semiconductor devises. Secondly, low-frequency C-V characterization is employed to investigate the interaction mechanism of hydrogen with diodes. As a result, it is suggested that the formation of a metal/semiconductor interfacial polarization could be attributed to hydrogen-related dipoles. In addition, using low-frequency C-V characterization leads to clear detection of 100 ppm hydrogen even at room temperature where it is hard to detect hydrogen by using conventional current-voltage (I-V) characterization, suggesting that low-frequency C-V method would be effective in detecting very low hydrogen concentrations. PMID:22346597

  3. Colorimetric Fluorescent Nanosensor Based on Hexamethylene Diisocyanate for Fluorescent Responses and Adsorption of Heavy Metal Ions.

    PubMed

    Xu, Yaohui; Zhou, Yang; Li, Ruixing

    2016-03-01

    An inorganic-organic hybrid material based on magnetic Fe3O4@SiO2 nanoparticles was synthesized for fluorescent responses and removal of heavy metal ions, in which superparamagnetic Fe3O4@SiO2 nanoparticles were firstly prepared and modified with hexamethylene diisocyanate (HDI) instead of 3-isocyanatopropyltriethoxysilane (IPTES) as the organic coupling agent, and then a rhodamine derivative with spirolactam structure (Rho-en) was conjugated on the HDI functionalized Fe3O4@SiO2 nanoparticles through isocyanate groups. Both of functionalized Fe3O4@SiO2 nanoparticles based on IPTES and HDI were characterized by FT-IR and XPS, and the results indicated that HDI was a good alternative as chemical bridge for surface modification on the surface of Fe3O4@SiO2 nanoparticles. The inorganic-organic hybrid composites synthesized based HDI showed naked-eye color changes and fluorescent responses towards Zn2+, Cd2+, Mn2+, Pb2+, Hg2+ and Fe3+, which could serve as the available proofs for the qualitative analysis. Moreover, the as-obtained composites not only had excellent adsorption capability for Pb2+ and Hg2+, but also showed strong magnetic sensitivity, which could help to the removal and separation of functionalized magnetic nanocomposites after capturing the heavy metal ions. In addition, the plausible interaction mode of functionalized Fe3O4@SiO2 nanoparticles with heavy metal ions was discussed. PMID:27455720

  4. Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.

    PubMed

    Ei Ei, Htwe; Nakama, Yuhi; Tanaka, Hiroshi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi

    2016-11-01

    The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials. PMID:27478958

  5. Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.

    PubMed

    Ei Ei, Htwe; Nakama, Yuhi; Tanaka, Hiroshi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi

    2016-11-01

    The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials.

  6. Graphene-based sensors for detection of heavy metals in water: a review.

    PubMed

    Chang, Jingbo; Zhou, Guihua; Christensen, Erik R; Heideman, Robert; Chen, Junhong

    2014-06-01

    Graphene (G) is attracting significant attention because of its unique physical and electronic properties. The production of graphene through the reduction of graphene oxide (GO) is a low-cost method. The reduction of GO can further lead to electrically conductive reduced GO. These graphene-based nanomaterials are attractive for high-performance water sensors due to their unique properties, such as high specific surface areas, high electron mobilities, and exceptionally low electronic noise. Because of potential risks to the environment and human health arising from heavy-metal pollution in water, G-/GO-based water sensors are being developed for rapid and sensitive detection of heavy-metal ions. In this review, a general introduction to graphene and GO properties, as well as their syntheses, is provided. Recent advances in optical, electrochemical, and electrical detection of heavy-metal ions using graphene or GO are then highlighted. Finally, challenges facing G/GO-based water sensor development and outlook for future research are discussed. PMID:24740529

  7. Extended-Gate Metal Oxide Semiconductor Field Effect Transistor-Based Biosensor for Detection of Deoxynivalenol

    NASA Astrophysics Data System (ADS)

    Kwon, Insu; Lee, Hee-Ho; Choi, Jinhyeon; Shin, Jang-Kyoo; Seo, Sang-Ho; Choi, Sung-Wook; Chun, Hyang Sook

    2011-06-01

    In this work, we present an extended-gate metal oxide semiconductor field effect transistor (MOSFET)-based biosensor for the detection of deoxynivalenol using a null-balancing circuit. An extended-gate MOSFET-based biosensor was fabricated by a standard complementary metal oxide semiconductor (CMOS) process and its characteristics were measured. A null-balancing circuit was used to measure the output voltage of the sensor directly, instead of measuring the drain current of the sensor. Au was used as the gate metal, which has a chemical affinity with thiol, which leads to the immobilization of a self-assembled monolayer (SAM) of mercaptohexadecanoic acid (MHDA). The SAM was used to immobilize the anti-deoxynivalenol antibody. The carboxyl group of the SAM was bound to the anti-deoxynivalenol antibody. The anti-deoxynivalenol antibody and deoxynivalenol were bound by their antigen-antibody reaction. The measurements were performed in phosphate buffered saline (PBS; pH 7.4) solution. A standard Ag/AgCl electrode was employed as a reference electrode. The bindings of a SAM, anti-deoxynivalenol antibody, and deoxynivalenol caused a variation in the output voltage of the extended-gate MOSFET-based biosensor. Surface plasmon resonance (SPR) measurement was performed to verify the interaction among the SAM, deoxynivalenol-antibody, and deoxynivalenol.

  8. Graphene-based sensors for detection of heavy metals in water: a review.

    PubMed

    Chang, Jingbo; Zhou, Guihua; Christensen, Erik R; Heideman, Robert; Chen, Junhong

    2014-06-01

    Graphene (G) is attracting significant attention because of its unique physical and electronic properties. The production of graphene through the reduction of graphene oxide (GO) is a low-cost method. The reduction of GO can further lead to electrically conductive reduced GO. These graphene-based nanomaterials are attractive for high-performance water sensors due to their unique properties, such as high specific surface areas, high electron mobilities, and exceptionally low electronic noise. Because of potential risks to the environment and human health arising from heavy-metal pollution in water, G-/GO-based water sensors are being developed for rapid and sensitive detection of heavy-metal ions. In this review, a general introduction to graphene and GO properties, as well as their syntheses, is provided. Recent advances in optical, electrochemical, and electrical detection of heavy-metal ions using graphene or GO are then highlighted. Finally, challenges facing G/GO-based water sensor development and outlook for future research are discussed.

  9. Defining the Proton Topology of the Zr6-Based Metal-Organic Framework NU-1000.

    PubMed

    Planas, Nora; Mondloch, Joseph E; Tussupbayev, Samat; Borycz, Joshua; Gagliardi, Laura; Hupp, Joseph T; Farha, Omar K; Cramer, Christopher J

    2014-11-01

    Metal-organic frameworks (MOFs) constructed from Zr6-based nodes have recently received considerable attention given their exceptional thermal, chemical, and mechanical stability. Because of this, the structural diversity of Zr6-based MOFs has expanded considerably and in turn given rise to difficulty in their precise characterization. In particular it has been difficult to assign where protons (needed for charge balance) reside on some Zr6-based nodes. Elucidating the precise proton topologies in Zr6-based MOFs will have wide ranging implications in defining their chemical reactivity, acid/base characteristics, conductivity, and chemical catalysis. Here we have used a combined quantum mechanical and experimental approach to elucidate the precise proton topology of the Zr6-based framework NU-1000. Our data indicate that a mixed node topology, [Zr6(μ3-O)4(μ3-OH)4(OH)4 (OH2)4](8+), is preferred and simultaneously rule out five alternative node topologies. PMID:26278741

  10. Zr-based bulk metallic glass as a cylinder material for high pressure apparatuses

    SciTech Connect

    Komatsu, Kazuki; Munakata, Koji; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Yokoyama, Yoshihiko; Sugiyama, Kazumasa; Matsuda, Masaaki

    2015-05-12

    Zirconium-based bulk metallic glass (Zr-based BMG) has outstanding properties as a cylinder mate- rial for piston-cylinder high pressure apparatuses and is especially useful for neutron scattering. The piston-cylinder consisting of a Zr-based BMG cylinder with outer/inner diameters of 8.8/2.5 mm sustains pressures up to 1.81 GPa and ruptured at 2.0 GPa, with pressure values determined by the superconduct- ing temperature of lead. The neutron attenuation of Zr-based BMG is similar to that of TiZr null-scattering alloy and more transparent than that of CuBe alloy. No contamination of sharp Bragg reflections is observed in the neutron diffraction pattern for Zr-based BMG. The magnetic susceptibility of Zr-based BMG is similar to that of CuBe alloy; this leads to a potential application for measurements of magnetic properties under pressure.

  11. Defining the Proton Topology of the Zr6-Based Metal-Organic Framework NU-1000.

    PubMed

    Planas, Nora; Mondloch, Joseph E; Tussupbayev, Samat; Borycz, Joshua; Gagliardi, Laura; Hupp, Joseph T; Farha, Omar K; Cramer, Christopher J

    2014-11-01

    Metal-organic frameworks (MOFs) constructed from Zr6-based nodes have recently received considerable attention given their exceptional thermal, chemical, and mechanical stability. Because of this, the structural diversity of Zr6-based MOFs has expanded considerably and in turn given rise to difficulty in their precise characterization. In particular it has been difficult to assign where protons (needed for charge balance) reside on some Zr6-based nodes. Elucidating the precise proton topologies in Zr6-based MOFs will have wide ranging implications in defining their chemical reactivity, acid/base characteristics, conductivity, and chemical catalysis. Here we have used a combined quantum mechanical and experimental approach to elucidate the precise proton topology of the Zr6-based framework NU-1000. Our data indicate that a mixed node topology, [Zr6(μ3-O)4(μ3-OH)4(OH)4 (OH2)4](8+), is preferred and simultaneously rule out five alternative node topologies.

  12. Novel Fluorinated 8-Hydroxyquinoline Based Metal Ionophores for Exploring the Metal Hypothesis of Alzheimer’s Disease

    PubMed Central

    2015-01-01

    Zinc, copper, and iron ions are involved in amyloid-beta (Aβ) deposition and stabilization in Alzheimer’s disease (AD). Consequently, metal binding agents that prevent metal-Aβ interaction and lead to the dissolution of Aβ deposits have become well sought therapeutic and diagnostic targets. However, direct intervention between diseases and metal abnormalities has been challenging and is partially attributed to the lack of a suitable agent to determine and modify metal concentration and distribution in vivo. In the search of metal ionophores, we have identified several promising chemical entities by strategic fluorination of 8-hydroxyquinoline drugs, clioquinol, and PBT2. Compounds 15–17 and 28–30 showed exceptional metal ionophore ability (6–40-fold increase of copper uptake and >2-fold increase of zinc uptake) and inhibition of zinc induced Aβ oligomerization (EC50s < ∼5 μM). These compounds are suitable for further development as drug candidates and/or positron emission tomography (PET) biomarkers if radiolabeled with 18F. PMID:26396692

  13. Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys

    NASA Technical Reports Server (NTRS)

    Gould, Jerry E.; Ritzert, Frank J.; Loewenthal, William S.

