Hierarchical Cu precipitation in lamellated steel after multistage heat treatment

NASA Astrophysics Data System (ADS)

Liu, Qingdong; Gu, Jianfeng

2017-09-01

The hierarchical distribution of Cu-rich precipitates (CRPs) and related partitioning and segregation behaviours of solute atoms were investigated in a 1.54 Cu-3.51 Ni (wt.%) low-carbon high-strength low-alloy (HSLA) steel after multistage heat treatment by using the combination of electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and atom probe tomography (APT). Intercritical tempering at 725 °C of as-quenched lathlike martensitic structure leads to the coprecipitation of CRPs at the periphery of a carbide precipitate which is possibly in its paraequilibrium state due to distinct solute segregation at the interface. The alloyed carbide and CRPs provide constituent elements for each other and make the coprecipitation thermodynamically favourable. Meanwhile, austenite reversion occurs to form fresh secondary martensite (FSM) zone where is rich in Cu and pertinent Ni and Mn atoms, which gives rise to a different distributional morphology of CRPs with large size and high density. In addition, conventional tempering at 500 °C leads to the formation of nanoscale Cu-rich clusters in α-Fe matrix. As a consequence, three populations of CRPs are hierarchically formed around carbide precipitate, at FSM zone and in α-Fe matrix. The formation of different precipitated features can be turned by controlling diffusion pathways of related solute atoms and further to tailor mechanical properties via proper multistage heat treatments.

Enhancing the ag precipitation by surface mechanical attrition treatment on Cu-Ag alloys

NASA Astrophysics Data System (ADS)

Liu, Jiabin; Zhang, Lehao; Liu, Jingjing; Huang, Liuyi; Gu, Hao; Fang, Youtong; Meng, Liang; Zhang, Jian

2016-09-01

The influence of surface mechanical attrition treatment (SMAT) on Ag precipitation in Cu-Ag alloys was investigated. Cu-6 wt% Ag was melt, cold rolled and solution treated to be Cu-Ag solid solution, which was either aged at 250 and 350 °C for 24 h directly or SMAT-ed before aging. Ag precipitates were hard be found in the directly aged Cu-Ag sample while they were observed clearly in the SMAT-ed counterpart at 250 °C. The Ag precipitates formed in the surface layer by SMAT are much coarser than those in the un-SMAT-ed sample. It is obvious that the precipitating behavior of Ag was promoted significantly by SMAT approach. A large number of defects were generated by SMAT and they were acting as fast atomic diffusion channels that facilitated the atomic diffusion of Ag.

Synthesis of ultrafine powders by microwave heating

DOEpatents

Meek, T.T.; Sheinberg, H.; Blake, R.D.

1987-04-24

A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has dissolved. The resulting material is an ultrafine powder. This method can be used to make Al/sub 2/O/sub 3/, NiO /plus/ Al/sub 2/O/sub 3/ and NiO as well as a number of other materials including GaBa/sub 2/Cu/sub 3/O/sub x/. 1 tab.

Main reinforcement effects of precipitation phase Mg2Cu3Si, Mg2Si and MgCu2 on Mg-Cu-Si alloys by ab initio investigation

NASA Astrophysics Data System (ADS)

Shi, Xue-Feng; Wang, Hai-Chen; Tang, Ping-Ying; Tang, Bi-Yu

2017-09-01

To predict and compare the main reinforcement effects of the key precipitation phases Mg2Cu3Si, Mg2Si and MgCu2 in Mg-Cu-Si alloy, the structural, mechanical and electronic properties of these phases have been studied by ab initio calculations. The lowest formation enthalpy and cohesive energy indicate that Mg2Cu3Si has the strongest alloying ability and structural stability. The mechanical modulus indicates that Mg2Cu3Si has the strongest resistance to reversible shear/volume distortion and has maximum hardness. The characterization of brittle (ductile) behavior manifests that MgCu2 has favorable ductility. Meanwhile the evaluation of elastic anisotropy indicates that Mg2Si possesses elastic isotropy. Debye temperature prediction shows that Mg2Si and Mg2Cu3Si have better thermal stability. To achieve an unbiased interpretation on the phase stability and mechanical behavior of these precipitation phases, the density of states and differential charge densities are also analyzed. The current study deepens the comprehensive understanding of main reinforcement effects of these precipitation phases on Mg-Cu-Si alloys, and also benefits to optimize the overall performances of Mg-Cu-Si alloy from the hardness, ductility and thermal stability by controlling these second precipitation phases during the heat treatment process.

[delta] precipitation in an Al-Li-Cu-Mg-Zr alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasad, K.S.; Mukhopadhyay, A.K.; Gokhale, A.A.

1994-05-15

AlLi based [delta] phase has an NaTl structure (i.e., a diamond cubic) with a = 0.637nm and is an equilibrium phase in the binary Al-Li system. In heat treated binary Al-Li alloys of appropriate compositions, [delta] phase can format grain boundaries as well as within the grains. In commercially heat treated Al-Li-Cu alloys of 2090 specification, the grain boundary precipitate [delta] of the binary Al-Li system is replaced by a combination of T[sub 2](Al[sub 6]CuLi[sub 3]), R(Al[sub 5]CuLi[sub 3]) and T[sub 1](Al[sub 2]CuLi) phases. In similarly treated Al-Li-Cu-Mg alloys of 8090 specification, the copper rich T[sub 2] phase, present inmore » the form of Al[sub 6]CuLi[sub 3[minus]x]Mg[sub x], is known to be the major coarse g.b. precipitate. The presence of an Al-Li-Cu-Mg based C phase at the grain boundaries of the commercially heat treated 8090 alloys has also been documented. No detailed study has yet been carried out to verify whether the [delta] phase can be present at the grain boundaries of the commercially heat treated 8090 alloys. Given the correlations between the g.b. phase morphology, g.b. phase chemistry, and the stress corrosion cracking resistance of these alloys, it is important that the g.b. precipitates be examined and identified. In this paper results using TEM are presented to show that the [delta] phase can be present in varying amounts at the grain boundaries in an 8090 alloy when heat treated in the temperature range of 170--350 C. An examination is also made of the [delta] precipitation within the grain to establish that the T[sub 2]/[alpha]-Al interface is the dominant nucleation site for the noncoherent [delta] phase.« less

Microstructure and Precipitate's Characterization of the Cu-Ni-Si-P Alloy

NASA Astrophysics Data System (ADS)

Zhang, Yi; Tian, Baohong; Volinsky, Alex A.; Sun, Huili; Chai, Zhe; Liu, Ping; Chen, Xiaohong; Liu, Yong

2016-04-01

Microstructure of the Cu-Ni-Si-P alloy was investigated by transmission electron microscopy (TEM). The alloy had 551 MPa tensile strength, 226 HV hardness, and 36% IACS electrical conductivity after 80% cold rolling and aging at 450 °C for 2 h. Under the same aging conditions, but without the cold rolling, the strength, hardness, and electrical conductivity were 379 MPa, 216 HV, and 32% IACS, respectively. The precipitates identified by TEM characterization were δ-Ni2Si. Some semi-coherent spherical precipitates with a typical coffee bean contrast were found after aging for 48 h at 450 °C. The average diameter of the observed semi-coherent precipitates is about 5 nm. The morphology of the fracture surface was observed by scanning electron microscopy. All samples showed typical ductile fracture. The addition of P refined the grain size and increased the nucleation rate of the precipitates. The precipitated phase coarsening was inhibited by the small additions of P. After aging, the Cu-Ni-Si-P alloy can gain excellent mechanical properties with 804 MPa strength and 49% IACS conductivity. This study aimed to optimize processing conditions of the Cu-Ni-Si-P alloys.

Corrosion behavior of ultrafine-grained AA2024 aluminum alloy produced by cryorolling

NASA Astrophysics Data System (ADS)

Laxman Mani Kanta, P.; Srivastava, V. C.; Venkateswarlu, K.; Paswan, Sharma; Mahato, B.; Das, Goutam; Sivaprasad, K.; Krishna, K. Gopala

2017-11-01

The objectives of this study were to produce ultrafine-grained (UFG) AA2024 aluminum alloy by cryorolling followed by aging and to evaluate its corrosion behavior. Solutionized samples were cryorolled to 85% reduction in thickness. Subsequent aging resulted in a UFG structure with finer precipitates of Al2CuMg in the cryorolled alloy. The (1) solutionized and (2) solutionized and cryorolled samples were uniformly aged at 160°C/24 h and were designated as CGPA and CRPA, respectively; these samples were subsequently subjected to corrosion studies. Potentiodynamic polarization studies in 3.5wt% NaCl solution indicated an increase in corrosion potential and a decrease in corrosion current density for CRPA compared to CGPA. In the case of CRPA, electrochemical impedance spectroscopic studies indicated the presence of two complex passive oxide layers with a higher charge transfer resistance and lower mass loss during intergranular corrosion tests. The improved corrosion resistance of CRPA was mainly attributed to its UFG structure, uniform distribution of fine precipitates, and absence of coarse grain-boundary precipitation and associated precipitate-free zones as compared with the CGPA alloy.

Kinetics and Equilibrium of Age-Induced Precipitation in Cu-4 At. Pct Ti Binary Alloy

NASA Astrophysics Data System (ADS)

Semboshi, Satoshi; Amano, Shintaro; Fu, Jie; Iwase, Akihiro; Takasugi, Takayuki

2017-03-01

Transformation kinetics and phase equilibrium of metastable and stable precipitates in age-hardenable Cu-4 at. pct Ti binary alloy have been investigated by monitoring the microstructural evolution during isothermal aging at temperatures between 693 K (420 °C) and 973 K (700 °C). The microstructure of the supersaturated solid solution evolves in four stages: compositional modulation due to spinodal decomposition, continuous precipitation of the needle-shaped metastable β'-Cu4Ti with a tetragonal structure, discontinuous precipitation of cellular components containing stable β-Cu4Ti lamellae with an orthorhombic structure, and eventually precipitation saturation at equilibrium. In specimens aged below 923 K (650 °C), the stable β-Cu4Ti phase is produced only due to the cellular reaction, whereas it can be also directly obtained from the intergranular needle-shaped β'-Cu4Ti precipitates in specimens aged at 973 K (700 °C). The precipitation kinetics and phase equilibrium observed for the specimens aged between 693 K (420 °C) and 973 K (700 °C) were characterized in accordance with a time-temperature-transformation (TTT) diagram and a Cu-Ti partial phase diagram, which were utilized to determine the alloy microstructure, strength, and electrical conductivity.

Cu assisted stabilization and nucleation of L1 2 precipitates in Al 0.3 CuFeCrNi 2 fcc-based high entropy alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gwalani, B.; Choudhuri, D.; Soni, V.

2017-05-01

A detailed investigation of precipitation of the ordered L12 (γ’) phase in a Al0.3CrCuFeNi2 high entropy alloy (HEA), more generally referred to as a complex concentrated alloy (CCA), reveals the role of copper (Cu) on stabilization and precipitation of the ordered L12 ( γ’) phase. Detailed characterization via coupling of scanning and transmission electron microscopy, and atom probe tomography revealed novel insights into Cu clustering within the face-centered cubic matrix of this HEA, leading to heterogeneous nucleation sites for the γ’ precipitates. The subsequent partitioning of Cu into the γ’ precipitates indicates their stabilization is due to Cu addition. Themore » γ’ order-disorder transition temperature was determined to be ~930 _C in this alloy, based on synchrotron diffraction experiments, involving in situ annealing. The growth and high temperature stability of the γ’ precipitates was also confirmed via systematic scanning electron microscopy investigations of samples annealed at temperatures in the range of 700-900 oC. The role of Cu revealed by this study can be employed in the design of precipitation strengthened HEAs, as well as in a more general sense applied to other types of superalloys, with the objective of potentially enhancing their mechanical properties at room and elevated temperatures« less

Fatigue and Creep-Fatigue Deformation of an Ultra-Fine Precipitate Strengthened Advanced Austenitic Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

M.C. Carroll; L.J. Carroll

An advanced austenitic alloy, HT-UPS (high-temperature ultrafine-precipitation-strengthened), has been identified as an ideal candidate material for the structural components of fast reactors and energy-conversion systems. HT-UPS alloys demonstrate improved creep resistance relative to 316 stainless steel (SS) through additions of Ti and Nb, which precipitate to form a widespread dispersion of stable nanoscale metallic carbide (MC) particles in the austenitic matrix. The low-cycle fatigue and creep-fatigue behavior of an HT-UPS alloy have been investigated at 650 °C and a 1.0% total strain, with an R-ratio of -1 and hold times at peak tensile strain as long as 150 min. Themore » cyclic deformation response of HT-UPS is directly compared to that of standard 316 SS. The measured values for total cycles to failure are similar, despite differences in peak stress profiles and in qualitative observations of the deformed microstructures. Crack propagation is primarily transgranular in fatigue and creep-fatigue of both alloys at the investigated conditions. Internal grain boundary damage in the form of fine cracks resulting from the tensile hold is present for hold times of 60 min and longer, and substantially more internal cracks are quantifiable in 316 SS than in HT-UPS. The dislocation substructures observed in the deformed material differ significantly; an equiaxed cellular structure is observed in 316 SS, whereas in HT-UPS the microstructure takes the form of widespread and relatively homogenous tangles of dislocations pinned by the nanoscale MC precipitates. The significant effect of the fine distribution of precipitates on observed fatigue and creep-fatigue response is described in three distinct behavioral regions as it evolves with continued cycling.« less

Effect of Low Cu Amounts and Pre-Deformation on the Precipitation in Al-Mg-Si Alloys

NASA Astrophysics Data System (ADS)

Saito, Takeshi; Muraishi, Shinji; Marioara, Calin D.; Holmestad, Randi

Transmission electron microscopy (TEM) studies were performed on two Al-Mg-Si alloys with low Cu additions (0.01 and 0.10 wt%) in order to investigate the effect of Cu and 10% pre-deformation on precipitate microstructure and its connection to mechanical properties. After 300 minutes aging at 190°C, fine microstructures associated with high hardness were observed in the alloy with 0.10% Cu. Pre-deformation led to heterogeneous distributions of precipitates along dislocations, causing microstructure coarsening. This effect was less pronounced in the alloy with the higher Cu amount.

Effects of welding and post-weld heat treatments on nanoscale precipitation and mechanical properties of an ultra-high strength steel hardened by NiAl and Cu nanoparticles

DOE PAGES

Jiao, Z. B.; Luan, J. H.; Guo, W.; ...

2016-09-01

The effects of welding and post-weld heat treatment (PWHT) on nanoscale co-precipitation, grain structure, and mechanical properties of an ultra-high strength steel were studied through a combination of atom probe tomography (APT) and mechanical tests. Our results indicate that the welding process dissolves all pre-existing nanoparticles and causes grain coarsening in the fusion zone, resulting in a soft and ductile weld without any cracks in the as-welded condition. A 550 °C PWHT induces fine-scale re-precipitation of NiAl and Cu co-precipitates with high number densities and ultra-fine sizes, leading to a large recovery of strength but a loss of ductility withmore » intergranular failure, whereas a 600 °C PWHT gives rise to coarse-scale re-precipitation of nanoparticles together with the formation of a small amount of reverted austenite, resulting in a great recovery in both strength and ductility. Our analysis indicates that the degree of strength recovery is dependent mainly upon the re-precipitation microstructure of nanoparticles, together with grain size and reversion of austenite, while the ductility recovery is sensitive to the grain-boundary structure. In conclusion, APT reveals that the grain-boundary segregation of Mn and P may be the main reason for the 550 °C embrittlement, and the enhanced ductility at 600 °C is ascribed to a possible reduction of the segregation and reversion of austenite.« less

Effects of welding and post-weld heat treatments on nanoscale precipitation and mechanical properties of an ultra-high strength steel hardened by NiAl and Cu nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Z. B.; Luan, J. H.; Guo, W.

The effects of welding and post-weld heat treatment (PWHT) on nanoscale co-precipitation, grain structure, and mechanical properties of an ultra-high strength steel were studied through a combination of atom probe tomography (APT) and mechanical tests. Our results indicate that the welding process dissolves all pre-existing nanoparticles and causes grain coarsening in the fusion zone, resulting in a soft and ductile weld without any cracks in the as-welded condition. A 550 °C PWHT induces fine-scale re-precipitation of NiAl and Cu co-precipitates with high number densities and ultra-fine sizes, leading to a large recovery of strength but a loss of ductility withmore » intergranular failure, whereas a 600 °C PWHT gives rise to coarse-scale re-precipitation of nanoparticles together with the formation of a small amount of reverted austenite, resulting in a great recovery in both strength and ductility. Our analysis indicates that the degree of strength recovery is dependent mainly upon the re-precipitation microstructure of nanoparticles, together with grain size and reversion of austenite, while the ductility recovery is sensitive to the grain-boundary structure. In conclusion, APT reveals that the grain-boundary segregation of Mn and P may be the main reason for the 550 °C embrittlement, and the enhanced ductility at 600 °C is ascribed to a possible reduction of the segregation and reversion of austenite.« less

Cu6Sn5 Whiskers Precipitated in Sn3.0Ag0.5Cu/Cu Interconnection in Concentrator Silicon Solar Cells Solder Layer

PubMed Central

Zhang, Liang; Liu, Zhi-quan; Yang, Fan; Zhong, Su-juan

2017-01-01

Cu6Sn5 whiskers precipitated in Sn3.0Ag0.5Cu/Cu interconnection in concentrator silicon solar cells solder layer were found and investigated after reflow soldering and during aging. Ag3Sn fibers can be observed around Cu6Sn5 whiskers in the matrix microstructure, which can play an active effect on the reliability of interconnection. Different morphologies of Cu6Sn5 whiskers can be observed, and hexagonal rod structure is the main morphology of Cu6Sn5 whiskers. A hollow structure can be observed in hexagonal Cu6Sn5 whiskers, and a screw dislocation mechanism was used to represent the Cu6Sn5 growth. Based on mechanical property testing and finite element simulation, Cu6Sn5 whiskers were regarded as having a negative effect on the durability of Sn3.0Ag0.5Cu/Cu interconnection in concentrator silicon solar cells solder layer. PMID:28772686

Effect of Prestrain on Precipitation Behaviors of Ti-2.5Cu Alloy

NASA Astrophysics Data System (ADS)

Lincai, Zhang; Xiaoming, Ding; Wei, Ye; Man, Zhang; Zhenya, Song

2018-04-01

As a special hardenable α titanium alloy, Ti-2.5 Cu alloy was a candidate material for high temperature components requiring high strength and plasticity. The effect of prestrain on the precipitation behaviors was investigated in the present study. Tensile tests show that elongation up to 22 % can be obtained after solid solution (SS) treatment. Thereafter, prestrain in tension with 5 %, 10 %, 15 % and 20 % was carried out for the SS samples and then duplex aging was applied. Transmitting electron microscopy (TEM) investigations show that larger Ti2Cu particles were observed in the prestrained condition than free aging one, as prestrain significantly speeds up the precipitation kinetics. The strength firstly increases and then decreases for the prestrained samples after duplex aging, where the competition between precipitation hardening and recovery softening should be responsible. With the consideration of SS, precipitation and recovery, a strength model for duplex aging combined with prestrain was established, which is in well agreement with experiments. Present study may provide a promising way to obtain the strength of deformed hcp materials in industry application.

Prediction of precipitate evolution and martensite transformation in Ti-Ni-Cu shape memory alloys by computational thermodynamics

NASA Astrophysics Data System (ADS)

Povoden-Karadeniz, A.; Cirstea, D. C.; Kozeschnik, E.

2016-04-01

Ti-50Ni to Ti-55Ni (at.%) can be termed as the pioneer of shape memory alloys (SMA). Intermetallic precipitates play an important role for strengthening. Their influence on the start temperature of the martensitic transformation is a crucial property for the shape memory effect. Efforts for increasing the martensite start temperature include replacement of a part of Ni atoms by Cu. The influence of Cu-addition to Ti-Ni SMA on T0- temperatures and the character of the austenite-martensite transformation is evaluated using a new thermodynamic database for the Ti-Ni-system extended by Cu. Trends of precipitation of intermetallic phases are simulated by combining the assessed thermodynamics of the Ti-Ni-Cu system with assessed diffusion mobility data and kinetic models, as implemented in the solid-state transformation software MatCalc and are presented in the form of time-temperature-precipitation diagrams. Thermodynamic equilibrium considerations, complemented by predictive thermo-kinetic precipitation simulation, facilitates SMA alloy design and definition of optimized aging conditions.

Precipitation of a new platelet phase during the quenching of an Al-Zn-Mg-Cu alloy

NASA Astrophysics Data System (ADS)

Zhang, Yong; Weyland, Matthew; Milkereit, Benjamin; Reich, Michael; Rometsch, Paul A.

2016-03-01

A previously undescribed high aspect ratio strengthening platelet phase, herein named the Y-phase, has been identified in a commercial Al-Zn-Mg-Cu alloy. Differential scanning calorimetry indicates that this phase only precipitates at temperature and cooling rate of about 150-250 °C and 0.05-300 K/s, respectively. This precipitate is shown to be responsible for a noticeable improvement in mechanical properties. Aberration corrected scanning transmission electron microscopy demonstrates the minimal thickness (~1.4 nm) precipitate plates are isostructural to those of the T1 (Al2CuLi) phase observed in Al-Cu-Li alloys. Low voltage chemical analysis by energy dispersive X-ray spectroscopy and electron energy loss spectroscopy gives evidence of the spatial partitioning of the Al, Cu and Zn within the Y-phase, as well as demonstrating the incorporation of a small amount of Mg.

Modeling copper precipitation hardening and embrittlement in a dilute Fe-0.3at.%Cu alloy under neutron irradiation

NASA Astrophysics Data System (ADS)

Bai, Xian-Ming; Ke, Huibin; Zhang, Yongfeng; Spencer, Benjamin W.

2017-11-01

Neutron irradiation in light water reactors can induce precipitation of nanometer sized Cu clusters in reactor pressure vessel steels. The Cu precipitates impede dislocation gliding, leading to an increase in yield strength (hardening) and an upward shift of ductile-to-brittle transition temperature (embrittlement). In this work, cluster dynamics modeling is used to model the entire Cu precipitation process (nucleation, growth, and coarsening) in a Fe-0.3at.%Cu alloy under neutron irradiation at 300°C based on the homogenous nucleation mechanism. The evolution of the Cu cluster number density and mean radius predicted by the modeling agrees well with experimental data reported in literature for the same alloy under the same irradiation conditions. The predicted precipitation kinetics is used as input for a dispersed barrier hardening model to correlate the microstructural evolution with the radiation hardening and embrittlement in this alloy. The predicted radiation hardening agrees well with the mechanical test results in the literature. Limitations of the model and areas for future improvement are also discussed in this work.

An atom probe perspective on phase separation and precipitation in duplex stainless steels

NASA Astrophysics Data System (ADS)

Guo, Wei; Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel; Young, George A.; Poplawsky, Jonathan D.

2016-06-01

Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α‧) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α‧ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36). ).

An atom probe perspective on phase separation and precipitation in duplex stainless steels

DOE PAGES

Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel A.; ...

2016-05-16

Here, three-dimensional chemical imaging of Fe–Cr alloys showing Fe-rich (α)/Cr-rich (α') phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe–Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100–10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni–Mn–Si–Cu-rich G-phase precipitates form at the α/α' interfaces in both alloys. For the 2101more » alloy, Cu clusters act to form a nucleus, around which a Ni–Mn–Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core–shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby–Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30–36).« less

Spall Fracture Patterns for the Heterophase Cu-Al-Ni Alloy in Ultrafine- and Coarse-Grained States Exposed to a Nanosecond Relativistic High-Current Electron Beam

NASA Astrophysics Data System (ADS)

Dudarev, E. F.; Markov, A. B.; Mayer, A. E.; Bakach, G. P.; Tabachenko, A. N.; Kashin, O. A.; Pochivalova, G. P.; Skosyrskii, A. B.; Kitsanov, S. A.; Zhorovkov, M. F.; Yakovlev, E. V.

2013-05-01

A comparative study of spall fracture patterns for the heterophase Cu - 8.45% Al - 5.06% Ni alloy (аt.%) in ultrafine- and coarse-grained states under shock-wave loading using the "SINUS-7" electron accelerator is carried out. For electron energy of 1.4 MeV, pulse duration of 50 ns, and power density of 1.6·1010 W/cm2, the shock wave amplitude was 8 GPa and the strain rate was ~2·105 s-1. It is established that the thickness of the spalled layer increased for both grained structures, and the degree of plastic strain decreased with increasing target thickness. Based on experimental data obtained and results of theoretical calculations, it is demonstrated that the spall strength of ultrafine- and coarse-grained structures is ~3 GPa. The data on the grained structure at different distances from the spall surface and spall fraction patterns and mechanism are presented.

Development of ultrafine-grained microstructure in Al-Cu-Mg alloy through equal-channel angular pressing

NASA Astrophysics Data System (ADS)

Sai Anuhya, Danam; Gupta, Ashutosh; Nayan, Niraj; Narayana Murty, S. V. S.; Manna, R.; Sastry, G. V. S.

2014-08-01

Al-Cu-Mg alloys are extensively used for riveting applications in aerospace industries due to their relatively high shear strength coupled with high plasticity. The significant advantage of using V65 aluminum alloy ((Al-4Cu-0.2Mg) for rivet application also stems from its significantly slower natural aging kinetics, which gives operational flexibility to carryout riveting operation even after 4 days of solution heat treatment, in contrast to its equivalent alloy AA2024.Rivets are usually made by cold heading of wire rods. In order to form a defect free rivet head, grain size control in wire rods is essential at each and every stage of processing right from casting onwards upto the final wire drawing stage. Wire drawing is carried out at room temperature to reduce diameter as well as impart good surface finish. In the present study, different microstructures in V65 alloy bars were produced by rolling at different temperatures (room temperature to 523K) and subsequently deformed by equal channel angular pressing (ECAP) at 423K upto an equivalent strain of 7. ECAP was carried out to study the effect of initial microstructure on grain refinement and degree of deformation on the evolution of ultrafine grain structure. The refinement of V65 alloy by ECAP is significantly influenced by Initial microstructure but amount of deformation strongly affects the evolution processes as revealed by optical microscopy and transmission electron microscopy.

Time Temperature-Precipitation Behavior in An Al-Cu-Li Alloy 2195

NASA Technical Reports Server (NTRS)

Chen, P. S.; Bhat, B. N.

1999-01-01

Al-Cu-Li alloy 2195, with its combination of good cryogenic properties, low density, and high modulus, has been selected by NASA to be the main structural alloy of the Super Light Weight Tank (SLWT) for the Space Shuttle. Alloy 2195 is strengthened by an aging treatment that precipitates a particular precipitate, labeled as T1(Al2CuLi). Other phases, such as GP zone, (theta)', (theta)", theta, (delta)', S' are also present in this alloy when artificially aged. Cryogenic strength and fracture toughness are critical to the -SLWT application, since the SLWT will house liquid oxygen and hydrogen. Motivation for the Time-Temperature-Precipitation (TTP) study at lower temperature (lower than 350 F) comes in part from a recent study by Chen, The study found that the cryogenic fracture toughness of alloy 2195 is greatly influenced by the phases present in the matrix and subgrain boundaries. Therefore, the understanding of TTP behavior can help develop a guideline to select appropriate heat treatment conditions for the desirable applications. The study of TTP behavior at higher temperature (400 to 1000 F) was prompted by the fact that the SLWT requires a welded construction. Heat conduction from the weld pool affects the microstructure in the heat-affected zone (HAZ), which leads to changes in the mechanical properties. Furthermore, the SLWT may need repair welding for more than one time and any additional thermal cycles will increase precipitate instability and promote phase transformation. As a result considerable changes in HAZ microstructure and mechanical properties are expected during the construction of the SLWT. Therefore, the TTP diagrams can serve to understand the thermal history of the alloy by analyzing the welded microstructure. In the case welding, the effects of thermal cycles on the microstructure and mechanical properties can be predicted with the aid of the TTP diagrams. The 2195 alloy (nominally Al + 4 pct Cu + 1 pct Li + 0.3 pct Ag + 0.3 pct Mg + 0

Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates

NASA Astrophysics Data System (ADS)

Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

2017-01-01

Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.

[Study on the determination of trace Cu and Mn in foodstuff preconcentration by precipitate flotation and FAAS].

PubMed

Li, Chun-xiang; Chen, Ting-yu; Yan, Yong-sheng

2007-10-01

In the present paper, the use of 8-hydroxyquinoline(oxine, HQ) complexs in precipitate flotation to separate and preconcentrate Cu and Mn, using SDBS as collector, followed by AAS spectrophotometric determination is proposed. The optimum conditions of precipitate flotation were studied. The effects of several parameters of flotation processes condition on single metal ions precipitation-flotation and multi-metal ions coprecipitation-flotation of Cu and Mn at pH 9 were investigated. The experimental results show that the flotation rate of Cu is supreme with pH 9. Under the condition of pH 9 and changing the ratio of concentration, when Mn/Cu> or =8, the recovery rate of Cu is less than 90%. This method is simple, rapid, accurate, sensitive and precise and avoids using the virulent organic solvent. The linear range of Cu is 0.5-5.0 microg x mL(-1) with the correlative coefficient of 0.9996, detection limit of this method was found to be 1.59 x 10(-3) microg x mL(-1), the linear range of Mn is 0.5-5.0 microg x mL(-1) with the correlative coefficient of 0.9987, and the detection limit of this method was found to be 3.52 x 10(-3) microg x mL(-1). The method was applied to the determination of Cu and Mn in foodstuff, and the recovery is 87.6%-100.7%. The result was satisfactory.

Modeling of light-induced degradation due to Cu precipitation in p-type silicon. II. Comparison of simulations and experiments

NASA Astrophysics Data System (ADS)

Vahlman, H.; Haarahiltunen, A.; Kwapil, W.; Schön, J.; Inglese, A.; Savin, H.

2017-05-01

The presence of copper impurities is known to deteriorate the bulk minority carrier lifetime of silicon. In p-type silicon, the degradation occurs only under carrier injection (e.g., illumination), but the reason for this phenomenon called copper-related light-induced degradation (Cu-LID) has long remained uncertain. To clarify the physics of this problem, a mathematical model of Cu-LID was introduced in Paper I of this article. Within the model, kinetic precipitation simulations are interlinked with a Schottky junction model for electric behavior of metallic precipitates. As this approach enables simulating precipitation directly at the minority carrier lifetime level, the model is verified in this second part with a direct comparison to the corresponding degradation experiments and literature data. Convincing agreement is found with different doping and Cu concentrations as well as at increased temperature, and in the dark, both simulated degradation and measured degradation are very slow. In addition, modeled final lifetimes after illumination are very close to experimental final lifetimes, and a correlation with the final precipitate size is found. However, the model underestimates experimentally observed differences in the degradation rate at different illumination intensities. Nevertheless, the results of this work support the theory of Cu-LID as a precipitate formation process. Part of the results also imply that heterogeneous nucleation sites play a role during precipitate nucleation. The model reveals fundamental aspects of the physics of Cu-LID including how doping and heterogeneous nucleation site concentrations can considerably influence the final recombination activity.

Facile synthesis of ultrafine cobalt oxide nanoparticles for high-performance supercapacitors.

PubMed

Liu, Fangyan; Su, Hai; Jin, Long; Zhang, Haitao; Chu, Xiang; Yang, Weiqing

2017-11-01

The ultrafine Co 3 O 4 nanoparticles are successfully prepared by a novel solvothermal-precipitation approach which exploits the supernatant liquid of Co 3 O 4 nanoflake micropheres synthesized by solvothermal method before. Interestingly, the water is only employed to obtain the ultrafine nanoparticles in supernatant liquid which was usually thrown away before. The microstructure measurement results of the as-grown samples present the homogeneous disperse ultrafine Co 3 O 4 nanoparticles with the size of around 5-10nm. The corresponding synthesis mechanism of the ultrafine Co 3 O 4 nanoparticles is proposed. More importantly, these ultrafine Co 3 O 4 nanoparticles obtained at 250°C show the highest specific capacitance of 523.0Fg -1 at 0.5Ag -1 , 2.6 times that of Co 3 O 4 nanoflake micropheres due to the quantum size effect. Meanwhile, the sample annealed under 350°C possesses the best cycling stability with capacitance retention of 104.9% after 1500 cycles. These results unambiguously demonstrate that this work not only provides a novel, facile, and eco-friendly approach to prepare high-performance Co 3 O 4 nanoparticles electrode materials for supercapacitors but also develops a widely used method for the preparation of other materials on a large scale. Copyright © 2017 Elsevier Inc. All rights reserved.

Precipitation strengthened high strength, high conductivity Cu-Cr-Nb alloys produced by chill block melt spinning. Final Report Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Ellis, David L.; Michal, Gary M.

1989-01-01

A series of Cu-based alloys containing 2 to 10 a/o Cr and 1 to 5 a/o Nb were produced by chill block melt spinning (CBMS). The melt spun ribbons were consolidated and hot rolled to sheet to produce a supersaturated Cu-Cr-Nb solid solution from which the high melting point intermetallic compound Cr2Nb could be precipitated to strengthen the Cu matrix. The results show that the materials possess electrical conductivities in excess of 90 percent that of pure Cu at 200 C and above. The strengths of the Cu-Cr-Nb alloys were much greater than Cu, Cu-0.6 Cr, NARloy-A, and NARloy-Z in the as-melt spun condition. The strengths of the consolidated materials were less than Cu-Cr and Cu-Cr-Zr below 500 C and 600 C respectively, but were significantly better above these temperatures. The strengths of the consolidated materials were greater than NARloy-Z, at all temperatures. The GLIDCOP possessed similar strength levels up to 750 C when the strength of the Cu-Cr-Nb alloys begins to degrade. The long term stability of the Cu-Cr-Nb alloys was measured by the microhardness of aged samples and the growth of precipitates. The microhardness measurements indicate that the alloys overage rapidly, but do not suffer much loss in strength between 10 and 100 hours which confirms the results of the electrical resistivity measurements taken during the aging of the alloys at 500 C. The loss in strength from peak strength levels is significant, but the strength remains exceptionally good. Transmission electron microscopy (TEM) of the as-melt spun samples revealed that Cr2Nb precipitates formed in the liquid Cu during the chill block melt spinning, indicating a very strong driving force for the formation of the precipitates. The TEM of the aged and consolidated materials indicates that the precipitates coarsen considerably, but remain in the submicron range.

The Effect of Ultrafine-Grained Microstructure on Creep Behaviour of 9% Cr Steel

PubMed Central

Kral, Petr; Dvorak, Jiri; Sklenicka, Vaclav; Masuda, Takahiro; Horita, Zenji; Kucharova, Kveta; Kvapilova, Marie; Svobodova, Marie

2018-01-01

The effect of ultrafine-grained size on creep behaviour was investigated in P92 steel. Ultrafine-grained steel was prepared by one revolution of high-pressure torsion at room temperature. Creep tensile tests were performed at 873 K under the initially-applied stress range between 50 and 160 MPa. The microstructure was investigated using transmission electron microscopy and scanning electron microscopy equipped with an electron-back scatter detector. It was found that ultrafine-grained steel exhibits significantly faster minimum creep rates, and there was a decrease in the value of the stress exponent in comparison with coarse-grained P92 steel. Creep results also showed an abrupt decrease in the creep rate over time during the primary stage. The abrupt deceleration of the creep rate during the primary stage was shifted, with decreasing applied stress with longer creep times. The change in the decline of the creep rate during the primary stage was probably related to the enhanced precipitation of the Laves phase in the ultrafine-grained microstructure. PMID:29757206

Flux pinning by precipitates in the Bi-Sr-Ca-Cu-O system

DOEpatents

Shi, Donglu

1992-01-01

A fundamental pinning mechanism has been identified in the Bi-Sr-Ca-Cu-O system. The pinning strength has been greatly increased by the introduction of calcium- and copper-rich precipitates into the sample matrix. The calcium and copper are supersaturated in the system by complete melting, and the fine calcium and copper particles precipitated during subsequent crystallization anneal to obtain the superconducting phases. The intragrain critical current density has been increased from the order of 10.sup.5 A/cm.sup.2 to 10.sup.7 A/cm.sup.2 at 5 T.

A Two-Step Approach for Producing an Ultrafine-Grain Structure in Cu-30Zn Brass (Postprint)

DTIC Science & Technology

2015-08-13

crystallization anneal at 400 °C (0.55Tm, where Tm is the melting point ) for times ranging from 1 min to 10 hours, followed by water quenching; an additional...200 words) A two-step approach involving cryogenic rolling and subsequent recrystallization annealing was developed to produce an ultrafine-grain...b s t r a c t A two-step approach involving cryogenic rolling and subsequent recrystallization annealing was devel- oped to produce an ultrafine

Substantial convection and precipitation enhancements by ultrafine aerosol particles

DOE PAGES

Fan, Jiwen; Rosenfeld, Daniel; Zhang, Yuwei; ...

2018-01-26

Aerosol-cloud interactions remain the largest uncertainty in climate projections. Ultrafine aerosol particles smaller than 50 nanometers (UAP <50) can be abundant in the troposphere, but are conventionally considered too small to affect cloud formation. However, observational evidence and numerical simulations of deep convective clouds (DCCs) over the Amazon show that DCCs forming in a low aerosol environment can develop very large vapor supersaturation because fast droplet coalescence reduces integrated droplet surface area and subsequent condensation. UAP <50 from pollution plumes that are ingested into such clouds can be activated to form additional cloud droplets on which excess supersaturation condenses andmore » forms additional cloud water and latent heating, thus intensifying convective strength. This mechanism suggests a strong anthropogenic invigoration of DCCs in previously pristine regions of the world.« less

High temperature coarsening of Cr2Nb precipitates in Cu-8 Cr-4 Nb alloy

NASA Technical Reports Server (NTRS)

Anderson, Kenneth Reed

1996-01-01

A new high-temperature-strength, high-conductivity Cu-Cr-Nb alloy with a CrNb ratio of 2:1 was developed to achieve improved performance and durability. The Cu-8 Cr4 Nb alloy studied has demonstrated remarkable thermal and microstructural stability after long exposures at temperatures up to 0.98 T(sub m). This stability was mainly attributed to the slow coarsening kinetics of the Cr2Nb precipitates present in the alloy. At all temperatures, the microstructure consists of a bimodal and sometimes trimodal distribution of strengthening Cr2Nb precipitates, depending on precipitation condition, i.e. from liquid or solid solution, and cooling rates. These precipitates remain in the same size range, i.e. large precipitates of approximately I pm, and small precipitates less dm 300 nm, and effectively pin the grain boundaries thus retaining a fine grain size of 2.7 micro-m after 100 h at 1323 K. (A relatively small number of Cr-rich and Nb-rich particles were also present.) This grain boundary pinning and sluggish coarsening of Cr2Nb particles explain the retention of good mechanical properties after prolonged holding at very high temperatures, e.g., 75% of the original hardness after aging for 100 h at 1273 K. Application of LSW-based coarsening models indicated that the coarsening kinetics of the large precipitates are most likely governed by grain boundary diffsion and, to a lesser extent, volume diffusion mechanisms.

Variation of Aging Precipitates and Mechanical Strength of Al-Cu-Li Alloys Caused by Small Addition of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Ma, Yun-long; Li, Jin-feng

2017-09-01

The effect of small rare earth (RE) addition of 0.11%Ce, 0.2%Er and 0.082%Sc on aging precipitates and mechanical strength of an Al-(3.3-4.2)Cu-1.2Li-X alloy were investigated. It is found that Cu-rich residual particles containing RE element exist in the solutionized alloy, which leads to a decrease of dissolved Cu concentration in the solutionized matrix. Like RE-free alloy, the main aging precipitate types in RE-containing alloy are T1 (Al2CuLi) and θ' (Al2Cu), but their fraction is decreased. The strength of the corresponding alloys is therefore lowered by the small RE addition. Combined with the analysis of some reported references, it is proposed that the effect of small RE addition on Al-Cu-Li alloy strength is also associated with the Cu and Li concentrations and their ratio.

Using precipitated Cr on the surface of Cu-Cr alloy powders as catalyst synthesizing CNTs/Cu composite powders by water-assisted CVD

NASA Astrophysics Data System (ADS)

Zhou, Honglei; Liu, Ping; Chen, Xiaohong; Bi, Liming; Zhang, Ke; Liu, Xinkuan; Li, Wei; Ma, Fengcang

2018-02-01

Given that the conventional catalyst is easily soluble in the matrix to result in the poor performance of the CNTs/Cu composite materials, the Cr nano-particles precipitated on the surface of Cu-Cr particles are first used as catalysts to prepare the CNTs/Cu composite powders by means of water-assisted chemical vapor deposition in situ synthesis. The results show that the morphological difference of the precipitated Cr nano-particle is obvious with the change of solution and aging treatment, and the morphology, length and diameter of the synthetic CNTs are also different. The catalyst of Cr nano-particle has the best morphology and the synthesized CNTs had a good wettability with Cu particles when the Cu-Cr composite powders was solution-treated at 1023 K for 60 min and then was aged at 723 K for 120 min. The length, diameter, yield and purity of the synthesized CNTs can be also affected by the moisture content in the reaction gas. It is the most suitable for the growth of CNTs when the moisture content is 0.4%, and the high purity and defect-free CNTs with the smooth pipe wall, a diameter of 20 ˜ 30 nm and a length of up to 1800 nm can be obtained. The yield of CNTs with the moisture content of 0.4% reached to 138%, which was increased by 119% to compare with that without moisture. In this paper, a feasible technology was offered for the preparation of high performance CNTs/Cu composites.

Dynamic room temperature precipitation during cyclic deformation of an Al-Zn-Mg-Cu alloy

NASA Astrophysics Data System (ADS)

Hutchinson, C. R.; de Geuser, F.; Deschamps, A.

The effect of pre-straining on a precipitation heat treatment is a well-chartered area and is relevant to a number of Al alloy manufacturing processes. When straining and precipitation occur concurrently, the situation is less clear. This may arise during creep, fatigue or elevated temperature forming operations. Straining introduces dislocations and strain-induced vacancies that may enhance nucleation and growth processes but the dislocations may also shear and/or cause precipitate dissolution. This study reports a systematic characterization of precipitation during room temperature cyclic deformation of the AA7050 (Al-Zn-Mg-Cu) alloy. The mechanical response is monitored using plastic strain controlled cyclic deformation tests and the precipitation state is characterized using small angle x-ray scattering. It is shown that the precipitate volume fraction increases with the number of deformation cycles and is well correlated with the hardening increment observed but the mean precipitate radii remains relatively constant during cycling at 4-5A.

Detailed Investigation of Core-Shell Precipitates in a Cu-Containing High Entropy Alloy

NASA Astrophysics Data System (ADS)

Alam, T.; Gwalani, B.; Viswanathan, G.; Fraser, H.; Banerjee, R.

2018-05-01

Due to the competing influences of configurational entropy and enthalpy of mixing, in recent years, secondary (including intermetallic) phases have been reported in many high entropy alloy (HEA) systems. These secondary phases offer great potential in terms of strengthening the HEA beyond the solid solution strengthening effects, and as such are of great interest in regards to alloy design for engineering applications. The present research investigates novel nano-scale core-shell precipitates forming within the disordered bcc matrix phase of an Al2CrCuFeNi2 HEA, utilizing complementary high-resolution microscopy techniques of atom probe tomography (APT) and transmission electron microscopy (TEM). The size, morphology, and local chemistry of these core-shell precipitates was measured by APT, and the composition was further corroborated by high-resolution scanning transmission electron microscopy-energy dispersive spectroscopy in an aberration-corrected TEM. Furthermore, high-resolution TEM imaging of the core-shell structure indicates that the Cu-rich core exhibits a bcc crystal structure.

Effect of Precipitate State on Mechanical Properties, Corrosion Behavior, and Microstructures of Al-Zn-Mg-Cu Alloy

NASA Astrophysics Data System (ADS)

Peng, Xiaoyan; Li, Yao; Xu, Guofu; Huang, Jiwu; Yin, Zhimin

2018-03-01

The mechanical properties, corrosion behavior and microstructures of the Al-Zn-Mg-Cu alloy under various ageing treatments were investigated comparatively. The results show that the tensile strength and corrosion resistance are strongly affected by the precipitate state. Massive fine intragranular precipitates contribute to high strength. Discontinuous coarse grain boundary precipitates containing high Cu content, as well as the narrow precipitate free zone, result in low corrosion susceptibility. After the non-isothermal ageing (NIA) treatment, the tensile strength of 577 MPa is equivalent to that of 579 MPa for the T6 temper. Meanwhile, the stress corrosion susceptibility r tf and the maximum corrosion depth are 97.8% and 23.5 μm, which are comparable to those of 92.8% and 26.7 μm for the T73 temper. Moreover, the total ageing time of the NIA treatment is only 7.25 h, which is much less than that of 48.67 h for the retrogression and re-ageing condition.

Antibacterial activities of amorphous cefuroxime axetil ultrafine particles prepared by high gravity antisolvent precipitation (HGAP).

PubMed

Zhao, Hong; Kang, Xu-liang; Chen, Xuan-li; Wang, Jie-xin; Le, Yuan; Shen, Zhi-gang; Chen, Jian-feng

2009-01-01

In vitro and in vivo antibacterial activities on the Staphylococcus aureus and Escherichia coli of the amorphous cefuroxime axetil (CFA) ultrafine particles prepared by HGAP method were investigated in this paper. The conventional sprayed CFA particles were studied as the control group. XRD, SEM, BET tests were performed to investigate the morphology changes of the samples before and after sterile. The in vitro dissolution test, minimal inhibitory concentrations (MIC) and the in vivo experiment on mice were explored. The results demonstrated that: (i) The structure, morphology and amorphous form of the particles could be affected during steam sterile process; (ii) CFA particles with different morphologies showed varied antibacterial activities; and (iii) the in vitro and in vivo antibacterial activities of the ultrafine particles prepared by HGAP is markedly stronger than that of the conventional sprayed amorphous particles.

Effect of Cu2+ substitution on the magnetic properties of co-precipitated Ni-Cu-Zn ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Ramakrishna, K. S.; Srinivas, Ch.; Tirupanyam, B. V.; Ramesh, P. N.; Meena, S. S.; Potukuchi, D. M.; Sastry, D. L.

2017-05-01

Spinel ferrite nanoparticles with chemical equation NixCu0.1Zn0.9-xFe2O4 (x = 0.5, 0.6, 0.7) have been synthsized using co-precipitation method followed by heat treatment at a temperature of 200 °C for 2h. The results of XRD, FE-SEM and VSM studies are reported. XRD patterns confirm the formation of cubic spinel phase of ferrite samples along with small amount of a secondary phase of α-Fe2O3 whose concentration decreases as Ni2+ concentration increases. The crystallite sizes (in the range of 7.5-13.9 nm) increase and the lattice parameter decreases with increase in Ni2+ ion concentration. These values are comparable to those of NiZn ferrite without Cu substitution. It has been observed that there is a considerable reduction in saturation magnetisation (Ms). This and differences in other magnetic parameters are attributed to considerable changes in cation distribution or core shell interactions of NiZn ferrite with 10 mole% Cu substitution in the place of Zn.

Effects of particle reinforcement and ECAP on the precipitation kinetics of an Al-Cu alloy

NASA Astrophysics Data System (ADS)

Härtel, M.; Wagner, S.; Frint, P.; F-X Wagner, M.

2014-08-01

The precipitation kinetics of Al-Cu alloys have recently been revisited in various studies, considering either the effect of severe plastic deformation (e.g., by equal-channel angular pressing - ECAP), or the effect of particle reinforcements. However, it is not clear how these effects interact when ECAP is performed on particle-reinforced alloys. In this study, we analyze how a combination of particle reinforcement and ECAP affects precipitation kinetics. After solution annealing, an AA2017 alloy (initial state: base material without particle reinforcement); AA2017 + 10 vol.-% Al2O3; and AA2017 + 10 vol.-% SiC were deformed in one pass in a 120° ECAP tool at a temperature of 140°C. Systematic differential scanning calorimetry (DSC) measurements of each condition were carried out. TEM specimens were prepared out of samples from additional DSC measurements, where the samples were immediately quenched in liquid nitrogen after reaching carefully selected temperatures. TEM analysis was performed to characterize the morphology of the different types of precipitates, and to directly relate microstructural information to the endo- and exothermic peaks in our DSC data. Our results show that both ECAP and particle reinforcement are associated with a shift of exothermic precipitation peaks towards lower temperatures. This effect is even more pronounced when ECAP and particle reinforcement are combined. The DSC data agrees well with our TEM observations of nucleation and morphology of different precipitates, indicating that DSC measurements are an appropriate tool for the analysis of how severe plastic deformation and particle reinforcement affect precipitation kinetics in Al-Cu alloys.

Determining the composition of small features in atom probe: bcc Cu-rich precipitates in an Fe-rich matrix.

PubMed

Morley, A; Sha, G; Hirosawa, S; Cerezo, A; Smith, G D W

2009-04-01

Aberrations in the ion trajectories near the specimen surface are an important factor in the spatial resolution of the atom probe technique. Near the boundary between two phases with dissimilar evaporation fields, ion trajectory overlaps may occur, leading to a biased measurement of composition in the vicinity of this interface. In the case of very small second-phase precipitates, the region affected by trajectory overlaps may extend to the centre of the precipitate prohibiting a direct measurement of composition. A method of quantifying the aberrant matrix contribution and thus estimating the underlying composition is presented. This method is applied to the Fe-Cu-alloy system, where the precipitation of low-nanometre size Cu-rich precipitates is of considerable technical importance in a number of materials applications. It is shown definitively that there is a non-zero underlying level of Fe within precipitates formed upon thermal ageing, which is augmented and masked by trajectory overlaps. The concentration of Fe in the precipitate phase is shown to be a function of ageing temperature. An estimate of the underlying Fe level is made, which is at lower levels than commonly reported by atom probe investigations.

On the effect of stress on nucleation and growth of precipitates in an Al-Cu-Mg-Ag alloy

NASA Astrophysics Data System (ADS)

Skrotzki, B.; Shiflet, G. J.; Starke, E. A.

1996-11-01

A study has been made of the effect of an externally applied tensile stress on Ω and Θ' precipitate nucleation and growth in an Al-Cu-Mg-Ag alloy and a binary Al-Cu alloy which was used as a model system. Both solutionized and solutionized and aged conditions were studied. The mechanical properties have been measured and the microstructures have been characterized by transmission electron microscopy (TEM). The volume fraction and number density, as well as the precipitate size, have been experimentally determined. It was found that for as-solutionized samples aged under stress, precipitation occurs preferentially parallel to the stress axis. A threshold stress has to be exceeded before this effect can be observed. The critical stress for influencing the precipitate habit plane is between 120 and 140 MPa for Ω and between 16 and 19 MPa for Θ' for the aging temperature of 160 °C. The major effect of the applied stress is on the nucleation process. The results are discussed in terms of the role of the lattice misfit between the matrix and the precipitate nucleus.

Precipitate statistics in an Al-Mg-Si-Cu alloy from scanning precession electron diffraction data

NASA Astrophysics Data System (ADS)

Sunde, J. K.; Paulsen, Ø.; Wenner, S.; Holmestad, R.

2017-09-01

The key microstructural feature providing strength to age-hardenable Al alloys is nanoscale precipitates. Alloy development requires a reliable statistical assessment of these precipitates, in order to link the microstructure with material properties. Here, it is demonstrated that scanning precession electron diffraction combined with computational analysis enable the semi-automated extraction of precipitate statistics in an Al-Mg-Si-Cu alloy. Among the main findings is the precipitate number density, which agrees well with a conventional method based on manual counting and measurements. By virtue of its data analysis objectivity, our methodology is therefore seen as an advantageous alternative to existing routines, offering reproducibility and efficiency in alloy statistics. Additional results include improved qualitative information on phase distributions. The developed procedure is generic and applicable to any material containing nanoscale precipitates.

Process and apparatus for producing ultrafine explosive particles

DOEpatents

McGowan, Michael J.

1992-10-20

A method and an improved eductor apparatus for producing ultrafine explosive particles is disclosed. The explosive particles, which when incorporated into a binder system, have the ability to propagate in thin sheets, and have very low impact sensitivity and very high propagation sensitivity. A stream of a solution of the explosive dissolved in a solvent is thoroughly mixed with a stream of an inert nonsolvent by obtaining nonlaminar flow of the streams by applying pressure against the flow of the nonsolvent stream, to thereby diverge the stream as it contacts the explosive solution, and violently agitating the combined stream to rapidly precipitate the explosive particles from the solution in the form of generally spheroidal, ultrafine particles. The two streams are injected coaxially through continuous, concentric orifices of a nozzle into a mixing chamber. Preferably, the nonsolvent stream is injected centrally of the explosive solution stream. The explosive solution stream is injected downstream of and surrounds the nonsolvent solution stream for a substantial distance prior to being ejected into the mixing chamber.

A novel recovery method of copper from waste printed circuit boards by supercritical methanol process: Preparation of ultrafine copper materials.

PubMed

Xiu, Fu-Rong; Weng, Huiwei; Qi, Yingying; Yu, Gending; Zhang, Zhigang; Zhang, Fu-Shen; Chen, Mengjun

2017-02-01

In this study, supercritical methanol (SCM) process was successfully used for the preparation of ultrafine copper materials from waste printed circuit boards (PCBs) after nitric acid pretreatment. Waste PCBs were pretreated twice in nitric acid. Sn and Pb were recovered by the first nitric acid pretreatment. The leach liquor with a high concentration of copper ions after the second nitric acid leaching was subjected to SCM process. The mixture of Cu and Cu 2 O with poor uniformity of particle size was formed due to the effect of ferric iron contained in the leach liquor of waste PCBs, while more uniform and spherical Cu particles with high monodispersity and smaller size could be prepared after the removal of Fe. The size of Cu particles increased obviously with the decline of SCM temperature, and particles became highly aggregated when the reaction temperature decreased to 300°C. The size of Cu particles decreased markedly with the decrease of initial concentration of copper ion in the leach liquor of waste PCBs. It is believed that the process developed in this study is simple and practical for the preparation of ultrafine copper materials from waste PCBs with the aim of recycling these waste resources as a high value-added product. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi, E-mail: ishiguro@rs.noda.tus.ac.jp

Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

Impact of Annealing Prior to Solution Treatment on Aging Precipitates and Intergranular Corrosion Behavior of Al-Cu-Li Alloy 2050

NASA Astrophysics Data System (ADS)

Ye, Zhi-hao; Cai, Wen-xin; Li, Jin-feng; Chen, Xiang-rong; Zhang, Rui-feng; Birbilis, Nick; Chen, Yong-lai; Zhang, Xu-hu; Ma, Peng-cheng; Zheng, Zi-qiao

2018-06-01

The influences of annealing prior to solution treatment on the grain structure, subsequent aging precipitates, and intergranular corrosion (IGC) of Al-Cu-Li alloy (AA2050) sheet with T6 aging at 448 K (175 °C) were investigated. Annealing impedes the full recrystallization during solution treatment, increasing the population density of T1 (Al2CuLi) precipitates, but decreasing that of θ' (Al2Cu) precipitates, of the aged alloy. Meanwhile, annealing leads to the heterogeneous distribution of T1 precipitates, increasing the alloy hardness, and decreasing the open-circuit potential of the aged alloy. With prolonged aging time, the corrosion mode of the aged AA2050 samples with and without annealing evolved in a similar manner. The corrosion mode as a function of aging may be summarized as local IGC with pitting and general IGC with pitting (following initial aging and under the underaged condition), pitting corrosion (later in the under-aging stage), pitting with slight IGC (near the peak-aged condition), and pitting with local IGC (under the overaging condition). The annealing treatment hinders IGC propagation on the rolling surface while accelerating the IGC on transverse surfaces.

Impact of Annealing Prior to Solution Treatment on Aging Precipitates and Intergranular Corrosion Behavior of Al-Cu-Li Alloy 2050

NASA Astrophysics Data System (ADS)

Ye, Zhi-hao; Cai, Wen-xin; Li, Jin-feng; Chen, Xiang-rong; Zhang, Rui-feng; Birbilis, Nick; Chen, Yong-lai; Zhang, Xu-hu; Ma, Peng-cheng; Zheng, Zi-qiao

2018-04-01

The influences of annealing prior to solution treatment on the grain structure, subsequent aging precipitates, and intergranular corrosion (IGC) of Al-Cu-Li alloy (AA2050) sheet with T6 aging at 448 K (175 °C) were investigated. Annealing impedes the full recrystallization during solution treatment, increasing the population density of T1 (Al2CuLi) precipitates, but decreasing that of θ' (Al2Cu) precipitates, of the aged alloy. Meanwhile, annealing leads to the heterogeneous distribution of T1 precipitates, increasing the alloy hardness, and decreasing the open-circuit potential of the aged alloy. With prolonged aging time, the corrosion mode of the aged AA2050 samples with and without annealing evolved in a similar manner. The corrosion mode as a function of aging may be summarized as local IGC with pitting and general IGC with pitting (following initial aging and under the underaged condition), pitting corrosion (later in the under-aging stage), pitting with slight IGC (near the peak-aged condition), and pitting with local IGC (under the overaging condition). The annealing treatment hinders IGC propagation on the rolling surface while accelerating the IGC on transverse surfaces.

A Novel Cu-10Zn-1.5Ni-0.34Si Alloy with Excellent Mechanical Property Through Precipitation Hardening

NASA Astrophysics Data System (ADS)

Chen, Wei; Wang, Mingpu; Li, Zhou; Dong, Qiyi; Jia, Yanlin; Xiao, Zhu; Zhang, Rui; Yu, Hongchun

2016-11-01

A novel Cu-10Zn-1.5Ni-0.34Si alloy was designed to replace the expensive tin-phosphor bronze in this paper. The alloy had better comprehensive mechanical properties than traditional C5191 alloy. The aged Cu-10Zn-1.5Ni-0.34Si alloy had a hardness of 220 HV, electrical conductivity of 28.5% IACS, tensile strength of 650 MPa, yield strength of 575 MPa and elongation of 13%. Ni2Si precipitates formed during aging, and the crystal orientation relationship between matrix and precipitates was: (001)α//(001)δ, and [110]α//[100]δ. Ductile fracture surface with deep cavities was found in the alloy. Solid solution strengthening, deformation strengthening and precipitation strengthening were found to be core strengthening mechanisms in the alloy.

Microstructure and Strengthening Mechanisms in an Ultrafine Grained Al-Mg-Sc Alloy Produced by Powder Metallurgy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tammy J. Harrell; Troy D. Topping; Haiming Wen

2014-12-01

Additions of Sc to an Al-Mg matrix were investigated, paying particular attention to the influence of Al3Sc precipitates and other dispersoids, as well as grain size, on mechanical behavior. Prior studies have shown that Sc significantly increases the strength of coarse-grained Al-Mg alloys. Prompted by these findings, we hypothesized that it would be of fundamental and technological interest to study the behavior of Sc additions to an ultrafine-grained (UFG) microstructure (e.g., 100’s nm). Accordingly, we investigated the microstructural evolution and mechanical behavior of a cryomilled ultrafine grained Al-5Mg-0.4Sc (wt pct) and compared the results to those of an equivalent fine-grainedmore » material (FG) produced by powder metallurgy. Experimental materials were consolidated by hot isostatic pressing (HIP’ing) followed by extrusion or dual mode dynamic forging. Under identical processing conditions, UFG materials generate large Al3Sc precipitates with an average diameter of 154 nm and spaced approximately 1 to 3 µm apart, while precipitates in the FG materials have a diameter of 24 nm and are spaced 50 to 200 nm apart. The strengthening mechanisms are calculated for all materials and it is determined that the greatest strengthening contributions for the UFG and FG materials are Mg-O/N dispersion strengthening and precipitate strengthening, respectively.« less

The Special Features of the Deformation Behavior of an Ultrafine-Grained Aluminum Alloy of the Al-Mg-Li System at Room Temperature

NASA Astrophysics Data System (ADS)

Naydenkin, E. V.; Mishin, I. P.; Ivanov, K. V.

2015-04-01

The special features of the deformation behavior of an ultrafine-grained aluminum alloy produced by severe plastic deformation are investigated. Unlike ultrafine-grained pure aluminum, the second-phase particles precipitated in the bulk and at the grain boundaries of the alloy are shown to hinder the development of grain boundary sliding and plastic strain localization. This increases the length of the strain hardening stage and uniformity of elongation of a heterogeneous aluminum alloy specimen as compared to pure aluminum.

The influence of Ag+Mg additions on the nucleation of strengthening precipitates in a non-cold-worked Al-Cu-Li alloy

NASA Technical Reports Server (NTRS)

1991-01-01

Aluminum-copper-lithium alloys generally require cold work to attain their highest strengths in artificially aged tempers. These alloys are usually strengthened by a combination of the metastable delta prime (Al3Li) and theta prime (Al2Cu) phases and the equilibrium T sub 1 (Al2CuLi) phase, and where the T sub 1 phase is a more potent strengthener than the delta prime. Various investigators have shown that the high strengths obtained after artificial aging associated with cold work result from the heterogeneous precipitation of T sub 1 on matrix dislocations. The objective here is to elucidate the mechanism by which the Ag+Mg additions stimulate the precipitation of T sub 1 type precipitates without cold work. To accomplish this, the microstructure of an Al-6.3Cu-1.3Li-0.14Zr model alloy was evaluated in a T6 type temper with and without the Ag+Mg addition.

One-step rapid synthesis of ultrafine γ-Ga2O3 nanocrystals by microwave hydrothermal method in ammonium hydroxide medium

NASA Astrophysics Data System (ADS)

Cui, Lu; Wang, Hong; Xin, Baifu; Mao, Guijie

2017-10-01

Ultrafine nanocrystals of γ-gallium oxide (γ-Ga2O3) were rapidly synthesized via microwave hydrothermal method at 140 °C, in which Ga(NO3)3 was used as the gallium source and urea was the precipitant. The samples were characterized by X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV-Vis), transmission electron microscopy (TEM), nitrogen physisorption and photoluminescence spectroscopy (PL). The crystallite size of ultrafine spinel γ-Ga2O3 was in the range from 4 to 5 nm and the optical bandgap was 4.61 eV. To improve the crystallinity, the ultrafine γ-Ga2O3 nanocrystals were calcined at 300-700 °C further. The ultrafine γ-Ga2O3 calcined at 500 °C (calcined-γ-Ga2O3) still remained the metastable γ-phase with relatively high crystallinity and the crystallite size around 5-7 nm. Photocatalytic performances of the synthesized samples were also evaluated by the degradation of rhodamine B (RhB). Results revealed that the ultrafine γ-Ga2O3 and the calcined-γ-Ga2O3 samples exhibited high photocatalytic efficiencies of 68.2 and 90.7%, respectively.

High-temperature studies of grain boundaries in ultrafine grained alloys by means of positron lifetime

NASA Astrophysics Data System (ADS)

Würschum, R.; Shapiro, E.; Dittmar, R.; Schaefer, H.-E.

2000-11-01

Atomic free volumes and vacancies in the ultrafine grained alloys Pd84Zr16, Cu 0.1 wt % ZrO2, and Fe91Zr9 were studied by means of positron lifetime. The thermally stable microstructures serve as a novel type of model system for studying positron trapping and annihilation as well as the thermal behavior of vacancy-sized free volumes over a wide temperature range up to ca. 1200 K by making use of a metallic 58Co positron source. In ultrafine grained Cu the thermal formation of lattice vacancies could be observed. In Pd84Zr16 an increase of the specific positron trapping rate of nanovoids and, in addition, detrapping of positrons from free volumes with a mean size slightly smaller than one missing atom in the grain boundaries contributes to a reversible increase of the positron lifetime of more than 60 ps with measuring temperature. In Fe91Zr9 similar linear high-temperature increases of the positron lifetime are observed in the nanocrystalline and the amorphous state. The question of thermal vacancy formation in grain boundaries is addressed taking into account the different types of interface structures of the present alloys.

A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles.

PubMed

Zhang, Chao; Zhu, Rong; Yang, Wenming

2016-03-18

Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm³. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 10⁴ /cm³ and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices.

A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles

PubMed Central

Zhang, Chao; Zhu, Rong; Yang, Wenming

2016-01-01

Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm3. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 104 /cm3 and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

A Miniature Aerosol Sensor for Detecting Polydisperse Airborne Ultrafine Particles.

PubMed

Zhang, Chao; Wang, Dingqu; Zhu, Rong; Yang, Wenming; Jiang, Peng

2017-04-22

Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion charging and electrical detection. The aerosol sensor comprises a couple of planar electrodes printed on two circuit boards assembled in parallel, where charging, precipitation and measurement sections are integrated into one chip, which can detect aerosol particle size in of 30-500 nm, number concentration in range of 5 × 10²-10⁷ /cm³. The average relative errors of the measured aerosol number concentration and the particle size are estimated to be 12.2% and 13.5% respectively. A novel measurement scheme is proposed to actualize a real-time detection of polydisperse particles by successively modulating the measurement voltage and deducing the particle size distribution through a smart data fusion algorithm. The effectiveness of the aerosol sensor is experimentally demonstrated via measurements of polystyrene latex (PSL) aerosol and nucleic acid aerosol, as well as sodium chloride aerosol particles.

Precipitation Behavior and Quenching Sensitivity of a Spray Deposited Al-Zn-Mg-Cu-Zr Alloy

PubMed Central

Lei, Qian; Xiao, Zhu; Wang, Mingpu

2017-01-01

Precipitation behavior and the quenching sensitivity of a spray deposited Al-Zn-Mg-Cu-Zr alloy during isothermal heat treatment have been studied systematically. Results demonstrate that both the hardness and the ultimate tensile strength of the studied alloy decreased with the isothermal treatment time at certain temperatures. More notably, the hardness decreases rapidly after the isothermal heat treatment. During isothermal heat treatment processing, precipitates readily nucleated in the medium-temperature zone (250–400 °C), while the precipitation nucleation was scarce in the low-temperature zone (<250 °C) and in the high-temperature zone (>400 °C). Precipitates with sizes of less than ten nanometers would contribute a significant increase in yield strength, while the ones with a larger size than 300 nm would contribute little strengthening effect. Quenching sensitivity is high in the medium-temperature zone (250–400 °C), and corresponding time-temperature-property (TTP) curves of the studied alloy have been established. PMID:28925964

Production and Precipitation Hardening of Beta-Type Ti-35Nb-10Cu Alloy Foam for Implant Applications

NASA Astrophysics Data System (ADS)

Mutlu, Ilven; Yeniyol, Sinem; Oktay, Enver

2016-04-01

In this study, beta-type Ti-35Nb-10Cu alloy foams were produced by powder metallurgy method for dental implant applications. 35% Nb was added to stabilize the beta-Ti phase with low Young's modulus. Cu addition enhanced sinterability and gave precipitation hardening capacity to the alloy. Sintered specimens were precipitation hardened in order to enhance the mechanical properties. Electrochemical corrosion behavior of the specimens was examined by electrochemical impedance spectroscopy in artificial saliva. Electrochemical impedance spectroscopy results indicated that the oxide film on the surface of foam is a bi-layer structure consisting of outer porous layer and inner barrier layer. Impedance values of barrier layer were higher than porous layer. Corrosion resistance of specimens decreased at high fluoride concentrations and at low pH of artificial saliva. Corrosion resistance of alloys was slightly decreased with aging. Mechanical properties, microstructure, and surface roughness of the specimens were also examined.

Origin of tension-compression asymmetry in ultrafine-grained fcc metals

NASA Astrophysics Data System (ADS)

Tsuru, T.

2017-08-01

A mechanism of anomalous tension-compression (T-C) asymmetry in ultrafine-grained (UFG) metals is proposed using large-scale atomistic simulations and dislocation theory. Unlike coarse-grained metals, UFG Al exhibits remarkable T-C asymmetry of the yield stress. The atomistic simulations reveal that the yield event is not related to intragranular dislocations but caused by dislocation nucleation from the grain boundaries (GBs). The dislocation core structure associated with the stacking fault energy in Al is strongly affected by the external stress compared with Cu; specifically, high tensile stress stabilizes the dissociation into partial dislocations. These dislocations are more likely to be nucleated from GBs and form deformation twins from an energetic viewpoint. The mechanism, which is different from well-known mechanisms for nanocrystalline and amorphous metals, is unique to high-strength UFG metals and can explain the difference in T-C asymmetry between UFG Cu and Al.

Electrical resistivity of ultrafine-grained copper with nanoscale growth twins

NASA Astrophysics Data System (ADS)

Chen, X. H.; Lu, L.; Lu, K.

2007-10-01

We have investigated electrical resistivities of high-purity ultrafine-grained Cu containing different concentrations of nanoscale growth twins, but having identical grain size. The samples were synthesized by pulsed electrodeposition, wherein the density of twins was varied systematically by adjusting the processing parameters. The electrical resistivity of the Cu specimen with a twin spacing of 15nm at room temperature (RT) is 1.75μΩcm (the conductivity is about 97% IACS), which is comparable to that of coarse-grained (CG) pure Cu specimen. A reduction in twin density for the same grain size (with twin lamellar spacings of 35 and 90nm, respectively) results in an increment in electrical resistivity from 1.75to2.12μΩcm. However, the temperature coefficient of resistivity at RT for these Cu specimens is insensitive to the twin spacing and shows a consistent value of ˜3.78×10-3/K, which is slightly smaller than that of CG Cu (3.98×10-3/K). The increased electrical resistivities of the Cu samples were ascribed dominantly to the intrinsic grain boundary (GB) scattering, while the GB defects and GB energy would decrease with increasing twin density. Transmission electron microscope observations revealed the GB configuration difference from the Cu samples with various twin densities. Plastic deformation would induce an apparent increase in the resistivity. The higher of the twin density, the higher increment of RT resistivity was detected in the Cu specimens subjected to 40% rolling strain. Both the deviated twin boundaries and strained GBs may give rise to an increase in the resistivity.

Co-precipitation synthesis of nanostructured Cu3SbSe4 and its Sn-doped sample with high thermoelectric performance.

PubMed

Li, Di; Li, Rui; Qin, Xiao-Ying; Song, Chun-Jun; Xin, Hong-Xing; Wang, Ling; Zhang, Jian; Guo, Guang-lei; Zou, Tian-Hua; Liu, Yong-Fei; Zhu, Xiao-Guang

2014-01-28

Large-scale fabrication of nanostructured Cu3SbSe4 and its Sn-doped sample Cu3Sb0.98Sn0.02Se4 through a low-temperature co-precipitation route is reported. The effects of hot-pressing temperatures, time and Sn doping on the thermoelectric properties of Cu3SbSe4 are explored. The maximum figure of merit ZTmax obtained here reaches 0.62 for the un-doped Cu3SbSe4, which is three times as large as that of Cu3SbSe4 synthesized by the fusion method. Due to the ameliorated power factor by optimized carrier concentration and the reduced lattice thermal conductivity by enhanced phonon scattering at grain interfaces, Sn doping leads to an improvement of thermoelectric performance as compared to Cu3SbSe4. The maximum ZT for Cu3Sb0.98Sn0.02Se4 is 1.05 in this work, which is 50% larger than the largest value reported.

Mechanical behavior of nanostructured and ultrafine-grained materials under shock wave loadings. experimental data and results of computer simulation

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir

2012-03-01

Features of mechanical behavior of nanostructured and ultrafine-grained metals under quasistatic and shock wave loadings are discussed. Features of mechanical behavior of nanostructured and ultrafine grained metals over a wide range of strain rates are discussed. A constitutive model for mechanical behavior of metal alloys under shock wave loading including a grain size distribution, a precipitate hardening, and physical mechanisms of shear stress relaxation is presented. Strain rate sensitivity of the yield stress of face-centered-cubic, hexagonal close-packed metal alloys depends on grain size, whereas the Hugoniot elastic limits of ultrafine-grained copper, aluminum, and titanium alloys are close to values of coarse-grained counterparts. At quasi-static loading the yield strength and the tensile strength of titanium alloys with grain size from 300 to 500 nm are twice higher than at coarse-grained counterparts. But the spall strength of the UFG titanium alloys exceeds the value of coarse-grained counterparts only for 10 percents.

A Miniature Aerosol Sensor for Detecting Polydisperse Airborne Ultrafine Particles

PubMed Central

Zhang, Chao; Wang, Dingqu; Zhu, Rong; Yang, Wenming; Jiang, Peng

2017-01-01

Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion charging and electrical detection. The aerosol sensor comprises a couple of planar electrodes printed on two circuit boards assembled in parallel, where charging, precipitation and measurement sections are integrated into one chip, which can detect aerosol particle size in of 30–500 nm, number concentration in range of 5 × 102–5 × 107 /cm3. The average relative errors of the measured aerosol number concentration and the particle size are estimated to be 12.2% and 13.5% respectively. A novel measurement scheme is proposed to actualize a real-time detection of polydisperse particles by successively modulating the measurement voltage and deducing the particle size distribution through a smart data fusion algorithm. The effectiveness of the aerosol sensor is experimentally demonstrated via measurements of polystyrene latex (PSL) aerosol and nucleic acid aerosol, as well as sodium chloride aerosol particles. PMID:28441740

Quantitative measurement for the microstructural parameters of nano-precipitates in Al-Mg-Si-Cu alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Kai

Size, number density and volume fraction of nano-precipitates are important microstructural parameters controlling the strengthening of materials. In this work a widely accessible, convenient, moderately time efficient method with acceptable accuracy and precision has been provided for measurement of volume fraction of nano-precipitates in crystalline materials. The method is based on the traditional but highly accurate technique of measuring foil thickness via convergent beam electron diffraction. A new equation is proposed and verified with the aid of 3-dimensional atom probe (3DAP) analysis, to compensate for the additional error resulted from the hardly distinguishable contrast of too short incomplete precipitates cutmore » by the foil surface. The method can be performed on a regular foil specimen with a modern LaB{sub 6} or field-emission-gun transmission electron microscope. Precisions around ± 16% have been obtained for precipitate volume fractions of needle-like β″/C and Q precipitates in an aged Al-Mg-Si-Cu alloy. The measured number density is close to that directly obtained using 3DAP analysis by a misfit of 4.5%, and the estimated precision for number density measurement is about ± 11%. The limitations of the method are also discussed. - Highlights: •A facile method for measuring volume fraction of nano-precipitates based on CBED •An equation to compensate for small invisible precipitates, with 3DAP verification •Precisions around ± 16% for volume fraction and ± 11% for number density.« less

Combined electron beam imaging and ab initio modeling of T1 precipitates in Al-Li-Cu alloys

NASA Astrophysics Data System (ADS)

Dwyer, C.; Weyland, M.; Chang, L. Y.; Muddle, B. C.

2011-05-01

Among the many considerable challenges faced in developing a rational basis for advanced alloy design, establishing accurate atomistic models is one of the most fundamental. Here we demonstrate how advanced imaging techniques in a double-aberration-corrected transmission electron microscope, combined with ab initio modeling, have been used to determine the atomic structure of embedded 1 nm thick T1 precipitates in precipitation-hardened Al-Li-Cu aerospace alloys. The results provide an accurate determination of the controversial T1 structure, and demonstrate how next-generation techniques permit the characterization of embedded nanostructures in alloys and other nanostructured materials.

Pulmonary effects induced by ultrafine PTFE particles.