    2006-01-01

    In this study, a range of joining technologies has been investigated for creating attachments between refractory metal and Ni-based superalloys. Refractory materials of interest include Mo-47%Re, T-111, and Ta-10%W. The Ni-based superalloys include Hastelloy X and MarM 247. During joining with conventional processes, these materials have potential for a range of solidification and intermetallic formation-related defects. For this study, three non-conventional joining technologies were evaluated. These included inertia welding, electro-spark deposition (ESD) welding, and magnetic pulse welding (MPW). The developed inertia welding practice closely paralleled that typically used for the refractory metals alloys. Metallographic investigations showed that forging during inertia welding occurred predominantly on the nickel base alloy side. It was also noted that at least some degree of forging on the refractory metal side of the joint was necessary to achieve consistent bonding. Both refractory metals were readily weldable to the Hastelloy X material. When bonding to the MarM 247, results were inconsistent. This was related to the higher forging temperatures of the MarM 247, and subsequent reduced deformation on that material during welding. ESD trials using a Hastelloy X filler were successful for all material combinations. ESD places down very thin (5- to 10- m) layers per pass, and interactions between the substrates and the fill were limited (at most) to that layer. For the refractory metals, the fill only appeared to wet the surface, with minimal dilution effects. Microstructures of the deposits showed high weld metal integrity with maximum porosity on the order of a few percent. Some limited success was also obtained with MPW. In these trials, only the T-111 tubes were used. Joints were possible for the T-111 tube to the Hastelloy X bar stock, but the stiffness of the tube (resisting collapse) necessitated the use of very high power levels. These power levels

  14. Ultrafast degradation of azo dyes catalyzed by cobalt-based metallic glass

    PubMed Central

    Qin, X. D.; Zhu, Z. W.; Liu, G.; Fu, H. M.; Zhang, H. W.; Wang, A. M.; Li, H.; Zhang, H. F.

    2015-01-01

    Reactivity and mass loss are considered mutually exclusive in conventional zero-valent metal (ZVM) technology to treat environmental contaminants. Here, we report the outstanding performance of Co-based metallic glass (MG) in degrading an aqueous solution of azo dye, thus eliminating this trade-off. Ball-milled Co-based MG powders completely degrade Acid Orange II at an ultrafast rate. The surface-area-normalized rate constant of Co-based MG powders was one order of magnitude higher than that of Co-based crystalline counterparts and three orders of magnitude higher than that of the widely studied Fe0 powders. The coordinatively unsaturated local structure in Co-based MG responds to the catalysis for degradation, resulting in very low mass loss. Wide applicability and good reusability were also present. Co-based MG is the most efficient material for azo dye degradation reported thus far, and will promote the practical application of MGs as functional materials. PMID:26656918

  15. Gas sorption and transition-metal cation separation with a thienothiophene based zirconium metal-organic framework

    NASA Astrophysics Data System (ADS)

    SK, Mostakim; Grzywa, Maciej; Volkmer, Dirk; Biswas, Shyam

    2015-12-01

    The modulated synthesis of the thienothiophene based zirconium metal-organic framework (MOF) material having formula [Zr6O4(OH)4(DMTDC)6]·4.8DMF·10H2O (1) (H2DMTDC=3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid; DMF=N,N'-dimethylformamide) was carried out by heating a mixture of ZrCl4, H2DMTDC linker and benzoic acid (used as a modulator) with a molar ratio of 1:1:30 in DMF at 150 °C for 24 h. Systematic investigations have been performed in order to realize the effect of ZrCl4/benzoic acid molar ratio on the crystallinity of the material. The activation (i.e., the removal of the guest solvent molecules from the pores) of as-synthesized compound was achieved by stirring it with methanol and subsequently heating under vacuum. A combination of X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric (TG) and elemental analysis was used to examine the phase purity of the as-synthesized and thermally activated 1. The material displays high thermal stability up to 310 °C in an air atmosphere. As revealed from the XRD measurements, the compound retains its crystallinity when treated with water, acetic acid and 1 M HCl solutions. The N2 and CO2 sorption analyses suggest that the material possesses remarkably high microporosity (SBET=1236 m2 g-1; CO2 uptake=3.5 mmol g-1 at 1 bar and 0 °C). The compound also shows selective adsorption behavior for Cu2+ over Co2+ and Ni2+ ions.

  16. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds; Synthesis, characterization and biological evolution

    NASA Astrophysics Data System (ADS)

    Kumar Naik, K. H.; Selvaraj, S.; Naik, Nagaraja

    2014-10-01

    Present work reviews that, the synthesis of (E)-N";-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M2+L]X2, where M2+ = Mn, Co, Ni, Cu, Sr and Cd, L = (7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X = Cl-. Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective α-glucosidase inhibitory activity than free Schiff base ligand.

  17. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds: synthesis, characterization and biological evolution.

    PubMed

    Kumar Naik, K H; Selvaraj, S; Naik, Nagaraja

    2014-10-15

    Present work reviews that, the synthesis of (E)-N'-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M(2+)L]X2, where M(2+)=Mn, Co, Ni, Cu, Sr and Cd, L=(7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X=Cl(-). Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective α-glucosidase inhibitory activity than free Schiff base ligand.

  18. Influence of metal-containing carbon fibers on the properties of carbon-filled plastics based on aromatic polyamide

    NASA Astrophysics Data System (ADS)

    Burya, A. I.; Safonova, A. M.; Rula, I. V.

    2012-07-01

    The influence of metal-containing carbon fibers on the thermal properties of carbon-filled phenylone-based plastics has been investigated. It has been shown that carbometallic fibers containing in their composition 20- 30 mass % of a finely dispersed metal (Co, Cu) are promising fillers of phenylone C-2 for making carbonfilled plastics working in frictional units of various machines and mechanisms.

  19. Creep rupture testing of alloy 617 and A508/533 base metals and weldments.

    SciTech Connect

    Natesan, K.; Li, M.; Soppet, W.K.; Rink, D.L.

    2012-01-17

    The NGNP, which is an advanced HTGR concept with emphasis on both electricity and hydrogen production, involves helium as the coolant and a closed-cycle gas turbine for power generation with a core outlet/gas turbine inlet temperature of 750-1000 C. Alloy 617 is a prime candidate for VHTR structural components such as reactor internals, piping, and heat exchangers in view of its resistance to oxidation and elevated temperature strength. However, lack of adequate data on the performance of the alloy in welded condition prompted to initiate a creep test program at Argonne National Laboratory. In addition, Testing has been initiated to evaluate the creep rupture properties of the pressure vessel steel A508/533 in air and in helium environments. The program, which began in December 2009, was certified for quality assurance NQA-1 requirements during January and February 2010. Specimens were designed and fabricated during March and the tests were initiated in April 2010. During the past year, several creep tests were conducted in air on Alloy 617 base metal and weldment specimens at temperatures of 750, 850, and 950 C. Idaho National Laboratory, using gas tungsten arc welding method with Alloy 617 weld wire, fabricated the weldment specimens. Eight tests were conducted on Alloy 617 base metal specimens and nine were on Alloy 617 weldments. The creep rupture times for the base alloy and weldment tests were up to {approx}3900 and {approx}4500 h, respectively. The results showed that the creep rupture lives of weld specimens are much longer than those for the base alloy, when tested under identical test conditions. The test results also showed that the creep strain at fracture is in the range of 7-18% for weldment samples and were much lower than those for the base alloy, under similar test conditions. In general, the weldment specimens showed more of a flat or constant creep rate region than the base metal specimens. The base alloy and the weldment exhibited tertiary creep

  20. 1H NMR spectroscopic analysis detects metabolic disturbances in rat urine on acute exposure to heavy metal tungsten alloy based metals salt.

    PubMed

    Tyagi, Ritu; Rana, Poonam; Gupta, Mamta; Bhatnagar, Deepak; Srivastava, Shatakshi; Roy, Raja; Khushu, Subash

    2014-03-25

    Heavy metal tungsten alloys (HMTAs) have been found to be safer alternatives for making military munitions. Recently, some studies demonstrating the toxic potential of HMTAs have raised concern over the safety issues, and further propose that HMTAs exposure may lead to physiological disturbances as well. To look for the systemic effect of acute toxicity of HMTA based metals salt, (1)H nuclear magnetic resonance ((1)H NMR) spectroscopic profiling of rat urine was carried out. Male Sprague Dawley rats were administered (intraperitoneal) low and high dose of mixture of HMTA based metals salt and NMR spectroscopy was carried out in urine samples collected at 8, 24, 72 and 120 h post dosing (p.d.). Serum biochemical parameters and liver histopathology were also conducted. The (1)H NMR spectra were analysed using multivariate analysis techniques to show the time- and dose-dependent biochemical variations in post HMTA based metals salt exposure. Urine metabolomic analysis showed changes associated with energy metabolism, amino acids, N-methyl nicotinamide, membrane and gut flora metabolites. Multivariate analysis showed maximum variation with best classification of control and treated groups at 24h p.d. At the end of the study, for the low dose group most of the changes at metabolite level reverted to control except for the energy metabolites; whereas, in the high dose group some of the changes still persisted. The observations were well correlated with histopathological and serum biochemical parameters. Further, metabolic pathway analysis clarified that amongst all the metabolic pathways analysed, tricarboxylic acid cycle was most affected at all the time points indicating a switchover in energy metabolism from aerobic to anaerobic. These results suggest that exposure of rats to acute doses of HMTA based metals salt disrupts physiological metabolism with moderate injury to the liver, which might indirectly result from heavy metals induced oxidative stress.

  1. Magnetic- and particle-based techniques to investigate metal deposition on urban green.

    PubMed

    Castanheiro, Ana; Samson, Roeland; De Wael, Karolien

    2016-11-15

    Urban green works as a recorder of atmospheric PM. This paper reports on the utility of combining magnetic- and particle-based techniques to investigate PM leaf deposition as a bio-indicator of metal pollution. Ivy (Hedera helix) leaves were collected from five different land use classes, i.e. forest, rural, roadside, industrial, train. Leaf magnetic measurements were done in terms of saturation isothermal remanent magnetization (leaf SIRM), while ca. 40,000 leaf-deposited particles were analyzed through SEM/EDX to estimate the elemental composition. The influence of the different land use classes was registered both magnetically and in terms of metal content. Leaf area-normalized SIRM values ranged from 19.9 to 444.0μA, in the following order forestmetals Cr and Cu. Although presenting a similar metal content, roadside and train were magnetically very distinct. By exhibiting a very high content in Pb, and with an Fe content being comparable to the one observed at the forest and rural land uses, the industrial leaf-deposited particles showed to be mainly due to industrial activity. While SEM/EDX is a suitable approach for detailed particle analysis, leaf SIRM of ivy can be used as a rapid discriminatory tool for metal pollution. Their complementary use delivers further knowledge on land use classes reflecting different PM conditions and/or sources. PMID:27422722

  2. Whispering gallery mode nanodisk resonator based on layered metal-dielectric waveguide.

    PubMed

    Lou, Fei; Yan, Min; Thylen, Lars; Qiu, Min; Wosinski, Lech

    2014-04-01

    This paper proposes a layered metal-dielectric waveguide consisting of a stack of alternating metal and dielectric films which enables an ultracompact mode confinement. The properties of whispering gallery modes supported by disk resonators based on such waveguides are investigated for achieving a large Purcell factor. We show that by stacking three layers of 10 nm thick silver with two layers of 50 nm dielectric layers (of refractive index n) in sequence, the disk radius can be as small as 61 nm ∼λ(0)/(7n) and the mode volume is only 0.0175(λ(0)/(2n))(3). When operating at 40 K, the cavity's Q-factor can be ~670; Purcell factor can be as large as 2.3×10(4), which is more than five times larger than that achievable in a metal-dielectric-metal disk cavity in the same condition. When more dielectric layers with smaller thicknesses are used, even more compact confinement can be achieved. For example, the radius of a cavity consisting of seven dielectric-layer waveguide can be shrunk down to λ(0)/(13.5n), corresponding to a mode volume of 0.005λ(0)/(2n))(3), and Purcell factor can be enhanced to 7.3×10(4) at 40 K. The influence of parameters like thicknesses of dielectric and metal films, cavity size, and number of dielectric layers is also comprehensively studied. The proposed waveguide and nanodisk cavity provide an alternative for ultracompact light confinement, and can find applications where a strong light-matter interaction is necessary.

  3. Effects of defect density on ultrathin graphene-based metal diffusion barriers

    SciTech Connect

    Oh, Sooyeoun; Jung, Younghun; Kim, Jihyun

    2015-11-15

    The authors investigated the effects of defect density on the performance of monolayer graphene as a barrier to metal diffusion. The defects were introduced to the graphene by controlled ultraviolet-ozone irradiation. The barrier performance of pristine graphene was found to be superior to that of defective graphene at temperatures up to 700 °C. Changes in surface morphology were more prevalent in the defective graphene-based films than in the pristine graphene-based film; the thermal stability of graphene films depends on their defect density. Defect density was found to be a determining factor in the barrier performance of graphene.

  4. Corrosion Characterization of Iron-Based High-Performance Amorphous-Metal Thermal-Spray Coatings

    SciTech Connect

    Farmer, J C; Haslam, J J; Day, S D; Branagan, D J; Blue, C A; Rivard, J K; Aprigliano, L F; Yang, N; Perepezko, J H; Beardsley, M B

    2005-03-21

    New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative corrosion resistance. Many of these materials can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS N06022) in some very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. One of these compositions, SAM1651, is discussed in detail to illustrate the promise of this general class of materials.

  5. Composition mediated serration dynamics in Zr-based bulk metallic glasses

    SciTech Connect

    Wang, Z.; Qiao, J. W. E-mail: mwchen@wpi-aimr.tohoku.ac.jp; Wang, B. C.; Xu, B. S.; Tian, H.; Sun, B. A.; Chen, M. W. E-mail: mwchen@wpi-aimr.tohoku.ac.jp

    2015-11-16

    The composition mediated serration dynamics in Zr-based bulk metallic glasses (BMGs) is investigated by statistics analyses of the elastic-energy density, and free volumes during shear-banding are beneficial to understand serrated-flow behavior. The amplitude and elastic-energy density display a gradually increasing and then decreasing trend with increasing the content of Zr. It is based on the free-volume theory describing the atomic-level structure of ternary Zr-Cu-Al BMGs. The good agreement between the molecular dynamics simulation and experimental results provides evidence for the variation of free volumes as the elementary mechanism of composition mediated serration dynamics.

  6. Gas Sensors Based on Semiconducting Metal Oxide One-Dimensional Nanostructures

    PubMed Central

    Huang, Jin; Wan, Qing

    2009-01-01

    This article provides a comprehensive review of recent (2008 and 2009) progress in gas sensors based on semiconducting metal oxide one-dimensional (1D) nanostructures. During last few years, gas sensors based on semiconducting oxide 1D nanostructures have been widely investigated. Additionally, modified or doped oxide nanowires/nanobelts have also been synthesized and used for gas sensor applications. Moreover, novel device structures such as electronic noses and low power consumption self-heated gas sensors have been invented and their gas sensing performance has also been evaluated. Finally, we also point out some challenges for future investigation and practical application. PMID:22303154

  7. Influence of Crystalline Nanoprecipitates on Shear-Band Propagation in Cu-Zr-Based Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Brink, Tobias; Peterlechner, Martin; Rösner, Harald; Albe, Karsten; Wilde, Gerhard

    2016-05-01

    The interaction of shear bands with crystalline nanoprecipitates in Cu-Zr-based metallic glasses is investigated by a combination of high-resolution TEM imaging and molecular-dynamics computer simulations. Our results reveal different interaction mechanisms: Shear bands can dissolve precipitates, can wrap around crystalline obstacles, or can be blocked depending on the size and density of the precipitates. If the crystalline phase has a low yield strength, we also observe slip transfer through the precipitate. Based on the computational results and experimental findings, a qualitative mechanism map is proposed that categorizes the various processes as a function of the critical stress for dislocation nucleation, precipitate size, and distance.

  8. The Gellyfish: An In-Situ Equilibrium-Based Sampler for Determining Multiple Free Metal Ion Concentrations in Marine Ecosystems

    PubMed Central

    Dong, Zhao; Lewis, Christopher G.; Burgess, Robert M.; Shine, James P.

    2016-01-01

    Free metal ions are usually the most bioavailable and toxic metal species to aquatic organisms, but they are difficult to measure due to their extremely low concentrations in the marine environment. Many of the current methods for determining free metal ions are complicated, time-consuming, and can only measure one metal at a time. We developed a new version of the ‘Gellyfish’, an in-situ equilibrium-based sampler, with significantly reduced equilibration time and the capability of measuring multiple free metal ions simultaneously. By calibrating the Gellyfish to account for its uptake of cationic metal complexes and validating them in multi-metal competition experiments, we were able to determine free metal ion concentrations previously collected over ten months at five locations in Boston Harbor for Cu, Zn, Pb, Ni, and Cd. This work generated one of the largest free metal ion datasets and demonstrated the applicability of the Gellyfish as an easy-to-use and inexpensive tool for monitoring free ion concentrations of metal mixtures in marine ecosystems. PMID:25598362

  9. The Gellyfish: An in situ equilibrium-based sampler for determining multiple free metal ion concentrations in marine ecosystems.

    PubMed

    Dong, Zhao; Lewis, Christopher G; Burgess, Robert M; Shine, James P

    2015-05-01

    Free metal ions are usually the most bioavailable and toxic metal species to aquatic organisms, but they are difficult to measure because of their extremely low concentrations in the marine environment. Many of the current methods for determining free metal ions are complicated and time-consuming, and they can only measure 1 metal at a time. The authors developed a new version of the "Gellyfish," an in situ equilibrium-based sampler, with significantly reduced equilibration time and the capability of measuring multiple free metal ions simultaneously. By calibrating the Gellyfish to account for its uptake of cationic metal complexes and validating them in multi-metal competition experiments, the authors were able to determine free metal ion concentrations previously collected over 10 mo at 5 locations in Boston Harbor for Cu, Zn, Pb, Ni, and Cd. This generated 1 of the largest free metal ion datasets and demonstrated the applicability of the Gellyfish as an easy-to-use and inexpensive tool for monitoring free ion concentrations of metal mixtures in marine ecosystems.

  10. On the Existence of Our Metals-Based Civilization: I. Phase Space Analysis

    SciTech Connect

    D.D. Macdonald

    2005-06-22

    than are equilibrium thermodynamic diagrams. Thus, KSDs more accurately account for the limits of passivity in highly acidic systems, where acid depassivation occurs, and at high potentials, where transition to the transpassive state may occur in some systems. In any event, phase space analysis of the PDM permits specification of the conditions over which reactive metals will remain passive in contact with aqueous systems and hence of the conditions that must be met for the existence of our metals-based civilization.

  11. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    SciTech Connect

    ME Petrichek

    2005-12-16

    Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel base alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed

  12. Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

    PubMed

    Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

    2014-02-01

    The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal.

  13. A numerical study of multi filament formation in metal-ion based CBRAM

    NASA Astrophysics Data System (ADS)

    Berco, Dan; Tseng, Tseung-Yuen

    2016-02-01

    This study investigates the underlying mechanisms of multiple conductive filaments (CF) creation in metal-ion based conductive bridge RRAM (CBRAM) by using the Metropolis Monte Carlo algorithm and suggests a possible explanation for this phenomenon. The simulation method is demonstrated over a Cu/HfO2 structure, starting from a random initial distribution of oxygen vacancies (OV) defects in the resistive switching layer, to a formed CF and ending in a ruptured state. the results indicate that "Hot Spots" (HS), where agglomeration of OV trap like states for electron hopping based conduction induce local heating, create favorable energy conditions to attract diffused metal species originating from the top electrode. While HS may be created and annihilated by random OV generation and recombination processes, the precipitated metal forms a stem out of which a CF could evolve. The CF stem's final growth stage is mainly driven by drift and diffusion. This process may lead to the formation of one or more CFs as a function of the forming bias voltage. This bias dependence is demonstrated over a large range, where the creation of a single, double and multiple CFs are shown. In addition, the reset process of the multi CF device is presented, and the experimentally observed, step like, gradual CBRAM reset is verified. The simulated results are in good agreement with experimental data and promote the idea that OV defect engineering may be used to improve CBRAM performance.