PubMed

Johnston, C J; Finkelstein, J N; Mercer, P; Corson, N; Gelein, R; Oberdörster, G

2000-11-01

PTFE (polytetrafluoroethylene) fumes consisting of large numbers of ultrafine (uf) particles and low concentrations of gas-phase compounds can cause severe acute lung injury. Our studies were designed to test three hypotheses: (i) uf PTFE fume particles are causally involved in the induction of acute lung injury, (ii) uf PTFE elicit greater pulmonary effects than larger sized PTFE accumulation mode particles, and (iii) preexposure to the uf PTFE fume particles will induce tolerance. We used uf Teflon (PTFE) fumes (count median particle size approximately 16 nm) generated by heating PTFE in a tube furnace to 486 degrees C to evaluate principles of ultrafine particle toxicity. Teflon fumes at ultrafine particle concentrations of 50 microg/m(3) were extremely toxic to rats when inhaled for only 15 min. We found that when generated in argon, the ultrafine Teflon particles alone are not toxic at these exposure conditions; neither were Teflon fume gas-phase constituents when generated in air. Only the combination of both phases when generated in air caused high toxicity, suggesting either the existence of radicals on the surface or a carrier mechanism of the ultrafine particles for adsorbed gas compounds. Aging of the fresh Teflon fumes for 3.5 min led to a predicted coagulation to >100 nm particles which no longer caused toxicity in exposed animals. This result is consistent with a greater toxicity of ultrafine particles compared to accumulation mode particles, although changes in particle surface chemistry during the aging process may have contributed to the diminished toxicity. Furthermore, the pulmonary toxicity of the ultrafine Teflon fumes could be prevented by adapting the animals with short 5-min exposures on 3 days prior to a 15-min exposure. Messages encoding antioxidants and chemokines were increased substantially in nonadapted animals, yet were unaltered in adapted animals. This study shows the importance of preexposure history for the susceptibility to acute

Ultrafine cementitious grout

DOEpatents

Ahrens, Ernst H.

1999-01-01

An ultrafine cementitious grout in three particle grades containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 30 wt. % to about 70 wt. % Portland cement; from about 30 wt. % to about 70 wt. % pumice containing at least 70% amorphous silicon dioxide; and from 1.2 wt. % to about 5.0 wt. % superplasticizer. The superplasticizer is dispersed in the mixing water prior to the addition of dry grout and the W/CM ratio is about 0.4 to 1/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 .mu.m in width.

Exposure to ultrafine particles in asphalt work.

PubMed

Elihn, Karine; Ulvestad, Bente; Hetland, Siri; Wallen, Anna; Randem, Britt Grethe

2008-12-01

An epidemiologic study has demonstrated that asphalt workers show increased loss of lung function and an increase of biomarkers of inflammation over the asphalt paving season. The aim of this study was to investigate which possible agent(s) causes the inflammatory reaction, with emphasis on ultrafine particles. The workers' exposure to total dust, polycyclic aromatic hydrocarbons, and NO(2) was determined by personal sampling. Exposure to ultrafine particles was measured by means of particle counters and scanning mobility particle sizer mounted on a van following the paving machine. The fractions of organic and elemental carbon were determined. Asphalt paving workers were exposed to ultrafine particles with medium concentration of about 3.4 x 10(4)/cm(3). Ultrafine particles at the paving site originated mainly from asphalt paving activities and traffic exhaust; most seemed to originate from asphalt fumes. Oil mist exceeded occupational limits on some occasions. Diesel particulate matter was measured as elemental carbon, which was low, around 3 microg/m(3). NO(2) and total dust did not exceed limits. Asphalt pavers were exposed to relatively high concentrations of ultrafine particles throughout their working day, with possible adverse health effects.

Performance of surface on ultrafine grained Ti-0.2Pd in simulated body fluid

NASA Astrophysics Data System (ADS)

Wang, Xiu-Lai; Zhou, Qing; Yang, Kai; Zou, Cheng-Hong; Wang, Lei

2018-03-01

Ti-0.2 wt% Pd (Ti-0.2Pd) which has high crevice corrosion resistance is highlighted for implant applications. In this work, Ti-0.2Pd alloy is subjected to equal channel angular pressing (ECAP) for grain refinement. The effect of the microstructure on the surface performance of Ti-0.2Pd in a simulated body fluid (SBF) adding bovine serum albumin is investigated. Heat-treated specimens including furnace cooled (FC) and water quenched (WQ) specimens are also prepared for comparison. The corrosion resistance is evaluated by the tests of potentiodynamic polarization and the measurement of electrochemical impedance spectroscopy (EIS). The composition and morphology of the surface after exposing to SBF 60 days were examined by X-ray photoelectronic spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show an ultrafine grained microstructure with average grain size of 3.6 μm is obtained after ECAP. The ultrafine grained Ti-0.2Pd has higher corrosion resistance than AR(as-received), WQ and FC specimens. The quantitative analysis of the surface shows larger numbers of precipitations formed on ECAPed Ti-0.2Pd than those formed on heat-treated. The precipitation contains more oxygen, calcium and phosphorus on ECAPed specimen than those on other specimens. The Ca:P ratio is ranged from 1:0.7 to 1:4.4, no dependent on the specimen type. A larger Warburg resistance is obtained on WQ specimen indicating a denser layer formation on WQ specimen. The precipitation formed on WQ specimens is the least among three kinds of specimens. Palladium is not found on the surfaces after exposure to SBF.

Three-dimensional characterization of BaHfO3 precipitates in GdBa2Cu3O7-y flim using STEM tomography.

PubMed

Nishiyama, T; Kaneko, K; Yamada, K; Teranishi, R; Kato, T; Hirayama, T; Tobita, H; Izumi, T; Shiohara, Y

2014-11-01

IntroductionSince the discovery of REBa2Cu3O7-y (RE: Rare Earth element, REBCO) superconductors, they have been expected as the best candidates for the power cable application due to its high critical temperature (Tc) and critical current density (Jc). Among those REBCO superconductors, GdBa2Cu3O7-y (GdBCO) have been receiving great interest because they have higher Tc and Jc than YBa2Cu3O7-y [1].GdBCO with various types of precipitates as artificial pinning centers (APCs) have been proposed to minimize the anisotropy of Jc characteristics under the magnetic field. Among those precipitates, BaHfO3 (BHO) was found most effective precipitates as APCs in GdBCO film prepared by pulsed laser deposition (PLD) method [2]. It is therefore necessary to investigate not only the morphologies but also the dispersion of BHO precipitates within the GdBCO, to understand the role of BHO for the superconducting characteristics. In this study, morphologies and dispersions of BHO precipitates were characterized three-dimensional by scanning transmission electron tomography ExperimentalBHO dispersed GdBCO films were fabricated on Hastelloy C-276TM substrates with buffer layers of CeO2/LaMnO3/MgO/ Gd2ZrO7 by PLD method.To observe microstructure of GdBCO film with BHO precipitates, cross-section TEM specimens were prepared by FIB method using Quanta 3D-200 (FEI, USA) with acceleration voltage from 2 to 30 kV. Three-dimensional information such as morphology and dispersion, of BHO precipitates were characterized by electron tomography using STEM-HAADF. Result and discussionFigure 1 shows three-dimensional reconstructed volume of BHO precipitates in GdBCO, which revealed that fine BHO precipitates have rod- and plate-like morphologies with homogeneous dispersion in GdBCO. In addition, growth directions of these precipitates were found with wide angular distributions from growth direction of GdBCO. Anisotropy of Jc in the magnetic fields was probably enhanced by various growth directions

Preparation and characterization of nanocrystalline CuO powders with the different surfactants and complexing agent mediated precipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajendran, V.; Gajendiran, J., E-mail: gaja.nanotech@gmail.com

2014-08-15

Highlights: • CuO nanostructures by surfactants mediated method. • Structural and optical properties of CuO nanostructures changes under the effect of surface modifier. • Citric acid assisted is the best, in terms of size, morphology and optical properties than that of CTAB, SDS and PEG-400. - Abstract: Nanostructures of copper oxide (CuO) was synthesized into crystallite sized ranging from 20 to 50 nm in the presence of different surfactants, and complex agent such as cityl tri methyl ammonium bromide (CTAB), sodium do decyl sulfate (SDS), poly ethylene glycol (PEG-400) and citric acid via a precipitation route. Variations in several parametersmore » and their effects on the structural and optical properties of CuO nanostructures (crystallite size, morphology and band gap) were investigated by XRD, FTIR, SEM and UV analysis. The UV–visible absorption spectra of the different surfactants and complexing agent assisted CuO nanostructures indicates that the estimated optical band gap energy value (1.94–1.98 eV) is higher than that of the bulk CuO value (1.4 eV), which is attributed to the quantum confinement effect. The formation mechanism of different surfactants and complexing agent assisted CuO nanostructures is also proposed.« less

Effect of Various Retrogression Regimes on Aging Behavior and Precipitates Characterization of a High Zn-Containing Al-Zn-Mg-Cu Alloy

NASA Astrophysics Data System (ADS)

Wen, Kai; Xiong, Baiqing; Zhang, Yongan; Li, Zhihui; Li, Xiwu; Huang, Shuhui; Yan, Lizhen; Yan, Hongwei; Liu, Hongwei

2018-03-01

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al-Zn-Mg-Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission electron microscopy (TEM) and high-resolution transmission electron microscopy techniques. Based on the matrix precipitate observations, the distributions of precipitate size and nearest inter-precipitate distance are extracted from bright-field TEM images projected along <110>Al orientation with the aid of an imaging analysis and an arithmetic method. The results show that GP zones and η' precipitates are the major precipitates and the precipitate size and its distribution range continuously enlarge with the retrogression regime expands to an extent of high temperature. The nearest inter-precipitate distance ranges obtained are quite the same and the average distance of nearest inter-precipitates show a slight increase. The influence of precipitates on mechanical properties is discussed through the interaction relationship between precipitates and dislocations.

Effect of Various Retrogression Regimes on Aging Behavior and Precipitates Characterization of a High Zn-Containing Al-Zn-Mg-Cu Alloy

NASA Astrophysics Data System (ADS)

Wen, Kai; Xiong, Baiqing; Zhang, Yongan; Li, Zhihui; Li, Xiwu; Huang, Shuhui; Yan, Lizhen; Yan, Hongwei; Liu, Hongwei

2018-05-01

In the present work, the influence of various retrogression treatments on hardness, electrical conductivity and mechanical properties of a high Zn-containing Al-Zn-Mg-Cu alloy is investigated and several retrogression regimes subjected to a same strength level are proposed. The precipitates are qualitatively investigated by means of transmission electron microscopy (TEM) and high-resolution transmission electron microscopy techniques. Based on the matrix precipitate observations, the distributions of precipitate size and nearest inter-precipitate distance are extracted from bright-field TEM images projected along <110>Al orientation with the aid of an imaging analysis and an arithmetic method. The results show that GP zones and η' precipitates are the major precipitates and the precipitate size and its distribution range continuously enlarge with the retrogression regime expands to an extent of high temperature. The nearest inter-precipitate distance ranges obtained are quite the same and the average distance of nearest inter-precipitates show a slight increase. The influence of precipitates on mechanical properties is discussed through the interaction relationship between precipitates and dislocations.

Measurements of hygroscopicity and volatility of atmospheric ultrafine particles during ultrafine particle formation events at urban, industrial, and coastal sites.

PubMed

Park, Kihong; Kim, Jae-Seok; Park, Seung Ho

2009-09-01

The tandem differential mobility analyzer (TDMA) technique was applied to determine the hygroscopicity and volatility of atmospheric ultrafine particles in three sites of urban Gwangju, industrial Yeosu, and coastal Taean in South Korea. A database for the hygroscopicity and volatility of the known compositions and sizes of the laboratory-generated particles wasfirst constructed for comparison with the measured properties of atmospheric ultrafine particles. Distinct differences in hygroscopicity and volatility of atmospheric ultrafine particles werefound between a "photochemical event" and a "combustion event" as well as among different sites. At the Gwangju site, ultrafine particles in the "photochemical event" were determined to be more hygroscopic (growth factor (GF) = 1.05-1.33) than those in the "combustion event" (GF = 1.02-1.12), but their hygroscopicity was not as high as pure ammonium sulfate or sulfuric acid particles in the laboratory-generated database, suggesting they were internally mixed with less soluble species. Ultrafine particles in the "photochemical event" at the Yeosu site, having a variety of SO2, CO, and VOC emission sources, were more hygroscopic (GF = 1.34-1.60) and had a higher amount of volatile species (47-75%)than those observed at the Gwangju site. Ultrafine particle concentration at the Taean site increased during daylight hours with low tide, having a higher GF (1.34-1.80) than the Gwangju site and a lower amount of volatile species (17-34%) than the Yeosu site. Occasionally ultrafine particles were externally mixed according to their hygroscopicity and volatility, and TEM/EDS data showed that each type of particle had a distinct morphology and elemental composition.

Ultrafine-grained titanium for medical implants

DOEpatents

Zhu, Yuntian T.; Lowe, Terry C.; Valiev, Ruslan Z.; Stolyarov, Vladimir V.; Latysh, Vladimir V.; Raab, Georgy J.

2002-01-01

We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

Precipitates studies in ultrafine-grained Al alloys with enhanced strength and conductivity

NASA Astrophysics Data System (ADS)

Sitdikov, V. D.; Murashkin, M. Yu.; Valiev, R. Z.

2017-05-01

The paper analyzes precipitation of nanosized particles in dynamically aged Al-Mg-Si alloy subjected to high pressure torsion in the temperature range from 25°C to 230°C. Precipitate types are identified and quantified within the frames of the modified X-ray phase analysis (XPA) technique. The generality and difference in the mechanisms and kinetics of precipitation during artificial and dynamic strain aging are analyzed, which opens new ways to further increase properties in promising aluminum conductors.

Anisotropic localized surface plasmon resonances in CuS nanoplates prepared by size-selective precipitation

NASA Astrophysics Data System (ADS)

Hamanaka, Yasushi; Yamada, Kaoru; Hirose, Tatsunori; Kuzuya, Toshihiro

2018-05-01

CuS nanoplates were synthesized by a colloidal method and separated into four fractions of nanoplates with different aspect ratios by a size-selective precipitation. In addition to a strong near infrared absorption band ascribed to the in-plane mode of the localized surface plasmon resonance (LSPR), we found a weak absorption band on the high frequency tail of the in-plane LSPR band. The frequency of the weak absorption band was almost constant and independent of the aspect ratio, while the in-plane LSPR band exhibited a strong aspect ratio dependence. These characteristics suggested that the weak absorption band is ascribed to the out-of-plane LSPR. Although the out-of-plane LSPR was expected to be difficult to observe for CuS nanoplates due to its low intensity and overlap with the strong in-plane resonance, we could successfully identify the out-of-plane mode by reducing the width of the size distribution and spectral broadening caused thereby.

Characterization of the evolution of the volume fraction of precipitates in aged AlMgSiCu alloys using DSC technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esmaeili, Shahrzad; Lloyd, David J.

2005-11-15

Differential scanning calorimetry is used to quantify the evolution of the volume fraction of precipitates during age hardening in AlMgSiCu alloys. The calorimetry tests are run on alloy samples after aging for various times at 180 deg. C and the change in the collective heat effects from the major precipitation and dissolution processes in each run are used to determine the precipitation state of the samples. The method is implemented on alloys with various thermal histories prior to artificial aging, including commercial pre-aging histories. The estimated values for the relative volume fraction of precipitates are compared with the results frommore » a newly developed analytical method using isothermal calorimetry and a related quantitative transmission electron microscopy work. Excellent agreement is obtained between the results from various methods.« less

Urban and rural ultrafine (PM 0.1) particles in the Helsinki area

NASA Astrophysics Data System (ADS)

Pakkanen, Tuomo A.; Kerminen, Veli-Matti; Korhonen, Christina H.; Hillamo, Risto E.; Aarnio, Päivi; Koskentalo, Tarja; Maenhaut, Willy

In June 1996-June 1997 Berner low-pressure impactors were used at an urban and at a rural site in the Helsinki area for sampling ultrafine particles (UFP, PM 0.1). Ten sample pairs, each pair measured simultaneously, were collected in the size range of 0.03-15 μm of particle aerodynamic diameter. More than 40 chemical components were measured. Surprisingly, the average UFP mass concentration was higher at the rural site (520 ng/m 3) than at the urban site (490 ng/m 3). The average chemical composition of UFP was similar at the two sites. The most abundant of the measured components were sulphate (32 and 40 ng/m 3 for the urban and rural sites, respectively), ammonium (22 and 25 ng/m 3), nitrate (4 and 11 ng/m 3) and the Ca 2+ ion (5 and 7 ng/m 3). The most important metals at both sites were Ca, Na, Fe, K and Zn with concentrations between 0.7 and 5 ng/m 3. Of the heavy metals, Ni, V, Cu, and Pb were important with average ultrafine concentrations between about 0.1 and 0.2 ng/m 3. Also the organic anions oxalate (urban 2.1 ng/m 3 and rural 1.9 ng/m 3) and methanesulphonate (1.3 and 1.7 ng/m 3) contributed similarly at both sites. The measured species accounted for only about 15-20% of the total ultrafine mass. The fraction that was not measured includes mainly carbonaceous material and water. It was estimated that the amount of water was about 10% (50 ng/m 3) and that of carbonaceous material about 70% (350 ng/m 3) at both sites. Aitken modes were observed for most components with the average mass mean mode diameters being between about 0.06 and 0.12 μm. The average concentrations in the Aitken mode differed clearly from those in the UFP for several components. The average contribution of ultrafine mass to the fine particle mass (PM 2.5) was about 7% at the urban site and 8.5% at the rural site. At both sites the contribution of ultrafine to fine was especially high for Se, Ag, B, and Ni (10-20%) and at the rural site also for Co (20%), Ca 2+ (16%) and Mo (11

Investigation and modeling of Al3(Sc, Zr) precipitation strengthening in the presence of enhanced supersaturation and within Al-Cu binary alloys

NASA Astrophysics Data System (ADS)

Deane, Kyle

Diffuse Al-Sc and Al-Zr alloys have been demonstrated in literature to be relatively coarsening resistant at higher temperatures when compared with commonly used precipitation strengthening alloys (e.g. 2000 series, 6000 series). However, because of a limited strengthening due to the low solubility of scandium and zirconium in aluminum, and owing to the scarcity and therefore sizeable price tag attached to scandium, little research has been done in the way of optimizing these alloys for commercial applications. With this in mind, this dissertation describes research which aims to tackle several important areas of Al-Sc-Zr research that have been yet unresolved. In Chapter 4, rapid solidification was utilized to enhance the achievable supersaturation of the alloy in an effort to increase the achievable precipitate strengthening. In Chapter 5, Additive Friction Stir processing (AFS), a novel method of mechanically combining materials without melting, was employed in an attempt to pass the benefits of supersaturation from melt spun ribbon into a more structurally useful bulk material. In Chapter 6, a Matlab program written to predict precipitate nucleation, growth, and coarsening with a modified Kampmann and Wagner Numerical (KWN) model, was used to predict heat treatment regimens for more efficient strengthening. Those predictions were then tested experimentally to test the validity of the results. And lastly, in Chapter 7, the effect of zirconium on Al-Cu secondary precipitates was studied in an attempt to increase their thermal stability, as much higher phase fractions of Al-Cu precipitates are achievable than Al-Zr precipitates.

First-principles calculation on the thermodynamic and elastic properties of precipitations in Al-Cu alloys

NASA Astrophysics Data System (ADS)

Sun, Dongqiang; Wang, Yongxin; Zhang, Xinyi; Zhang, Minyu; Niu, Yanfei

2016-12-01

First-principles calculations based on density functional theory was used to investigate the structural, thermodynamic and elastic properties of precipitations, θ″, θ‧ and θ, in Al-Cu alloys. The values of lattice constants accord with experimental results well. The structural stability of θ is the best, followed by θ‧ and θ″. In addition, due to the highest bulk modulus, shear modulus and Young's modulus, θ possesses the best reinforcement effect in precipitation hardening process considered only from mechanical properties of perfect crystal. According to the values of B/G, Poisson's ratio and C11-C12, θ‧ has the worst ductility, while θ″ has the best ductility, the ductility of θ is in the middle. The ideal tensile strength of θ″, θ‧ and θ calculated along [100] and [001] directions are 20.87 GPa, 23.11 GPa and 24.70 GPa respectively. The analysis of electronic structure suggests that three precipitations all exhibit metallic character, and number of bonding electrons and bonding strength are the nature of different thermodynamic and elastic properties for θ″, θ‧ and θ.

Method for synthesizing ultrafine powder materials

DOEpatents

Buss, Richard J.; Ho, Pauline

1988-01-01

A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400.degree. K. (127.degree.C.). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material.

Size-dependent proinflammatory effects of ultrafine polystyrene particles: a role for surface area and oxidative stress in the enhanced activity of ultrafines.

PubMed

Brown, D M; Wilson, M R; MacNee, W; Stone, V; Donaldson, K

2001-09-15

Studies into the effects of ultrafine particles in the lung have shown adverse effects considered to be due in part to the particle size. Air pollution particles (PM(10)) are associated with exacerbations of respiratory disease and deaths from cardiovascular causes in epidemiological studies and the ultrafine fraction of PM(10) has been hypothesized to play an important role. The aim of the present study was to investigate proinflammatory responses to various sizes of polystyrene particles as a simple model of particles of varying size including ultrafine. In the animal model, we demonstrated that there was a significantly greater neutrophil influx into the rat lung after instillation of 64-nm polystyrene particles compared with 202- and 535-nm particles and this was mirrored in other parameters of lung inflammation, such as increased protein and lactate dehydrogenase in bronchoalveolar lavage. When surface area instilled was plotted against inflammation, these two variables were directly proportional and the line passed through zero. This suggests that surface area drives inflammation in the short term and that ultrafine particles cause a greater inflammatory response because of the greater surface area they possess. In vitro, we measured the changes in intracellular calcium concentration in mono mac 6 cells in view of the potential role of calcium as a signaling molecule. Calcium changes after particle exposure may be important in leading to proinflammatory gene expression such as chemokines. We demonstrated that only ultrafine polystyrene particles induced a significant increase in cytosolic calcium ion concentration. Experiments using dichlorofluorescin diacetate demonstrated greater oxidant activity of the ultrafine particles, which may explain their activity in these assays. There were significant increases in IL-8 gene expression in A549 epithelial cells after treatment with the ultrafine particles but not particles of other sizes. These findings suggest

27Al, 63Cu NMR spectroscopy and electrical transport in Heusler Cu-Mn-Al alloy powders

NASA Astrophysics Data System (ADS)

Nadutov, V. M.; Perekos, A. O.; Kokorin, V. V.; Trachevskii, V. V.; Konoplyuk, S. M.; Vashchuk, D. L.

2018-02-01

The ultrafine powder of the Heusler Cu-13,1Mn-12,6Al (wt.%) alloy produced by electrical spark dispersion (ESD) in ethanol and the pellets prepared by pressing of the powders and aged in various gas environment (air, Ar, vacuum) were studied by XRD, nuclear magnetic resonance, magnetic and electric transport methods. The constituent phases were identified as b.c.c. α-Cu-Mn-Al, f.c.c. γ-Cu-Mn-Al, Cu2MnAl, and oxides. The sizes of the coherently scattering domains (CSD) and the saturation magnetizations were in the range of 4-90 nm and 0-1.5 Am2/kg, respectively. 27Al and 63Cu NMR spectra of the powders and pellets have shown hyperfine structure caused by contributions from atomic nuclei of the constituent phases. The aging of pellets in different gas environments had effect on their phase composition but no effect on dispersion of the phases. In contrast to the as-cast alloy, electrical resistance of the pellets evidenced semiconducting behavior at elevated temperatures due to the presence of metal oxides formed on the surfaces of nanoparticles.

Ultrafine cementitious grout

DOEpatents

Ahrens, Ernst H.

1998-01-01

An ultrafine cementitious grout having a particle size 90% of which are less than 6 .mu.m in diameter and an average size of about 2.5 .mu.m or less, and preferably 90% of which are less than 5 .mu.m in diameter and an average size of about 2 .mu.m or less containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 40 wt. % to about 50 wt. % Portland cement; from about 50 wt. % to about 60 wt. % pumice containing at least 60% amorphous silicon dioxide; and from 0.1 wt. % to about 1.5 wt. % superplasticizer. The grout is mixed with water in the W/CM ratio of about 0.4-0.6/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 .mu.m in width.

Friction Stir Welding of Al Alloy 2219-T8: Part I-Evolution of Precipitates and Formation of Abnormal Al2Cu Agglomerates

NASA Astrophysics Data System (ADS)

Kang, Ju; Feng, Zhi-Cao; Frankel, G. S.; Huang, I. Wen; Wang, Guo-Qing; Wu, Ai-Ping

2016-09-01

Friction stir welding was performed on AA2219-T8 plates with 6.31 wt pct Cu. The thermal cycles were measured in different regions of the joint during welding. Differential scanning calorimetry and transmission electron microscopy were utilized to analyze the evolution of precipitates in the joint. The relationships between welding peak temperature, precipitate evolution, and microhardness distribution are discussed. The temperature in the heat-affected zone (HAZ) ranged from 453 K to 653 K (180 °C to 380 °C). The θ″ and some θ' phases redissolved into the HAZ matrix, while the rest of the θ' phases coarsened. In the thermomechanically affected zone (TMAZ), the temperature range was from 653 K to 673 K (380 °C to 400 °C), causing both θ″ phase and θ' phase to redissolve. In the weld nugget zone (WNZ), all the θ″, θ', and some of the θ phase (Al2Cu) redissolved. Abnormal θ particles were observed in the WNZ, including agglomerated θ with sizes around 100 to 1000 µm and a ring-shaped distribution of normal size θ particles. The formation of abnormal θ particles resulted from metal plastic flow during welding and the high content of Cu in AA2219. No abnormal θ particles were observed in joints of another AA2219 plate, which had a lower Cu content of 5.83 wt pct.

High resolution electron microscopy study of a high Cu variant of Weldalite (tm) 049 and a high strength Al-Cu-Ag-Mg-Zr alloy

NASA Technical Reports Server (NTRS)

Herring, R. A.; Gayle, Frank W.; Pickens, Joseph R.

1991-01-01

Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy that is strengthened in artificially aged tempers primarily by very thin plate-like precipitates lying on the set of (111) matrix planes. This precipitate might be expected to be the T(sub 1) phase, Al2CuLi, which has been observed in Al-Cu-Li alloys. However, in several ways this precipitate is similar to the omega phase which also appears as the set of (111) planes plates and is found in Al-Cu-Ag-Mg alloys. The study was undertaken to identify the set of (111) planes precipitate or precipitates in Weldalite (trademark) 049 in the T8 (stretched and artificially aged) temper, and to determine whether T(sub 1), omega, or some other phase is primarily responsible for the high strength (i.e., 700 MPa tensile strength) in this Al-Cu-Li-Ag-Mg alloy.

Concentrated ambient ultrafine particle exposure induces cardiac change in young healthy volunteers

EPA Science Inventory

Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis. To characterize the effects of ultrafine particles in ...

Ultrafine cementitious grout

DOEpatents

Ahrens, E.H.

1998-07-07

An ultrafine cementitious grout is described having a particle size 90% of which are less than 6 {micro}m in diameter and an average size of about 2.5 {micro}m or less, and preferably 90% of which are less than 5 {micro}m in diameter and an average size of about 2 {micro}m or less containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 40 wt. % to about 50 wt. % Portland cement; from about 50 wt. % to about 60 wt. % pumice containing at least 60% amorphous silicon dioxide; and from 0.1 wt. % to about 1.5 wt. % superplasticizer. The grout is mixed with water in the W/CM ratio of about 0.4--0.6/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 {micro}m in width. 4 figs.

Surgical smoke and ultrafine particles

PubMed Central

Brüske-Hohlfeld, Irene; Preissler, Gerhard; Jauch, Karl-Walter; Pitz, Mike; Nowak, Dennis; Peters, Annette; Wichmann, H-Erich

2008-01-01

Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine (<100 nm) and accumulation mode particles (< 1 μm). Epidemiological and toxicological studies have shown that exposure to particulate air pollution is associated with adverse cardiovascular and respiratory health effects. Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc.) was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3) of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure. PMID:19055750

The Femtosecond Laser Ablation on Ultrafine-Grained Copper

NASA Astrophysics Data System (ADS)

Lu, Jianxun; Wu, Xiaoyu; Ruan, Shuangchen; Guo, Dengji; Du, Chenlin; Liang, Xiong; Wu, Zhaozhi

2018-07-01

To investigate the effects of femtosecond laser ablation on the surface morphology and microstructure of ultrafine-grained copper, point, single-line scanning, and area scanning ablation of ultrafine-grained and coarse-grained copper were performed at room temperature. The ablation threshold gradually increased and materials processing became more difficult with decreasing grain size. In addition, the ablation depth and width of the channels formed by single-line scanning ablation gradually increased with increasing grain size for the same laser pulse energy. The microhardness of the ablated specimens was also evaluated as a function of laser pulse energy using area scanning ablation. The microhardness difference before and after ablation increased with decreasing grain size for the same laser pulse energy. In addition, the microhardness after ablation gradually decreased with increasing laser pulse energy for the ultrafine-grained specimens. However, for the coarse-grained copper specimens, no clear changes of the microhardness were observed after ablation with varying laser pulse energies. The grain sizes of the ultrafine-grained specimens were also surveyed as a function of laser pulse energy using electron backscattered diffraction (EBSD). The heat generated by laser ablation caused recrystallization and grain growth of the ultrafine-grained copper; moreover, the grain size gradually increased with increasing pulse energy. In contrast, no obvious changes in grain size were observed for the coarse-grained copper specimens with increasing pulse energy.

The Femtosecond Laser Ablation on Ultrafine-Grained Copper

NASA Astrophysics Data System (ADS)

Lu, Jianxun; Wu, Xiaoyu; Ruan, Shuangchen; Guo, Dengji; Du, Chenlin; Liang, Xiong; Wu, Zhaozhi

2018-05-01

To investigate the effects of femtosecond laser ablation on the surface morphology and microstructure of ultrafine-grained copper, point, single-line scanning, and area scanning ablation of ultrafine-grained and coarse-grained copper were performed at room temperature. The ablation threshold gradually increased and materials processing became more difficult with decreasing grain size. In addition, the ablation depth and width of the channels formed by single-line scanning ablation gradually increased with increasing grain size for the same laser pulse energy. The microhardness of the ablated specimens was also evaluated as a function of laser pulse energy using area scanning ablation. The microhardness difference before and after ablation increased with decreasing grain size for the same laser pulse energy. In addition, the microhardness after ablation gradually decreased with increasing laser pulse energy for the ultrafine-grained specimens. However, for the coarse-grained copper specimens, no clear changes of the microhardness were observed after ablation with varying laser pulse energies. The grain sizes of the ultrafine-grained specimens were also surveyed as a function of laser pulse energy using electron backscattered diffraction (EBSD). The heat generated by laser ablation caused recrystallization and grain growth of the ultrafine-grained copper; moreover, the grain size gradually increased with increasing pulse energy. In contrast, no obvious changes in grain size were observed for the coarse-grained copper specimens with increasing pulse energy.

ULTRAFINE AEROSOL INFLUENCE ON THE SAMPLING BY CASCADE IMPACTOR.

PubMed

Vasyanovich, M; Mostafa, M Y A; Zhukovsky, M

2017-11-01

Cascade impactors based on inertial deposition of aerosols are widely used to determine the size distribution of radioactive aerosols. However, there are situations where radioactive aerosols are represented by particles with a diameter of 1-5 nm. In this case, ultrafine aerosols can be deposited on impactor cascades by diffusion mechanism. The influence of ultrafine aerosols (1-5 nm) on the response of three different types of cascade impactors was studied. It was shown that the diffusion deposition of ultrafine aerosols can distort the response of the cascade impactor. The influence of diffusion deposition of ultrafine aerosols can be considerably removed by the use of mesh screens or diffusion battery installed before cascade impactor during the aerosol sampling. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere.

PubMed

Lü, Senlin; Zhang, Rui; Yao, Zhenkun; Yi, Fei; Ren, Jingjing; Wu, Minghong; Feng, Man; Wang, Qingyue

2012-01-01

Ambient coarse particles (diameter 1.8-10 microm), fine particles (diameter 0.1-1.8 microm), and ultrafine particles (diameter < 0.1 microm) in the atmosphere of the city of Shanghai were sampled during the summer of 2008 (from Aug 27 to Sep 08). Microscopic characterization of the particles was investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). Mass concentrations of Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb in the size-resolved particles were quantified by using synchrotron radiation X-ray fluorescence (SRXRF). Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 +/- 2.18, 8.82 +/- 3.52, and 2.02 +/- 0.41 microg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.

Discontinuous precipitation at the deformation band in copper alloy

NASA Astrophysics Data System (ADS)

Han, Seung Zeon; Ahn, Jee Hyuk; You, Young Soo; Lee, Jehyun; Goto, Masahiro; Kim, Kwangho; Kim, Sangshik

2018-01-01

The Cu-Ni-Si alloy is known as a precipitation hardening alloy, where the Ni2Si intermetallic compound is precipitated in the matrix during aging. There are two types of precipitation of Ni2Si: continuous and discontinuous cellular. The discontinuous cellular precipitation is generally initiated at interfaces especially grain boundaries in the matrix. To observe the grain boundary effect on the discontinuous precipitation, a large-grained Cu-Ni-Si-Ti alloy was intentionally fabricated by unidirectional solidification and plastically deformed by groove rolling. While discontinuous cellular precipitation has been generally known to occur only at the high angled grain boundaries in the alloys, we found that it was also generated inside the grains, at the deformation bands formed by plastic deformation.

Characterizing precipitate evolution of an Al–Zn–Mg–Cu-based commercial alloy during artificial aging and non-isothermal heat treatments by in situ electrical resistivity monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Fulin; Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7; Zurob, Hatem S., E-mail: zurobh@mcmaster.ca

In situ electrical resistivity monitoring technique was employed to continuously evaluate the precipitate evolution of an Al–Zn–Mg–Cu-based commercial alloy during typical artificial aging treatments. The effects of artificial aging on the precipitates stability during non-isothermal heat treatments were also explored. Conventional hardness test, transmission electron microscopy and differential scanning calorimetry were also adopted to verify the electrical resistivity results. The results indicated that both the precipitation process and its timely rate could be followed by the monitored electrical resistivity during artificial aging treatments. The electrical resistivity results gave overall information on continuous precipitation and dissolution processes, especially under high heatingmore » rates. Samples artificial aging heat treated at 120 °C for 24 h followed by aging at 150 °C for 24 h presented more stable state and coarser precipitates than the samples only artificial aging heat treated at 120 °C for 24 h or triple artificial aging heat treated at 120 °C/24 h + 195 °C/15 min + 120 °/24 h. While the incoherent η precipitates in the samples artificial aging heat treated at 120 °C for 24 h followed by aging at 150 °C for 24 h were more easiness to coarsening and dissolve during non-isothermal heat treatments as well. - Highlights: • In situ electrical resistivity monitoring technique was employed on an Al-Zn-Mg-Cu alloy. • The precipitate evolution during typical artificial aging treatments was studied. • The precipitate stability during non-isothermal heat treatments was explored. • The electrical resistivity wonderfully monitored continuous precipitation and dissolution. • The alloy submitted to a T7 treatment presents a more stable state during heating due to incoherent η precipitates.« less

a Calorimetric Study of the Precipitation Hardening Mechanisms in AN Al-Cu-Mg-Si Alloy

NASA Astrophysics Data System (ADS)

Hayoune, Abdelali

2013-08-01

The precipitation phenomena and the related hardening in an Al-Cu-Mg-Si alloy were studied by calorimetry, X-ray diffraction analysis and microhardness measurements. The main calorimetric peaks were identified to be due to β‧‧, θ‧ and Q‧ phases precipitation. The hardening during aging at room temperature and 160°C, was respectively, explained by atomic clusters and GP zones formation and by GP zones and β‧‧/θ‧ phases coprecipitation. Although the mechanical properties variation during aging at 200°C is simple, the corresponding microstructural evolution is complex: on the basis of the DSC results, the increasing of microhardness values, is mainly due to the coprecipitation of GP zones and β‧‧/θ‧ phases, however, the maximum hardening is explained by the coexistence of β‧‧/θ‧ and θ‧‧ phases. Another important conclusion is that during aging at 160°C and 200°C, the θ‧ phase is essentially developed from GP zones.

Precipitation Behaviors of a New Antibacterial Maraging Stainless Steel for Medical Instruments

NASA Astrophysics Data System (ADS)

Zhang, H. W.; Xu, Y. L.; Chen, L. J.; Wang, X. W.; Wu, Z. Y.; Li, S.; Li, J.; Xiao, X. S.

2018-06-01

A new antibacterial maraging stainless steel with high hardness and good antibacterial property has been developed. The hardness of the new maraging stainless steel with a cold rolling deformation of 85 pct reaches the peak about 58.5 HRC after aging heat treatment, which is mainly due to the ɛ-Cu and Ni-, Al-, Ti-rich precipitates. Reverted austenite transformed from the martensite is responsible for the decrease of hardness when aging at higher temperature. Three-dimensional atom probe (3DAP) and transmission electric microscope (TEM) were used to investigate the precipitates formed in the martensite matrix after aging at 713 K for 4 hours. The ɛ-Cu and Ni-, Al-, Ti-rich precipitates distribute uniformly in the martensite matrix, and the Ni-, Al-, Ti-rich precipitates are nucleated on the Cu-rich precipitates. Because of the ɛ-Cu precipitates, the new maraging stainless steel possesses an excellent antibacterial property with the rate about 95.08 pct, which has a wide application prospect on scalpels and surgical needles.