  14. Synchrotron-based investigation of transition-metal getterability in n-type multicrystalline silicon

    NASA Astrophysics Data System (ADS)

    Morishige, Ashley E.; Jensen, Mallory A.; Hofstetter, Jasmin; Yen, Patricia X. T.; Wang, Chenlei; Lai, Barry; Fenning, David P.; Buonassisi, Tonio

    2016-05-01

    Solar cells based on n-type multicrystalline silicon (mc-Si) wafers are a promising path to reduce the cost per kWh of photovoltaics; however, the full potential of the material and how to optimally process it are still unknown. Process optimization requires knowledge of the response of the metal-silicide precipitate distribution to processing, which has yet to be directly measured and quantified. To supply this missing piece, we use synchrotron-based micro-X-ray fluorescence (μ-XRF) to quantitatively map >250 metal-rich particles in n-type mc-Si wafers before and after phosphorus diffusion gettering (PDG). We find that 820 °C PDG is sufficient to remove precipitates of fast-diffusing impurities and that 920 °C PDG can eliminate precipitated Fe to below the detection limit of μ-XRF. Thus, the evolution of precipitated metal impurities during PDG is observed to be similar for n- and p-type mc-Si, an observation consistent with calculations of the driving forces for precipitate dissolution and segregation gettering. Measurements show that minority-carrier lifetime increases with increasing precipitate dissolution from 820 °C to 880 °C PDG, and that the lifetime after PDG at 920 °C is between the lifetimes achieved after 820 °C and 880 °C PDG.

  15. Exploring the DNA binding mode of transition metal based biologically active compounds

    NASA Astrophysics Data System (ADS)

    Raman, N.; Sobha, S.

    2012-01-01

    Few novel 4-aminoantipyrine derived Schiff bases and their metal complexes were synthesized and characterized. Their structural features and other properties were deduced from the elemental analysis, magnetic susceptibility and molar conductivity as well as from mass, IR, UV-vis, 1H NMR and EPR spectral studies. The binding of the complexes with CT-DNA was analyzed by electronic absorption spectroscopy, viscosity measurement, and cyclic voltammetry. The interaction of the metal complexes with DNA was also studied by molecular modeling with special reference to docking. The experimental and docking results revealed that the complexes have the ability of interaction with DNA of minor groove binding mode. The intrinsic binding constants ( Kb) of the complexes with CT-DNA were found out which show that they are minor groove binders. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the pUC19 DNA in the presence of AH 2 (ascorbic acid). Moreover, the oxidative cleavage studies using distamycin revealed the minor groove binding for the newly synthesized 4-aminoantipyrine derived Schiff bases and their metal complexes. Evaluation of antibacterial activity of the complexes against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, and Klebsiella pneumoniae exhibited that the complexes have potent biocidal activity than the free ligands.

  16. Fracto-emission in lanthanum-based metallic glass microwires under quasi-static tensile loading

    NASA Astrophysics Data System (ADS)

    Banerjee, Amit; Jiang, Chenchen; Lohiya, Lokesh; Yang, Yong; Lu, Yang

    2016-04-01

    Plastic deformation in metallic glasses is highly localized and often associated with shear banding, which may cause momentary release of heat upon fracture. Here, we report an explosive fracture phenomenon associated with momentary (˜10 ms) light emission (flash) in Lanthanum-based (LaAlNi) metallic glass microwires (dia. ˜50 μm) under quasi-static tensile loading. The load-displacement data as well as the visual information of the tensile deformation process were acquired through an in situ measurement set-up, which clearly showed nonlinear stress (σ)-strain ( ɛ) curves prior to yielding and also captured the occurrence of the flash at high fracture stresses (˜1 GPa). Through the postmortem fractographic analysis, it can be revealed that the fracto-emission upon quasi-static loading could be mainly attributed to the localized adiabatic work accumulated at a very large elastic strain confined within the microscale sample volume, followed by a localized high temperature rise up to ˜1000 K at the fracture surface through localized energy dissipation. Our findings suggest that the La-based metallic glass microwires could be useful for energetic microchips, micro-ignition devices, and other functional applications.

  17. Investigating extent of dissolved organic carbon stabilization by metal based coagulant in a wetland environment

    NASA Astrophysics Data System (ADS)

    Henneberry, Y.; Mourad, D.; Kraus, T.; Bachand, P.; Fujii, R.; Horwath, W.

    2008-12-01

    This study is part of a larger project designed to investigate the feasibility of using metal-based coagulants to remove dissolved organic carbon (DOC) from island drainage water in the San Joaquin Delta and subsequently retaining the metal-DOC precipitate (floc) in wetlands constructed at the foot of levees to promote levee stability. Dissolved organic carbon is a constituent of concern as some forms of DOC can be converted to carcinogenic compounds during drinking water treatment. The focus of this work is to assess floc stability over time and to determine whether floc can be permanently sequestered as part of wetland sediment. Drainage water collected seasonally from Twitchell Island was coagulated with ferric sulfate and polyaluminum chloride at optimal and 50%-optimal dosage levels. Floc was incubated in the laboratory under anaerobic conditions for six weeks under various conditions including different DOC concentrations, microbial inoculants, and addition of nutrients. Preliminary results indicate the floc is a stable system; little to no DOC was released from the floc into the water column under incubations with native microbial inoculate. In addition, floc incubated with previously coagulated water appeared to remove additional DOC from the water column. Future work will involve field and laboratory studies using 13C labeled plant material to examine the effects of fresh plant matter and the effects of peat soil DOC on floc stability, in order to elucidate mechanisms behind carbon stabilization by metal-based floc.

  18. Microfluidic-based metal enhanced fluorescence for capillary electrophoresis by Ag nanorod arrays

    NASA Astrophysics Data System (ADS)

    Xiao, Chenyu; Cao, Zhen; Deng, Junhong; Huang, Zhifeng; Xu, Zheng; Fu, Junxue; Yobas, Levent

    2014-06-01

    As metal nanorods show much higher metal enhanced fluorescence (MEF) than metal nanospheres, microfluidic-based MEF is first explored with Ag nanorod (ND) arrays made by oblique angle deposition. By measuring the fluorescein isothiocyanate (FITC) solution sandwiched between the Ag NDs and a piece of cover slip, the enhancement factors (EFs) are found as 3.7 ± 0.64 and 6.74 ± 2.04, for a solution thickness at 20.8 μm and 10 μm, respectively. Because of the strong plasmonic coupling between the adjacent Ag NDs, only the emission of the fluorophores present in the three-dimensional NDs array gets enhanced. Thus, the corresponding effective enhancement factors (EEFs) are revealed to be relatively close, 259 ± 92 and 340 ± 102, respectively. To demonstrate the application of MEF in microfluidic systems, a multilayer of SiO2 NDs/Ag NDs is integrated with a capillary electrophoresis device. At a microchannel depth of 10 μm, an enhancement of 6.5 fold is obtained for amino acids separation detection. These results are very encouraging and open the possibility of MEF applications for the Ag ND arrays decorated microchannels. With the miniaturization of microfluidic devices, microfluidic-based MEF by Ag ND arrays will likely find more applications with further enhancement.

  19. Efficiently Evaluating Heavy Metal Urban Soil Pollution Using an Improved Entropy-Method-Based Topsis Model.

    PubMed

    Liu, Jie; Liu, Chun; Han, Wei

    2016-10-01

    Urban soil pollution is evaluated utilizing an efficient and simple algorithmic model referred to as the entropy method-based Topsis (EMBT) model. The model focuses on pollution source position to enhance the ability to analyze sources of pollution accurately. Initial application of EMBT to urban soil pollution analysis is actually implied. The pollution degree of sampling point can be efficiently calculated by the model with the pollution degree coefficient, which is efficiently attained by first utilizing the Topsis method to determine evaluation value and then by dividing the evaluation value of the sample point by background value. The Kriging interpolation method combines coordinates of sampling points with the corresponding coefficients and facilitates the formation of heavy metal distribution profile. A case study is completed with modeling results in accordance with actual heavy metal pollution, proving accuracy and practicality of the EMBT model.

  20. Tuning the Magnetic Properties of Cobalt-Based Metallic Glass Nanocomposites

    NASA Astrophysics Data System (ADS)

    Veligatla, Medha; Das, Santanu; Lee, Won Ki; Hwang, Junyeon; Thumthan, Orathai; Hao, Yaowu; Mukherjee, Sundeep

    2016-01-01

    Temperature-induced variation in magnetic properties for cobalt-based metallic glass was investigated. The formation of metastable nanocrystalline phases prior to complete devitrification and their effect on magnetic properties for Co72B19.2Si4.8Cr4 metallic glass was studied. The nature, shape, and distribution of the intermediate nanocrystalline phases were characterized using transmission electron microscopy and x-ray diffraction. A drastic change in magnetic properties was found in going from a fully amorphous state to different stages of nanocrystallization. The coercivity changes from amorphous soft magnetic state ( H c ~ 0.12 Oe) to a nanocrystalline-dispersed hard magnetic state ( H c ~ 187 Oe), with no significant change in saturation magnetization. This suggests potential use in futuristic magnetic switches, fluxgate sensors, and electromagnetic shielding devices.

  1. In2O3-based multicomponent metal oxide films and their prospects for thermoelectric applications

    NASA Astrophysics Data System (ADS)

    Korotcenkov, G.; Brinzari, V.; Cho, B. K.

    2016-02-01

    Thermoelectric properties of In2O3-SnO2-based multi-component metal oxide films formed by spray pyrolysis method are studied. It is shown that the introduction of additional components such as gallium and zinc can control the parameters of the deposited layers. At that, the doping with gallium is more effective for optimization of the efficiency of the thermoelectric conversion. The explanation of the observed changes in the electro-physical and thermoelectric properties of the films at the composition change is given. It is found that the main changes in the properties of multicomponent metal oxide films take place at concentrations of dopants which correspond to their limit solubility in the dominant oxide.

  2. Improved Photo-Induced Stability in Amorphous Metal-Oxide Based TFTs for Transparent Displays.

    PubMed

    Koo, Sang-Mo; Ha, Tae-Jun

    2015-10-01

    In this paper, we investigate the origin of photo-induced instability in amorphous metal-oxide based thin-film transistors (oxide-TFTs) by exploring threshold voltage (Vth) shift in transfer characteristics. The combination of photo irradiation and prolonged gate bias stress enhanced the shift in Vth in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs. Such results stem from the extended trapped charges at the localized defect states related to oxygen vacancy which play a role in a screening effect on the electric field induced by gate voltage. We also demonstrate the chemically clean interface in oxide-TFTs by employing oxygen annealing which reduces the density of trap states, thereby resulting in improved photo-induced stability. We believe that this work stimulates the research society of transparent electronics by providing a promising approach to suppress photo-induced instability in metal-oxide TFTs. PMID:26726416

  3. Metal shell technology based upon hollow jet instability. [for inertial confinement fusion

    NASA Technical Reports Server (NTRS)

    Kendall, J. M.; Lee, M. C.; Wang, T. G.

    1982-01-01

    Spherical shells of submillimeter size are sought as ICF targets. Such shells must be dimensionally precise, smooth, of high strength, and composed of a high atomic number material. A technology for the production of shells based upon the hydrodynamic instability of an annular jet of molten metal is described. Shells in the 0.7-2.0 mm size range have been produced using tin as a test material. Specimens exhibit good sphericity, fair concentricity, and excellent finish over most of the surface. Work involving a gold-lead-antimony alloy is in progress. Droplets of this are amorphous and possess superior surface finish. The flow of tin models that of the alloy well; experiments on both metals show that the technique holds considerable promise.

  4. Graphene-based half-metal and spin-semiconductor for spintronic applications

    NASA Astrophysics Data System (ADS)

    Qi, Jingshan; Chen, Xiaofang; Hu, Kaige; Feng, Ji

    2016-03-01

    In this letter we propose a strategy to make graphene become a half-metal or spin-semiconductor by combining the magnetic proximity effects and sublattice symmetry breaking in graphone/graphene and graphone/graphene/BN heterostructures. Exchange interactions lift the spin degeneracy and sublattice symmetry breaking opens a band gap in graphene. More interestingly, the gap opening depends on the spin direction and the competition between the sublattice asymmetry and exchange field determines the system is a half-metal or a spin-semiconductor. By first-principles calculations and a low-energy effective model analysis, we elucidate the underlying physical mechanism of spin-dependent gap opening and spin degeneracy splitting. This offers an alternative practical platform for graphene-based spintronics.

  5. [Eco-toxicological effect of metal-based nanoparticles on plants: Research progress].

    PubMed

    Zhang, Hai; Peng, Cheng; Yang, Jian-Jun; Shi, Ji-yan

    2013-03-01

    The rapid development of nanotechnology and the potential environmental risk of wide application of artificial nanoparticles (NPs) have raised considerable concerns. Metal-based nanoparticles (MB NPs) have dual-toxicity of metal and NPs, and thus, their bio-toxicity and ecological risk are the hotspots in the studies of nanotoxicology. Plant, as a main component of ecosystem, is a potential pathway for NPs bioaccumulation and entering into food chain. This paper discussed the MB NPs absorption, translocation, and accumulation by plants, and summarized the eco-toxicological effect of MB NPs on plants and related mechanisms. The factors affecting the phytotoxicity of MB NPs were approached, and the research progress on the eco-toxicological effect of MB NPs on plants, especially on food crops, was reviewed. Also, the existing problems in present MB NPs phytotoxicity studies were analyzed, and the future research directions were proposed.

  6. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles

    NASA Astrophysics Data System (ADS)

    Choudhury, Snehashis; Mangal, Rahul; Agrawal, Akanksha; Archer, Lynden A.

    2015-12-01

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

  7. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles.

    PubMed

    Choudhury, Snehashis; Mangal, Rahul; Agrawal, Akanksha; Archer, Lynden A

    2015-12-04

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

  8. Mechanical and electrical cold bonding based on metallic nanowire surface fasteners.

    PubMed

    Ju, Yang; Amano, Masahiro; Chen, Mingji

    2012-09-14

    Mass production of surface mount devices (SMDs) relies heavily on reflow soldering and has become the cornerstone of today's electronic industry. However, the traditional reflow soldering technique is characterized by high heating temperatures, toxic solder materials and low recycling rate of SMDs. Here, we propose a new patterned structure of Au nanowire arrays named a surface fastener through which cold bonding for surface mount technology can be realized. The mechanical bonding enables normal and shear bonding strengths of more than 5 N cm(-2). Simultaneously, the parasitic resistance of a pair of surface fasteners is only approximately 2 Ω. The present technique can be performed at room temperature, thereby improving the process compatibility and reliability of SMDs. Surface fasteners based on high melting point metallic nanowires are temperature-resistant for many critical applications. In addition, bonding without solder material is positive for the recycling of rare metals in SMDs.

  9. Improved Photo-Induced Stability in Amorphous Metal-Oxide Based TFTs for Transparent Displays.

    PubMed

    Koo, Sang-Mo; Ha, Tae-Jun

    2015-10-01

    In this paper, we investigate the origin of photo-induced instability in amorphous metal-oxide based thin-film transistors (oxide-TFTs) by exploring threshold voltage (Vth) shift in transfer characteristics. The combination of photo irradiation and prolonged gate bias stress enhanced the shift in Vth in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs. Such results stem from the extended trapped charges at the localized defect states related to oxygen vacancy which play a role in a screening effect on the electric field induced by gate voltage. We also demonstrate the chemically clean interface in oxide-TFTs by employing oxygen annealing which reduces the density of trap states, thereby resulting in improved photo-induced stability. We believe that this work stimulates the research society of transparent electronics by providing a promising approach to suppress photo-induced instability in metal-oxide TFTs.

  10. Efficiently Evaluating Heavy Metal Urban Soil Pollution Using an Improved Entropy-Method-Based Topsis Model.

    PubMed

    Liu, Jie; Liu, Chun; Han, Wei

    2016-10-01

    Urban soil pollution is evaluated utilizing an efficient and simple algorithmic model referred to as the entropy method-based Topsis (EMBT) model. The model focuses on pollution source position to enhance the ability to analyze sources of pollution accurately. Initial application of EMBT to urban soil pollution analysis is actually implied. The pollution degree of sampling point can be efficiently calculated by the model with the pollution degree coefficient, which is efficiently attained by first utilizing the Topsis method to determine evaluation value and then by dividing the evaluation value of the sample point by background value. The Kriging interpolation method combines coordinates of sampling points with the corresponding coefficients and facilitates the formation of heavy metal distribution profile. A case study is completed with modeling results in accordance with actual heavy metal pollution, proving accuracy and practicality of the EMBT model. PMID:27469469

  11. Method for separating metal chelates from other materials based on solubilities in supercritical fluids

    DOEpatents

    Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

    2001-01-01

    A method for separating a desired metal or metalloi from impurities using a supercritical extraction process based on solubility differences between the components, as well as the ability to vary the solvent power of the supercritical fluid, is described. The use of adduct-forming agents, such as phosphorous-containing ligands, to separate metal or metalloid chelates in such processes is further disclosed. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones; phosphine oxides, such as trialkylphosphine oxides, triarylphosphine oxides and alkylarylphosphine oxides; phosphinic acids; carboxylic acids; phosphates, such as trialkylphosphates, triarylphosphates and alkylarylphosphates; crown ethers; dithiocarbamates; phosphine sulfides; phosphorothioic acids; thiophosphinic acids; halogenated analogs of these chelating agents; and mixtures of these chelating agents. In especially preferred embodiments, at least one of the chelating agents is fluorinated.

  12. Tunable nonreciprocal terahertz transmission and enhancement based on metal/magneto-optic plasmonic lens.

    PubMed

    Fan, Fei; Chen, Sai; Wang, Xiang-Hui; Chang, Sheng-Jiang

    2013-04-01

    A tunable metal/magneto-optic plasmonic lens for terahertz isolator is demonstrated. Based on the magneto-optical effect of the semiconductor material and non-symmetrical structure, this plasmonic lens has not only the focusing feature but also nonreciprocal transmission property. Moreover, a transmission enhancement through this device greatly larger than that of the ordinary metallic slit arrays is contributed by the extraordinary optical transmission effect of the magneto surface plasmon polaritons. The results show that the proposed isolator has an isolation bandwidth of larger than 0.4THz and the maximum isolation of higher than 110dB, and its operating frequency also can be broadly tuned by changing the external magnetic field or temperature. This low-loss, high isolation, broadband tunable nonreciprocal terahertz transmission mechanism has a great potential for terahertz application systems. PMID:23571951

  13. Metal-organic frameworks as biosensors for luminescence-based detection and imaging.

    PubMed

    Miller, Sophie E; Teplensky, Michelle H; Moghadam, Peyman Z; Fairen-Jimenez, David

    2016-08-01

    Metal-organic frameworks (MOFs), formed by the self-assembly of metal centres or clusters and organic linkers, possess many key structural and chemical features that have enabled them to be used in sensing platforms for a variety of environmentally, chemically and biomedically relevant compounds. In particular, their high porosity, large surface area, tuneable chemical composition, high degree of crystallinity, and potential for post-synthetic modification for molecular recognition make MOFs promising candidates for biosensing applications. In this review, we separate our discussion of MOF biosensors into two categories: quantitative sensing, focusing specifically on luminescence-based sensors for the direct measurement of a specific analyte, and qualitative sensing, where we describe MOFs used for fluorescence microscopy and as magnetic resonance imaging contrast agents. We highlight several key publications in each of these areas, concluding that MOFs present an exciting, versatile new platform for biosensing applications and imaging, and we expect to see their usage grow as the field progresses.