Structural, optical and morphological characterization of Cu-doped α-Fe2O3 nanoparticles synthesized through co-precipitation technique

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

2017-11-01

Pure and copper (Cu concentration varying from 2 to 8%) doped hematite (α-Fe2O3) nanocrystals were synthesized through co-precipitation method using simple equipment. X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA) and Ultraviolet-Visible (UV-Vis) techniques were used to characterize the synthesized samples. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. These results along with TEM and SEM show that the size of the nanoparticles decreases with Cu-doping down to 21 nm. FT-IR confirm the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we synthesized pure and Cu-doped hematite but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The UV-Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.12 eV for pure α-Fe2O3 down to 1.91 eV for 8% Cu-doped α-Fe2O3. 8% Cu-doped hematite had the smallest size, the best crystallinity and the lowest band gap.

Unstable plastic deformation of ultrafine-grained copper at 0.5 K

NASA Astrophysics Data System (ADS)

Isaev, N. V.; Grigorova, T. V.; Shumilin, S. E.; Polishchuk, S. S.; Davydenko, O. A.

2017-12-01

We investigate the relation between the strain-hardening rate and flow instability of polycrystalline Cu-OF deformed by tension at a constant rate in a liquid 3He atmosphere. The microstructure of the ultrafine-grained crystal, obtained by the equal-channel angular hydro-extrusion method, was varied by annealing at recovery and recrystallization temperatures and was monitored by x-ray diffraction. It is shown that that the flow instability, manifesting itself as macroscopic stress serrations on the tension curve, appears at a threshold tension sufficient for activation of a dynamic recovery that leads to a decrease of the strain-hardening coefficient. We discuss the effect of grain size and the initial dislocation density on the evolution of the dislocation structure that determines the scale and the statistical properties of the flow instability in the investigated crystals at low temperature.

Development of ultrafine Ti-Fe-Sn in-situ composite with enhanced plasticity

NASA Astrophysics Data System (ADS)

Mondal, B.; Samal, S.; Biswas, K.; Govind

2012-01-01

The present investigation is aimed at developing ultrafine eutectic/dendrite Ti-Fe-Sn in-situ composite with balanced combination of strength and plasticity. It also studies the microstructure evolution in the series of hypereutectic Ti-Fe-Sn ternary alloys. Sn concentration of these alloys has been varied from 0 - 10 atom% in the binary alloy (Ti71Fe29) keeping the Ti concentration fixed. These alloys have been prepared by arc melting under an Ar atmosphere on a water-cooled Cu hearth, which are subsequently suction cast in a split Cu-mold under an Ar atmosphere. Detailed X-ray diffraction (XRD) study shows the presence of TiFe, β-Ti, and Ti3Sn phases. The SEM micrographs reveal that the microstructures consist of fine scale eutectic matrix (β-Ti and TiFe) with primary dendrite phases (TiFe and/or Ti3Sn) depending on concentration of Sn. α -Ti forms as a eutectoid reaction product of β-Ti. The room temperature uniaxial compressive test reveals simultaneous improvement in the strength (1942 MPa) and plasticity (13.1 %) for Ti71Fe26Sn3 ternary alloy. The fracture surface indicates a ductile mode of fracture for the alloy.

Structure functions in decomposing CuRh systems

NASA Astrophysics Data System (ADS)

Prem, M.; Blaschko, O.; Rosta, L.

1997-02-01

The time evolution of a CuRh alloy quenched within the miscibility gap is investigated by small and wide angle neutron scattering techniques. Near fundamental Bragg reflections diffuse satellites arising from a lattice parameter modulation induced by the precipitation pattern are investigated. The results show that in CuRh the precipitation morphology and its time evolution are quite different from decomposition characteristics recently observed in the system AuPt. The results are discussed and related to the larger lattice misfit present in CuRh in comparison to AuPt.

Cytocompatible and water stable ultrafine protein fibers for tissue engineering

NASA Astrophysics Data System (ADS)

Jiang, Qiuran

This dissertation proposal focuses on the development of cytocompatible and water stable protein ultrafine fibers for tissue engineering. The protein-based ultrafine fibers have the potential to be used for biomedicine, due to their biocompatibility, biodegradability, similarity to natural extracellular matrix (ECM) in physical structure and chemical composition, and superior adsorption properties due to their high surface to volume ratio. However, the current technologies to produce the protein-based ultrafine fibers for biomedical applications still have several problems. For instance, the current electrospinning and phase separation technologies generate scaffolds composed of densely compacted ultrafine fibers, and cells can spread just on the surface of the fiber bulk, and hardly penetrate into the inner sections of scaffolds. Thus, these scaffolds can merely emulate the ECM as a two dimensional basement membrane, but are difficult to mimic the three dimensional ECM stroma. Moreover, the protein-based ultrafine fibers do not possess sufficient water stability and strength for biomedical applications, and need modifications such as crosslinking. However, current crosslinking methods are either high in toxicity or low in crosslinking efficiency. To solve the problems mentioned above, zein, collagen, and gelatin were selected as the raw materials to represent plant proteins, animal proteins, and denatured proteins in this dissertation. A benign solvent system was developed specifically for the fabrication of collagen ultrafine fibers. In addition, the gelatin scaffolds with a loose fibrous structure, high cell-accessibility and cell viability were produced by a novel ultralow concentration phase separation method aiming to simulate the structure of three dimensional (3D) ECM stroma. Non-toxic crosslinking methods using citric acid as the crosslinker were also developed for electrospun or phase separated scaffolds from these three proteins, and proved to be

Phase Transformations and Formation of Ultra-Fine Microstructure During Hydrogen Sintering and Phase Transformation (HSPT) Processing of Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Sun, Pei; Fang, Zhigang Zak; Koopman, Mark; Xia, Yang; Paramore, James; Ravi Chandran, K. S.; Ren, Yang; Lu, Jun

2015-12-01

The hydrogen sintering and phase transformation (HSPT) process is a novel powder metallurgy method for producing Ti alloys, particularly the Ti-6Al-4V alloy, with ultra-fine microstructure in the as-sintered state. The ultra-fine microstructure is obtained as a direct result of the use of H2 gas during sintering. The refinement of the microstructure during HSPT is similar to that of thermal hydrogen processing (THP) of bulk Ti alloys. For both THP and HSPT of Ti-6Al-4V alloy, the mechanisms of the grain refinement depend on the phase equilibria and phase transformations in the presence of hydrogen, which are surprisingly still not well established to date and are still subjected to research and debate. In recent work by the present authors, a pseudo-binary phase diagram of (Ti-6Al-4V)-H has been determined by using in situ synchrotron XRD and TGA/DSC techniques. Aided by this phase diagram, the current paper focuses on the series of phase transformations during sintering and cooling of Ti-6Al-4V in a hydrogen atmosphere and the mechanisms for the formation of the ultra-fine microstructures obtained. Using experimental techniques, including in situ synchrotron XRD, SEM, EBSD, and TEM, the microstructural refinement was found to be the result of (1) the precipitation of ultra-fine α/α2 within coarse β grains during an isothermal hold at intermediate temperatures, and (2) the eutectoid transformation of β → α + δ at approximately 473 K (200 °C).

Magnetic studies of CuFe{sub 2}O{sub 4} nanoparticles prepared by co-precipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subha, A.; Shalini, M. Govindaraj; Sahoo, Subasa C., E-mail: subasa@cukerala.ac.in

2016-05-06

Cu-ferrite nanoparticles were synthesized by co-precipitation method and were annealed at different temperatures ranging from 400 to l000°C in air for 4 hours. The as-prepared sample and the sample annealed at 400°C showed small peaks of cubic Cu-ferrite in X-ray diffraction studies. For the intermediate temperature 600°C, some additional peaks of α-Fe{sub 2}O{sub 3} were observed. As the annealing temperature increased further only tetragonal Cu-ferrite peaks were observed. In all the samples some traces of CuO was noted. Grain size was increased from 2lnm for the as prepared sample to 42nm for the sample annealed at l000°C. Spontaneous magnetization valuemore » was found to be very small for the as prepared sample and it was increased monotonically with the increase in annealing temperature. Maximum magnetization of 29.7emu/g was observed at 300K for the sample annealed at l000°C. The remanent magnetization was increased with the increase in annealing temperature up to 900°C and then decreased whereas for the coercivity a peak was observed for the sample annealed at 800°C. The highest coercivity of l402 Oe was observed at 300K for the sample annealed at 800°C. As the measurement temperature decreased from 300K to 60K, magnetization and coercivity values were increased. The observed magnetic behaviour may be understood on the basis of phase transformation, grain growth with the increase in annealing temperature and reduced thermal energy at low measurement temperature.« less

Dispersion strengthening of precipitation hardened Al-Cu-Mg alloys prepared by rapid solidification and mechanical alloying

NASA Technical Reports Server (NTRS)

Gilman, P. S.; Sankaran, K. K.

1988-01-01

Several Al-4Cu-1Mg-1.5Fe-0.75Ce alloys have been processed from either rapidly solidified or mechanically alloyed powder using various vacuum degassing parameters and consolidation techniques. Strengthening by the fine subgrains, grains, and the dispersoids individually or in combination is more effective when the alloys contain shearable precipitates; consequently, the strength of the alloys is higher in the naturally aged rather than the artificially aged condition. The strengths of the mechanically alloyed variants are greater than those produced from prealloyed powder. Properties and microstructural features of these dispersion strengthened alloys are discussed in regards to their processing histories.

Ultrasound assisted co-precipitation of nanostructured CuO-ZnO-Al2O3 over HZSM-5: effect of precursor and irradiation power on nanocatalyst properties and catalytic performance for direct syngas to DME.

PubMed

Allahyari, Somaiyeh; Haghighi, Mohammad; Ebadi, Amanollah; Hosseinzadeh, Shahin

2014-03-01

Nanostructured CuO-ZnO-Al2O3/HZSM-5 was synthesized from nitrate and acetate precursors using ultrasound assisted co-precipitation method under different irradiation powers. The CuO-ZnO-Al2O3/HZSM-5 nanocatalysts were characterized using XRD, FESEM, BET, FTIR and EDX Dot-mapping analyses. The results indicated precursor type and irradiation power have significant influences on phase structure, morphology, surface area and functional groups. It was observed that the acetate formulated CuO-ZnO-Al2O3/HZSM-5 nanocatalyst have smaller CuO crystals with better dispersion and stronger interaction between components in comparison to nitrate based nanocatalysts. Ultrasound assisted co-precipitation synthesis method resulted in nanocatalyst with more uniform morphology compared to conventional method and increasing irradiation power yields smaller particles with better dispersion and higher surface area. Additionally the crystallinity of CuO is lower at high irradiation powers leading to stronger interaction between metal oxides. The nanocatalysts performance were tested at 200-300 °C, 10-40 bar and space velocity of 18,000-36,000 cm(3)/g h with the inlet gas composition of H2/CO = 2/1 in a stainless steel autoclave reactor. The acetate based nanocatalysts irradiated with higher levels of power exhibited better reactivity in terms of CO conversion and DME yield. While there is an optimal temperature for CO conversion and DME yield in direct synthesis of DME, CO conversion and DME yield both increase with the pressure increase. Furthermore ultrasound assisted co-precipitation method yields more stable CuO-ZnO-Al2O3/HZSM-5 nanocatalyst while conventional precipitated nanocatalyst lost their activity ca. 18% and 58% in terms of CO conversion and DME yield respectively in 24 h time on stream test.

Suppression of polymethyl methacrylate dust explosion by ultrafine water mist/additives.

PubMed

Gan, Bo; Li, Bei; Jiang, Haipeng; Bi, Mingshu; Gao, Wei

2018-06-05

The suppressions of ultrafine water mists containing additives (NaCl and NaHCO 3 ) on 100 nm, 5 μm, and 30 μm polymethyl methacrylate (PMMA) dust explosions were experimentally studied in a dust-explosion apparatus. High-speed photography showed that maximum vertical positions and flame propagation velocities were significantly decreased by suppression with ultrafine water mist/additives. Flame propagation velocities in 100 nm, 5 μm, and 30 μm dust explosions suppressed by the ultrafine pure water mist were reduced by 48.2%, 27.7%, and 15.3%, respectively. Maximum temperatures and temperature rising rates measured by a fine thermocouple in nano- and micro-PMMA dust explosions were also significantly decreased. It was proved that the addition of NaCl and NaHCO 3 improved the suppression effects of the ultrafine pure water mist. The improvement of explosion suppression by an 8% NaHCO 3 mist was superior to that of a 16% NaCl mist. The suppression mechanisms of ultrafine water mist/additives are further discussed by analyzing the physical and chemical effects. Copyright © 2018 Elsevier B.V. All rights reserved.

Structural properties of ultrafine Ba-hexaferrite nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makovec, Darko, E-mail: Darko.Makovec@ijs.si; Primc, Darinka; Sturm, Saso

2012-12-15

Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Moessbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH{sup -}. The ultrafine nanoparticles were formed in a discoid shape, {approx}10 nm wide and only {approx}3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction.more » The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe{sub 12}O{sub 19} formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization. - Graphical abstract: Left: HREM image of an ultrafine Ba-hexaferrite nanoparticle (inset: TEM image of the nanoparticles); Right: the experimental HRTEM image is compared with calculated image and corresponding atomic model. Highlights: Black-Right-Pointing-Pointer Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was compared to the structure of the bulk. Black-Right-Pointing-Pointer Thickness the discoid nanoparticles was comparable to the size of the hexagonal unit cell in the c-direction. Black-Right-Pointing-Pointer Considerable disorder of the nanoparticles' structure is most probably responsible for their low magnetization.« less

Features of Crystallization of Rapidly Quenched Ni45Ti32Hf18Cu5 and Ni25Ti32Hf18Cu25 Alloys from Melt with High-Temperature Shape Memory Effect

NASA Astrophysics Data System (ADS)

Pushin, A. V.; Pushin, V. G.; Kuntsevich, T. E.; Kuranova, N. N.; Makarov, V. V.; Uksusnikov, A. N.; Kourov, N. I.

2017-12-01

A comparative study of the structure and the chemical and phase composition of Ni45Ti32Hf18Cu5 and Ni25Ti32Hf18Cu25 amorphous alloys obtained by fast-quenching of melt stream by spinning has been carried out by transmission and scanning electron microscopy and X-ray diffraction. The critical temperatures of their devitrification were determined by the data of temperatures measurements of electrical resistance. The features of the formation of ultrafine structure and the phase transformation at the vitrification depending on the regimes of heat treatment and chemical composition of alloy have been established.

Preparation of an Ultrafine Rebamipide Ophthalmic Suspension with High Transparency.

PubMed

Matsuda, Takakuni; Hiraoka, Shogo; Urashima, Hiroki; Ogura, Ako; Ishida, Tatsuhiro

2017-01-01

A 2% commercially available, milky-white, rebamipide micro-particle suspension is used to treat dry eyes, and it causes short-term blurring of the patient's vision. In the current study, to improve the transparency of a rebamipide suspension, we attempted to obtain a clear rebamipide suspension by transforming the rebamipide particles to an ultrafine state. In the initial few efforts, various rebamipide suspensions were prepared using a neutralizing crystallization method with additives, but the suspensions retained their opaque quality. However, as a consequence of several critical improvements in the neutralizing crystallization methods such as selection of additives for crystallization, process parameters during crystallization, the dispersion method, and dialysis, we obtained an ultrafine rebamipide suspension (2%) that was highly transparent (transmittance at 640 nm: 59%). The particle size and transparency demonstrated the fewest level of changes at 25°C after 3 years, compared to initial levels. During that period, no obvious particle sedimentation was observed. The administration of this ultrafine rebamipide suspension (2%) increased the conjunctival mucin, which was comparable to the commercially available micro-particle suspension (2%). The corneal and conjunctival concentration of rebamipide following ocular administration of the ultrafine suspension was slightly higher than that of the micro-particle suspension. The ultrafine rebamipide suspension (eye-drop formulation) with a highly transparent ophthalmic clearness should improve a patient's QOL by preventing even a shortened period of blurred vision.

High temperature mechanical properties of a zirconium-modified, precipitation- strengthened nickel, 30 percent copper alloy

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1974-01-01

A precipitation-strengthened Monel-type alloy has been developed through minor alloying additions of zirconium to a base Ni-30Cu alloy. The results of this exploratory study indicate that thermomechanical processing of a solution-treated Ni-30Cu-0.2Zr alloy produced a dispersion of precipitates. The precipitates have been tentatively identified as a Ni5Zr compound. A comparison of the mechanical properties, as determined by testing in air, of the zirconium-modified alloy to those of a Ni-30Cu alloy reveals that the precipitation-strengthened alloy has improved tensile properties to 1200 K and improved stress-rupture properties to 1100 K. The oxidation characteristics of the modified alloy appeared to be equivalent to those of the base Ni-30Cu alloy.

Preparation of uniaxially aligned TiO2 ultrafine fibers by electrospinning.

PubMed

Nien, Yu-Hsun; Tsai, Yan-Sheng; Wang, Jia-Yi; Syu, Shu-Ping

2012-11-01

TiO2 nanofibers are often produced by electrospinning using a collector consisting of two parallel electrodes. In this work, a high speed rotating drum was used as a collector to produce uniaxially aligned TiO2 ultrafine fibers. The apparatus to manufacture uniaxially aligned TiO2 ultrafine fiber consisted of a high-speed roller, a high-voltage power supply, a controllable syringe pump and a syringe. Titanium (IV) isopropoxide and polyvinylpyrrolidone were used as precursor and auxiliary, respectively. Titanium (IV) isopropoxide and polyvinylpyrrolidone were well mixed with other essential reagents to form the polymer solution. The polymer solution was poured into the syringe and pumped at various flow rates. The electrospun ultrafine fibers collected on the roller were heat treated up to 600 degrees C and the uniaxially aligned TiO2 ultrafine fibers were formed and characterized using scanning electron microscope and X-ray diffraction.

Formation of Copper Sulfide Precipitate in Solid Iron

NASA Astrophysics Data System (ADS)

Urata, Kentaro; Kobayashi, Yoshinao

The growth rate of copper sulfide precipitates has been measured in low carbon steel samples such as Fe-0.3mass%Cu-0.03mass%S-0.1mass%C and Fe-0.1mass%Cu-0.01mass%S- 0.1mass%C. Heat-treatment of the samples was conducted at 1273, 1423 and 1573 K for 100 s - 14.4 ks for precipitation of copper sulfides and then the samples were observed by a scanning electron microscope and a transmission electron microscope to measure the diameter of copper sulfides precipitated in the samples. The growth rate of copper sulfide has been found to be well described by the Ostwald growth model, as follows: R\

Nanoscale precipitation in a maraging steel studied by APFIM.

PubMed

Stiller, Krystyna; Hättestrand, Mats

2004-06-01

This article summarizes findings from our previous investigations and recent studies concerning precipitation in a maraging steel of type 13Cr-9Ni-2Mo-2Cu (at.%) with small additions of Ti (1 at.%) and Al (0.7 at.%). The material was investigated after aging at 475 degrees C up to 400 h using both conventional and three-dimensional atom-probe analyses. The process of phase decomposition in the steel proved to be complicated. It consisted of precipitation of several phases with different chemistry. A Cu-rich phase was first to precipitate and Mo was last in the precipitation sequence. The influence of the complex precipitation path on the material properties is discussed. The investigation clearly demonstrated the usefulness of the applied techniques for investigation of nanoscale precipitation. It is also shown that, complementary methods (such as TEM and EFTEM) giving structural and chemical information on a larger scale must be applied to explain the good properties of the steel after prolonged aging.

Ultrafine sulfur nanoparticles in conducting polymer shell as cathode materials for high performance lithium/sulfur batteries.

PubMed

Chen, Hongwei; Dong, Weiling; Ge, Jun; Wang, Changhong; Wu, Xiaodong; Lu, Wei; Chen, Liwei

2013-01-01

We report the synthesis of ultrafine S nanoparticles with diameter 10 ~ 20 nm via a membrane-assisted precipitation technique. The S nanoparticles were then coated with conducting poly (3,4-ethylenedioxythiophene) (PEDOT) to form S/PEDOT core/shell nanoparticles. The ultrasmall size of S nanoparticles facilitates the electrical conduction and improves sulfur utilization. The encapsulation of conducting PEDOT shell restricts the polysulfides diffusion, alleviates self-discharging and the shuttle effect, and thus enhances the cycling stability. The resulting S/PEDOT core/shell nanoparticles show initial discharge capacity of 1117 mAh g(-1) and a stable capacity of 930 mAh g(-1) after 50 cycles.

Ultrafine Sulfur Nanoparticles in Conducting Polymer Shell as Cathode Materials for High Performance Lithium/Sulfur Batteries

PubMed Central

Chen, Hongwei; Dong, Weiling; Ge, Jun; Wang, Changhong; Wu, Xiaodong; Lu, Wei; Chen, Liwei

2013-01-01

We report the synthesis of ultrafine S nanoparticles with diameter 10 ~ 20 nm via a membrane-assisted precipitation technique. The S nanoparticles were then coated with conducting poly (3,4-ethylenedioxythiophene) (PEDOT) to form S/PEDOT core/shell nanoparticles. The ultrasmall size of S nanoparticles facilitates the electrical conduction and improves sulfur utilization. The encapsulation of conducting PEDOT shell restricts the polysulfides diffusion, alleviates self-discharging and the shuttle effect, and thus enhances the cycling stability. The resulting S/PEDOT core/shell nanoparticles show initial discharge capacity of 1117 mAh g−1 and a stable capacity of 930 mAh g−1 after 50 cycles. PMID:23714786

Ultrafine Sulfur Nanoparticles in Conducting Polymer Shell as Cathode Materials for High Performance Lithium/Sulfur Batteries

NASA Astrophysics Data System (ADS)

Chen, Hongwei; Dong, Weiling; Ge, Jun; Wang, Changhong; Wu, Xiaodong; Lu, Wei; Chen, Liwei

2013-05-01

We report the synthesis of ultrafine S nanoparticles with diameter 10 ~ 20 nm via a membrane-assisted precipitation technique. The S nanoparticles were then coated with conducting poly (3,4-ethylenedioxythiophene) (PEDOT) to form S/PEDOT core/shell nanoparticles. The ultrasmall size of S nanoparticles facilitates the electrical conduction and improves sulfur utilization. The encapsulation of conducting PEDOT shell restricts the polysulfides diffusion, alleviates self-discharging and the shuttle effect, and thus enhances the cycling stability. The resulting S/PEDOT core/shell nanoparticles show initial discharge capacity of 1117 mAh g-1 and a stable capacity of 930 mAh g-1 after 50 cycles.

[A technological study on the extraction of ultra-fine powder of Panax notoginsen].

PubMed

Huang, Yaohai; Huang, Mingqing; Zeng, Huifang; Guo, Wei; Xi, Ping

2005-12-01

To investigate the extraction of ultra-fine powder Panax notoginsen. The extraction rate of ginseng saponin Rg1, Re, Rb1, notoginseng saponin R1 and filtrated time were determined by alcoholic and aqueous extraction of Panax notoginsen in tablet, coarse powder, ultra-fine powder and recostitution granules of ultra-fine powder. The filtered time of ultra-fine powder of Panax notoginsen extraction and that of the tablet of Panax notoginsen extraction were similar, while the extraction rates of various saponins of it were high. The method of aqueous extrction in ltra-fine powder of Panax notoginsen is easy in filtrationer, higher in extraction rate of Panax notoginsen and lower in production cost.

Associations of Mortality with Long-Term Exposures to Fine and Ultrafine Particles, Species and Sources: Results from the California Teachers Study Cohort

PubMed Central

Hu, Jianlin; Goldberg, Debbie; Reynolds, Peggy; Hertz, Andrew; Bernstein, Leslie; Kleeman, Michael J.

2015-01-01

Background Although several cohort studies report associations between chronic exposure to fine particles (PM2.5) and mortality, few have studied the effects of chronic exposure to ultrafine (UF) particles. In addition, few studies have estimated the effects of the constituents of either PM2.5 or UF particles. Methods We used a statewide cohort of > 100,000 women from the California Teachers Study who were followed from 2001 through 2007. Exposure data at the residential level were provided by a chemical transport model that computed pollutant concentrations from > 900 sources in California. Besides particle mass, monthly concentrations of 11 species and 8 sources or primary particles were generated at 4-km grids. We used a Cox proportional hazards model to estimate the association between the pollutants and all-cause, cardiovascular, ischemic heart disease (IHD), and respiratory mortality. Results We observed statistically significant (p < 0.05) associations of IHD with PM2.5 mass, nitrate, elemental carbon (EC), copper (Cu), and secondary organics and the sources gas- and diesel-fueled vehicles, meat cooking, and high-sulfur fuel combustion. The hazard ratio estimate of 1.19 (95% CI: 1.08, 1.31) for IHD in association with a 10-μg/m3 increase in PM2.5 is consistent with findings from the American Cancer Society cohort. We also observed significant positive associations between IHD and several UF components including EC, Cu, metals, and mobile sources. Conclusions Using an emissions-based model with a 4-km spatial scale, we observed significant positive associations between IHD mortality and both fine and ultrafine particle species and sources. Our results suggest that the exposure model effectively measured local exposures and facilitated the examination of the relative toxicity of particle species. Citation Ostro B, Hu J, Goldberg D, Reynolds P, Hertz A, Bernstein L, Kleeman MJ. 2015. Associations of mortality with long-term exposures to fine and ultrafine

Structure and photoluminescence studies of CeO2·CuAlO2 mixed metal oxide fabricated by co-precipitation method

NASA Astrophysics Data System (ADS)

Subhan, Md Abdus; Ahmed, Tanzir; Awal, M. R.; Kim, B. Moon

2015-01-01

A novel mixed metal oxide, CeO2·CuAlO2 was fabricated by co-precipitation method in aqueous medium. CeO2·CuAlO2 was characterized by XRD, SEM, EDS, TEM, FTIR and PL spectra. The optical properties of the nanoparticles were studied by photoluminescence (PL) spectra. PL spectra at different excitations were recorded. The composite showed emission in UV, visible and NIR region depending on the excitation wavelength. The special spectral feature observed for this composite is that it showed six emission bands at 364, 409, 434, 448, 465 and 481 nm when excited at 298 nm. The green and red emissions observed at 512 and 669 nm are originated from cubic CeO2 phase when excited at 450 nm. The PL spectra were found to be dependent on excitation wavelength violating Kasha's rule. The X-ray diffraction reveals a cubic CeO2 phase and hexagonal CuAlO2 phase. EDS spectra revealed the presence of cerium (Ce), copper (Cu), aluminum (Al) and oxygen (O) elements. The particle size of the CeO2·CuAlO2 mixed oxide was estimated using Scherrer's formula, which was found to be in the range of 17.2-34.2 nm. The TEM image showed particles are almost uniform size of approximately 15-50 nm with spherical morphology.

Initiation and growth of the discontinuous precipitation reaction at [0 1 1] symmetric tilt boundaries in Cu-Be alloy bicrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monzen, R.; Watanabe, C.; Mino, D.

2005-02-01

The initiation and growth of discontinuous precipitation (DP) at [0 1 1] symmetric tilt boundaries in Cu-0.75 wt% Be alloy bicrystals have been studied. Transmission electron microscopy revealed that {gamma} precipitates tended to nucleate at a boundary in such a manner that their habit plane, (1 1 2){sub {alpha}} or (4 4 5){sub {alpha}}, with one of the adjoining grains lay as close as possible to the boundary. The habit plane with a low energy formed on both sides of the precipitates behind an initially migrating boundary, indicating the importance of the existence of the low-energy habit plane for themore » initial boundary migration. The incubation period to initiate DP and cell growth rate for a boundary show a good correlation with the energy of the boundary. A kinetic analysis of DP using the models of Turnbull, and Petermann and Hornbogen has yielded boundary diffusion data. A higher-energy boundary has a higher diffusivity with a smaller activation energy.« less

Polymer degradation and ultrafine particles - Potential inhalation hazards for astronauts

NASA Technical Reports Server (NTRS)

Ferin, J.; Oberdoerster, G.

1992-01-01

To test the hypothesis that exposure to ultrafine particles results in an increased interstiatilization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO2 particles access the pulmonary interstitium to a larger extent than fine particles and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

Structure and phase composition of ultrafine-grained TiNb alloy after high-temperature annealings

NASA Astrophysics Data System (ADS)

Eroshenko, Anna Yu.; Glukhov, Ivan A.; Mairambekova, Aikol; Tolmachev, Alexey I.; Sharkeev, Yurii P.

2017-12-01

The paper presents the experimental data observed in the microstructure and phase composition of ultrafine-grained Ti-40 mass % Nb (Ti40Nb) alloy after high-temperature annealings. The ultrafine-grained Ti40Nb alloy is produced by severe plastic deformation (SPD). This method includes multiple abc-pressing and multi-pass rolling followed by further pre-recrystallizing annealing which, in its turn, enhances the formation of ultrafine-grained structures with mean size of 0.28 µm involving stable β- and α-phase and metastable nanosized ω-phase in the alloy. It is shown that annealing at 500°C preserves the ultrafine-grained structure and phase composition. In cases of annealing at 800°C the ultrafine-grained state transforms into the coarse-grained state. The stable β-phase and the nanosized metastable ω-phase have been identified in the coarse-grained structure.

Nanocrystallization in Cu-Zr-Al-Sm Bulk Metallic Glasses

NASA Astrophysics Data System (ADS)

Sikan, Fatih; Yasar, Bengisu; Kalay, Ilkay

2018-04-01

The effect of rare-earth element (Sm) microalloying on the thermal stability and crystallization kinetics of melt-spun ribbons and suction-cast rods of Zr48Cu38.4Al9.6Sm4 alloy were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), and atom probe tomography (APT). The XRD results of constant heating rate annealing indicated that amorphous Zr48Cu38.4Al9.6Sm4 melt-spun ribbons devitrifies into Cu2Sm at 673 K (400 °C). The sequence continues with the precipitation of Cu10Zr7 and then these two phases coexist. XRD and TEM studies on 1 mm diameter as suction-cast rods indicated the precipitation of 30-nm-mean size Cu2Sm crystals during solidification. TEM investigation of the isothermal crystallization sequence of melt-spun ribbons and 1-mm-diameter suction-cast rods revealed the precipitation of Cu2Sm nanocrystals at the onset of crystallization and the restriction of the growth of these nanocrystals up to 10 nm diameter with further annealing. APT analysis of 1-mm-diameter suction-cast rods showed that the limited growth of Cu2Sm nanocrystals is due to sluggish diffusion of Sm and Al-Zr pile up at the interface.

On the assessment of exposure to airborne ultrafine particles in urban environments.

PubMed

Gomes, João Fernando Pereira; Bordado, João Carlos Moura; Albuquerque, Paula Cristina Silva

2012-01-01

The aim of this study was to contribute to the assessment of exposure levels of ultrafine particles in the urban environment of Lisbon, Portugal, due to automobile traffic, by monitoring lung deposited alveolar surface area (resulting from exposure to ultrafine particles) in a major avenue leading to the town center during late spring, as well as in indoor buildings facing it. Data revealed differentiated patterns for week days and weekends, consistent with PM(2.5) and PM₁₀ patterns currently monitored by air quality stations in Lisbon. The observed ultrafine particulate levels may be directly correlated with fluxes in automobile traffic. During a typical week, amounts of ultrafine particles per alveolar deposited surface area varied between 35 and 89.2 μm²/cm³, which are comparable with levels reported for other towns in Germany and the United States. The measured values allowed for determination of the number of ultrafine particles per cubic centimeter, which are comparable to levels reported for Madrid and Brisbane. In what concerns outdoor/indoor levels, we observed higher levels (32 to 63%) outdoors, which is somewhat lower than levels observed in houses in Ontario.

Co-Precipitation, Strength and Electrical Resistivity of Cu–26 wt % Ag–0.1 wt % Fe Alloy

PubMed Central

Li, Rui; Wang, Engang

2017-01-01

Both a Cu–26 wt % Ag (Fe-free) alloy and Cu–26 wt % Ag–0.1 wt % Fe (Fe-doping) alloy were subjected to different heat treatments. We studied the precipitation kinetics of Ag and Cu, microstructure evolution, magnetization, hardness, strength, and electrical resistivity of the two alloys. Fe addition was incapable of changing the precipitation kinetics of Ag and Cu; however, it decreased the size and spacing of rod-shaped Ag precipitates within a Cu matrix, because Fe might affect the elastic strain field and diffusion field, suppressing the nucleation of Ag precipitates. Magnetization curves showed that γ-Fe precipitates were precipitated out of the Cu matrix, along with Ag precipitates in Fe-doping alloy after heat treatments. The yield strength of the Fe-doping alloy was higher than that of the Fe-free alloy, and the maximum increment was about 41.3%. The electrical conductivity in the aged Fe-doping alloy was up to about 67% IACS (International Annealed Copper Standard). Hardness, strength, and electrical resistivity were intensively discussed, based on the microstructural characterization and solute contributions of both alloys. Our results demonstrated that an increasing fraction of nanoscale γ-Fe precipitates and decreasing spacing between Ag precipitates resulted in the increasing strength of the Fe-doping alloy. PMID:29207505

Influence of Ultrafine 2CaO·SiO₂ Powder on Hydration Properties of Reactive Powder Concrete.

PubMed

Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

2015-09-17

In this research, we assessed the influence of an ultrafine 2CaO·SiO₂ powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO₂. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO₂ powder has the potential to improve the performance of a reactive powder cementitious system.

Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors.

PubMed

Cheng, Yu-Hsiang; Huang, Cheng-Hsiung; Huang, Hsiao-Lin; Tsai, Chuen-Jinn

2010-12-15

Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about <6 nm and a minor mode at about 40 nm was observed at the tollbooth. The high amounts of nanoparticles in this study can be attributed to gas-to-particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk. Copyright © 2010 Elsevier B.V. All rights reserved.

Focusing particle concentrator with application to ultrafine particles

DOEpatents

Hering, Susanne; Lewis, Gregory; Spielman, Steven R.

2013-06-11

Technology is presented for the high efficiency concentration of fine and ultrafine airborne particles into a small fraction of the sampled airflow by condensational enlargement, aerodynamic focusing and flow separation. A nozzle concentrator structure including an acceleration nozzle with a flow extraction structure may be coupled to a containment vessel. The containment vessel may include a water condensation growth tube to facilitate the concentration of ultrafine particles. The containment vessel may further include a separate carrier flow introduced at the center of the sampled flow, upstream of the acceleration nozzle of the nozzle concentrator to facilitate the separation of particle and vapor constituents.

Ultrafine particle transport and deposition in a large scale 17-generation lung model.

PubMed

Islam, Mohammad S; Saha, Suvash C; Sauret, Emilie; Gemci, Tevfik; Yang, Ian A; Gu, Y T

2017-11-07

To understand how to assess optimally the risks of inhaled particles on respiratory health, it is necessary to comprehend the uptake of ultrafine particulate matter by inhalation during the complex transport process through a non-dichotomously bifurcating network of conduit airways. It is evident that the highly toxic ultrafine particles damage the respiratory epithelium in the terminal bronchioles. The wide range of in silico available and the limited realistic model for the extrathoracic region of the lung have improved understanding of the ultrafine particle transport and deposition (TD) in the upper airways. However, comprehensive ultrafine particle TD data for the real and entire lung model are still unavailable in the literature. Therefore, this study is aimed to provide an understanding of the ultrafine particle TD in the terminal bronchioles for the development of future therapeutics. The Euler-Lagrange (E-L) approach and ANSYS fluent (17.2) solver were used to investigate ultrafine particle TD. The physical conditions of sleeping, resting, and light activity were considered in this modelling study. A comprehensive pressure-drop along five selected path lines in different lobes was calculated. The non-linear behaviour of pressure-drops is observed, which could aid the health risk assessment system for patients with respiratory diseases. Numerical results also showed that ultrafine particle-deposition efficiency (DE) in different lobes is different for various physical activities. Moreover, the numerical results showed hot spots in various locations among the different lobes for different flow rates, which could be helpful for targeted therapeutical aerosol transport to terminal bronchioles and the alveolar region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogen isotope trapping in Al-Cu binary alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, Paul; Karnesky, Richard A.

In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol –1 (0.19 ± 0.03 eV). Typical occupancy of this trap ismore » high; for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D 2 for 68 days, there is ca. there is 3.15×10 –7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.« less

Hydrogen isotope trapping in Al-Cu binary alloys

DOE PAGES

Chao, Paul; Karnesky, Richard A.

2016-01-01

In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol –1 (0.19 ± 0.03 eV). Typical occupancy of this trap ismore » high; for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D 2 for 68 days, there is ca. there is 3.15×10 –7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.« less

Ultrafine particle emissions from modern Gasoline and Diesel vehicles: An electron microscopic perspective.