  14. A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

    PubMed Central

    Bai, Min; Huang, Hui; Hao, Jian; Zhang, Ji; Wu, Haibo; Qu, Bo

    2015-01-01

    Trace analysis of liquid samples has wide applications in life science and environmental monitor. In this paper, a compact and low-cost photometer based on metal-waveguide-capillary (MWC) was developed for ultra-sensitive absorbance detection. The optical-path can be greatly enhanced and much longer than the physical length of MWC, because the light scattered by the rippled and smooth metal sidewall can be confined inside the capillary regardless of the incident-angle. For the photometer with a 7 cm long MWC, the detection limit is improved ~3000 fold compared with that of commercial spectrophotometer with 1 cm-cuvette, owing to the novel nonlinear optical-path enhancement as well as fast sample switching, and detecting glucose of a concentration as low as 5.12 nM was realized with conventional chromogenic reagent. PMID:26020222

  15. A new method for the characterisation and quantitative speciation of base metal smelter stack particulates.

    PubMed

    Skeaff, James M; Thibault, Yves; Hardy, David J

    2011-06-01

    Base metal smelters may be a source of particulates containing metals of environmental concern released to the atmosphere. Knowledge of the quantitative chemical speciation of particulate releases from base metal smelters will be of value in smelter emission fingerprinting, site-specific risk assessments, predictions of the behaviour of smelter stack particulates released to the environment and in resolving liability issues related to current and historic releases. Accordingly, we have developed an innovative approach comprising bulk chemical analysis, a leaching procedure, X-ray diffraction analysis and scanning electron microscopy/electron probe microanalysis characterisation in a step-wise apportioning procedure to derive the quantitative speciation of particulate samples from the stacks of three copper smelters designated as A, B and C. For the A smelter stack particulates, the major calculated percentages were 29 CuSO(4), 20 ZnSO(4).H(2)O, 13 (Cu(0.94)Zn(0.06))(2)(AsO(4))(OH), 11 PbSO(4) and four As(2)O(3). For the B smelter stack particulates, the primary calculated percentages were 20 ZnSO(4).H(2)O, 20 PbSO(4), 12 CuSO(4) and nine As(2)O(3). Finally, we calculated that the C smelter stack particulates mostly comprised 34 ZnSO(4).H(2)O, 19 (Cu(0.84)Zn(0.16))(AsO(3)OH), 11 PbSO(4), 10 As(2)O(3) and nine Zn(3)(AsO(4))(2). Between 56% and 67% by weight of the smelter stack particulates, including the As, was soluble in water. For these and other operations, the data and approach may be useful in estimating metals partitioning among water, soil and sediment, as well as predictions of the effects of the stack particulates released to the environment. PMID:20676929

  16. Metal-filled carbon nanotube based optical nanoantennas: bubbling, reshaping, and in situ characterization.

    PubMed

    Fan, Zheng; Tao, Xinyong; Cui, Xudong; Fan, Xudong; Zhang, Xiaobin; Dong, Lixin

    2012-09-21

    Controlled fabrication of metal nanospheres on nanotube tips for optical antennas is investigated experimentally. Resembling soap bubble blowing using a straw, the fabrication process is based on nanofluidic mass delivery at the attogram scale using metal-filled carbon nanotubes (m@CNTs). Two methods have been investigated including electron-beam-induced bubbling (EBIB) and electromigration-based bubbling (EMBB). EBIB involves the bombardment of an m@CNT with a high energy electron beam of a transmission electron microscope (TEM), with which the encapsulated metal is melted and flowed out from the nanotube, generating a metallic particle on a nanotube tip. In the case where the encapsulated materials inside the CNT have a higher melting point than what the beam energy can reach, EMBB is an optional process to apply. Experiments show that, under a low bias (2.0-2.5 V), nanoparticles can be formed on the nanotube tips. The final shape and crystallinity of the nanoparticles are determined by the cooling rate. Instant cooling occurs with a relatively large heat sink and causes the instant shaping of the solid deposit, which is typically similar to the shape of the molten state. With a smaller heat sink as a probe, it is possible to keep the deposit in a molten state. Instant cooling by separating the deposit from the probe can result in a perfect sphere. Surface and volume plasmons characterized with electron energy loss spectroscopy (EELS) prove that resonance occurs between a pair of as-fabricated spheres on the tip structures. Such spheres on pillars can serve as nano-optical antennas and will enable devices such as scanning near-field optical microscope (SNOM) probes, scanning anodes for field emitters, and single molecule detectors, which can find applications in bio-sensing, molecular detection, and high-resolution optical microscopy.

  17. Metal oxide based multisensor array and portable database for field analysis of antioxidants

    PubMed Central

    Sharpe, Erica; Bradley, Ryan; Frasco, Thalia; Jayathilaka, Dilhani; Marsh, Amanda; Andreescu, Silvana

    2014-01-01

    We report a novel chemical sensing array based on metal oxide nanoparticles as a portable and inexpensive paper-based colorimetric method for polyphenol detection and field characterization of antioxidant containing samples. Multiple metal oxide nanoparticles with various polyphenol binding properties were used as active sensing materials to develop the sensor array and establish a database of polyphenol standards that include epigallocatechin gallate, gallic acid, resveratrol, and Trolox among others. Unique charge-transfer complexes are formed between each polyphenol and each metal oxide on the surface of individual sensors in the array, creating distinct optically detectable signals which have been quantified and logged into a reference database for polyphenol identification. The field-portable Pantone/X-Rite© CapSure® color reader was used to create this database and to facilitate rapid colorimetric analysis. The use of multiple metal-oxide sensors allows for cross-validation of results and increases accuracy of analysis. The database has enabled successful identification and quantification of antioxidant constituents within real botanical extractions including green tea. Formation of charge-transfer complexes is also correlated with antioxidant activity exhibiting electron transfer capabilities of each polyphenol. The antioxidant activity of each sample was calculated and validated against the oxygen radical absorbance capacity (ORAC) assay showing good comparability. The results indicate that this method can be successfully used for a more comprehensive analysis of antioxidant containing samples as compared to conventional methods. This technology can greatly simplify investigations into plant phenolics and make possible the on-site determination of antioxidant composition and activity in remote locations. PMID:24610993

  18. Metal oxide based multisensor array and portable database for field analysis of antioxidants.

    PubMed

    Sharpe, Erica; Bradley, Ryan; Frasco, Thalia; Jayathilaka, Dilhani; Marsh, Amanda; Andreescu, Silvana

    2014-03-31

    We report a novel chemical sensing array based on metal oxide nanoparticles as a portable and inexpensive paper-based colorimetric method for polyphenol detection and field characterization of antioxidant containing samples. Multiple metal oxide nanoparticles with various polyphenol binding properties were used as active sensing materials to develop the sensor array and establish a database of polyphenol standards that include epigallocatechin gallate, gallic acid, resveratrol, and Trolox among others. Unique charge-transfer complexes are formed between each polyphenol and each metal oxide on the surface of individual sensors in the array, creating distinct optically detectable signals which have been quantified and logged into a reference database for polyphenol identification. The field-portable Pantone/X-Rite© CapSure® color reader was used to create this database and to facilitate rapid colorimetric analysis. The use of multiple metal-oxide sensors allows for cross-validation of results and increases accuracy of analysis. The database has enabled successful identification and quantification of antioxidant constituents within real botanical extractions including green tea. Formation of charge-transfer complexes is also correlated with antioxidant activity exhibiting electron transfer capabilities of each polyphenol. The antioxidant activity of each sample was calculated and validated against the oxygen radical absorbance capacity (ORAC) assay showing good comparability. The results indicate that this method can be successfully used for a more comprehensive analysis of antioxidant containing samples as compared to conventional methods. This technology can greatly simplify investigations into plant phenolics and make possible the on-site determination of antioxidant composition and activity in remote locations. PMID:24610993

  19. Precision of image-based registration for intraoperative navigation in the presence of metal artifacts: Application to corrective osteotomy surgery.

    PubMed

    Dobbe, J G G; Curnier, F; Rondeau, X; Streekstra, G J

    2015-06-01

    Navigation for corrective osteotomy surgery requires patient-to-image registration. When registration is based on intraoperative 3-D cone-beam CT (CBCT) imaging, metal landmarks may be used that deteriorate image quality. This study investigates whether metal artifacts influence the precision of image-to-patient registration, either with or without intermediate user intervention during the registration procedure, in an application for corrective osteotomy of the distal radius. A series of 3-D CBCT scans is made of a cadaver arm with and without metal landmarks. Metal artifact reduction (MAR) based on inpainting techniques is used to improve 3-D CBCT images hampered by metal artifacts. This provides three sets of images (with metal, with MAR, and without metal), which enable investigating the differences in precision of intraoperative registration. Gray-level based point-to-image registration showed a better correlation coefficient if intraoperative images with MAR are used, indicating a better image similarity. The precision of registration without intermediate user intervention during the registration procedure, expressed as the residual angulation and displacement error after repetitive registration was very low and showed no improvement when MAR was used. By adding intermediate user intervention to the registration procedure however, precision was very high but was not affected by the presence of metal artifacts in the specific application.

  20. Spatial-based assessment of heavy metal contamination in agricultural soils surrounding a non-ferrous metal smelting zone.

    PubMed

    Liang, Shuxuan; Li, Xiaoyan; Xu, Hao; Wang, Xin; Gao, Ning

    2013-11-01

    This work aimed to assess the degree of anthropogenic influence and severity of heavy metal from a non-ferrous metal smelting industrial zone. The results suggested that anthropogenic inputs played a dominant role in the enrichment of Cu, Zn, Pb, Sb and Cd. These metals showed similar spatial distribution patterns. Multivariate analysis showed strongly significant relationships between Cu-Zn,Cd-Zn, Cd-Sb, Sb, Sb, Cu, Zn, and Pb. Strong relationship was found between Cr, Ni, Cu, Zn, Sb and organic matter in soil. Risk evaluation results within the soil investigated profile was in the following order: Cd > Sb > Cu > Zn > Pb. Nemerow's synthetical contamination index revealed that there is substantial ecotoxicological risk among the sampling sites with 8 of 9 of these locations exceeding the Nemerow criteria for seriously impacted sites and another site was close to moderately polluted domain.

  1. Selective extraction of metals from mixed oxide matrixes using choline-based ionic liquids.

    PubMed

    Abbott, Andrew P; Capper, Glen; Davies, David L; Rasheed, Raymond K; Shikotra, Pragna

    2005-09-19

    The solubility of a range of metal oxides in a eutectic mixture of urea/choline chloride is quantified, and it is shown that the dissolved metals can be reclaimed from a mixed metal oxide matrix using electrodeposition. PMID:16156600

  2. Detection of DNA damage based on metal-mediated molecular beacon and DNA strands displacement reaction.

    PubMed

    Xiong, Yanxiang; Wei, Min; Wei, Wei; Yin, Lihong; Pu, Yuepu; Liu, Songqin

    2014-01-24

    DNA hairpin structure probes are usually designed by forming intra-molecular duplex based on Watson-Crick hydrogen bonds. In this paper, a molecular beacon based on silver ions-mediated cytosine-Ag(+)-cytosine base pairs was used to detect DNA. The inherent characteristic of the metal ligation facilitated the design of functional probe and the adjustment of its binding strength compared to traditional DNA hairpin structure probes, which make it be used to detect DNA in a simple, rapid and easy way with the help of DNA strands displacement reaction. The method was sensitive and also possesses the good specificity to differentiate the single base mismatched DNA from the complementary DNA. It was also successfully applied to study the damage effect of classic genotoxicity chemicals such as styrene oxide and sodium arsenite on DNA, which was significant in food science, environmental science and pharmaceutical science.