PubMed

Liati, Anthi; Schreiber, Daniel; Arroyo Rojas Dasilva, Yadira; Dimopoulos Eggenschwiler, Panayotis

2018-08-01

Ultrafine (<100 nm) particles related to traffic are of high environmental and human health concern, as they are supposed to be more toxic than larger particles. In the present study transmission electron microscopy (TEM) is applied to obtain a concrete picture on the nature, morphology and chemical composition of non-volatile ultrafine particles in the exhaust of state-of-the-art, Euro 6b, Gasoline and Diesel vehicles. The particles were collected directly on TEM grids, at the tailpipe, downstream of the after-treatment system, during the entire duration of typical driving cycles on the chassis dynamometer. Based on TEM imaging coupled with Energy Dispersive X-ray (EDX) analysis, numerous ultrafine particles could be identified, imaged and analyzed chemically. Particles <10 nm were rarely detected. The ultrafine particles can be distinguished into the following types: soot, ash-bearing soot and ash. Ash consists of Ca, P, Mg, Zn, Fe, S, and minor Sn compounds. Most elements originate from lubricating oil additives; Sn and at least part of Fe are products of engine wear; minor W ± Si-bearing nearly spherical particles in Diesel exhaust derive from catalytic coating material. Ultrafine ash particles predominate over ultrafine soot or are nearly equal in amount, in contrast to emissions of larger sizes where soot is by far the prevalent particle type. This is probably due to the low ash amount per volume fraction in the total emissions, which does not favor formation of large ash agglomerates, opposite to soot, which is abundant and thus easily forms agglomerates of sizes larger than those of the ultrafine range. No significant differences of ultrafine particle characteristics were identified among the tested Gasoline and Diesel vehicles and driving cycles. The present TEM study gives information also on the imaging and chemical composition of the solid fraction of the unregulated sub-23 nm size category particles. Copyright © 2018 Elsevier Ltd. All

Effect of different Zr contents on properties and microstructure of Cu-Cr-Zr alloys

NASA Astrophysics Data System (ADS)

Jinshui, Chen; Bin, Yang; Junfeng, Wang; Xiangpeng, Xiao; Huiming, Chen; Hang, Wang

2018-02-01

The crystallography and morphology of precipitate particles of Cu-Cr-Zr alloys with varying Zr contents were studied by transmission electron microscopy (TEM) after solution treatments at 950 °C for 1 h and aging treatments at 500 °C for different times ranged from 0.5 h to 24 h. The microhardness and electrical conductivity of Cu-Cr-Zr alloys after various aging process were tested. The results show that the microhardness and electrical conductivity rapidly increased at first, then the microhardness decreased slowly after reaching the peak, while the conductivity continues to increase. Nano-scaled precipitates exhibit two kinds of morphology (coffee bean and ellipse shaped). With increasing Zr content, the Zr-containing precipitation sequence of Cu-Cr-Zr alloys at peak-ageing is Heusler CrCu2Zr → Cu5Zr → Cu4Zr. The Heusler CrCu2Zr phase decomposed into fine and homogeneous Cr and Cu4Zr, resulting in improved alloy properties.

Defect investigations of micron sized precipitates in Al alloys

NASA Astrophysics Data System (ADS)

Klobes, B.; Korff, B.; Balarisi, O.; Eich, P.; Haaks, M.; Kohlbach, I.; Maier, K.; Sottong, R.; Staab, T. E. M.

2011-01-01

A lot of light aluminium alloys achieve their favourable mechanical properties, especially their high strength, due to precipitation of alloying elements. This class of age hardenable Al alloys includes technologically important systems such as e.g. Al-Mg-Si or Al-Cu. During ageing different precipitates are formed according to a specific precipitation sequence, which is always directed onto the corresponding intermetallic equilibrium phase. Probing the defect state of individual precipitates requires high spatial resolution as well as high chemical sensitivity. Both can be achieved using the finely focused positron beam provided by the Bonn Positron Microprobe (BPM) [1] in combination with the High Momentum Analysis (HMA) [2]. Employing the BPM, structures in the micron range can be probed by means of the spectroscopy of the Doppler broadening of annihilation radiation (DBAR). On the basis of these prerequisites single precipitates of intermetallic phases in Al-Mg-Si and Al-Cu, i.e. Mg2Si and Al2Cu, were probed. A detailed interpretation of these measurements necessarily relies on theoretical calculations of the DBAR of possible annihilation sites. These were performed employing the DOPPLER program. However, previous to the DBAR calculation the structures, which partly contain vacancies, were relaxed using the ab-initio code SIESTA, i.e. the atomic positions in presence of a vacancy were recalculated.

Structure and photoluminescence studies of CeO2·CuAlO2 mixed metal oxide fabricated by co-precipitation method.

PubMed

Subhan, Md Abdus; Ahmed, Tanzir; Awal, M R; Kim, B Moon

2015-01-25

A novel mixed metal oxide, CeO2·CuAlO2 was fabricated by co-precipitation method in aqueous medium. CeO2·CuAlO2 was characterized by XRD, SEM, EDS, TEM, FTIR and PL spectra. The optical properties of the nanoparticles were studied by photoluminescence (PL) spectra. PL spectra at different excitations were recorded. The composite showed emission in UV, visible and NIR region depending on the excitation wavelength. The special spectral feature observed for this composite is that it showed six emission bands at 364, 409, 434, 448, 465 and 481 nm when excited at 298 nm. The green and red emissions observed at 512 and 669 nm are originated from cubic CeO2 phase when excited at 450 nm. The PL spectra were found to be dependent on excitation wavelength violating Kasha's rule. The X-ray diffraction reveals a cubic CeO2 phase and hexagonal CuAlO2 phase. EDS spectra revealed the presence of cerium (Ce), copper (Cu), aluminum (Al) and oxygen (O) elements. The particle size of the CeO2·CuAlO2 mixed oxide was estimated using Scherrer's formula, which was found to be in the range of 17.2-34.2 nm. The TEM image showed particles are almost uniform size of approximately 15-50 nm with spherical morphology. Copyright © 2014 Elsevier B.V. All rights reserved.

Copper Oxide Precipitates in NBS Standard Reference Material 482

PubMed Central

Windsor, Eric S.; Carlton, Robert A.; Gillen, Greg; Wight, Scott A.; Bright, David S.

2002-01-01

Copper oxide has been detected in the copper containing alloys of NBS Standard Reference Material (SRM) 482. This occurrence is significant because it represents heterogeneity within a standard reference material that was certified to be homogeneous on a micrometer scale. Oxide occurs as elliptically to spherically shaped precipitates whose size differs with alloy composition. The largest precipitates occur in the Au20-Cu80 alloy and range in size from submicrometer up to 2 μm in diameter. Precipitates are observed using light microscopy, electron microscopy, and secondary ion mass spectrometry (SIMS). SIMS has demonstrated that the precipitates are present within all the SRM 482 wires that contain copper. Only the pure gold wire is precipitate free. Initial results from the analysis of the Au20-Cu80 alloy indicate that the percentage of precipitates is less than 1 % by area. Electron probe microanalysis (EPMA) of large (2 μm) precipitates in this same alloy indicates that precipitates are detectable by EPMA and that their composition differs significantly from the certified alloy composition. The small size and low percentage of these oxide precipitates minimizes the impact that they have upon the intended use of this standard for electron probe microanalysis. Heterogeneity caused by these oxide precipitates may however preclude the use of this standard for automated EPMA analyses and other microanalysis techniques. PMID:27446759

A facile arrested precipitation method for synthesis of pure wurtzite Cu{sub 2}ZnSnS{sub 4} nanocrystals using thiourea as a sulfur source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chunya; Key Laboratory of Analytical Chemistry of the State Ethnic Affairs Commission, College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074; Ha, Enna

2012-11-15

Graphical abstract: High-resolution TEM image of wurtzite Cu{sub 2}ZnSnS{sub 4} nanocrystals. Highlights: ► Wurtzite Cu{sub 2}ZnSnS{sub 4} nanocrystals were synthesized by arrested precipitation method. ► XRD, EDX, TEM demonstrate that the CZTS nanocrystals are purely wurtzite structure. ► The average diameter of the bulk CZTS products is found to be 10 ± 1.1 nm. ► The estimated direct bandgap energy is 1.56 eV for wurtzite CZTS nanocrystals. ► The electrical resistivity of the wurtzite CZTS nanocrystals is low. -- Abstract: A facile route for the synthesis of wurtzite Cu{sub 2}ZnSnS{sub 4} (CZTS) nanocrystals was developed by an arrested precipitation methodmore » at 240 °C under simple reaction conditions with diethanolamine as the solvent and thiourea as sulfur source. The structure and morphology of the CZTS nanocrystals were characterized by X-ray diffraction and transmission electron microscopy. Control experiments demonstrated that CZTS nanocrystals which are purely wurtzite structure are readily obtained. The average diameter of the bulk CZTS products is found to be 10 ± 1.1 nm. The estimated direct bandgap energy is 1.56 eV, which indicates that the CZTS nanocrystals produced by this method possess promising applications in photovoltaic devices.« less

Method of producing .sup.67 Cu

DOEpatents

O'Brien, Jr., Harold A.; Barnes, John W.; Taylor, Wayne A.; Thomas, Kenneth E.; Bentley, Glenn E.

1984-01-01

A method of producing carrier-free .sup.67 Cu by proton spallation combined with subsequent chemical separation and purification is disclosed. A target consisting essentially of pressed zinc oxide is irradiated with a high energy, high current proton beam to produce a variety of spallogenic nuclides, including .sup.67 Cu and other copper isotopes. The irradiated target is dissolved in a concentrated acid solution to which a palladium salt is added. In accordance with the preferred method, the spallogenic copper is twice coprecipitated with palladium, once with metallic zinc as the precipitating agent and once with hydrogen sulfide as the precipitating agent. The palladium/copper precipitate is then dissolved in an acid solution and the copper is separated from the palladium by liquid chromatography on an anion exchange resin.

Method for producing /sup 67/Cu

DOEpatents

O'Brien, H.A. Jr.; Barnes, J.W.; Taylor, W.A.; Thomas, K.E.; Bentley, G.E.

A method of producing carrier-free /sup 67/Cu by proton spallation combined with subsequent chemical separation and purification is disclosed. A target consisting essentially of pressed zinc oxide is irradiated with a high energy, high current proton beam to produce a variety of spallogenic nuclides, including /sup 67/Cu and other copper isotopes. The irradiated target is dissolved in a concentrated acid solution to which a palladium salt is added. In accordance with the preferred method, the spallogenic copper is twice coprecipitated with palladium, once with metallic zinc as the precipitating agent and once with hydrogen sulfide as the precipitating agent. The palladium/copper precipitate is then dissolved in an acid solution and the copper is separated from the palladium by liquid chromatography on an anion exchange resin.

Exposure to Ambient Ultrafine Particles and Nitrogen Dioxide and Incident Hypertension and Diabetes.

PubMed

Bai, Li; Chen, Hong; Hatzopoulou, Marianne; Jerrett, Michael; Kwong, Jeffrey C; Burnett, Richard T; van Donkelaar, Aaron; Copes, Ray; Martin, Randall V; Van Ryswyk, Keith; Lu, Hong; Kopp, Alexander; Weichenthal, Scott

2018-05-01

Previous studies reported that long-term exposure to traffic-related air pollution may increase the incidence of hypertension and diabetes. However, little is known about the associations of ultrafine particles (≤0.1 μm in diameter) with these two conditions. We conducted a population-based cohort study to investigate the associations between exposures to ultrafine particles and nitrogen dioxide (NO2) and the incidence of diabetes and hypertension. Our study population included all Canadian-born residents aged 30 to 100 years who lived in the City of Toronto, Canada, from 1996 to 2012. Outcomes were ascertained using validated province-wide databases. We estimated annual concentrations of ultrafine particles and NO2 using land-use regression models and assigned these estimates to participants' annual postal code addresses during the follow-up period. Using random-effects Cox proportional hazards models, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for ultrafine particles and NO2, adjusted for individual- and neighborhood-level covariates. We considered both single- and multipollutant models. Each interquartile change in exposure to ultrafine particles was associated with increased risk of incident hypertension (HR = 1.03; 95% CI = 1.02, 1.04) and diabetes (HR = 1.06; 95% CI = 1.05, 1.08) after adjusting for all covariates. These results remained unaltered with further control for fine particulate matter (≤2.5 μm; PM2.5) and NO2. Similarly, NO2 was positively associated with incident diabetes (HR = 1.06; 95% CI = 1.05, 1.07) after controlling for ultrafine particles and PM2.5. Exposure to traffic-related air pollution including ultrafine particles and NO2 may increase the risk for incident hypertension and diabetes. See video abstract at, http://links.lww.com/EDE/B337.

Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

PubMed Central

Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

2015-01-01

In this research, we assessed the influence of an ultrafine 2CaO·SiO2 powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO2. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO2 powder has the potential to improve the performance of a reactive powder cementitious system. PMID:28793560

The occurrence of ultrafine particles in the specific environment of children.

PubMed

Burtscher, Heinz; Schüepp, Karen

2012-06-01

Interest in ultrafine particles (UFP) has been increasing due to their specific physico-chemical characteristics. Ultrafine particles are those with an aerodynamic diameter of <0.1 μm and are also commonly know as nanoparticles (0.1 μm = 100 nm). Due to their small size UFP contribute mostly to particle number concentrations and are therefore underestimated in actual pollution measurements, which commonly measure mass concentration. Children represent the most vulnerable group in regard to particulate exposure due to their developing status and different exposures compared to adults. This review discusses the sources of ultrafine particles as well as the specific exposures of children highlighting the importance and uniqueness of this age group. Copyright © 2011 Elsevier Ltd. All rights reserved.

The effect of Mn/Ni on thermodynamic properties of critical nucleus in Fe-Cu-Mn (Ni) ternary alloys

DOE PAGES

Li, Boyan; Zhang, Lei; Li, Chengliang; ...

2018-04-18

The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation resultsmore » show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.« less

The effect of Mn/Ni on thermodynamic properties of critical nucleus in Fe-Cu-Mn (Ni) ternary alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Boyan; Zhang, Lei; Li, Chengliang

The aging- or radiation-induced hardening of Cu/Mn/Ni precipitates in Fe alloys is one of property degradation mechanisms in structural materials in nuclear reactors. Experiments show that aging or radiation leads the formation of Cu-rich precipitates, and the addition of Mn or Ni elements enhances the precipitation kinetics. In this study, the phase-field model coupled with the constrained string method have been applied to investigate the thermodynamic properties of critical nuclei such as the minimum energy path of Cu/Mn/Ni precipitation in Fe-Cu-Mn and Fe-Cu-Ni ternary alloys. The chemical free energies used in the model are taken from CALPHAD. The simulation resultsmore » show that the formation of Cu/Mn/Ni clusters needs to overcome an energy barrier, and the precipitate has a Core-Shell structure. The thermodynamic properties of the critical nucleus are influenced by temperature and Cu/Mn/Ni overall concentrations, which are in accordance with the simulation results as well as the experimental observations.« less

Strong, ductile, and thermally stable Cu-based metal-intermetallic nanostructured composites.

PubMed

Dusoe, Keith J; Vijayan, Sriram; Bissell, Thomas R; Chen, Jie; Morley, Jack E; Valencia, Leopolodo; Dongare, Avinash M; Aindow, Mark; Lee, Seok-Woo

2017-01-09

Bulk metallic glasses (BMGs) and nanocrystalline metals (NMs) have been extensively investigated due to their superior strengths and elastic limits. Despite these excellent mechanical properties, low ductility at room temperature and poor microstructural stability at elevated temperatures often limit their practical applications. Thus, there is a need for a metallic material system that can overcome these performance limits of BMGs and NMs. Here, we present novel Cu-based metal-intermetallic nanostructured composites (MINCs), which exhibit high ultimate compressive strengths (over 2 GPa), high compressive failure strain (over 20%), and superior microstructural stability even at temperatures above the glass transition temperature of Cu-based BMGs. Rapid solidification produces a unique ultra-fine microstructure that contains a large volume fraction of Cu 5 Zr superlattice intermetallic compound; this contributes to the high strength and superior thermal stability. Mechanical and microstructural characterizations reveal that substantial accumulation of phase boundary sliding at metal/intermetallic interfaces accounts for the extensive ductility observed.

Ultrafine particle concentration and new particle formation in a coastal arid environment

NASA Astrophysics Data System (ADS)

Alfoldy, Balint; Kotob, Mohamed; Obbard, Jeffrey P.

2017-04-01

Arid environments can be generally characterised by high coarse aerosol load due to the wind-driven erosion of the upper earth crust (i.e. Aeolian dust). On the other hand, anthropogenic activities and/or natural processes also generate significant numbers of particles in the ultrafine size range. Ultrafine particles (also referred as nano-particles) is considered as aerosol particles with the diameter less than 100 nm irrespectively their chemical composition. Due to their small size, these particles represent negligible mass portion in the total atmospheric particulate mass budget. On the other hand, these particles represent the majority of the total particle number budget and have the major contribution in the total aerosol surface distribution. Ultrafine particles are characterised by high mobility (diffusion) and low gravitational settling velocity. Consequently, these particles can be transported long distances and their atmospheric lifetime is relatively high (i.e. in the Accumulation Mode). Ultrafine particles play important role in the atmosphere as they take part in the atmospheric chemistry (high surface), impact the climate (sulphate vs. black carbon), and implies significant health effects due to their deep lung penetration and high mobility in the body. The Atmospheric Laboratory of Qatar University is conducting real-time monitoring of ultrafine particles and regularly taking aerosol samples for chemical analysis at the university campus. In this paper, recent results are presented regarding the size distribution and chemical composition of the ultrafine aerosol particles. Based on the concentration variation in time, sources of ultrafine particles can be clearly separated from the sources of fine or coarse particles. Several cases of new particle formation events have been observed and demonstrated in the paper, however, the precursors of the secondary aerosol particles are still unknown. Literature references suggest that among the sulphuric acid

Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

PubMed

Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

2012-09-01

This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

Mechanical properties and microstructures of Al-Cu Thin films with various heat treatments

NASA Astrophysics Data System (ADS)

Joo, Young-Chang

1998-10-01

The relationship between microstructure and mechanical properties has been investigated in Al-Cu thin films. The Cu content in Al-Cu samples used in this study ranges from 0 to 2 wt.% and substrate curvature measurement was used to measure film stress. In thin films, the constraints on the film by the substrate influence the microstructure and mechanical properties. Al-Cu thin films cooled from high temperatures have a large density of dislocations due to the plastic deformation caused by the thermal mismatch between the film and substrate. The high density of dislocations in the thin film enables precipitates to form inside the grain even during a very rapid quenching. The presence of a large density of dislocations and precipitates will in turn cause precipitation hardening of the Al-Cu films. The precipitation hardening is dominant at lower temperatures, and solid solution hardening is observed at higher temperatures in the tensile regime. Pure Al films showed the same values of tensile and compressive yield stresses at a given temperature during stress-temperature cycling.

Mechanisms of ultrafine-grained austenite formation under different isochronal conditions in a cold-rolled metastable stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Celada-Casero, C., E-mail: c.celada@cenim.csic.es

The primary objective of this work is to obtain fundamental insights on phase transformations, with focus on the reaustenitization process (α′→γ transformation), of a cold-rolled (CR) semi-austenitic metastable stainless steel upon different isochronal conditions (0.1, 1, 10 and 100 °C/s). For this purpose, an exhaustive microstructural characterization has been performed by using complementary experimental such as scanning and transmission electron microscopy (SEM and TEM), electron backscattered diffraction (EBSD), electron probe microanalysis (EPMA), micro-hardness Vickers and magnetization measurements. It has been detected that all microstructural changes shift to higher temperatures as the heating rate increases. The reaustenitization occurs in two-steps formore » all heating rates, which is attributed to the chemical banding present in the CR state. The α′→γ transformation is controlled by the migration of substitutional alloying elements across the austenite/martensite (γ/α′) interface, which finally leads to ultrafine-grained reaustenitized microstructures (440–280 nm). The morphology of the martensite phase in the CR state has been found to be the responsible for such a grain refinement, along with the presence of χ-phase and nanometric Ni{sub 3}(Ti,Al) precipitates that pin the austenite grain growth, especially upon slowly heating at 0.1 °C/s. - Highlights: •Ultrafine-grained austenite structures are obtained isochronally at 0.1–100 °C/s •The α′→γ transformation occurs in two steps due to the initial chemical banding •A diffusional mechanism governs the α′→γ transformation for all heating rates •The dislocation-cell-type of martensite promotes a diffusional mechanism •Precipitates located at α′/γ interfaces hinder the austenite growth.« less

A mechanism for the production of ultrafine particles from concrete fracture.

PubMed

Jabbour, Nassib; Rohan Jayaratne, E; Johnson, Graham R; Alroe, Joel; Uhde, Erik; Salthammer, Tunga; Cravigan, Luke; Faghihi, Ehsan Majd; Kumar, Prashant; Morawska, Lidia

2017-03-01

While the crushing of concrete gives rise to large quantities of coarse dust, it is not widely recognized that this process also emits significant quantities of ultrafine particles. These particles impact not just the environments within construction activities but those in entire urban areas. The origin of these ultrafine particles is uncertain, as existing theories do not support their production by mechanical processes. We propose a hypothesis for this observation based on the volatilisation of materials at the concrete fracture interface. The results from this study confirm that mechanical methods can produce ultrafine particles (UFP) from concrete, and that the particles are volatile. The ultrafine mode was only observed during concrete fracture, producing particle size distributions with average count median diameters of 27, 39 and 49 nm for the three tested concrete samples. Further volatility measurements found that the particles were highly volatile, showing between 60 and 95% reduction in the volume fraction remaining by 125 °C. An analysis of the volatile fraction remaining found that different volatile material is responsible for the production of particles between the samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Understanding dual precipitation strengthening in ultra-high strength low carbon steel containing nano-sized copper precipitates and carbides

NASA Astrophysics Data System (ADS)

Phaniraj, M. P.; Shin, Young-Min; Jung, Woo-Sang; Kim, Man-Ho; Choi, In-Suk

2017-07-01

Low carbon ferritic steel alloyed with Ti, Mo and Cu was hot rolled and interrupt cooled to produce nano-sized precipitates of copper and (Ti,Mo)C carbides. The steel had a tensile strength of 840 MPa, an increase in yield strength of 380 MPa over that of the plain carbon steel and reasonable ductility. Transmission electron microscopy and small angle neutron scattering were used to characterize size and volume fraction of the precipitates in the steels designed to form only copper precipitates and only (Ti,Mo)C carbides. The individual and combined precipitation strengthening contributions was calculated using the size and volume fraction of precipitates and compared with the measured values.

An Atom Probe Tomographic Investigation of High-Strength, High-Toughness Precipitation Strengthened Steels for Naval Applications

NASA Astrophysics Data System (ADS)

Hunter, Allen H.

Novel high-strength high-toughness alloys strengthened by precipitation are investigated for use in naval applications. The mechanical properties of an experimental steel alloy, NUCu-140, are evaluated and are not suitable for the naval requirements due to poor impact toughness at -40°C. An investigation is conducted to determine optimum processing conditions to restore toughness. A detailed aging study is conducted at 450, 500, and 550°C to determine the evolution of the microstructure and mechanical properties. A combination of transmission electron microscopy (TEM), synchrotron X-ray Diffraction (XRD), and Local electrode atom probe (LEAP) tomography are used to measure the evolution of the Cu precipitates, austenite, NbC, and cementite phases during aging. The evolution of the Cu precipitates significantly affects the yield strength of the steel, but low temperature toughness is controlled by the cementite precipitates. Extended aging is effective at improving the impact toughness but the yield strength is also decreased due to coarsening of the Cu precipitates. To provide a foundation for successful welding of NUCu-140 steel, an investigation of the effects of gas metal arc welding (GMAW) are performed. The microstructures in the base metal (BM), heat affected zone (HAZ), and fusion zone (FZ) of a GMAW sample are analyzed to determine the effects of the welding thermal cycle. Weld simulation samples with known thermal histories are prepared and analyzed by XRD and LEAP tomography. A significant loss in microhardness is observed as a result of dissolution of the Cu precipitates after the weld thermal cycle. The cooling time is too rapid to allow significant precipitation of Cu. In addition to the NUCu-140 alloy, a production HSLA-115 steel alloy is investigated using TEM, XRD, and LEAP tomography. The strength of the HSLA-115 is found to be derived primarily from Cu precipitates. The volume fractions of cementite, austenite, and NbC are measured by XRD

Ultrafine particle and fiber production in microgravity

NASA Technical Reports Server (NTRS)

Webb, George W. (Inventor)

1988-01-01

In a system and method for producing ultrafine particles and ultrafine fibers of a given source material by evaporating and condensing the material in a gas atmosphere that includes inert gas. A smaller, more narrow size distribution is accomplished by producing the particles and fibers in a microgravity environment in order to reduce particle coalescence caused by convection currents. Particle coalescence also is reduced in an Earth gravity environment by controlling the convection currents. Condensed particles are collected either by providing an electrostatic field or a spatially varying magnetic field or by causing the gas to move through a filter which collects the particles. Nonferromagnetic material fibers are produced and collected by electrodes which produce an electro- static field. Ferromagnetic particles are collected by spatially varying magnetic fields.

Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound

PubMed Central

Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

2016-01-01

The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys. PMID:27488621

Effect of severe plastic deformation on the structure and mechanical properties of Al-Cu-Mg alloy

NASA Astrophysics Data System (ADS)

Khafizova, E.; Islamgaliev, R.

2014-08-01

Aluminum Al-Cu-Mg alloy has been subjected to high pressure torsion (HPT) and equal-channel angular pressing (ECAP) at various temperatures. An ultrafine-grained (UFG) structure thermally stable up to a temperature of 175 °C was produced in all the investigated samples. Simultaneous increase in strength and ductility has been demonstrated in an ECAPed sample in comparison with a coarse-grained sample subjected to standard treatment.

Primitive ultrafine matrix in ordinary chondrites

NASA Technical Reports Server (NTRS)

Rambaldi, E. R.; Fredriksson, B. J.; Fredriksson, K.

1981-01-01

Ultrafine matrix material has been concentrated by sieving and filtering disaggregated samples of six ordinary chondrites of different classes. This component(s), 'Holy Smoke' (HS), is enriched in both volatile, e.g. Na, K, Zn, Sb, and Pb, as well as refractory elements, e.g. W and REE; however, the element ratios vary greatly among the different chondrites. SEM studies show that HS contains fragile crystals, differing in composition, and apparently in gross disequilibrium not only among themselves but also with the major mineral phases and consequently thermodynamic equilibration did not occur. Thus HS must have originated from impacting bodies and/or was inherent in the 'primitive' regolith. Subsequent impact brecciation and reheating appears to have altered, to varying degrees, the original composition of this ultrafine matrix material. Recent 'cosmic dust' studies may indicate that HS still exists in the solar system. Survival of such delicate material must be considered in all theories for the origin of chondrites.

Developing precipitation hardenable high entropy alloys

NASA Astrophysics Data System (ADS)

Gwalani, Bharat

High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi 2 (0 < x < 1.5) complex concentrated alloys as a candidate system. The composition gradient has been achieved from CrCuFeNi2 to Al 1.5CrCuFeNi2 over a length of ˜25 mm, deposited using the laser engineered net shaping process from a blend of elemental powders. With increasing Al content, there was a gradual change from an fcc-based microstructure (including the ordered L12 phase) to a bcc-based microstructure (including the ordered B2 phase), accompanied with a progressive increase in microhardness. Based on this combinatorial assessment, two promising fcc-based precipitation strengthened systems have been identified; Al0.3CuCrFeNi2 and Al0.3CoCrFeNi, and both compositions were subsequently thermo-mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1Co

Association of particulate air pollution and acute mortality: involvement of ultrafine particles?

NASA Technical Reports Server (NTRS)

Oberdorster, G.; Gelein, R. M.; Ferin, J.; Weiss, B.; Clarkson, T. W. (Principal Investigator)

1995-01-01

Recent epidemiological studies show an association between particulate air pollution and acute mortality and morbidity down to ambient particle concentrations below 100 micrograms/m3. Whether this association also implies a causality between acute health effects and particle exposure at these low levels is unclear at this time; no mechanism is known that would explain such dramatic effects of low ambient particle concentrations. Based on results of our past and most recent inhalation studies with ultrafine particles in rats, we propose that such particles, that is, particles below approximately 50 nm in diameter, may contribute to the observed increased mortality and morbidity In the past we demonstrated that inhalation of highly insoluble particles of low intrinsic toxicity, such as TiO2, results in significantly increased pulmonary inflammatory responses when their size is in the ultrafine particle range, approximately 20 nm in diameter. However, these effects were not of an acute nature and occurred only after prolonged inhalation exposure of the aggregated ultrafine particles at concentrations in the milligrams per cubic meter range. In contrast, in the course of our most recent studies with thermodegradation products of polytetrafluoroethylene (PTFE) we found that freshly generated PTFE fumes containing singlet ultrafine particles (median diameter 26 nm) were highly toxic to rats at inhaled concentrations of 0.7-1.0 x 10(6) particles/cm3, resulting in acute hemorrhagic pulmonary inflammation and death after 10-30 min of exposure. We also found that work performance of the rats in a running wheel was severely affected by PTFE fume exposure. These results confirm reports from other laboratories of the highly toxic nature of PTFE fumes, which cannot be attributed to gas-phase components of these fumes such as HF, carbonylfluoride, or perfluoroisobutylene, or to reactive radicals. The calculated mass concentration of the inhaled ultrafine PTFE particles in our

Effective removal of coordinated copper from wastewater using a new dithiocarbamate-type supramolecular heavy metal precipitant.

PubMed

Fu, Fenglian; Zeng, Haiyan; Cai, Qinhong; Qiu, Rongliang; Yu, Jimmy; Xiong, Ya

2007-11-01

A new dithiocarbamate-type heavy metal precipitant, sodium 1,3,5-hexahydrotriazinedithiocarbamate (HTDC), was prepared and used to remove coordinated copper from wastewater. In the reported dithiocarbamate-type precipitants, HTDC possesses the highest percentage of the effective functional groups. It could effectively precipitate copper to less than 0.5mgl(-1) from both synthetic and actual industrial wastewater containing CuEDTA in the range of pH 3-9. UV-vis spectral investigation and elemental analysis suggested that the precipitate was a kind of coordination supramolecular compound, [Cu(3)(HTDC)(2)](n). The toxicity characteristic leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) indicated that the supramolecular precipitate was non-hazardous and stable in weak acid and alkaline conditions. Tests of an anion exchange resin D231 provided a clue to simultaneously remove excess HTDC and residual CuEDTA in practical process of wastewater treatment.

Mechanical Properties of Cu-Cr-Nb Alloys

NASA Technical Reports Server (NTRS)

Ellis, David L.

1997-01-01

The chemical compositions of the alloys are listed. The alloying levels were near the values for stochiometric Cr2Nb. A slight excess of Cr was chosen for increased hydrogen embrittlement resistance. The microstructures of all Cu-Cr-Nb alloys were very similar. Two typical transmission electron microscope (TEM) micrographs are presented. The images show the presence of large mount of Cr2Nb precipitates in a nearly pure Cu matrix. The interactions between dislocations and precipitates are currently under investigations, but as the images demonstrates, the extremely fine (less then 15 nm) Cr2Nb are the primary strengtheners for the alloy.

Corrosion characteristics of alpha-Ti and Ti2Cu composing Ti-Cu alloys.

PubMed

Takada, Yukyo; Okuno, Osamu

2005-12-01

A series of binary Ti-Cu alloys containing 5-20 mass% Cu was prepared, and the corrosion behavior of alpha-Ti and Ti2Cu composing the Ti-Cu alloys were examined based on the anodic polarization curves and released ions in 0.9% NaCl and 1% lactic acid solutions. In both solutions, the Ti-Cu alloys showed the same anodic polarization curves as titanium in the condition below 1.4 V. However, precipitation of Ti2Cu contributed to a small increase in current densitiy in the transpassive region beyond 1.4 V. The amount of Cu ions released from Ti2Cu was 0.260 and 1.003 (microg/cm2/7 days) in 0.9% NaCl and 1% lactic acid solutions respectively. Although these values were larger than those from alpha-Ti (0.0379 +/- 0.0041 and 0.0962 +/- 0.0327 (microg/cm2/7days) in NaCl and lactic acid solutions respectively), they were not greater than those from type 4 gold alloy under the same conditions.

Effects of Small Addition of Ti on Strength and Microstructure of a Cu-Ni-Si Alloy

NASA Astrophysics Data System (ADS)

Watanabe, Chihiro; Takeshita, Satoshi; Monzen, Ryoichi

2015-06-01

The effect of addition of 0.04 or 0.2 mass pct Ti on the mechanical properties of a Cu-2.0 mass pct Ni-0.5 mass pct Si alloy has been investigated. The addition of 0.04 mass pct Ti enhances the strength of the Cu-Ni-Si alloy without reducing its electrical conductivity. This increase in strength is caused by the decrease in inter-precipitate spacing of δ-Ni2Si precipitates. The addition of trace Ti reduces the equilibrium concentration of Ni and Si atoms in the alloy bearing the δ precipitates, resulting in an increase in the volume fraction of δ precipitates and decrease in the inter-precipitate spacing. However, the addition of 0.2 mass pct Ti to the Cu-Ni-Si alloy decreases the strength of the alloy. The reduction in strength is attributed to the decrease in the volume fraction of δ precipitates caused by the reduction in Ni and Si atoms in the Cu matrix resulting from the formation of Ni16Si7Ti6 particles.

Li-atoms-induced structure changes of Guinier–Preston–Bagaryatsky zones in AlCuLiMg alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, S.Y.; Le, Z.; Chen, Z.K.

2016-11-15

Guinier–Preston–Bagaryatsky (GPB) zones are the well-known strengthening precipitates of AlCuMg alloys formed upon thermal ageing. Here we report that when formed in AlCuLiMg alloys the GPB zones can change significantly in morphology and structure. It is shown that though they do still consist of Al, Cu and Mg elements fundamentally, the GPB zones in AlCuLiMg alloys have a rather different structure due to a featured Li-segregation at their interfaces with the matrix and possible Li-replacement of partial Mg atoms in the structure. As such the Li-containing GPB zones often develop from one-dimensional to quasi-two-dimensional precipitates. - Highlights: • We observemore » Guinier–Preston–Bagaryatsky zone variants in AlCuLiMg alloys. • We obtain atomic-resolution images of the precipitates and model their structures. • Li-atoms play a key role in modifying the structure of these precipitate variants.« less

Multi-component Cu-Strengthened Steel Welding Simulations: Atom Probe Tomography and Synchrotron X-ray Diffraction Analyses

NASA Astrophysics Data System (ADS)

Hunter, Allen H.; Farren, Jeffrey D.; DuPont, John N.; Seidman, David N.

2015-07-01

An experimental steel with the composition Fe-1.39Cu-2.70Ni-0.58Al-0.48Mn-0.48Si-0.065Nb-0.05C (wt pct) or alternatively Fe-1.43Cu-2.61Ni-1.21Al-0.48Mn-0.98Si-0.039Nb-0.23C (at. pct) has been developed at Northwestern University, which has both high toughness and high strength after quenching and aging treatments. Simulated heat-affected zone (HAZ) samples are utilized to analyze the microstructures typically obtained after gas metal arc welding (GMAW). Dissolution within the HAZ of cementite (Fe3C) and NbC (F.C.C.) is revealed using synchrotron X-ray diffraction, while dissolution of Cu precipitates is measured employing local electrode atom probe tomography. The results are compared to Thermo-Calc equilibrium calculations. Comparison of measured Cu precipitate radii, number density, and volume fraction with similar measurements from a GMAW sample suggests that the cooling rate in the simulations is faster than in the experimental GMAW sample, resulting in significantly less Cu precipitate nucleation and growth during the cooling part of the weld thermal cycle. The few Cu precipitates detected in the simulated samples are primarily located on grain boundaries resulting from heterogeneous nucleation. The dissolution of NbC precipitates and the resultant austenite coarsening in the highest-temperature sample, coupled with a rapid cooling rate, results in the growth of bainite, and an increase in the strength of the matrix in the absence of significant Cu precipitation.

Cellular response of preosteoblasts to nanograined/ultrafine-grained structures.

PubMed

Misra, R D K; Thein-Han, W W; Pesacreta, T C; Hasenstein, K H; Somani, M C; Karjalainen, L P

2009-06-01

Metallic materials with submicron- to nanometer-sized grains provide surfaces that are different from conventional polycrystalline materials because of the large proportion of grain boundaries with high free energy. In the study described here, the combination of cellular and molecular biology, materials science and engineering advances our understanding of cell-substrate interactions, especially the cellular activity between preosteoblasts and nanostructured metallic surfaces. Experiments on the effect of nano-/ultrafine grains have shown that cell attachment, proliferation, viability, morphology and spread are favorably modulated and significantly different from conventional coarse-grained structures. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions on nanograined/ultrafine-grained substrate. These observations suggest enhanced cell-substrate interaction and activity. The differences in the cellular response on nanograined/ultrafine-grained and coarse-grained substrates are attributed to grain size and degree of hydrophilicity. The outcomes of the study are expected to reduce challenges to engineer bulk nanostructured materials with specific physical and surface properties for medical devices with improved cellular attachment and response. The data lay the foundation for a new branch of nanostructured materials for biomedical applications.

High-temperature in-situ TEM straining of the interaction with dislocations and particles for Cu-added ferritic stainless steel.

PubMed

Kobayashi, Shuhei; Kaneko, Kenji; Yamada, Kazuhiro; Kikuchi, Masao; Kanno, Norihiro; Hamada, Junichi

2014-11-01

IntroductionCu is always present in the matrix when ferritic steels were prepared from ferrous scrap. When the ferritic steels are aged thermally, Cu precipitates start appear and disperse finely and homogeneously [1], which may make the steels strengthened by precipitation hardening. In this study, the interaction between Cu precipitates and dislocations was exmined via high-temperature in-situ TEM straining. ExperimentalCu-added ferritic stainless steel (Fe-18.4%Cr-1.5%Cu) was used in the present study. Specimen was aged at1073 K for 360 ks. Samples for TEM observation were prepared by focused ion beam (FIB; Quanta 3D 200i) method. Microstructure of specimen was analyzed by JEM-3200FSK and high-temperature in-situ TEM straining was conducted using JEM-1300NEF. Results and discussionInteraction between Cu precipitates and dislocation is seen from consecutive TEM images acquired by in-situ TEM straining at 1073 K, as shown in Fig.1. The size of Cu precipitates was about 70 nm and several dislocations were present within the field of view. In particular, progressing dislocations contacted with the Cu precipitate at right angle, as indicated by arrows in Fig.1 (b) to (d). This result implies that there is an attractive interaction between dislocations and the Cu precipitate. This is attributed to the fact that Stress field of dislocations was easily relaxed in interface between the Cu precipitate and matrix because of lattice and interface diffusion as well as slip in the interface [2,3]. Furthermore, dislocations pass through the particle after contacting it, so that the interaction with dislocations and particles should be explained by Srolovitz mechanism [4].jmicro;63/suppl_1/i28/DFU083F1F1DFU083F1Fig. 1.TEM images foucused on interaction with dislocations and partticles. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Precipitation hardening behaviour of Al-Mg-Si alloy processed by cryorolling and room temperature rolling

NASA Astrophysics Data System (ADS)

Hussain, Maruff; Nageswara rao, P.; Singh, Dharmendra; Jayaganthan, R.