  3. Detection of DNA damage based on metal-mediated molecular beacon and DNA strands displacement reaction

    NASA Astrophysics Data System (ADS)

    Xiong, Yanxiang; Wei, Min; Wei, Wei; Yin, Lihong; Pu, Yuepu; Liu, Songqin

    2014-01-01

    DNA hairpin structure probes are usually designed by forming intra-molecular duplex based on Watson-Crick hydrogen bonds. In this paper, a molecular beacon based on silver ions-mediated cytosine-Ag+-cytosine base pairs was used to detect DNA. The inherent characteristic of the metal ligation facilitated the design of functional probe and the adjustment of its binding strength compared to traditional DNA hairpin structure probes, which make it be used to detect DNA in a simple, rapid and easy way with the help of DNA strands displacement reaction. The method was sensitive and also possesses the good specificity to differentiate the single base mismatched DNA from the complementary DNA. It was also successfully applied to study the damage effect of classic genotoxicity chemicals such as styrene oxide and sodium arsenite on DNA, which was significant in food science, environmental science and pharmaceutical science.

  4. Plastic deformation behaviors of Ni- and Zr-based bulk metallic glasses subjected to nanoindentation

    SciTech Connect

    Weizhong, Liang; Zhiliang, Ning; Zhenqian, Dang; Linzhi, Wu

    2013-12-15

    Plastic deformation behaviors of Ni{sub 42}Ti{sub 20}Zr{sub 21.5}Al{sub 8}Cu{sub 5}Si{sub 3.5} and Zr{sub 51}Ti{sub 5}Ni{sub 10}Cu{sub 25}Al{sub 9} bulk metallic glasses at room temperature were studied by nanoindentation testing and atomic force microscopy under equivalent indentation experimental conditions. The different chemical composition of these two bulk metallic glasses produced variant tendencies for displacement serrated flow to occur during the loading process. The nanoindentation strain rate was calculated as a function of indentation displacement in order to verify the occurrence of displacement serrated flow at different loading rates. Atomic force microscopy revealed decreasing numbers of discrete shear bands around the indentation sites as loading rates increased from 0.025 to 2.5 mNs{sup −1}. Variations in plastic deformation behaviors between Ni and Zr-based glasses materials can be explained by the different metastable microstructures and thermal stabilities of the two materials. The mechanism governing plastic deformation of these metallic glasses was analyzed in terms of an established model of the shear transformation zone. - Highlights: • Plastic deformation of Ni- and Zr-based BMG is studied under identical conditions • Zr-based BMG undergoes a greater extent of plastic deformation than Ni-based BMG • Nanoindentation strain rate is studied to clarify variation in plastic deformation • Metastable microstructure, thermal stability affect BMG plastic deformation.

  5. High-energy in-beam neutron measurements of metal-based shielding for accelerator-driven spallation neutron sources

    NASA Astrophysics Data System (ADS)

    DiJulio, D. D.; Cooper-Jensen, C. P.; Björgvinsdóttir, H.; Kokai, Z.; Bentley, P. M.

    2016-05-01

    Metal-based shielding plays an important role in the attenuation of harmful and unwanted radiation at an accelerator-driven spallation neutron source. At the European Spallation Source, currently under construction in Lund, Sweden, metal-based materials are planned to be used extensively as neutron guide substrates in addition to other shielding structures around neutron guides. The usage of metal-based materials in the vicinity of neutron guides however requires careful consideration in order to minimize potential background effects in a neutron instrument at the facility. Therefore, we have carried out a combined study involving high-energy neutron measurements and Monte Carlo simulations of metal-based shielding, both to validate the simulation methodology and also to investigate the benefits and drawbacks of different metal-based solutions. The measurements were carried out at The Svedberg Laboratory in Uppsala, Sweden, using a 174.1 MeV neutron beam and various thicknesses of aluminum-, iron-, and copper-based shielding blocks. The results were compared to geant4 simulations and revealed excellent agreement. Our combined study highlights the particular situations where one type of metal-based solution may be preferred over another.

  6. Aqueous batteries based on mixed monovalence metal ions: a new battery family.

    PubMed

    Chen, Liang; Zhang, Leyuan; Zhou, Xufeng; Liu, Zhaoping

    2014-08-01

    As existing battery technologies struggle to meet the requirements for widespread use in the field of large-scale energy storage, new concepts are urgently needed to build batteries with high energy density, low cost, and good safety. Here, we demonstrate two new aqueous batteries based on two monovalence metal ions (Li(+) /K(+) and Na(+) /K(+) ) as charge-transfer ions, Ni1 Zn1 HCF/TiP2 O7 and Ni1 Zn1 HCF/NaTi2 (PO4 )3 . These new batteries are unlike the conventional "rocking-chair" aqueous metal-ion batteries based on the migration of one type of shuttle ion between cathode and anode. They can deliver specific energy of 46 Wh kg(-1) and 53 Wh kg(-1) based on the total mass of active materials; this is superior to current aqueous battery systems based on sodium-ion and/or potassium-ion technologies. These two new batteries together with the previously developed Li(+) /Na(+) mixed-ion battery not only constitute a new battery family for energy storage, but also greatly broaden our horizons for battery research.

  7. [An optical-fiber-sensor-based spectrophotometer for soil non-metallic nutrient determination].

    PubMed

    He, Dong-xian; Hu, Juan-xiu; Lu, Shao-kun; He, Hou-yong

    2012-01-01

    In order to achieve rapid, convenient and efficient soil nutrient determination in soil testing and fertilizer recommendation, a portable optical-fiber-sensor-based spectrophotometer including immersed fiber sensor, flat field holographic concave grating, and diode array detector was developed for soil non-metallic nutrient determination. According to national standard of ultraviolet and visible spectrophotometer with JJG 178-2007, the wavelength accuracy and repeatability, baseline stability, transmittance accuracy and repeatability measured by the prototype instrument were satisfied with the national standard of III level; minimum spectral bandwidth, noise and excursion, and stray light were satisfied with the national standard of IV level. Significant linear relationships with slope of closing to 1 were found between the soil available nutrient contents including soil nitrate nitrogen, ammonia nitrogen, available phosphorus, available sulfur, available boron, and organic matter measured by the prototype instrument compared with that measured by two commercial single-beam-based and dual-beam-based spectrophotometers. No significant differences were revealed from the above comparison data. Therefore, the optical-fiber-sensor-based spectrophotometer can be used for rapid soil non-metallic nutrient determination with a high accuracy. PMID:22497162

  8. 6-Pyrazolylpurine as an Artificial Nucleobase for Metal-Mediated Base Pairing in DNA Duplexes

    PubMed Central

    Léon, J. Christian; Sinha, Indranil; Müller, Jens

    2016-01-01

    The artificial nucleobase 6-pyrazol-1-yl-purine (6PP) has been investigated with respect to its usability in metal-mediated base pairing. As was shown by temperature-dependent UV spectroscopy, 6PP may form weakly stabilizing 6PP–Ag(I)–6PP homo base pairs. Interestingly, 6PP can be used to selectively recognize a complementary pyrimidine nucleobase. The addition of Ag(I) to a DNA duplex comprising a central 6PP:C mispair (C = cytosine) leads to a slight destabilization of the duplex. In contrast, a stabilizing 6PP–Ag(I)–T base pair is formed with a complementary thymine (T) residue. It is interesting to note that 6PP is capable of differentiating between the pyrimidine moieties despite the fact that it is not as sterically crowded as 6-(3,5-dimethylpyrazol-1-yl)purine, an artificial nucleobase that had previously been suggested for the recognition of nucleic acid sequences via the formation of a metal-mediated base pair. Hence, the additional methyl groups of 6-(3,5-dimethylpyrazol-1-yl)purine may not be required for the specific recognition of the complementary nucleobase. PMID:27089326

  9. Transition-metal-nitride-based thin films as novel energy harvesting materials

    PubMed Central

    Kerdsongpanya, Sit; Alling, Björn

    2016-01-01

    The last few years have seen a rise in the interest in early transition-metal and rare-earth nitrides, primarily based on ScN and CrN, for energy harvesting by thermoelectricity and piezoelectricity. This is because of a number of important advances, among those the discoveries of exceptionally high piezoelectric coupling coefficient in (Sc,Al)N alloys and of high thermoelectric power factors of ScN-based and CrN-based thin films. These materials also constitute well-defined model systems for investigating thermodynamics of mixing for alloying and nanostructural design for optimization of phase stability and band structure. These features have implications for and can be used for tailoring of thermoelectric and piezoelectric properties. In this highlight article, we review the ScN- and CrN-based transition-metal nitrides for thermoelectrics, and drawing parallels with piezoelectricity. We further discuss these materials as a models systems for general strategies for tailoring of thermoelectric properties by integrated theoretical–experimental approaches. PMID:27358737

  10. Transition Metal(II) Complexes with Cefotaxime-Derived Schiff Base: Synthesis, Characterization, and Antimicrobial Studies

    PubMed Central

    Amzoiu, Emilia; Spînu, Cezar Ionuţ

    2014-01-01

    New [ML2(H2O)2] complexes, where M = Co(II), Ni(II), Cu(II), and Zn(II) while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehyde in situ in the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II), Ni(II), and Zn(II) complexes while a tetragonal geometry for Cu(II) complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested for in vitro antibacterial activity against some pathogenic bacterial strains, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base. PMID:24688454

  11. Systematically biological prioritizing remediation sites based on datasets of biological investigations and heavy metals in soil

    NASA Astrophysics Data System (ADS)

    Lin, Wei-Chih; Lin, Yu-Pin; Anthony, Johnathen

    2015-04-01

    Heavy metal pollution has adverse effects on not only the focal invertebrate species of this study, such as reduction in pupa weight and increased larval mortality, but also on the higher trophic level organisms which feed on them, either directly or indirectly, through the process of biomagnification. Despite this, few studies regarding remediation prioritization take species distribution or biological conservation priorities into consideration. This study develops a novel approach for delineating sites which are both contaminated by any of 5 readily bioaccumulated heavy metal soil contaminants and are of high ecological importance for the highly mobile, low trophic level focal species. The conservation priority of each site was based on the projected distributions of 6 moth species simulated via the presence-only maximum entropy species distribution model followed by the subsequent application of a systematic conservation tool. In order to increase the number of available samples, we also integrated crowd-sourced data with professionally-collected data via a novel optimization procedure based on a simulated annealing algorithm. This integration procedure was important since while crowd-sourced data can drastically increase the number of data samples available to ecologists, still the quality or reliability of crowd-sourced data can be called into question, adding yet another source of uncertainty in projecting species distributions. The optimization method screens crowd-sourced data in terms of the environmental variables which correspond to professionally-collected data. The sample distribution data was derived from two different sources, including the EnjoyMoths project in Taiwan (crowd-sourced data) and the Global Biodiversity Information Facility (GBIF) ?eld data (professional data). The distributions of heavy metal concentrations were generated via 1000 iterations of a geostatistical co-simulation approach. The uncertainties in distributions of the heavy

  12. Systems and Methods for Implementing Bulk Metallic Glass-Based Strain Wave Gears and Strain Wave Gear Components

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas C. (Inventor); Wilcox, Brian (Inventor)

    2016-01-01

    Bulk metallic glass-based strain wave gears and strain wave gear components. In one embodiment, a strain wave gear includes: a wave generator; a flexspline that itself includes a first set of gear teeth; and a circular spline that itself includes a second set of gear teeth; where at least one of the wave generator, the flexspline, and the circular spline, includes a bulk metallic glass-based material.