2018-04-01

The precipitation hardenable aluminium alloy (Al-Mg-Si) plates were solutionized and subjected to rolling at room temperature and liquid nitrogen temperature (RTR, CR) up to a true strain of ∼2.7. The rolled sheets were uniformly aged at room temperature and above room temperature (125 °C) to induce precipitation. The rolled and aged samples were analysed using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), hardness and tensile tests. The strength and ductility were simultaneously improved after controlled ageing of the cryorolled (CR) and room temperature rolled (RTR) samples. However, the increment in strength is more in RTR material than CR material with same ductility. Transmission electron microscopy analysis revealed the formation of ultrafine grains (UFG) filled with dislocations and nanosized precipitates in the CR and RTR conditions after ageing treatment. The behaviour of CR and RTR alloy is same under natural ageing conditions.

Application of precipitation methods for the production of water-insoluble drug nanocrystals: production techniques and stability of nanocrystals.

PubMed

Xia, Dengning; Gan, Yong; Cui, Fude

2014-01-01

This review focuses on using precipitation (bottom-up) method to produce water-insoluble drug nanocrystals, and the stability issues of nanocrystals. The precipitation techniques for production of ultra-fine particles have been widely researched for last few decades. In these techniques, precipitation of solute is achieved by addition of a non-solvent for solute called anti-solvent to decrease the solvent power for the solute dissolved in a solution. The anti-solvent can be water, organic solvents or supercritical fluids. In this paper, efforts have been made to review the precipitation techniques involving the anti-solvent precipitation by simple mixing, impinging jet mixing, multi-inlet vortex mixing, the using of high-gravity, ultrasonic waves and supercritical fluids. The key to the success of yielding stable nanocrystals in these techniques is to control the nucleation kinetics and particle growth through mixing during precipitation based on crystallization theories. The stability issues of the nanocrystals, such as sedimentation, Ostwald ripening, agglomeration and cementing of crystals, change of crystalline state, and the approaches to stabilizing nanocrystals are also discussed in detail.

Effect of Nb and Cu on the high temperature creep properties of a high Mn–N austenitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Kyu-Ho, E-mail: kyuhos@korea.ac.kr; Department of Materials Science and Engineering, Korea University, Seoul 136-713; Suh, Jin-Yoo, E-mail: jinyoo@kist.re.kr

2013-09-15

The effect of Nb and Cu addition on the creep properties of a high Mn–N austenitic stainless steel was investigated at 600 and 650 °C. In the original high Mn–N steel, which was initially precipitate-free, the precipitation of M{sub 23}C{sub 6} (M = Cr, Fe) and Cr{sub 2}N took place mostly on grain boudaries during creep deformation. On the other hand, the minor addition of Nb resulted in high number density of Z-phases (CrNbN) and MX (M = Nb; X = C, N) carbonitrides inside grains by combining with a high content of N, while suppressing the formation of Cr{submore » 2}N. The addition of Cu gave rise to the independent precipitation of nanometer-sized metallic Cu particles. The combination of the different precipitate-forming mechanisms associated with Z-phase, MX and Cu-rich precipitates turned out to improve the creep-resistance significantly. The thermodynamics and kinetics of the precipitation were discussed using thermo-kinetic simulations. - Highlights: • The creep rupture life was improved by Nb and Cu addition. • The creep resistance of the steel A2 in this study was comparable to that of TP347HFG. • The size of Z-phase and MX carbonitride did not change significantly after creep test. • The nanometer sized Cu-rich precipitate was observed after creep. • The predicted size of precipitates by MatCalc agreed well with measured size.« less

Ultrafine particle measurement and related EPA research studies

EPA Science Inventory

Webinar slides to present information on measuring ultrafine particles at the request of the 2013 MARAMA Monitoring Committee. The talk covers near-road monitoring, instrument intercomparison, and general overview of UFP monitoring technology.

Ultra-fine grained microstructure of metastable beta Ti-15Mo alloy and its effects on the phase transformations

NASA Astrophysics Data System (ADS)

Václavová, K.; Stráský, J.; Zháňal, P.; Veselý, J.; Polyakova, V.; Semenova, I.; Janeček, M.

2017-05-01

Processing of metastable titanium alloys by severe plastic deformation provides an opportunity to achieve exceptional grain refinement, to enhance the strength and to affect phase transformations occurring during thermal treatment. The main aim of this study is to investigate the microstructure of ultra-fine grained (UFG) material and effect of microstructural changes on phase transformations in metastable β-Ti alloy Ti-15Mo. Metastable β-Ti alloys are currently the most studied Ti-based materials with prospective use in medicine. Ti-15Mo alloy after solution treatment contains metastable β-phase. Metastable ω-phase and stable α-phase particles are formed upon annealing,. Solution treated Ti-15Mo alloy was deformed by high pressure torsion (HPT) at room temperature. Severely deformed structure after HPT with grain size of ~200 nm was studied by transmission electron microscopy. In-situ electrical resistance measurements showed significant changes in undergoing phase transformations when compared to coarse-grained (CG) material. Scanning electron microscopy revealed heterogeneous precipitation of α-particles at grain boundaries (GB). Due to the high density of GBs in UFG structure, these precipitates are very fine and equiaxed. The study demonstrates that SPD is capable of enhancing mechanical properties due to grain refinement and via affecting precipitation processes in metastable β-Ti alloys.

Determinants of personal exposure to PM2.5, ultrafine particle counts, and CO in a transport microenvironment.

PubMed

Kaur, S; Nieuwenhuijsen, M J

2009-07-01

Short-term human exposure concentrations to PM2.5, ultrafine particle counts (particle range: 0.02-1 microm), and carbon monoxide (CO) were investigated at and around a street canyon intersection in Central London, UK. During a four week field campaign, groups of four volunteers collected samples at three timings (morning, lunch, and afternoon), along two different routes (a heavily trafficked route and a backstreet route) via five modes of transport (walking, cycling, bus, car, and taxi). This was followed by an investigation into the determinants of exposure using a regression technique which incorporated the site-specific traffic counts, meteorological variables (wind speed and temperature) and the mode of transport used. The analyses explained 9, 62, and 43% of the variability observed in the exposure concentrations to PM2.5, ultrafine particle counts, and CO in this study, respectively. The mode of transport was a statistically significant determinant of personal exposure to PM2.5, ultrafine particle counts, and CO, and for PM2.5 and ultrafine particle counts it was the most important determinant. Traffic count explained little of the variability in the PM2.5 concentrations, but it had a greater influence on ultrafine particle count and CO concentrations. The analyses showed that temperature had a statistically significant impact on ultrafine particle count and CO concentrations. Wind speed also had a statistically significant effect but smaller. The small proportion in variability explained in PM2.5 by the model compared to the largest proportion in ultrafine particle counts and CO may be due to the effect of long-range transboundary sources, whereas for ultrafine particle counts and CO, local traffic is the main source.

Ultrafine particulate matter impairs mitochondrial redox homeostasis and activates phosphatidylinositol 3-kinase mediated DNA damage responses in lymphocytes.

PubMed

Bhargava, Arpit; Tamrakar, Shivani; Aglawe, Aniket; Lad, Harsha; Srivastava, Rupesh Kumar; Mishra, Dinesh Kumar; Tiwari, Rajnarayan; Chaudhury, Koel; Goryacheva, Irina Yu; Mishra, Pradyumna Kumar

2018-03-01

Particulate matter (PM), broadly defined as coarse (2.5-10 μm), fine (0.1-2.5 μm) and ultrafine particles (≤0.1 μm), is a major constituent of ambient air pollution. Recent studies have linked PM exposure (coarse and fine particles) with several human diseases including cancer. However, the molecular mechanisms underlying ultrafine PM exposure induced cellular and sub-cellular repercussions are ill-defined. Since mitochondria are one of the major targets of different environmental pollutants, we herein aimed to understand the molecular repercussion of ultrafine PM exposure on mitochondrial machinery in peripheral blood lymphocytes. Upon comparative analysis, a significantly higher DCF fluorescence was observed in ultrafine PM exposed cells that confirmed the strong pro-oxidant nature of these particles. In addition, the depleted activity of antioxidant enzymes, glutathione reductase and superoxide dismutase suggested the strong association of ultrafine PM with oxidative stress. These results further coincided with mitochondrial membrane depolarization, altered mitochondrial respiratory chain enzyme activity and decline in mtDNA copy number. Moreover, the higher accumulation of DNA damage response proteins (γH2AX, pATM, p-p53), suggested that exposure to ultrafine PM induces DNA damage and triggers phosphatidylinositol 3 kinase mediated response pathway. Further, the alterations in mitochondrial machinery and redox balance among ultrafine PM exposed cells were accompanied by a considerably elevated pro-inflammatory cytokine response. Interestingly, the lower apoptosis levels observed in ultrafine particle treated cells suggest the possibility that the marked alterations may lead to the impairment of mitochondrial-nuclear cross talk. Together, our results showed that ultrafine PM, because of their smaller size possesses significant ability to disturb mitochondrial redox homeostasis and activates phosphatidylinositol 3 kinase mediated DNA damage response

Ultrafine Condensation Particle Counter Instrument Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuang, C.

2016-02-01

The Model 3776 Ultrafine Condensation Particle Counter (UCPC; pictured in Appendix A) is designed for researchers interested in airborne particles smaller than 20 nm. With sensitivity to particles down to 2.5 nm in diameter, this UCPC is ideally suited for atmospheric and climate research, particle formation and growth studies, combustion and engine exhaust research, and nanotechnology research.

Effect of γ-IRRADIATION on the Mechanical Properties of Al-Cu Alloy

NASA Astrophysics Data System (ADS)

Abo-Elsoud, M.; Ismail, H.; Sobhy, Maged S.

SEM observations and Vickers hardness tests were performed to identify the irradiation effects. γ-irradiation effect during the aging hardening process can be explained depending on the composition of the alloy and is used to derive quantitative information on the kinetics of the transformation precipitates. Increasing the Cu content of an Al-Cu alloy can improve the aging hardness. The present results of the hardness behavior, with SEM observations of surveillance specimens at different doses, suggest that the radiation-induced defects are probably complex valence-solute clusters. These clusters act as nuclei for the precipitation of θ-Al2Cu type. This can be effectively utilized to study the systematics of nucleation of precipitates at vacancy-type defects. γ-irradiation probably plays the key role in defects responsible for material strengthening and embrittlement.

Personal exposure to ultrafine particles from PVC welding and concrete work during tunnel rehabilitation.

PubMed

Jørgensen, Rikke Bramming; Buhagen, Morten; Føreland, Solveig

2016-07-01

To investigate the exposure to number concentration of ultrafine particles and the size distribution in the breathing zone of workers during rehabilitation of a subsea tunnel. Personal exposure was measured using a TSI 3091 Fast Mobility Particle Sizer (FMPS), measuring the number concentration of submicrometre particles (including ultrafine particles) and the particle size distribution in the size range 5.6-560 nm. The measurements were performed in the breathing zone of the operators by the use of a conductive silicone tubing. Working tasks studied were operation of the slipforming machine, operations related to finishing the verge, and welding the PVC membrane. In addition, background levels were measured. Arithmetic mean values of ultrafine particles were in the range 6.26×10(5)-3.34×10(6). Vertical PVC welding gave the highest exposure. Horizontal welding was the work task with the highest maximum peak exposure, 8.1×10(7) particles/cm(3). Background concentrations of 4.0×10(4)-3.1×10(5) were found in the tunnel. The mobility diameter at peak particle concentration varied between 10.8 nm during horizontal PVC welding and during breaks and 60.4 nm while finishing the verge. PVC welding in a vertical position resulted in very high exposure of the worker to ultrafine particles compared to other types of work tasks. In evaluations of worker exposure to ultrafine particles, it seems important to distinguish between personal samples taken in the breathing zone of the worker and more stationary work area measurements. There is a need for a portable particle-sizing instrument for measurements of ultrafine particles in working environments. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Size resolved ultrafine particles emission model--a continues size distribution approach.

PubMed

Nikolova, Irina; Janssen, Stijn; Vrancken, Karl; Vos, Peter; Mishra, Vinit; Berghmans, Patrick

2011-08-15

A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving. The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E+14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found. For the size distributions it is found that the measured distributions consist of three modes--Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.04-0.05 μm) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed. Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected. The UFPEM emission model can be used as a source term in dispersion models. Copyright © 2011 Elsevier B.V. All rights reserved.

Comparison of corrosion behavior between coarse grained and nano/ultrafine grained alloy 690

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Ting, Guo

2016-01-01

The effect of grain refinement on corrosion resistance of alloy 690 was investigated. The electron work function value of coarse grained alloy 690 was higher than that of nano/ultrafine grained one. The grain refinement reduced the electron work function of alloy 690. The passive films formed on coarse grained and nano/ultrafine grained alloy 690 in borate buffer solution were studied by potentiodynamic curves and electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results showed that the grain refinement improved corrosion resistance of alloy 690. This was attributed to the fact that grain refinement promoted the enrichment of Cr2O3 and inhibited Cr(OH)3 in the passive film. More Cr2O3 in passive film could significantly improve the corrosion resistance of the nano/ultrafine grained alloy 690.

Synthesis and reactivity of ultra-fine coal liquefaction catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linehan, J.C.; Matson, D.W.; Fulton, J.L.

1992-10-01

The Pacific Northwest Laboratory is currently developing ultra-fine iron-based coal liquefaction catalysts using two new particle production technologies: (1) modified reverse micelles (MRM) and (2) rapid thermal decomposition of solutes (RTDS). These methodologies have been shown to allow control over both particle size (from 1 nm to 60 nm) and composition when used to produce ultra-fine iron-based materials. Powders produced using these methods are found to be selective catalysts for carbon-carbon bond scission using the naphthyl bibenzylmethane model compound, and to promote the production of THF soluble coal products during liquefaction studies. This report describes the materials produced by bothmore » MRM and the RTDS methods and summarizes the results of preliminary catalysis studies using these materials.« less

Structure and Growth of Rod-Shaped Mn Ultrafine Particle

NASA Astrophysics Data System (ADS)

Kido, Osamu; Suzuki, Hitoshi; Saito, Yoshio; Kaito, Chihiro

2003-09-01

The structure of rod-shaped Mn ultrafine particles was elucidated by electron microscopy. Mn ultrafine particles have characteristic tristetrahedron (α-Mn), rhombic dodecahedron (β-Mn) and rod-shape crystal habits. It was found that the rod-shaped particle resulted from the parallel coalescence of β-Mn particles with the size of 50 nm. Detailed analysis of the defects seen in large rod-shaped particles with the width of 100 nm indicated a mixture of α- and β-phases. A size effect on the phase transition from β to α was observed throughout the rod-shaped crystal structure. The structure and growth of Mn particles were discussed based on the outline of the smoke and the temperature distribution in the smoke.

Effect of ultrafine zinc oxide (ZnO) nanoparticles on induction of oral tolerance in mice.

PubMed

Matsumura, Misa; Takasu, Nobuo; Nagata, Masafumi; Nakamura, Kazuichi; Kawai, Motoyuki; Yoshino, Shin

2010-01-01

Ultrafine nanoparticles of zinc oxide (ZnO) recently became available as a substitute for larger-size fine ZnO particles. However, the biological activity of ultrafine ZnO currently remains undefined. In the present study, we investigated the effect of ultrafine ZnO on oral tolerance that plays an important role in the prevention of food allergy. Oral tolerance was induced in mice by a single oral administration (i.e., gavage) of 25 mg of ovalbumin (OVA) 5 days prior to a subcutaneous immunization with OVA (Day 0). Varying doses of ultrafine (diameter: approximately 21 nm) as well as fine (diameter: < 5 microm) ZnO particles were given orally at the same time during the OVA gavage. The results indicated that a single oral administration of OVA was followed by significant decreases in serum anti-OVA IgG, IgG(1), IgG(2a), and IgE antibodies and in the proliferative responses to the antigen by these hosts' spleen cells. The decreases in these immune responses to OVA were associated with a marked suppression of secretion of interferon (IFN)gamma, interleukin (IL)-5, and IL-17 by these lymphoid cells. Treatment with either ultrafine or fine ZnO failed to affect the oral OVA-induced suppression of antigen-specific IgG, IgG(1), IgG(2a), and IgE production or lymphoid cell proliferation. The suppression induced by the oral OVA upon secretion of IFN gamma, IL-5, and IL-17 was also unaffected by either size of ZnO. These results indicate that ultrafine particles of ZnO do not appear to modulate the induction of oral tolerance in mice.

Effect of Cu concentration on morphology of Sn-Ag-Cu solders by mechanical alloying

NASA Astrophysics Data System (ADS)

Kao, Szu-Tsung; Duh, Jenq-Gong

2004-12-01

The mechanical alloying (MA) process is considered an alternative approach to produce solder materials. In this study, the effect of Cu concentration in the ternary Sn-3.5Ag-xCu (x=0.2, 0.7, and 1) solder by MA was investigated. The (Cu,Sn) solid solution was precipitated as the Cu6Sn5 intermetallic compound (IMC), which was distributed nonuniformly through the microstructure. The Cu6Sn5 IMC, which was present in the SnAgCu solder with high Cu composition, causes the as-milled MA particle to fracture to a smaller size. Appreciable distinction on morphology of as-milled MA powders with different Cu content was revealed. When the Cu concentration was low (x=0.2), MA particle aggregated to a spherical ingot with large particle size. For higher Cu concentration (x=0.7 and x=1), the MA particle turned to flakes with smaller particle size. The distinction of the milling mechanism of Sn-3.5Ag-xCu (x=0.2, 0.7, and 1) solder by the MA process was discussed. An effective approach was developed to reduce the particle size of the SnAgCu solder from 1 mm down to 10-100 µm by doping the Cu6Sn5 nanoparticle during the MA process. In addition, the differential scanning calorimetry (DSC) results also ensure the compatibility to apply the solder material for the reflow process.

Association Between Short-term Exposure to Ultrafine Particles and Mortality in Eight European Urban Areas.

PubMed

Stafoggia, Massimo; Schneider, Alexandra; Cyrys, Josef; Samoli, Evangelia; Andersen, Zorana Jovanovic; Bedada, Getahun Bero; Bellander, Tom; Cattani, Giorgio; Eleftheriadis, Konstantinos; Faustini, Annunziata; Hoffmann, Barbara; Jacquemin, Bénédicte; Katsouyanni, Klea; Massling, Andreas; Pekkanen, Juha; Perez, Noemi; Peters, Annette; Quass, Ulrich; Yli-Tuomi, Tarja; Forastiere, Francesco

2017-03-01

Epidemiologic evidence on the association between short-term exposure to ultrafine particles and mortality is weak, due to the lack of routine measurements of these particles and standardized multicenter studies. We investigated the relationship between ultrafine particles and particulate matter (PM) and daily mortality in eight European urban areas. We collected daily data on nonaccidental and cardiorespiratory mortality, particle number concentrations (as proxy for ultrafine particle number concentration), fine and coarse PM, gases and meteorologic parameters in eight urban areas of Finland, Sweden, Denmark, Germany, Italy, Spain, and Greece, between 1999 and 2013. We applied city-specific time-series Poisson regression models and pooled them with random-effects meta-analysis. We estimated a weak, delayed association between particle number concentration and nonaccidental mortality, with mortality increasing by approximately 0.35% per 10,000 particles/cm increases in particle number concentration occurring 5 to 7 days before death. A similar pattern was found for cause-specific mortality. Estimates decreased after adjustment for fine particles (PM2.5) or nitrogen dioxide (NO2). The stronger association found between particle number concentration and mortality in the warmer season (1.14% increase) became null after adjustment for other pollutants. We found weak evidence of an association between daily ultrafine particles and mortality. Further studies are required with standardized protocols for ultrafine particle data collection in multiple European cities over extended study periods.

Traffic emission factors of ultrafine particles: effects from ambient air.

PubMed

Janhäll, Sara; Molnar, Peter; Hallquist, Mattias

2012-09-01

Ultrafine particles have a significant detrimental effect on both human health and climate. In order to abate this problem, it is necessary to identify the sources of ultrafine particles. A parameterisation method is presented for estimating the levels of traffic-emitted ultrafine particles in terms of variables describing the ambient conditions. The method is versatile and could easily be applied to similar datasets in other environments. The data used were collected during a four-week period in February 2005, in Gothenburg, as part of the Göte-2005 campaign. The specific variables tested were temperature (T), relative humidity (RH), carbon monoxide concentration (CO), and the concentration of particles up to 10 μm diameter (PM(10)); all indicators are of importance for aerosol processes such as coagulation and gas-particle partitioning. These variables were selected because of their direct effect on aerosol processes (T and RH) or as proxies for aerosol surface area (CO and PM(10)) and because of their availability in local monitoring programmes, increasing the usability of the parameterization. Emission factors are presented for 10-100 nm particles (ultrafine particles; EF(ufp)), for 10-40 nm particles (EF(10-40)), and for 40-100 nm particles (EF(40-100)). For EF(40-100) no effect of ambient conditions was found. The emission factor equations are calculated based on an emission factor for NO(x) of 1 g km(-1), thus the particle emission factors are easily expressed in units of particles per gram of NO(x) emitted. For 10-100 nm particles the emission factor is EF(ufp) = 1.8 × 10(15) × (1 - 0.095 × CO - 3.2 × 10(-3) × T) particles km(-1). Alternative equations for the EFs in terms of T and PM(10) concentration are also presented.

Corrosion behavior and oxide properties of Zr 1.1 wt%Nb 0.05 wt%Cu alloy

NASA Astrophysics Data System (ADS)

Park, Jeong-Yong; Choi, Byung-Kwon; Yoo, Seung Jo; Jeong, Yong Hwan

2006-12-01

The corrosion behavior and oxide properties of Zr-1.1 wt%Nb-0.05 wt%Cu (ZrNbCu) and Zircaloy-4 have been investigated. The corrosion rate of the ZrNbCu alloy was much lower than that of the Zirclaoy-4 in the 360 °C water and 360 °C PWR-simulating loop condition without a neutron flux and it was increased with an increase of the final annealing temperature from 470 °C to 570 °C. TEM observations revealed that the precipitates in the ZrNbCu were β-Nb and ZrNbFe-precipitate with β-Nb being more frequently observed and that the precipitates were more finely distributed in the ZrNbCu alloy. It was also observed that the oxides of the ZrNbCu and Zircaloy-4 consisted of two and seven layers, respectively, after 1000 days in the PWR-simulating loop condition and that the thickness of a fully-developed layer was higher in the ZrNbCu than in the Zircaloy-4. It was also found that the β-Nb in ZrNbCu was oxidized more slowly when compared to the Zr(Fe, Cr) 2 in Zirclaoy-4 when the precipitates in the oxide were observed by TEM. Cracks were observed in the vicinity of the oxidized Zr(Fe, Cr) 2, while no cracks were formed near β-Nb which had retained a metallic state. From the results obtained, it is suggested that the oxide formed on the ZrNbCu has a more protective nature against a corrosion when compared to that of the Zircaloy-4.

Thermodynamic and kinetic modeling of Mn-Ni-Si precipitates in low-Cu reactor pressure vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ke, Huibin; Wells, Peter; Edmondson, Philip D.

Formation of large volume fractions of Mn-Ni-Si precipitates (MNSPs) causes excess irradiation embrittlement of reactor pressure vessel (RPV) steels at high, extended-life fluences. Thus, a new and unique, semi-empirical cluster dynamics model was developed to study the evolution of MNSPs in low-Cu RPV steels. The model is based on CALPHAD thermodynamics and radiation enhanced diffusion kinetics. The thermodynamics dictates the compositional and temperature dependence of the free energy reductions that drive precipitation. The model treats both homogeneous and heterogeneous nucleation, where the latter occurs on cascade damage, like dislocation loops. The model has only four adjustable parameters that were fitmore » to an atom probe tomography (APT) database. The model predictions are in semi-quantitative agreement with systematic Mn, Ni and Si composition variations in alloys characterized by APT, including a sensitivity to local tip-to-tip variations even in the same steel. The model predicts that heterogeneous nucleation plays a critical role in MNSP formation in lower alloy Ni contents. Single variable assessments of compositional effects show that Ni plays a dominant role, while even small variations in irradiation temperature can have a large effect on the MNSP evolution. Within typical RPV steel ranges, Mn and Si have smaller effects. Furthermore, the delayed but then rapid growth of MNSPs to large volume fractions at high fluence is well predicted by the model. For purposes of illustration, the effect of MNSPs on transition temperature shifts are presented based on well-established microstructure-property and property-property models.« less

Thermodynamic and kinetic modeling of Mn-Ni-Si precipitates in low-Cu reactor pressure vessel steels

DOE PAGES

Ke, Huibin; Wells, Peter; Edmondson, Philip D.; ...

2017-07-12

Formation of large volume fractions of Mn-Ni-Si precipitates (MNSPs) causes excess irradiation embrittlement of reactor pressure vessel (RPV) steels at high, extended-life fluences. Thus, a new and unique, semi-empirical cluster dynamics model was developed to study the evolution of MNSPs in low-Cu RPV steels. The model is based on CALPHAD thermodynamics and radiation enhanced diffusion kinetics. The thermodynamics dictates the compositional and temperature dependence of the free energy reductions that drive precipitation. The model treats both homogeneous and heterogeneous nucleation, where the latter occurs on cascade damage, like dislocation loops. The model has only four adjustable parameters that were fitmore » to an atom probe tomography (APT) database. The model predictions are in semi-quantitative agreement with systematic Mn, Ni and Si composition variations in alloys characterized by APT, including a sensitivity to local tip-to-tip variations even in the same steel. The model predicts that heterogeneous nucleation plays a critical role in MNSP formation in lower alloy Ni contents. Single variable assessments of compositional effects show that Ni plays a dominant role, while even small variations in irradiation temperature can have a large effect on the MNSP evolution. Within typical RPV steel ranges, Mn and Si have smaller effects. Furthermore, the delayed but then rapid growth of MNSPs to large volume fractions at high fluence is well predicted by the model. For purposes of illustration, the effect of MNSPs on transition temperature shifts are presented based on well-established microstructure-property and property-property models.« less

Atom probe tomography investigation of lath boundary segregation and precipitation in a maraging stainless steel.

PubMed

Thuvander, Mattias; Andersson, Marcus; Stiller, Krystyna

2013-09-01

Lath boundaries in a maraging stainless steel of composition 13Cr-8Ni-2Mo-2Cu-1Ti-0.7Al-0.3Mn-0.2Si-0.03C (at%) have been investigated using atom probe tomography following aging at 475 °C for up to 100 h. Segregation of Mo, Si and P to the lath boundaries was observed already after 5 min of aging, and the amount of segregation increases with aging time. At lath boundaries also precipitation of η-Ni₃(Ti, Al) and Cu-rich 9R, in contact with each other, takes place. These co-precipitates grow with time and because of coarsening the area number density decreases. After 100 h of aging a ∼5 nm thick film-like precipitation of a Mo-rich phase was observed at the lath boundaries. From the composition of the film it is suggested that the phase in question is the quasicrystalline R' phase. The film is perforated with Cu-rich 9R and η-Ni₃(Ti, Al) co-precipitates. Not all precipitate types present in the matrix do precipitate at the lath boundaries; the Si-containing G phase and γ'-Ni₃(Ti, Al, Si) and the Cr-rich α' phase were not observed at the lath boundaries. Copyright © 2012 Elsevier B.V. All rights reserved.

Microstructure control of Al-Cu films for improved electromigration resistance

DOEpatents

Frear, Darrel R.; Michael, Joseph R.; Romig, Jr., Alton D.

1994-01-01

A process for the forming of Al-Cu conductive thin films with reduced electromigration failures is useful, for example, in the metallization of integrated circuits. An improved formation process includes the heat treatment or annealing of the thin film conductor at a temperature within the range of from 200.degree. C. to 300.degree. C. for a time period between 10 minutes and 24 hours under a reducing atmosphere such as 15% H.sub.2 in N.sub.2 by volume. Al-Cu thin films annealed in the single phase region of a phase diagram, to temperatures between 200.degree. C. and 300.degree. C. have .theta.-phase Al.sub.2 Cu precipitates at the grain boundaries continuously become enriched in copper, due, it is theorized, to the formation of a thin coating of .theta.-phase precipitate at the grain boundary. Electromigration behavior of the aluminum is, thus, improved because the .theta.-phase precipitates with copper hinder aluminum diffusion along the grain boundaries. Electromigration, then, occurs mainly within the aluminum grains, a much slower process.

Microstructure control of Al-Cu films for improved electromigration resistance

DOEpatents

Frear, D.R.; Michael, J.R.; Romig, A.D. Jr.

1994-04-05

A process for the forming of Al-Cu conductive thin films with reduced electromigration failures is useful, for example, in the metallization of integrated circuits. An improved formation process includes the heat treatment or annealing of the thin film conductor at a temperature within the range of from 200 C to 300 C for a time period between 10 minutes and 24 hours under a reducing atmosphere such as 15% H[sub 2] in N[sub 2] by volume. Al-Cu thin films annealed in the single phase region of a phase diagram, to temperatures between 200 C and 300 C have [theta]-phase Al[sub 2] Cu precipitates at the grain boundaries continuously become enriched in copper, due, it is theorized, to the formation of a thin coating of [theta]-phase precipitate at the grain boundary. Electromigration behavior of the aluminum is, thus, improved because the [theta]-phase precipitates with copper hinder aluminum diffusion along the grain boundaries. Electromigration, then, occurs mainly within the aluminum grains, a much slower process. 5 figures.

Acute health effects of urban fine and ultrafine particles on children with atopic dermatitis.

PubMed

Song, Sanghwan; Lee, Kiyoung; Lee, Young-Mi; Lee, Jung-Hyun; Lee, Sang Il; Yu, Seung-Do; Paek, Domyung

2011-04-01

Although ambient particulate pollutants have been shown to exacerbate existing allergic symptoms of mucous membranes including rhinitis and asthma, the effects on skin such as atopic dermatitis in childhood deserve further study. We investigated the effects of urban particulate pollutants including ultrafine particles on atopic severity in children with atopic dermatitis. We included 41 schoolchildren, 8-12 years old, who had been diagnosed with atopic dermatitis. For 67 consecutive days, all of them measured their symptoms in a diary. To assess exposure, the daily ambient mass concentrations of particulate matter less than 10, 2.5 and 1 μm (PM(10), PM(2.5) and PM(1), respectively) and concentrations of submicron particles (0.01- 1 μm) were measured at a local school. The mean mass concentrations of PM(10), PM(2.5) and PM(1) were 74.0, 57.8 and 50.8 μg/m(3), respectively. The mean concentrations were 41,335/cm(3) ultrafine particles (UFPs) and 8577/cm(3) accumulation mode (0.1-1 μm) particles. Significant associations were found between the concentrations of ultrafine particles and the itchiness symptom in children with atopic dermatitis. An interquartile range (IQR) increase in previous day ultrafine particles concentration (IQR: 28-140/m(3)) was significantly associated with a 3.1% (95% confidence interval, 0.2-6.1) increase in the itch symptom score for children with atopic dermatitis. The results suggested that the concentration of ambient ultrafine particles may exacerbate skin symptoms in children with atopic dermatitis. Copyright © 2011. Published by Elsevier Inc.

Metal transport and remobilisation in a basin affected by acid mine drainage: the role of ochreous amorphous precipitates.

PubMed

Consani, Sirio; Carbone, Cristina; Dinelli, Enrico; Balić-Žunić, Tonci; Cutroneo, Laura; Capello, Marco; Salviulo, Gabriella; Lucchetti, Gabriella

2017-06-01

Metal-polluted mine waters represent a major threat to the quality of waters and sediments in a downstream basin. At the confluence between acidic mine waters and the unpolluted waters of the Gromolo Torrent (Liguria, North-West Italy), the massive formation of an ochreous amorphous precipitate takes place. This precipitate forms a soft blanket that covers the torrent bed and can be observed down to its mouth in the sea. The aim of this work is to evaluate the dispersion of metals in the Gromolo Torrent basin from the abandoned Cu-Fe sulphide mine of Libiola to the Ligurian Sea and to assess the metal remobilisation from the amorphous precipitates. The mineralogy of the superficial sediments collected in the torrent bed and the concentrations of different elements of environmental concern (Cu, Zn, Cd, Co, Cr, Mn, Ni, Pb, As, and Sb) were therefore analysed. The results showed that the precipitates contain high concentration of Fe, Al, Cu, and Zn, significantly modifying the bulk chemistry of the Gromolo Torrent sediments. In order to evaluate the possible remobilisation of ecotoxic elements from the amorphous precipitates, bulk leaching tests were performed with both deionised and seawater. Bulk leaching tests with deionised water mobilised primarily high Pb amounts, but also relatively high concentrations of Fe, Al, Cu, and Zn are released in the leachate. In seawater tests, Fe, Al, Cu, and Zn were released in smaller amounts, while other elements like Mn, Cd, Co, and Ni increased in the released fraction. Pb was still strongly released as in deionised water experiments. The results show that the interaction of precipitates and seawater can remobilise high concentrations of metals, thus affecting the surrounding environment.

Oxidation behaviour of zirconium alloys and their precipitates - A mechanistic study

NASA Astrophysics Data System (ADS)

Proff, C.; Abolhassani, S.; Lemaignan, C.

2013-01-01

The precipitate oxidation behaviour of binary zirconium alloys containing 1 wt.% Fe, Ni, Cr or 0.6 wt.% Nb was characterised in TEM on FIB prepared transverse sections of the oxide and reported in previous studies [1,2]. In the present study the following alloys: Zr1%Cu, Zr0.5%Cu0.5%Mo and pure Zr are analysed to add to the available information. In all cases, the observed precipitate oxidation behaviour in the oxide close to the metal-oxide interface could be described either with delayed oxidation with respect to the matrix or simultaneous oxidation as the surrounding zirconium matrix. Attempt was made to explain these observations, with different parameters such as precipitate size and structure, composition and thermodynamic properties. It was concluded that the thermodynamics with the new approach presented could explain most precisely their behaviour, considering the precipitate stoichiometry and the free energy of oxidation of the constituting elements. The surface topography of the oxidised materials, as well as the microstructure of the oxide presenting microcracks have been examined. A systematic presence of microcracks above the precipitates exhibiting delayed oxidation has been found; the height of these crack calculated using the Pilling-Bedworth ratios of different phases present, can explain their origin. The protrusions at the surface in the case of materials containing large precipitates can be unambiguously correlated to the presence of these latter, and the height can be correlated to the Pilling-Bedworth ratios of the phases present as well as the diffusion of the alloying elements to the surface and their subsequent oxidation. This latter behaviour was much more considerable in the case of Fe and Cu with Fe showing systematically diffusion to the outer surface.

Synthesis and microwave modification of CuO nanoparticles: crystallinity and morphological variations, catalysis, and gas sensing.

PubMed

Yang, Chao; Xiao, Feng; Wang, Jide; Su, Xintai

2014-12-01

CuO nanoparticles with different morphologies were synthesized by chemical precipitation and subsequently modified by microwave hydrothermal processing. The nanoparticles were precipitated by the introduction of a strong base to an aqueous solution of copper cations in the presence/absence of the polyethylene glycol and urea additives. The modification of the nanoparticles was subsequently carried out by a microwave hydrothermal treatment of suspensions of the precipitates, precipitated with and without the additives. X-ray powder diffraction analysis indicated that the crystallinity and crystallite size of the CuO nanoparticles increased after the microwave hydrothermal modification. Microscopy observations revealed the morphology changes induced by microwave hydrothermal processing. The thermal decomposition of ammonium perchlorate and the detection of volatile gases were performed to evaluate the catalytic and gas sensing properties of the synthesized CuO nanoparticles. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

PubMed

Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

2016-05-01

The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Varied dose exposures to ultrafine particles in the motorcycle smoke cause kidney cell damages in male mice.

PubMed

Wardoyo, Arinto Y P; Juswono, Unggul P; Noor, Johan A E

2018-01-01

Ultrafine particles (UFPs) are one of motorcycle exhaust emissions which can penetrate the lung alveoli and deposit in the kidney. This study was aimed to investigate mice kidney cell physical damage (deformation) due to motorcycle exhaust emission exposures. The motorcycle exhaust emissions were sucked from the muffler with the rate of 33 cm 3 /s and passed through an ultrafine particle filter system before introduced into the mice exposure chamber. The dose concentration of the exhaust emissions was varied by setting the injected time of the 20s, 40s, 60s, 80s, and 100s. The mice were exposed to the smoke in the chamber for 100 s twice a day. The impact of the ultrafine particles on the kidney was observed by identifying the histological image of the kidney cell deformation using a microscope. The exposure was conducted for 10 days. The kidney observations were carried out on day 11. The results showed that there was a significant linear correlation between the total concentration of ultrafine particles deposited in the kidneys and the physical damage percentages. The increased concentrations of ultrafine particles caused larger cell deformation to the kidneys.

Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

DOE PAGES

Jiao, Z. B.; Luan, J. H.; Miller, M. K.; ...

2016-02-19

The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for twomore » interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. Lastly, the co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.« less

Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

PubMed Central

Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

2016-01-01

The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

Environmental and health impacts of fine and ultrafine metallic particles: Assessment of threat scores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goix, Sylvaine; UMR 5245 CNRS-INP-UPS, EcoLab; Lévêque, Thibaut

2014-08-15

This study proposes global threat scores to prioritize the harmfulness of anthropogenic fine and ultrafine metallic particles (FMP) emitted into the atmosphere at the global scale. (Eco)toxicity of physicochemically characterized FMP oxides for metals currently observed in the atmosphere (CdO, CuO, PbO, PbSO{sub 4}, Sb{sub 2}O{sub 3}, and ZnO) was assessed by performing complementary in vitro tests: ecotoxicity, human bioaccessibility, cytotoxicity, and oxidative potential. Using an innovative methodology based on the combination of (eco)toxicity and physicochemical results, the following hazard classification of the particles is proposed: CdCl{sub 2}∼CdO>CuO>PbO>ZnO>PbSO{sub 4}>Sb{sub 2}O{sub 3}. Both cadmium compounds exhibited the highest threat score duemore » to their high cytotoxicity and bioaccessible dose, whatever their solubility and speciation, suggesting that cadmium toxicity is due to its chemical form rather than its physical form. In contrast, the Sb{sub 2}O{sub 3} threat score was the lowest due to particles with low specific area and solubility, with no effects except a slight oxidative stress. As FMP physicochemical properties reveal differences in specific area, crystallization systems, dissolution process, and speciation, various mechanisms may influence their biological impact. Finally, this newly developed and global approach could be widely used in various contexts of pollution by complex metal particles and may improve risk management. - Highlights: • Seven micro- and nano- monometallic characterized particles were studied as references. • Bioaccessibility, eco and cytotoxicity, and oxidative potential assays were performed. • According to calculated threat scores: CdCl{sub 2}∼CdO>CuO>PbO>ZnO>PbSO{sub 4}>Sb{sub 2}O{sub 3}.« less

Size-resolved ultrafine particle composition analysis 2. Houston

NASA Astrophysics Data System (ADS)

Phares, Denis J.; Rhoads, Kevin P.; Johnston, Murray V.; Wexler, Anthony S.

2003-04-01

Between 23 August and 18 September 2000, a single-ultrafine-particle mass spectrometer (RSMS-II) was deployed just east of Houston as part of a sampling intensive during the Houston Supersite Experiment. The sampling site was located just north of the major industrial emission sources. RSMS-II, which simultaneously measures the aerodynamic size and composition of individual ultrafine aerosols, is well suited to resolving some of the chemistry associated with secondary particle formation. Roughly 27,000 aerosol mass spectra were acquired during the intensive period. These were classified and labeled based on the spectral peak patterns using the neural networks algorithm, ART-2a. The frequency of occurrence of each particle class was correlated with time and wind direction. Some classes were present continuously, while others appeared intermittently or for very short time durations. The most frequently detected species at the site were potassium and silicon, with lesser amounts of organics and heavier metals.

Environmental and health impacts of fine and ultrafine metallic particles: assessment of threat scores.

PubMed

Goix, Sylvaine; Lévêque, Thibaut; Xiong, Tian-Tian; Schreck, Eva; Baeza-Squiban, Armelle; Geret, Florence; Uzu, Gaëlle; Austruy, Annabelle; Dumat, Camille

2014-08-01

This study proposes global threat scores to prioritize the harmfulness of anthropogenic fine and ultrafine metallic particles (FMP) emitted into the atmosphere at the global scale. (Eco)toxicity of physicochemically characterized FMP oxides for metals currently observed in the atmosphere (CdO, CuO, PbO, PbSO(4), Sb(2)O(3), and ZnO) was assessed by performing complementary in vitro tests: ecotoxicity, human bioaccessibility, cytotoxicity, and oxidative potential. Using an innovative methodology based on the combination of (eco)toxicity and physicochemical results, the following hazard classification of the particles is proposed: CdCl2~CdO>CuO>PbO>ZnO>PbSO(4)>Sb(2)O(3). Both cadmium compounds exhibited the highest threat score due to their high cytotoxicity and bioaccessible dose, whatever their solubility and speciation, suggesting that cadmium toxicity is due to its chemical form rather than its physical form. In contrast, the Sb(2)O(3) threat score was the lowest due to particles with low specific area and solubility, with no effects except a slight oxidative stress. As FMP physicochemical properties reveal differences in specific area, crystallization systems, dissolution process, and speciation, various mechanisms may influence their biological impact. Finally, this newly developed and global approach could be widely used in various contexts of pollution by complex metal particles and may improve risk management. Copyright © 2014 Elsevier Inc. All rights reserved.

Microstructure of warm rolling and pearlitic transformation of ultrafine-grained GCr15 steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Jun-Jie; Lian, Fu-Liang; Liu, Hong-Ji

2014-09-15

Pearlitic transformation mechanisms have been investigated in ultra-fine grained GCr15 steel. The ultrafine-grained steel, whose grain size was less than 1 μm, was prepared by thermo-mechanical treatment at 873 K and then annealing at 923 K for 2 h. Pearlitic transformation was conducted by reheating the ultra-fine grained samples at 1073 K and 1123 K for different periods of time and then cooling in air. Scanning electron microscope observation shows that normal lamellar pearlite, instead of granular cementite and ferrite, cannot be formed when the grain size is approximately less than 4(± 0.6) μm, which yields a critical grain sizemore » for normal lamellar pearlitic transformations in this chromium alloyed steel. The result confirms that grain size has a great influence on pearlitic transformation by increasing the diffusion rate of carbon atoms in the ultra-fine grained steel, and the addition of chromium element doesn't change this pearlitic phase transformation rule. Meanwhile, the grain growth rate is reduced by chromium alloying, which is beneficial to form fine grains during austenitizing, thus it facilitating pearlitic transformation by divorced eutectoid transformation. Moreover, chromium element can form a relatively high gradient in the frontier of the undissolved carbide, which promotes carbide formation in the frontier of the undissolved carbide, i.e., chromium promotes divorced eutectoid transformation. - Highlights: • Ultrafine-grained GCr15 steel was obtained by warm rolling and annealing technology. • Reduction of grain size makes pearlite morphology from lamellar to granular. • Adding Cr does not change normal pearlitic phase transformation rule in UFG steel. • Cr carbide resists grain growth and facilitates pearlitic transformation by DET.« less

ULTRAFINE CARBON PARTICLES INDUCE IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS THROUGH A POST-TRANSCRIPTIONAL MECHANISM

EPA Science Inventory

Ultrafine carbon particles induce IL-8 expression in human airway
epithelial cells through a post-transcritpional mechanism
Epidemiological studies suggest that ultrafine particles contribute to
particulate matter (PM) - induced adverse health effects. IL-8 is an
i...

Atom-Probe Tomographic Investigations of a Precipitation-Strengthened HSLA-115 Steel and a Ballistic-Resistant 10 wt. % Ni Steel for Naval Applications

NASA Astrophysics Data System (ADS)

Jain, Divya

High performance structural materials are needed for Naval applications which require an excellent combination of yield strength, low-temperature impact toughness, ductility, ballistic-resistance, and weldability. This research investigates precipitation-strengthened HSLA-115 steels and ballistic-resistant 10 wt. % Ni steels, which have emerged as promising alternatives to the widely used HSLA-100 steels for Naval applications. HSLA-115 is a Cu-bearing high-strength low-carbon martensitic steel and has been used in the flight deck of the recently built U.S. Navy CVN-78 aircraft carrier. It is typically used in conditions with overaged Cu precipitates, to obtain acceptable impact toughness and ductility at 115 ksi (793 MPa) yield strength. However, overaging of Cu precipitates limits its strength and applications. This research demonstrates that aging at 550 °C facilitates the co-precipitation of sub-nanometer sized M2C carbides and Cu precipitates in high number density (˜1023 m-3) in HSLA-115. 3-D atom-probe tomography (APT) investigation reveals that Cu precipitates form first, followed by the nucleation of M2C carbides, which are co-located with Cu precipitates and are distributed heterogeneously at lath-boundaries and dislocations, indicating heterogeneous nucleation of M2C. Carbon redistribution during quenching (following the austenitization) and subsequent aging at 550 °C is followed using APT. Segregation of C (3-6 at. % C) is observed at martensitic lath-boundaries in the as-quenched and 0.12 h aged conditions. On further aging, C redistributes, forming cementite and M 2C carbides, whose composition and morphology evolves with aging time. Precipitation kinetics of M2C carbides is intertwined with Cu precipitates; temporal evolution of Cu precipitates and M2C carbides is characterized in terms of their mean radii, number densities, and volume fractions and correlated with the bulk mechanical properties. Precipitation of M2C carbides offsets the softening

Apportionment of motor vehicle emissions from fast changes in number concentration and chemical composition of ultrafine particles near a roadway intersection.

PubMed

Klems, Joseph P; Pennington, M Ross; Zordan, Christopher A; McFadden, Lauren; Johnston, Murray V

2011-07-01

High frequency spikes in ultrafine number concentration near a roadway intersection arise from motor vehicles that accelerate after a red light turns green. The present work describes a method to determine the contribution of motor vehicles to the total ambient ultrafine particle mass by correlating these number concentration spikes with fast changes in ultrafine particle chemical composition measured with the nano aerosol mass spectrometer, NAMS. Measurements were performed at an urban air quality monitoring site in Wilmington, Delaware during the summer and winter of 2009. Motor vehicles were found to contribute 48% of the ultrafine particle mass in the winter measurement period, but only 16% of the ultrafine particle mass in the summer period. Chemical composition profiles and contributions to the ultrafine particle mass of spark vs diesel vehicles were estimated by correlating still camera images, chemical composition and spike contribution at each time interval.. The spark and diesel contributions were roughly equal, but the uncertainty in the split was large. The distribution of emissions from individual vehicles was determined by correlating camera images with the spike contribution to particle number concentration at each time interval. A small percentage of motor vehicles were found to emit a disproportionally large concentration of ultrafine particles, and these high emitters included both spark ignition and diesel vehicles.

Characterization of pure Ni ultrafine/nanoparticles synthesized by electromagnetic levitational gas condensation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodaei, Azin, E-mail: Azin.Khodaei@gmail.com; Hasannasab, Malihe; Amousoltani, Narges

2016-02-15

Highlights: • Ni ultrafine/nanoparticles were produced using the single-step ELGC method. • Ar and He–20%Ar gas mixtures were used as the condensing gas under 1 atm. • Effects of gas type and flow rate on particle size distribution were investigated. • The nanoparticles showed both high saturation magnetization and low coercivity. - Abstract: In this work, Ni ultrafine/nanoparticles were directly produced using the one-step, relatively large-scale electromagnetic levitational gas condensation method. In this process, Ni vapors ascending from the levitated droplet were condensed by Ar and He–20%Ar gas mixtures under atmospheric pressure. Effects of type and flow rate of themore » condensing gas on the size, size distribution and crystallinity of Ni particles were investigated. The particles were characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer (VSM). The process parameters for the synthesis of the crystalline Ni ultrafine/nanoparticles were determined.« less

Exposure to airborne ultrafine particles from cooking in Portuguese homes.

PubMed

Bordado, J C; Gomes, J F; Albuquerque, P C

2012-10-01

Cooking was found to be a main source of submicrometer and ultrafine aerosols from gas combustion in stoves. Therefore, this study consisted of the determination of the alveolar deposited surface area due to aerosols resulting from common domestic cooking activities (boiling fish, vegetables, or pasta, and frying hamburgers and eggs). The concentration of ultrafine particles during the cooking events significantly increased from a baseline of 42.7 microm2/cm3 (increased to 72.9 microm2/cm3 due to gas burning) to a maximum of 890.3 microm2/cm3 measured during fish boiling in water and a maximum of 4500 microm2/cm3 during meat frying. This clearly shows that a domestic activity such as cooking can lead to exposures as high as those of occupational exposure activities. The approach of this study considers the determination of alveolar deposited surface area of aerosols generated from cooking activities, namely, typical Portuguese dishes. This type of measurement has not been done so far, in spite of the recognition that cooking activity is a main source of submicrometer and ultrafine aerosols. The results have shown that the levels of generated aerosols surpass the outdoor concentrations in a major European town, which calls for further determinations, contributing to a better assessment of exposure of individuals to domestic activities such as this one.

Grain Size Threshold for Enhanced Irradiation Resistance in Nanocrystalline and Ultrafine Tungsten

DOE PAGES

El Atwani, Osman; Hinks, Jonathan; Greaves, Graeme; ...

2017-02-21

Nanocrystalline metals are considered highly radiation-resistant materials due to their large grain boundary areas. Here, the existence of a grain size threshold for enhanced irradiation resistance in high-temperature helium-irradiated nanocrystalline and ultrafine tungsten is demonstrated. Average bubble density, projected bubble area and the corresponding change in volume were measured via transmission electron microscopy and plotted as a function of grain size for two ion fluences. Nanocrystalline grains of less than 35 nm size possess ~10–20 times lower change in volume than ultrafine grains and this is discussed in terms of the grain boundaries defect sink efficiency.

Electronic and structural properties of B i2S e3:Cu

NASA Astrophysics Data System (ADS)

Sobczak, Kamil; Strak, Pawel; Kempisty, Pawel; Wolos, Agnieszka; Hruban, Andrzej; Materna, Andrzej; Borysiuk, Jolanta

2018-04-01

Electronic and structural properties of B i2S e3 and its extension to copper doped B i2S e3:Cu were studied using combined ab initio simulations and transmission electron microscopy based techniques, including electron energy loss spectroscopy, energy filtered transmission electron microscopy, and energy dispersive x-ray spectroscopy. The stability of the mixed phases was investigated for substitutional and intercalation changes of basic B i2S e3 structure. Four systems were compared: B i2S e3 , structures obtaining by Cu intercalation of the van der Waals gap, by substitution of Bi by Cu in quintuple layers, and C u2Se . The structures were identified and their electronic properties were obtained. Transmission electron microscopy measurements of B i2S e3 and the B i2S e3:Cu system identified the first structure as uniform and the second as composite, consisting of a nonuniform lower-Cu-content matrix and randomly distributed high-Cu-concentration precipitates. Critical comparison of the ab initio and experimental data identified the matrix as having a B i2S e3 dominant part with randomly distributed Cu-intercalated regions having 1Cu-B i2S e3 structure. The precipitates were determined to have 3Cu-B i2S e3 structure.

Aging behavior of an in-situ TiB{sub 2}/Al-Cu-Li-x matrix composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yanwei; Hong, Tianran; Geng, Jiwei

Transmission electron microscopy, differential scanning calorimetry and hardness tests have been performed on an in-situ TiB{sub 2}/Al-3.3Cu-1.0Li-0.60Mg-0.40Ag-0.14Zr-0.13Si composite to study its aging behavior at 175 °C. A cubic phase suspected to be the σ (Al{sub 5}Cu{sub 6}Mg{sub 2}) phase or its variant is precipitated at all aging stages studied, and this phase is not typically observed in the Al-Cu-Li alloys. The primary hardening (aging for 3 h) phases consist of δ′ (Al{sub 3}Li), β′ (Al{sub 3}Zr) and the cubic phase. After aging for 18 h, all precipitates including T{sub 1} (Al{sub 2}CuLi), S (Al{sub 2}CuMg), θ′ (Al{sub 2}Cu), δ′, β′more » and the cubic phase have appeared, and the formation of T{sub 1} and S results in a rapid increase in hardness. With prolonging of aging time, the apparent coarsening of T{sub 1} and S results in a decline in hardness. - Highlights: •The aging behavior of an in-situ TiB{sub 2}/Al-Cu-Li-x composite was studied. •A cubic phase suspected to be σ (Al{sub 5}Cu{sub 6}Mg{sub 2}) or its variant was precipitated. •The hardness change was dominated by the evolution of T{sub 1} (Al{sub 2}CuLi) and S (Al{sub 2}CuMg).« less

CARDIOVASCULAR EFFECTS OF ULTRAFINE CARBON PARTICLES IN HYPERTENSIVE RATS (SHR)

EPA Science Inventory

Rationale: Epidemiological evidence suggests that ultrafine particles are associated with adverse cardiovascular effects, specifically in elderly individuals with preexisting cardiovascular disease. The objective of this study was (i) to assess cardiopulmonary responses in adult ...

Effect of HIP temperature on microstructure and low cycle fatigue strength of CuCrZr alloy

NASA Astrophysics Data System (ADS)

Nishi, Hiroshi; Enoeda, Mikio

2011-10-01

In order to investigate the effect of the HIP cycle temperatures on the metallurgic degradation and the mechanical properties of CuCrZr alloy, assessments of the microstructure, tensile test, Charpy impact test and low cycle fatigue test are performed for various heat treated CuCrZr alloys, which were solution-annealed followed by water-quenched and aged state of CuCrZr with simulated HIP cycle at temperatures of 980 and 1045 °C. Grain growth occurred on 1045 °C HIP CuCrZr, though slightly on 980 °C HIP CuCrZr. Metallurgic degradation such as voids was not found by optical and SEM observations. There were coarse precipitates in all the CuCrZr and the precipitates did not easily dissolve at 980 °C. The low cycle fatigue strength of 1045 °C HIP CuCrZr was lower than that of other CuCrZr because of the metallurgic degradation caused by the heat cycle, while that of other CuCrZr was corresponding to the best fit curve of ITER MPH.

Phase-field simulations of coherent precipitate morphologies and coarsening kinetics

NASA Astrophysics Data System (ADS)

Vaithyanathan, Venugopalan

2002-09-01

The primary aim of this research is to enhance the fundamental understanding of coherent precipitation reactions in advanced metallic alloys. The emphasis is on a particular class of precipitation reactions which result in ordered intermetallic precipitates embedded in a disordered matrix. These precipitation reactions underlie the development of high-temperature Ni-base superalloys and ultra-light aluminum alloys. Phase-field approach, which has emerged as the method of choice for modeling microstructure evolution, is employed for this research with the focus on factors that control the precipitate morphologies and coarsening kinetics, such as precipitate volume fractions and lattice mismatch between precipitates and matrix. Two types of alloy systems are considered. The first involves L1 2 ordered precipitates in a disordered cubic matrix, in an attempt to model the gamma' precipitates in Ni-base superalloys and delta' precipitates in Al-Li alloys. The effect of volume fraction on coarsening kinetics of gamma' precipitates was investigated using two-dimensional (2D) computer simulations. With increase in volume fraction, larger fractions of precipitates were found to have smaller aspect ratios in the late stages of coarsening, and the precipitate size distributions became wider and more positively skewed. The most interesting result was associated with the effect of volume fraction on the coarsening rate constant. Coarsening rate constant as a function of volume fraction extracted from the cubic growth law of average half-edge length was found to exhibit three distinct regimes: anomalous behavior or decreasing rate constant with volume fraction at small volume fractions ( ≲ 20%), volume fraction independent or constant behavior for intermediate volume fractions (˜20--50%), and the normal behavior or increasing rate constant with volume fraction for large volume fractions ( ≳ 50%). The second alloy system considered was Al-Cu with the focus on understanding

Health hazards of ultrafine metal and metal oxide powders

NASA Technical Reports Server (NTRS)

Boylen, G. W., Jr.; Chamberlin, R. I.; Viles, F. J.

1969-01-01

Study reveals that suggested threshold limit values are from two to fifty times lower than current recommended threshold limit values. Proposed safe limits of exposure to the ultrafine dusts are based on known toxic potential of various materials as determined in particle size ranges.

Perspectives of Using Ultra-Fine Metals as Universal Safe BioStimulators to Get Cattle Breeding Quality Products

NASA Astrophysics Data System (ADS)

Polishchuk, S.

2015-11-01

We have conducted investigations of ultra-fine metals biological activity with lab non-pedigree white rats, rabbits breed “Soviet chinchilla” and cattle young stock of the black and white breed as the most widely spread in the central part of Russia. One can see the possibility of using microelements of ultra-fine iron, cobalt and copper as cheap, non-toxic and highly effective biological catalyst of biochemical processes in the organism that improve physiological state, morphological and biochemical blood parameters increasing activity of the experimental animals’ ferment systems and their productivity and meat biological value. We have proved the ultra-fine powders safety when adding them to the animals’ diet.

Environmentally persistent free radicals amplify ultrafine particle mediated cellular oxidative stress and cytotoxicity

PubMed Central

Balakrishna, Shrilatha; Lomnicki, Slawo; McAvey, Kevin M; Cole, Richard B; Dellinger, Barry; Cormier, Stephania A

2009-01-01

Background Combustion generated particulate matter is deposited in the respiratory tract and pose a hazard to the lungs through their potential to cause oxidative stress and inflammation. We have previously shown that combustion of fuels and chlorinated hydrocarbons produce semiquinone-type radicals that are stabilized on particle surfaces (i.e. environmentally persistent free radicals; EPFRs). Because the composition and properties of actual combustion-generated particles are complex, heterogeneous in origin, and vary from day-to-day, we have chosen to use surrogate particle systems. In particular, we have chosen to use the radical of 2-monochlorophenol (MCP230) as the EPFR because we have previously shown that it forms a EPFR on Cu(II)O surfaces and catalyzes formation of PCDD/F. To understand the physicochemical properties responsible for the adverse pulmonary effects of combustion by-products, we have exposed human bronchial epithelial cells (BEAS-2B) to MCP230 or the CuO/silica substrate. Our general hypothesis was that the EPFR-containing particle would have greater toxicity than the substrate species. Results Exposure of BEAS-2B cells to our combustion generated particle systems significantly increased reactive oxygen species (ROS) generation and decreased cellular antioxidants resulting in cell death. Resveratrol treatment reversed the decline in cellular glutathione (GSH), glutathione peroxidase (GPx), and superoxide dismutase (SOD) levels for both types of combustion-generated particle systems. Conclusion The enhanced cytotoxicity upon exposure to MCP230 correlated with its ability to generate more cellular oxidative stress and concurrently reduce the antioxidant defenses of the epithelial cells (i.e. reduced GSH, SOD activity, and GPx). The EPFRs in MCP230 also seem to be of greater biological concern due to their ability to induce lipid peroxidation. These results are consistent with the oxidizing nature of the CuO/silica ultrafine particles and the

Precipitation of T1 and θ′ Phase in Al-4Cu-1Li-0.25Mn During Age Hardening: Microstructural Investigation and Phase-Field Simulation

PubMed Central

Häusler, Ines; Schwarze, Christian; Bilal, Muhammad Umer; Valencia Ramirez, Daniela; Hetaba, Walid; Darvishi Kamachali, Reza; Skrotzki, Birgit

2017-01-01

Experimental and phase field studies of age hardening response of a high purity Al-4Cu-1Li-0.25Mn-alloy (mass %) during isothermal aging are conducted. In the experiments, two hardening phases are identified: the tetragonal θ′ (Al2Cu) phase and the hexagonal T1 (Al2CuLi) phase. Both are plate shaped and of nm size. They are analyzed with respect to the development of their size, number density and volume fraction during aging by applying different analysis techniques in TEM in combination with quantitative microstructural analysis. 3D phase-field simulations of formation and growth of θ′ phase are performed in which the full interfacial, chemical and elastic energy contributions are taken into account. 2D simulations of T1 phase are also investigated using multi-component diffusion without elasticity. This is a first step toward a complex phase-field study of T1 phase in the ternary alloy. The comparison between experimental and simulated data shows similar trends. The still unsaturated volume fraction indicates that the precipitates are in the growth stage and that the coarsening/ripening stage has not yet been reached. PMID:28772481

Preparation and characterization of ultrafine nanoparticles of Cu doped lithium tetraborate

NASA Astrophysics Data System (ADS)

Khalilzadeh, Nasrin; Saion, Elias Bin; Mirabolghasemi, Hamed; Crouse, Karen A.; Shaari, Abdul Halim Bin; Hashim, Mansor Bin

This study details an innovative single-step thermal synthesis of nano-sized lithium tetraborate doped with 0.1 %wt copper and its characterization. The heating temperature for the synthesis of the nanoparticle material was optimized by variation between 200 and 850 °C. The optimum amount of polyvinyl pyrrolidone (PVP) the capping agent was determined to be 0.027 mol per 1 g LTB-Cu. The calcination time was 2 h. Characterization of the samples was carried out using Thermogravimetry Analysis (TGA), Derivative Thermogravimetry (DTG), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffractometer (XRD), transmission electron microscopy (TEM) and Ultraviolet-Visible (UV-Vis) spectroscopy. The product was thermally stable above 450 °C. FTIR, XRD and TEM results confirmed the formation of pure nano-crystalline copper doped lithium tetraborate between 450 and 750 °C. The optical bandgap was estimated to be 5.02-6.05 eV in the presence of different amounts of PVP at various calcination temperatures.

Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite

PubMed Central

Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

2014-01-01

The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897

In Situ Imaging the Oxygen Reduction Reactions of Solid State Na-O2 Batteries with CuO Nanowires as the Air Cathode.

PubMed

Liu, Qiunan; Yang, Tingting; Du, Congcong; Tang, Yongfu; Sun, Yong; Jia, Peng; Chen, Jingzhao; Ye, Hongjun; Shen, Tongde; Peng, Qiuming; Zhang, Liqiang; Huang, Jianyu

2018-06-13

We report real time imaging of the oxygen reduction reactions (ORRs) in all solid state sodium oxygen batteries (SOBs) with CuO nanowires (NWs) as the air cathode in an aberration-corrected environmental transmission electron microscope under an oxygen environment. The ORR occurred in a distinct two-step reaction, namely, a first conversion reaction followed by a second multiple ORR. In the former, CuO was first converted to Cu 2 O and then to Cu; in the latter, NaO 2 formed first, followed by its disproportionation to Na 2 O 2 and O 2 . Concurrent with the two distinct electrochemical reactions, the CuO NWs experienced multiple consecutive large volume expansions. It is evident that the freshly formed ultrafine-grained Cu in the conversion reaction catalyzed the latter one-electron-transfer ORR, leading to the formation of NaO 2 . Remarkably, no carbonate formation was detected in the oxygen cathode after cycling due to the absence of carbon source in the whole battery setup. These results provide fundamental understanding into the oxygen chemistry in the carbonless air cathode in all solid state Na-O 2 batteries.

Resistance spot welding of ultra-fine grained steel sheets produced by constrained groove pressing: Optimization and characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodabakhshi, F.; Kazeminezhad, M., E-mail: mkazemi@sharif.edu; Kokabi, A.H.

2012-07-15

Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel sheets. The ultra-fine grained sheets are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the sheets with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained sheet spot welds have been investigated in the present paper and the welding current and time of resistance spot welding process according to thesemore » subjects are optimized. Failure mode and failure load obtained in tensile-shear test, microhardness, X-ray diffraction, transmission electron microscope and scanning electron microscope images have been used to describe the performance of spot welds. The region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. The results show that optimum welding parameters (welding current and welding time) for ultra-fine grained sheets are shifted to lower values with respect to those for as-received specimens. In ultra-fine grained sheets, one new region is formed named recrystallized zone in addition to fusion zone, heat affected zone and base metal. It is shown that microstructures of different zones in ultra-fine grained sheets are finer than those of as-received sheets. - Highlights: Black-Right-Pointing-Pointer Resistance spot welding process is optimized for joining of UFG steel sheets. Black-Right-Pointing-Pointer Optimum welding current and time are decreased with increasing the CGP pass number. Black-Right-Pointing-Pointer Microhardness at BM, HAZ, FZ and recrystallized zone is enhanced due to CGP.« less

Ultrafine particles dispersion modeling in a street canyon: development and evaluation of a composite lattice Boltzmann model.

PubMed

Habilomatis, George; Chaloulakou, Archontoula

2013-10-01

Recently, a branch of particulate matter research concerns on ultrafine particles found in the urban environment, which originate, to a significant extent, from traffic sources. In urban street canyons, dispersion of ultrafine particles affects pedestrian's short term exposure and resident's long term exposure as well. The aim of the present work is the development and the evaluation of a composite lattice Boltzmann model to study the dispersion of ultrafine particles, in urban street canyon microenvironment. The proposed model has the potential to penetrate into the physics of this complex system. In order to evaluate the model performance against suitable experimental data, ultrafine particles levels have been monitored on an hourly basis for a period of 35 days, in a street canyon, in Athens area. The results of the comparative analysis are quite satisfactory. Furthermore, our modeled results are in a good agreement with the results of other computational and experimental studies. This work is a first attempt to study the dispersion of an air pollutant by application of the lattice Boltzmann method. Copyright © 2013 Elsevier B.V. All rights reserved.

HUMAN CLINICAL STUDIES OF CONCENTRATED AMBIENT ULTRAFINE AND FINE PARTICLES

EPA Science Inventory

Confirmation of our hypothesis that exposure to ambient ultrafine and fine particles promotes coagulation and alters cardiac function will have important implications for air pollution regulatory efforts, and will provide new approaches for the prevention of cardiovascular hea...

ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD

EPA Science Inventory

Individuals affected with chronic obstructive pulmonary disease (COPD) have increased susceptibility to adverse health effects from exposure to particulate air pollution. The dosimetry of ultrafine aerosols (diameter # 0.1 :m) is not well characterized in the healthy or diseas...

LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)

EPA Science Inventory

On-line analysis of ultrafine aerosol particle in the 12 to 150 nm size range is performed by
laser desorption/ionization. Particles are size selected with a differential mobility analyzer and then
sent into a linear time-of-flight mass spectrometer where they are ablated w...

White beam analysis of coupling between precipitation and plasticdeformation during electromigration in a passivated Al(0.5wt. percent Cu)interconnect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barabash, R.I.; Ice, G.E.; Tamura, N.

2005-09-01

The scaling of device dimensions with a simultaneous increase in functional density imposes a challenge to materials technology and reliability of interconnects. White beam X-ray microdiffraction is particularly well suited for the in situ study of electromigration. M.A. Krivoglaz theory was applied for the interpretation of white beam diffraction. The technique was used to probe microstructure in interconnects and has recently been able to monitor the onset of plastic deformation induced by mass transport during electromigration in Al(Cu) lines even before any macroscopic damage became visible. In the present paper, we demonstrate that the evolution of the dislocation structure duringmore » electromigration is highly inhomogeneous and results in the formation of unpaired randomly distributed geometrically necessary dislocations as well as geometrically necessary dislocation boundaries. When almost all unpaired dislocations and dislocation walls with the density n+ are parallel (as in the case of Al-based interconnects), the anisotropy in the scattering properties of the material becomes important, and the electrical properties of the interconnect depend strongly on the direction of the electric current relative to the orientation of the dislocation network. A coupling between the dissolution, growth and reprecipitation of Al2Cu precipitates and the electromigration-induced plastic deformation of grains in interconnects is observed.« less

ULTRAFINE ASH AEROSOLS FROM COAL COMBUSTION: CHARACTERIZATION AND HEALTH EFFECTS

EPA Science Inventory

Ultrafine coal fly ash particles, defined here as those with diameters less than 0.5 micrometer, typically comprise less than 1% of the total fly ash mass. These particles are formed almost exclusively through ash vaporization, nucleation, and coagulation/condensation mechanisms,...

Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yinxi; Liu, Dan; Zhang, Huifeng

Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPHmore » oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

Ultrafine and Fine Particulate Matter Inside and Outside of Mechanically Ventilated Buildings

PubMed Central

Miller, Shelly L.; Facciola, Nick A.; Toohey, Darin; Zhai, John

2017-01-01

The objectives of this study were to measure levels of particulate matter (PM) in mechanically ventilated buildings and to improve understanding of filtration requirements to reduce exposure. With the use of an Ultra High Sensitivity Aerosol Spectrometer and an Aerodyne Mass Spectrometer, ultrafine (0.055–0.1 μm) and fine (0.1–0.7 μm) indoor and outdoor PM was measured as a function of time in an office, a university building, and two elementary schools. Indoor particle levels were highly correlated with outdoor levels. Indoor and outdoor number concentrations in Denver were higher than those in Boulder, with the highest number concentrations occurring during summer and fall. The ratio of indoor-to-outdoor (I/O) PM was weakly but positively correlated with the amount of ventilation provided to the indoor environment, did not vary much with particle size (ranged between 0.48 and 0.63 for the entire size range), and was similar for each period of the week (weekend vs. weekday, night vs. day). Regression analyses showed that ultrafine indoor PM baseline concentrations were higher at night from nighttime infiltration. A lag time was observed between outdoor and indoor measurements. Weekday days had the shortest lag time of 11 min, and weekend nighttime lags when the HVAC was not in use were 50 to 148 min. Indoor-outdoor PM concentration plots showed ultrafine PM was more correlated compared to fine, and especially when the HVAC system was on. Finally, AMS data showed that most of the PM was organic, with occasional nitrate events occurring outdoors. During nitrate events, there were less indoor particles detected, indicating a loss of particulate phase nitrate. The results from this study show that improved filtration is warranted in mechanically ventilated buildings, particularly for ultrafine particles, and that nighttime infiltration is significant depending on the building design. PMID:28134841

Ultrafine and Fine Particulate Matter Inside and Outside of Mechanically Ventilated Buildings.

PubMed

Miller, Shelly L; Facciola, Nick A; Toohey, Darin; Zhai, John

2017-01-28

The objectives of this study were to measure levels of particulate matter (PM) in mechanically ventilated buildings and to improve understanding of filtration requirements to reduce exposure. With the use of an Ultra High Sensitivity Aerosol Spectrometer and an Aerodyne Mass Spectrometer, ultrafine (0.055-0.1 μm) and fine (0.1-0.7 μm) indoor and outdoor PM was measured as a function of time in an office, a university building, and two elementary schools. Indoor particle levels were highly correlated with outdoor levels. Indoor and outdoor number concentrations in Denver were higher than those in Boulder, with the highest number concentrations occurring during summer and fall. The ratio of indoor-to-outdoor (I/O) PM was weakly but positively correlated with the amount of ventilation provided to the indoor environment, did not vary much with particle size (ranged between 0.48 and 0.63 for the entire size range), and was similar for each period of the week (weekend vs. weekday, night vs. day). Regression analyses showed that ultrafine indoor PM baseline concentrations were higher at night from nighttime infiltration. A lag time was observed between outdoor and indoor measurements. Weekday days had the shortest lag time of 11 min, and weekend nighttime lags when the HVAC was not in use were 50 to 148 min. Indoor-outdoor PM concentration plots showed ultrafine PM was more correlated compared to fine, and especially when the HVAC system was on. Finally, AMS data showed that most of the PM was organic, with occasional nitrate events occurring outdoors. During nitrate events, there were less indoor particles detected, indicating a loss of particulate phase nitrate. The results from this study show that improved filtration is warranted in mechanically ventilated buildings, particularly for ultrafine particles, and that nighttime infiltration is significant depending on the building design.

The role of surface/interfacial Cu{sup 2+} sites in the photocatalytic activity of coupled CuO-TiO{sub 2} nanocomposites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, G.; Dimitrijevic, N. M.; Chen, L.

Coupled CuO-TiO{sub 2} nanocomposite photocatalysts were prepared by a deposition precipitation method and were characterized with a variety of techniques. Electron paramagnetic resonance (EPR) spectroscopy was employed to study the local structures of surface/interfacial Cu{sup 2+}+ sites using Cu{sup 2+} as a sensitive paramagnetic probe. The addition of bulk CuO to TiO{sub 2} led to decreased photocatalytic efficiency in the degradation of methylene blue. However, doping with a very small amount of CuO (0.1 wt % copper loading) significantly enhanced the photocatalytic activity of TiO{sub 2}. EPR study of the TiO{sub 2} surface revealed the presence of both highly dispersedmore » CuO clusters and substitutional Cu{sup 2+} sites (Ti-O-Cu linkages) at 0.1 wt % copper loading. The data suggest that the Ti-O-Cu linkages contributed to the improved photooxidative activity of the 0.1% CuO-TiO{sub 2} nanocomposite. In contrast, at higher loadings the bulk form of CuO created charge recombination centers lowering the photoactivity of the composites.« less

Application of glucose as a green capping agent and reductant to fabricate CuI micro/nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavakoli, Farnosh; Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir; Ghanbari, Davood

Graphical abstract: - Highlights: • CuI nanostructures were prepared via a simple precipitation method. • Glucose as a green capping agent and reductant was applied. • The effect of glucose concentration on the morphology of CuI was investigated. • According to XRD results, pure cubic phase CuI have been formed by using glucose. - Abstract: In this work, CuI micro/nanostructures have been successfully prepared via a simple precipitation route at room temperature. By using glucose as a clean reducing agent with different concentrations, CuI micro/nanostructures with various morphologies were obtained. Besides glucose, Na{sub 2}SO{sub 3}, KBH{sub 4} and N{sub 2}H{submore » 4}·H{sub 2}O have been applied as reductant. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectroscopy, X-ray energy dispersive spectroscopy (EDS) and Fourier transformed infrared (FT-IR) spectroscopy were used to characterize the as-produced CuI micro/nanostructures. According to the XRD results, it was found that pure cubic phase CuI have been formed by using glucose.« less

Effect of surface moisture on dielectric behavior of ultrafine BaTiO3 particulates.

NASA Technical Reports Server (NTRS)

Mountvala, A. J.

1971-01-01

The effects of adsorbed H2O on the dielectric properties of ultrafine BaTiO3 particulates of varying particle size and environmental history were determined. The dielectric behavior depends strongly on surface hydration. No particle size dependence of dielectric constant was found for dehydroxylated surfaces in ultrafine particulate (unsintered) BaTiO3 materials. For equivalent particle sizes, the ac conductivity is sensitive to surface morphology. Reactions with H2O vapor appear to account for the variations in dielectric properties. Surface dehydration was effectively accomplished by washing as-received powders in isopropanol.