  13. Enhancement of sensitivity of paper-based sensor array for the identification of heavy-metal ions.

    PubMed

    Feng, Liang; Li, Xiao; Li, Hui; Yang, Wei; Chen, Liang; Guan, Yafeng

    2013-05-30

    Paper-based microfluidic devices have been widely investigated in recent years. Among various detection techniques, colorimetric method plays a very important role in paper-based microfluidic devices. The limitation, however, is also clear: they generally require highly sensitive indicators. In this work, we have developed a novel enrichment-based paper test for the discrimination of heavy-metal ions. Comparing to regular paper-based microfluidic devices, enrichment-based technique showed largely improved sensitivity. Combining with eight pyridylazo compounds and array technologies-based pattern-recognition, we have obtained the discrimination capability of eight different heavy-metal ions at same concentration as low as 50 μM using our enrichment-based pyridylazo compounds array paper. Identification of the heavy-metal ions was readily achieved using a standard chemometric approach. This method can be, of course, used for other analytes as well.

  14. A sinogram based technique for image correction and removal of metal clip artifacts in cone beam breast CT

    NASA Astrophysics Data System (ADS)

    Wang, T.; Shen, Y.; Zhong, Y.; Lai, C.-J.; Wang, J.; Shaw, C. C.

    2014-03-01

    Cone beam CT (CBCT) technique provides true three-dimensional (3D) images of a breast; however, metal clips and needles used for surgical planning can cause artifacts, which may extend to many adjacent slices, in the reconstructed images obtained by the Feldkamp-Davis-Kress (FDK) filtered backprojection method,. In this paper, a sinogram based method to remove the metal clips in the projection image data is described and discussed for improving the quality of reconstructed breast images. First, the original projection data was reconstructed using the FDK algorithm to obtain a volumetric image with metal clips and artifacts. Second, the volumetric image was segmented by using the threshold method to obtain a 3D map of metal objects. Third, a forward projection algorithm is applied to the metal object map to obtain projection map of metal objects. Finally, the original projection images and projection map of metal objects are reorganized into sinograms for correction in the angular space on a pixel-by-pixel basis. Cone beam CT images of a mastectomy breast specimen are used to demonstrate the feasibility of using this technique for removal of metal object artifacts. Preliminary results have demonstrated that metal objects artifacts in 3D images were reduced and the image quality were improved.

  15. [Analysis of heavy-metal-mediated disease and development of a novel remediation system based on fieldwork and experimental research].

    PubMed

    Yajima, Ichiro; Zou, Cunchao; Li, Xiang; Nakano, Chizuru; Omata, Yasuhiro; Kumasaka, Mayuko Y

    2015-01-01

    Heavy-metal pollution occurs in various environments, including water, air and soil, and has serious effects on human health. Since heavy-metal pollution in drinking water causes various diseases including skin cancer, it has become a global problem worldwide. However, there is limited information on the mechanism of development of heavy-metal-mediated disease. We performed both fieldwork and experimental studies to elucidate the levels of heavy-metal pollution and mechanisms of development of heavy-metal-related disease and to develop a novel remediation system. Our fieldwork in Bangladesh, Vietnam and Malaysia demonstrated that drinking well water in these countries was polluted with high concentrations of several heavy metals including arsenic, barium, iron and manganese. Our experimental studies based on the data from our fieldwork demonstrated that these heavy metals caused skin cancer and hearing loss. Further experimental studies resulted in the development of a novel remediation system with which toxic heavy metals were absorbed from polluted drinking water. Implementation of both fieldwork and experimental studies is important for prediction, prevention and therapy of heavy-metal-mediated diseases.

  16. An eddy-current-based sensor for preventing knots in metallic wire drawing processes

    NASA Astrophysics Data System (ADS)

    Esteban, Bernat; Riba, Jordi-Roger; Baquero, Grau; Ferrater, Cèsar

    2011-06-01

    During metallic wire drawing processes, the presence of knots and the failure to detect them can lead to long production interruptions, significant economic losses and a lower quality of final product. Consequently, there is a pressing need to develop methods for real-time detection and prevention of this fault. In this paper, a sensor to prevent the formation of knots during the metallic wire drawing process is presented and evaluated by means of experimental data. This fast, inexpensive, non-contact sensor is based on electromagnetic principles such as eddy current induction, magnetic reluctance variations and magnetic coupling. The proposed sensor without direct contact can detect knots in a target metallic wire by measuring the impedance variations of a calibrated sensing coil caused by either a knot or an unwound loop rising from a wire rod. The incorporation of this type of sensor into a wire-drawing machine can avoid the tightening of the knot, thereby reducing downtime and increasing the security and reliability of the process. Experiments were conducted using a scale model of the above proposed system. This allowed highlighting the sensor's potential by carrying out an automatic, real-time knot detection during steel wire drawing.

  17. Facile hydrophobicity/hydrophilicity modification of SMP surface based on metal constrained cracking

    NASA Astrophysics Data System (ADS)

    Han, Yu; Li, Peng; Zhao, Liangyu; Wang, Wenxin; Leng, Jinsong; Jin, Peng

    2015-04-01

    This study demonstrates an easy way to change surface characteristics, the water contact angle on styrene based shape memory polymer (SMP) surface alters before and after cracking formation and recovery. The contact angle of water on the original SMP surface is about 85 degree, after coating with Al and then kneading from side face at glass transition temperature Tg, cracking appeared both on Al film and SMP; cooling down and removing the Al film, cracks remain on SMP surface while the contact angle reduced to about 25 degree. When reheated above Tg, the cracks disappeared, and the contact angle go back to about 85 degree. The thin Al film bonded on SMP surface was coated by spurting, that constrains the deformation of SMP. Heating above Tg, there are complex interactions between soft SMP and hard metal film under kneading. The thin metal film cracked first with the considerable deformation of soft polymer, whereafter, the polymer was ripped by the metal cracks thus polymer cracked as well. Cracks on SMP can be fixed cooling down Tg, while reheated, cracks shrinking and the SMP recovers to its original smooth surface. Surface topography changed dramatically while chemical composition showed no change during the deformation and recovery cycle, as presented by SEM and EDS. Furthermore, the wetting cycle is repeatable. This facile method can be easily extended to the hydropobicity/hydrophilicity modification of other stimuli-responsive polymers and put forward many potential applications, such as microfluidic switching and molecule capture and release.

  18. Analysis of metal contents in Portland Type V and MTA-based cements.

    PubMed

    Dorileo, Maura Cristiane Gonçales Orçati; Bandeca, Matheus Coelho; Pedro, Fábio Luis Miranda; Volpato, Luiz Evaristo Ricci; Guedes, Orlando Aguirre; Dalla Villa, Ricardo; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique

    2014-01-01

    The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS), the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P < 0.05). Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion.

  19. Metals in Human Gall, Bladder, and Kidney Stones Based on an Electron Microprobe Investigation.

    PubMed

    Moser, Reinhard; Zaccarini, Federica; Moser, Waltraud; Schrittwieser, Rudolf; Kerbl, Reinhold

    2015-10-01

    Several particles of copper accompanied by a few particles of nickel, lead, and a compound composed of selenium containing minor Ni, Si, Cu, and Co were found in human gall, kidney, and bladder stones. The investigated particles occur as tiny grains, <10 µm in size, that are irregularly dispersed in the stones. Therefore, they were studied by scanning electron microscopy and qualitatively analyzed by energy dispersive system. One grain of copper contained a small amount of Ni and Zn, and some grains of nickel proved to contain Cr as trace element. Most of the discovered metals formed a single-phase grain. However, a few grains found in two gallstones were associated with inclusions of calcium and apatite. Based on the results presented in this contribution, we argue that most of the studied metals can be classified as endogenous particles, i.e., directly precipitated from the same fluids that formed their host human stones. This observation suggests that the precipitation and accumulation of metals in some human stones can be considered an efficient way to eliminate them from the human body.

  20. High temperature strain sensor based on a fiber Bragg grating and rhombus metal structure.

    PubMed

    Zhang, Liang; Liu, Yueming; Gao, Xiaoliang; Xia, Zhongcheng

    2015-10-01

    In this paper, a novel high temperature strain sensor based on a polyimide-coated fiber Bragg grating (FBG) and a rhombus metal structure is presented and experimentally demonstrated. By heating low softening point glass via a micro torch, the polyimide-coated FBG could be fixed into the rhombus metal structure. Consequently, when the rhombus structure is stretched and compressed, respectively, then the FBG will be subjected to a reverse state. Moreover, the strain sensitivity is controllable and enhanced by adjusting the dimension of the rhombus metal structure appropriately. The experiment was then carried out by using an equi-intensity cantilever beam and high temperature chamber, and the result showed that the proposed high temperature strain sensor could be used at the high temperature of 300°C. A resolution of ∼10  με has been experimentally achieved. The average wavelength strain sensitivity at 300°C is 1.821 and 1.814 pm/με, for the compressed and stretched states, respectively. PMID:26479639