A hybrid aluminium alloy and its zoo of interacting nano-precipitates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wenner, Sigurd, E-mail: sigurd.wenner@ntnu.no; Marioara, Calin Daniel; Andersen, Sigmund Jarle

An alloy with aluminium as its base element is heat treated to form a multitude of precipitate phases known from different classes of industrial alloys: Al–Cu(–Mg), Al–Mg–Si–Cu, and Al–Zn–Mg. Nanometer-sized needle-shaped particles define the starting point of the phase nucleation, after which there is a split in the precipitation sequence into six phases of highly diverse compositions and morphologies. There are several unique effects of phases from different alloy systems being present in the same host lattice, of which we concentrate on two: the replacement of Ag by Zn on the Ω interface and the formation of combined plates ofmore » the θ′ and C phases. Using atomically resolved scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy, we investigate the formation mechanisms, crystal structures and compositions of the precipitates. - Graphical abstract: Display Omitted - Highlights: • An aluminium alloy composition in-between the 2/6/7xxx systems was investigated. • Six different phases from the three systems coexist in an over-aged state. • All phases with 〈001〉{sub Al} coherencies can nucleate on 6xxx needle precipitates. • Modified theta′ and omega interfaces are observed.« less

Analysis of the ultrafine fraction of the Apollo 14 regolith

NASA Technical Reports Server (NTRS)

Finkelman, R. B.

1973-01-01

Analyses were obtained on more than 2400 randomly selected particles from the sub-37 micron (ultrafine) fraction of ten Apollo 14 regolith samples. The analyses were conducted with an energy dispersive electron microprobe system. The semiquantitative data were used to group the particles into ten categories. The pyroxene/plagioclase and olivine/plagioclase ratios are inconsistent with those ratios in the Apollo 14 breccias and rocks. The data suggest that fragmented basalts similar to Apollo 12 olivine basalts may have made significant contributions to the ultrafine fraction of the Fra Mauro regolith. Among a number of unusual particles encountered are brown, birefringent lath-shaped grains with 60 wt % SiO2 and 34 wt % FeO(FeSi2O5) and a glass with 20 to 25 wt % CaO, 0 to 8 wt % MgO, 40 to 45 wt % Al2O3 and approximately 30 wt % SiO2.

Synthesis of ultrafine ZrB2 powders by sol-gel process

NASA Astrophysics Data System (ADS)

Yang, Li-Juan; Zhu, Shi-Zhen; Xu, Qiang; Yan, Zhen-Yu; Liu, Ling

2010-09-01

Ultrafine zirconium diboride (ZrB2) powders have been synthesized by sol-gel process using zirconium oxychloride (ZrOCl2·8H2O), boric acid (H3BO3) and phenolic resin as sources of zirconia, boron oxide and carbon, respectively. The effects of the reaction temperature, B/Zr ratio, holding time, and EtOH/H2O ratio on properties of the synthesized ZrB2 powders were investigated. It was revealed that ultrafine (average crystallite size between 100 and 400 nm) ZrB2 powders can be synthesized with the optimum processing parameters as follows: (i) the ratio of B/Zr is 4; (ii) the solvent is pure ethanol; (iii) the condition of carbothermal reduction heat treatment is at 1550°C for 20 min.

Age hardening and creep resistance of cast Al–Cu alloy modified by praseodymium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Zhihao; Qiu, Feng; Wu, Xiaoxue

The effects of praseodymium on age hardening behavior and creep resistance of cast Al–Cu alloy were investigated. The results indicated that praseodymium facilitated the formation of the θ′ precipitates during the age process and improved the hardness of the Al–Cu alloy. Besides, praseodymium resulted in the formation of the Al{sub 11}Pr{sub 3} phase in the grain boundaries and among the dendrites of the modified alloy. Because of the good thermal stability of Al{sub 11}Pr{sub 3} phase, it inhibits grain boundary migration and dislocation movement during the creep process, which contributes to the improvement in the creep resistance of the modifiedmore » alloy at elevated temperatures. - Highlights: • Pr addition enhances the hardness and creep resistance of the Al–Cu alloy. • Pr addition facilitates the formation of the θ′ precipitates. • Pr addition results in the formation of the Al11Pr3 phase in the Al–Cu alloy.« less

Fabrication of solar cells based on Cu2ZnSnS4 prepared from Cu2SnS3 synthesized using a novel chemical procedure

NASA Astrophysics Data System (ADS)

Correa, John M.; Becerra, Raúl A.; Ramírez, Asdrubal A.; Gordillo, Gerardo

2016-11-01

Solar cells based on kesterite-type Cu2ZnSnS4 (CZTS) thin films were fabricated using a chemical route to prepare the CZTS films, consisting in sequential deposition of Cu2SnS3 (CTS) and ZnS thin films followed by annealing at 550 °C in nitrogen atmosphere. The CTS compound was prepared in a one-step process using a novel chemical procedure consisting of simultaneous precipitation of Cu2S and SnS2 performed by diffusion membranes assisted CBD (chemical bath deposition) technique. Diffusion membranes were used to optimize the kinetic growth through a moderate control of release of metal ions into the work solution. As the conditions for the formation in one step of the Cu2SnS3 compound have not yet been reported in literature, special emphasis was put on finding the parameters that allow growing the Cu2SnS3 thin films by simultaneous precipitation of Cu2S and SnS2. For that, we propose a methodology that includes numerical solution of the equilibrium equations that were established through a study of the chemical equilibrium of the system SnCl2, Na3C6H5O7·2H2O, CuCl2 and Na2S2O3·5H2O. The formation of thin films of CTS and CZTS free of secondary phases grown with a stoichiometry close to that corresponding to the Cu2SnS3 and Cu2ZnSnS4 phases, was verified through measurements of X-ray diffraction (XRD) and Raman spectroscopy. Solar cell with an efficiency of 4.2%, short circuit current of 16.2 mA/cm2 and open-circuit voltage of 0.49 V was obtained.

Removal of Cu(II) ions from contaminated waters using a conducting microfiltration membrane.

PubMed

Wang, Xueye; Wang, Zhiwei; Chen, Haiqin; Wu, Zhichao

2017-10-05

Efficient removal of toxic metals using low-pressure membrane processes from contaminated waters is an important but challenging task. In the present work, a conducting microfiltration membrane prepared by embedding a stainless steel mesh in the active layer of a polyvinylidene fluoride membrane is developed to remove Cu(II) ions from contaminated waters. Results showed that the conducting membrane had favorable electrochemical properties and stability as cathode. Batch tests showed that Cu(II) removal efficiency increased with the increase of voltages and leveled off with the further enhancement of electric field. The optimal voltages were determined to be 1.0V and 2.0V for the influent Cu(II) concentrations of 5mg/L and 30mg/L, respectively. X-ray photoelectron spectroscopy and X-ray diffraction results demonstrated the presence of Cu(0) and Cu(OH) 2 on the membrane surface. The removal mechanisms involved the intrinsic adsorption of membrane, electrosorption of membrane, adsorption of deposited layer, chemical precipitation of Cu(OH) 2 and deposition of Cu(0) which were aided by electrophoresis and electrochemical oxidation-reduction. Long-term tests showed that the major contributors for Cu(II) removal were the deposition of Cu(0) by electrochemical reduction-oxidation (47.3%±8.5%) and chemical precipitation (41.1%±0.2%), followed by electrosorption, adsorption by the fouling layer and membrane intrinsic sorption. Copyright © 2017 Elsevier B.V. All rights reserved.

Associations Between Ultrafine Particles and Co-Pollutant Concentrations in the Tampa Bay Area.

PubMed

Desai, Ushang; Watson, Alain

2016-05-01

Ultrafine particles (UFPs) are ubiquitous in urban air and have been recognized as a risk to human health. The aim of this study was to measure the relationships among ultrafine particles and other ambient air pollutants and meteorological factors in the Tampa Bay Area. This study measured continuous UFPs, black carbon, oxides of nitrogen (NO(x)), nitrogen dioxide (NO2), nitric oxide (NO), carbon monoxide (CO), ozone (O3), sulfur dioxide (SO2), particulate matter having an aerodynamic diameter of 10 microns or less (PM10), relative humidity, wind speed, and ambient temperature during January to March 2014. Moreover, the study compared the relationship between UFPs and various co-pollutants daily, including during morning rush hour periods. This study found a moderate correlation among UFPs and black carbon, NO(x), NO2, and NO during hourly continuous measurements and rush hour periods, and a low level of correlation among UFPs and CO, O3, SO2, PM10, relative humidity, wind speed, and ambient temperature. This study indicates that co-pollutants should not be used as a surrogate to assess the human health risk from ultrafine particles exposure.

LASER DESORPTION/IONIZATION OF SINGLE ULTRAFINE MULTICOMPONENT AEROSOLS. (R823980)

EPA Science Inventory

Laser desorption/ionization characteristics of single
ultrafine multicomponent aerosols have been investigated.
The results confirm earlier findings that (a) the negative
ion spectra are dominated by free electrons and (b) the ion
yield-to-mass ratio is higher for ...

Cu2S-Cu-TiO2 mesoporous carbon composites for the degradation of high concentration of methyl orange under visible light

NASA Astrophysics Data System (ADS)

Zhang, Liang; Zhao, Yuan; Zhong, Lvling; Wang, Yang; Chai, Shouning; Yang, Tao; Han, Xuanli

2017-11-01

A Schiff base compound was used to prepare a Cu2S-Cu-TiO2 mesoporous carbon composite photocatalyst (Cu2S-Cu-TiO2/MC) by a simple precipitation-carbonization method with a carbonization temperature of 750 °C. X-ray diffraction and x-ray photoelectron spectroscopy studies show that Cu2S, Cu, and TiO2 exist in Cu2S-Cu-TiO2/MC in the form of nanometer-sized particles. Scanning electron microscope and transmission electron microscope images show that the composites form a spherical carbon structure inlaid with Cu2S and Cu and coated TiO2. The Brunauer-Emmett-Teller test shows that the material has a large specific surface area (76.14 m2/g) and mesoporous structure. UV-vis diffuse reflection spectroscopy and photoluminescence spectroscopy indicate that the recombination of photo-generated electrons and holes in the samples were inhibited. The composites show good degradation performance in a high concentration (300 mg/L) of methyl orange (MO) solution under visible light. The composites exhibit great potential in the treatment of dyes for wastewater treatment.

Vascular effects of ultrafine particles in persons with type 2 diabetes

EPA Science Inventory

BACKGROUND: Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE: We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. ...

Air pollution ultrafine particles: toxicity beyond the lung.

PubMed

Terzano, C; Di Stefano, F; Conti, V; Graziani, E; Petroianni, A

2010-10-01

Ultrafine particles or nanoparticles (UFPs or PM0.1) are the fraction of ambient particulates with an aerodynamic diameter smaller than 0.1 microm. Currently UFPs are emerging as the most abundant particulate pollutants in urban and industrial areas, as their exposures have increased dramatically because of anthropogenic sources such as internal combustion engines, power plants, incinerators and many other sources of thermo-degradation. Ultrafine particles have been less studied than PM2.5 and PM10 particulates, mass concentrations of particles smaller than 2.5 and 10 microm, respectively. OBJECTIVE, EVIDENCE AND INFORMATION SOURCES: We examined the current scientific literature about the health effects of ultrafine particles exposure. UFPs are able to inhibit phagocytosis, and to stimulate inflammatory responses, damaging epithelial cells and potentially gaining access to the interstitium. They could be responsible for consistent reductions in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) in patients with asthma. Chronic exposure to UFPs can produce deleterious effects on the lung, also causing oxidative stress and enhancing pro-inflammatory effects in airways of COPD patients. Cardiovascular detrimental consequences due to UFPs exposure have observed in epidemiological studies, and could likely be explained by translocation of UFPs from the respiratory epithelium towards circulation and subsequent toxicity to vascular endothelium; alteration of blood coagulation; triggering of autonomic nervous system reflexes eventually altering the cardiac frequency and function. Once deposited deeply into the lung, UFPs--in contrast to larger-sized particles--appear to access to the blood circulation by different transfer routes and mechanisms, resulting in distribution throughout the body, including the brain, with potential neurotoxic consequences. UFPs represent an area of toxicology of emerging concern. A new concept of environmental medicine

CARDIOVASCULAR RESPONSES TO ULTRAFINE CARBON PARTICLE EXPOSURES IN RATS

EPA Science Inventory

TD-02-042 (U. KODAVANTI) GPRA # 10108

Cardiovascular Responses to Ultrafine Carbon Particle Exposures in Rats.
V. Harder1, B. Lentner1, A. Ziesenis1, E. Karg1, L. Ruprecht1, U. Kodavanti2, A. Stampfl3, J. Heyder1, H. Schulz1
GSF- Institute for Inhalation Biology1, I...

Evidence for Cu2-xSe platelets at grain boundaries and within grains in Cu(In,Ga)Se2 thin films

NASA Astrophysics Data System (ADS)

Simsek Sanli, E.; Ramasse, Q. M.; Mainz, R.; Weber, A.; Abou-Ras, D.; Sigle, W.; van Aken, P. A.

2017-07-01

Cu(In,Ga)Se2 (CIGS)-based solar cells reach high power-conversion efficiencies of above 22%. In this work, a three-stage co-evaporation method was used for their fabrication. During the growth stages, the stoichiometry of the absorbers changes from Cu-poor ([Cu]/([In] + [Ga]) < 1) to Cu-rich ([Cu]/([In] + [Ga]) > 1) and finally becomes Cu-poor again when the growth process is completed. It is known that, according to the Cu-In-Ga-Se phase diagram, a Cu-rich growth leads to the presence of Cu2-xSe (x = 0-0.25), which is assumed to assist in recrystallization, grain growth, and defect annihilation in the CIGS layer. So far, Cu2-xSe precipitates with spatial extensions on the order of 10-100 nm have been detected only in Cu-rich CIGS layers. In the present work, we report Cu2-xSe platelets with widths of only a few atomic planes at grain boundaries and as inclusions within grains in a polycrystalline, Cu-poor CIGS layer, as evidenced by high-resolution scanning transmission electron microscopy (STEM). The chemistry of the Cu-Se secondary phase was analyzed by electron energy-loss spectroscopy, and STEM image simulation confirmed the identification of the detected phase. These results represent additional experimental evidence for the proposed topotactical growth model for Cu-Se-assisted CIGS thin-film formation under Cu-rich conditions.

Tensile Properties and Fracture Characteristics of Nanostructured Copper and Cu-SiC Nanocomposite Produced by Mechanical Milling and Spark Plasma Sintering Process

NASA Astrophysics Data System (ADS)

Akbarpour, M. R.

2018-03-01

The presence of large grains within nanometric and ultrafine grain matrix is an effective method in order to enhance strength while keeping the high ductility of metals. For this purpose, in this research, spark plasma sintering (SPS) was used to consolidate milled Cu and Cu-SiC powders. In SPS process, local sparks with high temperature between particles take place and locally lead to intense grain growth, and therefore, this method has the ability to produce bimodal grain structures in copper and copper-based composites. Microstructural and mechanical studies showed ≈ 185 and ≈ 437 nm matrix grain sizes, high tensile yield strength values of ≈ 188.4 and ≈ 296.9 MPa, and fracture strain values of 15.1 and 6.7% for sintered Cu and Cu-4 vol.% SiC nanocomposite materials, respectively. The presence of nanoparticles promoted the occurrence of static recrystallization and decreased the fraction of coarse grains in microstructure. The high tensile properties of the produced materials are attributed to fine grain size, homogenous dispersion of nanoparticles and retarded grain boundary migration during sintering.

Comparison Between Different Processing Schedules for the Development of Ultrafine-Grained Dual-Phase Steel

NASA Astrophysics Data System (ADS)

Karmakar, Anish; Sivaprasad, S.; Nath, S. K.; Misra, R. D. K.; Chakrabarti, Debalay

2014-05-01

A comparative study was carried out on the development of ultrafine-grained dual-phase (DP) (ferrite-martensite) structures in a low-carbon microalloyed steel processed using two thermomechanical processing routes, (i) intercritical deformation and (ii) warm-deformation and intercritical annealing. The samples were deformed using Gleeble3500® simulator, maintaining a constant total strain ( ɛ = 1) and strain rate ( = 1/s). Evolution of microstructure and micro-texture was investigated by SEM, TEM, and EBSD. Ultrafine-grained DP structures could be formed by careful selection of deformation temperature, T def (for intercritical deformation) or annealing temperature, T anneal (for warm-deformation and annealing). Overall, the ferrite grain sizes ranged from 1.5 to 4.0 μm, and the sizes and fractions of the uniformly distributed fine-martensitic islands ranged from 1.5 to 3.0 μm and 15 to 45 pct, respectively. Dynamic strain-induced austenite-to-ferrite transformation followed by continuous (dynamic) recrystallization of the ferrite dictated the grain refinement during intercritical deformation, while, continuous (static) recrystallization by pronounced recovery dictated the grain refinement during the warm-deformation and the annealing. Regarding intercritical deformation, the samples cooled to T def indicated finer grain size compared with the samples heated to T def, which are explained in terms of the effects of strain partitioning on the ferrite and the heating during deformation. Alpha-fiber components dominated the texture in all the samples, and the fraction of high-angle boundaries (with >15 deg misorientation) increased with the increasing T def or T anneal, depending on the processing schedule. Fine carbide particles, microalloyed precipitates and austenitic islands played important roles in defining the mechanism of grain refinement that involved retarding conventional ferrite recrystallization and ferrite grain growth. With regard to the intercritical

[Research on NEDC ultrafine particle emission characters of a port fuel injection gasoline car].

PubMed

Hu, Zhi-Yuan; Li, Jin; Tan, Pi-Qiang; Lou, Di-Ming

2012-12-01

A Santana gasoline car with multi-port fuel injection (PFI) system was used as the research prototype and an engine exhaust particle sizer (EEPS) was employed to investigate the exhaust ultrafine particle number and size distribution characters of the tested vehicle in new European driving cycle (NEDC). The tested results showed that the vehicle's nuclear particle number, accumulation particle number, as well as the total particle number emission increased when the car drove in accelerated passage, and the vehicle's particle number emission was high during the first 40 seconds after test started and when the speed was over 90 km x h(-1) in extra urban driving cycle (EUDC) in NEDC. The ultrafine particle distribution of the whole NEDC showed a single peak logarithmic distribution, with diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameter was 24 nm. The ultrafine particle distribution of the urban driving cycle named by the economic commission for Europe (ECE) e. g. ECE I, ECE II - IV, the extra urban driving cycle e. g. EUDC, and the idling, constant speed, acceleration, deceleration operation conditions of NEDC all showed a single peak logarithmic distribution, also with particle diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameters of different driving cycle and different driving mode were from 14 nm to 42 nm. Therefore, the ultrafine particle emissions of the tested PFI gasoline car were mainly consisted of nuclear mode particles with a diameter of less than 50 nm.

Microstructure and properties of ultrafine grain nickel 200 after hydrostatic extrusion processes

NASA Astrophysics Data System (ADS)

Sitek, R.; Krajewski, C.; Kamiński, J.; Spychalski, M.; Garbacz, H.; Pachla, W.; Kurzydłowski, K. J.

2012-09-01

This paper presents the results of the studies of the structure and properties of ultrafine grained nickel 200 obtained by hydrostatic extrusion processes. Microstructure was characterized by means of optical microscopy and electron transmission microscopy. Corrosion resistance was studied by impedance and potentiodynamic methods using an AutoLab PGSTAT 100 potentiostat in 0.1 M Na2SO4 solution and in acidified (by addition of H2SO4) 0.1 M NaCl solution at pH = 4.2 at room temperature. Microhardness tests were also performed. The results showed that hydrostatic extrusion produces a heterogeneous, ultrafine-grained microstructure in nickel 200. The corrosive resistance tests showed that the grain refinement by hydrostatic extrusion is accompanied by a decreased corrosive resistance of nickel 200.

Soot, organics and ultrafine ash from air- and oxy-fired coal ...

EPA Pesticide Factsheets

This paper is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practically relevant stoichiometric ratios (SR = 1.2-1.4), but with the ability to maintain constant residence times (2.3 s). Experiments were conducted using a pulverized bituminous coal under air-combustion and three oxy-combustion inlet oxygen conditions (28, 32, and 36%). Size-classified fly ash samples were collected, and measurements focused on the composition of the total and ultrafine (<0.6 µm) fly ash produced, in particular the soot, elemental carbon (EC), and organic carbon (OC) fractions. Results indicate that although the total fly ash carbon, as measured by loss on ignition, was always acceptably low (<2%) with all three oxy-combustion conditions lower than air-combustion, the ultrafine fly ash for both air-fired and oxy-fired combustion conditions consists primarily of carbonaceous material (50-95%). Subsequent analyses of the carbonaceous component on particles <0.6 µm by a thermal optical method showed that large fractions (52-93%) consisted of OC rather than EC, as expected. This observation was supported by thermogravimetric analysis indicating that for the air, 28% oxy, and 32% oxy conditions, 14-71% of this material may be OC volatilizing between 100 and 550 °C with the remaining

Ultrafine fibers of zein and anthocyanins as natural pH indicator.

PubMed

Prietto, Luciana; Pinto, Vania Zanella; El Halal, Shanise Lisie Mello; de Morais, Michele Greque; Costa, Jorge Alberto Vieira; Lim, Loong-Tak; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa

2018-05-01

pH-sensitive indicator membranes, which are useful for pharmaceutical, food, and packaging applications, can be formed by encapsulating halochromic compounds within various solid supports. Accordingly, electrospinning is a versatile technique for the development of these indicators, by entrapping pH dyes within ultrafine polymer fibers. The ultrafine zein fibers, containing 5% (w/v) anthocyanins, had an average diameter of 510 nm. The pH-sensitive membrane exhibited color changes from pink to green when exposed to acidic and alkaline buffers, respectively. The contact angle was negligible after 10 and 2 s for neat and 5% anthocyanin-loaded zein membranes, respectively. The pH membranes exhibited color changes in a board pH range, which can potentially be used in various active packaging applications. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Microstructures and Mechanical Properties of Cu and Cu-Zn Alloys

NASA Astrophysics Data System (ADS)

Ma, Xiaolong

Strength and ductility are two crucial mechanical properties of structural materials, which, unfortunately, are often mutually exclusive based on the conventional design of microstructures and their deformation physics. This is also true in most nanostructured (NS) metals and alloys although they exhibit record-high strength. However, the disappointingly inadequate ductility becomes the major roadblock to their practical utilities due to the threat of catastrophic failure in load-bearing applications. Therefore, simultaneous improvement of strength and ductility or a well-defined trade-off between these two properties, i.e. increasing either of them without significant loss of the other, in NS materials has garnered extensive efforts from the research community. A few strategies have been explored to handle this long-standing challenge with promise. In this dissertation work, two of those strategies, deformation twins and laminate/gradient structures are specified with particular interests in NS Cu and Cu-Zn alloys. The author believes the observation and the revealed underlying mechanism are fundamental and therefore shed lights on their universal application to other metallic material systems. Deformation twins have been frequently observed in ultra-fined grained (UFG) and NS face-centered cubic (FCC) metals and alloys, which is closely related to the better strengthening and strain hardening in mechanical performance. Previous findings even show that there exist an optimum grain size range within nano scale, where the deformation twins are of most frequency, i.e. most stable in pure FCC metals. However, such grain-size dependent twinning phenomenon is still unclear in FCC alloys. We report, for the first time in systematic experiments, the observed optimum grain sizes for deformation twins in NS Cu-Zn alloys slightly increase with increasing Zn content. Our results indicate that alloying changes the relationship between the stacking-fault and twin-fault energy

About the contrast of δ' precipitates in bulk Al-Cu-Li alloys in reflection mode with a field-emission scanning electron microscope at low accelerating voltage.

PubMed

Brodusch, Nicolas; Voisard, Frédéric; Gauvin, Raynald

2017-11-01

Characterising the impact of lithium additions in the precipitation sequence in Al-Li-Cu alloys is important to control the strengthening of the final material. Since now, transmission electron microscopy (TEM) at high beam voltage has been the technique of choice to monitor the size and spatial distribution of δ' precipitates (Al 3 Li). Here we report on the imaging of the δ' phase in such alloys using backscattered electrons (BSE) and low accelerating voltage in a high-resolution field-emission scanning electron microscope. By applying low-energy Ar + ion milling to the surface after mechanical polishing (MP), the MP-induced corroded layers were efficiently removed and permitted the δ's to be visible with a limited impact on the observed microstructure. The resulting BSE contrast between the δ's and the Al matrix was compared with that obtained using Monte Carlo modelling. The artefacts possibly resulting from the sample preparation procedure were reviewed and discussed and permitted to confirm that these precipitates were effectively the metastable δ's. The method described in this report necessitates less intensive sample preparation than that required for TEM and provides a much larger field of view and an easily interpretable contrast compared to the transmission techniques. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

High solar-light photocatalytic activity of using Cu3Se2/rGO nanocomposites synthesized by a green co-precipitation method

NASA Astrophysics Data System (ADS)

Nouri, Morteza; Saray, Abdolali Moghaddam; Azimi, H. R.; Yousefi, Ramin

2017-11-01

Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu2Se3 with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu2Se3/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.

First-principles calculations of stability, electronic and elastic properties of the precipitates present in 7055 aluminum alloy

NASA Astrophysics Data System (ADS)

Huang, Cheng; Shao, Hongbang; Ma, Yunlong; Huang, Yuanchun; Xiao, Zhengbing

2018-04-01

The structural stability, electronic structures and elastic properties of the strengthening precipitates, namely Al3Zr, MgZn2, Al2CuMg and Al2Cu, present in 7055 aluminum alloy were investigated by the first-principles calculations based on density functional theory (DFT). The optimized structural parameters are in good agreement with literature values available. It is found that Al3Zr has the strongest alloying ability and structural stability, while for MgZn2, its structural stability is the worst. The calculated electronic results indicate that covalent bonding is the dominant cohesion of Al3Zr, whereas the fractional ionic interactions coexisting with metallic bonding are found in MgZn2, Al2CuMg and Al2Cu. The elastic constants Cij of these precipitates were calculated, and the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and universal elastic anisotropy were derived. It is suggested that MgZn2 is ductile, whereas Al3Zr, Al2CuMg and Al2Cu are brittle, and the elastic anisotropies of them increase in the following sequence: Al3Zr CuMg Cu. The formation of MgZn2 and Al3Zr should be promoted by increasing the compositions of Zn and Zr to improve the alloy’s performance further.

Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

NASA Astrophysics Data System (ADS)

Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

2016-11-01

The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones.

An empirical method for estimating instream pre-mining pH and dissolved Cu concentration in catchments with acidic drainage and ferricrete

USGS Publications Warehouse

Nimick, D.A.; Gurrieri, J.T.; Furniss, G.

2009-01-01

Methods for assessing natural background water quality of streams affected by historical mining are vigorously debated. An empirical method is proposed in which stream-specific estimation equations are generated from relationships between either pH or dissolved Cu concentration in stream water and the Fe/Cu concentration ratio in Fe-precipitates presently forming in the stream. The equations and Fe/Cu ratios for pre-mining deposits of alluvial ferricrete then were used to reconstruct estimated pre-mining longitudinal profiles for pH and dissolved Cu in three acidic streams in Montana, USA. Primary assumptions underlying the proposed method are that alluvial ferricretes and modern Fe-precipitates share a common origin, that the Cu content of Fe-precipitates remains constant during and after conversion to ferricrete, and that geochemical factors other than pH and dissolved Cu concentration play a lesser role in determining Fe/Cu ratios in Fe-precipitates. The method was evaluated by applying it in a fourth, naturally acidic stream unaffected by mining, where estimated pre-mining pH and Cu concentrations were similar to present-day values, and by demonstrating that inflows, particularly from unmined areas, had consistent effects on both the pre-mining and measured profiles of pH and Cu concentration. Using this method, it was estimated that mining has affected about 480 m of Daisy Creek, 1.8 km of Fisher Creek, and at least 1 km of Swift Gulch. Mean values of pH decreased by about 0.6 pH units to about 3.2 in Daisy Creek and by 1-1.5 pH units to about 3.5 in Fisher Creek. In Swift Gulch, mining appears to have decreased pH from about 5.5 to as low as 3.6. Dissolved Cu concentrations increased due to mining almost 40% in Daisy Creek to a mean of 11.7 mg/L and as much as 230% in Fisher Creek to 0.690 mg/L. Uncertainty in the fate of Cu during the conversion of Fe-precipitates to ferricrete translates to potential errors in pre-mining estimates of as much as 0.25 units

[The study of ultra-fine diamond powder used in magnetic head polishing slurry].

PubMed

Jin, Hong-Yun; Hou, Shu-En; Pan, Yong; Xiao, Hong-Yan

2008-05-01

In the present paper, atomic absorption spectrometry(AAS), inductively-coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and laser Raman spectroscopy (RM) were employed to study the commercial ultra-fine diamond powders prepared by the static pressure-catalyst method and used in magnetic head polishing slurry. The results of AAS and ICP-MS indicated that there were silicon oxide, Fe, Ni, Al and some other metal elements in the ultra-fine powders. XRD patterns showed the peaks of SiO2 at 2theta = 35.6 degrees, 39.4 degrees and 59.7 degrees and diamond sharp peaks in agreement with the results above. Diamond sharp peaks implied perfect crystal and high-hardness beneficial to high-efficiency in polishing. The broader Raman band of graphite at 1 592 cm(-1) observed by Raman analysis proved graphite existing in the diamond powders. In the TEM images, the size of ultra-fine powders was estimated between 0.1 and 0.5 microm distributed in a wide scope, however, sharp edges of the powder particles was useful to polish. The ultra-fine diamond powders have many advantages, for example, high-hardness, well abrasion performance, high-polishing efficiency and being useful in magnetic head polishing slurry. But, the impurities influence the polishing efficiency, shortening its service life and the wide distribution reduces the polishing precision. Consequently, before use the powders must be purified and classified. The purity demands is 99.9% and trace silicon oxide under 0.01% should be reached. The classification demands that the particle distribution should be in a narrower scope, with the mean size of 100 nm and the percentage of particles lager than 200 nm not over 2%.

The influence of reagent type on the kinetics of ultrafine coal flotation

USGS Publications Warehouse

Read, R.B.; Camp, L.R.; Summers, M.S.; Rapp, D.M.

1989-01-01

A kinetic study has been conducted to determine the influence of reagent type on flotation rates of ultrafine coal. Two ultrafine coal samples, the Illinois No. 5 (Springfield) and Pittsburgh No. 8, have been evaluated with various reagent types in order to derive the rate constants for coal (kc), ash (ka), and pyrite (kc). The reagents used in the study include anionic surfactants, anionic surfactant-alcohol mixtures, and frothing alcohols. In general, the surfactant-alcohol mixtures tend to float ultrafine coal at a rate three to four times faster than either pure alcohols or pure anionic surfactants. Pine oil, a mixture of terpene alcohols and hydrocarbons, was an exception to this finding; it exhibited higher rate constants than the pure aliphatic alcohols or other pure anionic surfactants studied; this may be explained by the fact that the sample of pine oil used (70% alpha-terpineol) acted as a frother/collector system similar to alcohol/kerosene. The separation efficiencies of ash and pyrite from coal, as evidenced by the ratios of kc/ka or kc/kp, tend to indicate, however, that commercially available surfactant-alcohol mixtures are not as selective as pure alcohols such as 2-ethyl-1-hexanol or methylisobutylcarbinol. Some distinct differences in various rate constants, or their ratios, were noted between the two coals studied, and are possibly attributable to surface chemistry effects. ?? 1989.

Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

NASA Astrophysics Data System (ADS)

Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

2016-07-01

An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

Physicochemical properties and ability to generate free radicals of ambient coarse, fine, and ultrafine particles in the atmosphere of Xuanwei, China, an area of high lung cancer incidence

NASA Astrophysics Data System (ADS)

Lu, Senlin; Yi, Fei; Hao, Xiaojie; Yu, Shang; Ren, Jingjing; Wu, Minghong; Jialiang, Feng; Yonemochi, Shinich; Wang, Qingyue

2014-11-01

The link between the high incidence of lung cancer and harmful pollutants emitted by local coal combustion in Xuanwei, Yunnan province, China, has been a focus of study since the 1980s. However, the mechanisms responsible for the high lung cancer rate remain unclear, necessitating further study. Since a close relationship between ambient air particle pollution and respiratory diseases exists, we sampled size-resolved ambient particles from the atmosphere of Xuanwei. In our indoor experiment, cutting-edge methods, including scanning electron microscopy coupled with energy dispersive X-ray detection (SEM/EDX), particle-induced X-ray emission (PIXE), electronic paramagnetic resonance (EPR) and the cell-free DCFH-DA assay, were employed to investigate the physicochemical properties, the potential to generate free radicals and the oxidative potential of ambient coarse (diameter, 1.8-10 μm), fine (diameter, 0.1-1.8 μm), and ultrafine (diameter, <0.1 μm) particles. We found the total mass concentrations of the size-resolved particles collected in spring were higher than that in early winter. Mass percentage of fine particles accounted for 68% and 61% of the total particulate mass in spring and in early winter samples, respectively, indicating that fine particles were the major component of the Xuanwei ambient particulate matters. On the other hand, the results of SEM/EDX analysis showed that the coarse particles were dominated by minerals, the fine particles by soot aggregates and fly ashes, and the ultrafine particles by soot particles and unidentified particles. Our PIXE results revealed that crustal elements (Ca, Ti Si, Fe) were mainly distributed in coarse particles, while trace metals (Cr, Mn, Ni, Cu, Zn, Pb) dominated in the fine particle fraction, and S, a typical element emitted by coal combustion, mainly resided in fine particles collected from the winter atmosphere. EPR results indicated that the magnitude of free radical intensity caused by size

Ultrafine particles in cities.

PubMed

Kumar, Prashant; Morawska, Lidia; Birmili, Wolfram; Paasonen, Pauli; Hu, Min; Kulmala, Markku; Harrison, Roy M; Norford, Leslie; Britter, Rex

2014-05-01

Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Estimation of the contribution of ultrafine particles to lung deposition of particle-bound mutagens in the atmosphere.

PubMed

Kawanaka, Youhei; Matsumoto, Emiko; Sakamoto, Kazuhiko; Yun, Sun-Ja

2011-02-15

The present study was performed to estimate the contributions of fine and ultrafine particles to the lung deposition of particle-bound mutagens in the atmosphere. This is the first estimation of the respiratory deposition of atmospheric particle-bound mutagens. Direct and S9-mediated mutagenicity of size-fractionated particulate matter (PM) collected at roadside and suburban sites was determined by the Ames test using Salmonella typhimurium strain TA98. Regional deposition efficiencies in the human respiratory tract of direct and S9-mediated mutagens in each size fraction were calculated using the LUDEP computer-based model. The model calculations showed that about 95% of the lung deposition of inhaled mutagens is caused by fine particles for both roadside and suburban atmospheres. Importantly, ultrafine particles were shown to contribute to the deposition of mutagens in the alveolar region of the lung by as much as 29% (+S9) and 26% (-S9) for the roadside atmosphere and 11% (+S9) and 13% (-S9) for the suburban atmosphere, although ultrafine particles contribute very little to the PM mass concentration. These results indicated that ultrafine particles play an important role as carriers of mutagens into the lung. Copyright © 2010 Elsevier B.V. All rights reserved.

[Spatial variations of heavy metals in precipitation at Mount Taishan region].

PubMed

Wang, Yan; Liu, Xiao-Huan; Jin, Ling-Ren; Yue, Tai-Xing; Wang, De-Zhong; Wang, Wen-Xing

2007-11-01

Zn, Al, Mn, Fe, Pb, Cu, Ni, Cr, As, Cd in rain samples collected from two sites at Mount Taishan region were determined by ICP-MS, to evaluate the spatial variation characteristics of heavy metals in precipitation. Individual rain events were sampled for one whole year from Jan. to Dec. 2006. High concentrations of heavy metals were found at both sites, indicating serious heavy metal pollution. Zn was the most abundant element, accounting for 54% - 57% of the total metals concentrations. Its volume-weighted mean concentrations of precipitation at Mt-top and Mt-foot sites were 92.94 microg/L and 70.41 microg/L respectively. The following elements were Fe, Al and Mn and their concentrations were much higher than toxic heavy metals (As, Cd and Cd) except Pb (8.04 microg/L and 7.79 microg/L at two sites respectively). Comparison results between two sites suggested that heavy metal characteristics of precipitation at two sites were different, due to the influences of different ambient air conditions. Correlation analysis between two sites showed that Al, Mn, Fe, As, Cd, Pb influenced by air mass origin greatly, while Ni, Cu, Zn affected by other different factors.

An Investigation of Physico-Mechanical Properties of Ultrafine-Grained Magnesium Alloys Subjected to Severe Plastic Deformation

NASA Astrophysics Data System (ADS)

Kozulyn, A. A.; Skripnyak, V. A.; Krasnoveikin, V. A.; Skripnyak, V. V.; Karavatskii, A. K.

2015-01-01

The results of investigations of physico-mechanical properties of specimens made from the structural Mg-based alloy (Russian grade Ma2-1) in its coarse-grained and ultrafine-grained states after SPD processing are presented. To form the ultrafine-grained structure, use was made of the method of orthogonal equal-channel angular pressing. After four passes through the die, a simultaneous increase was achieved in microhardness, yield strength, ultimate tensile strength and elongation to failure under conditions of uniaxial tensile loading.

Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into intact and tape-stripped human skin

NASA Astrophysics Data System (ADS)

Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Major, I.; Borbíró, I.; Kiss, Á. Z.; Hunyadi, J.

2010-06-01

Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the small particle size makes the product more transparent compared to formulations containing coarser particles. In the present work the penetration of ultrafine zinc oxide into intact and tape-stripped human skin was investigated using nuclear microprobe techniques, such as proton induced X-ray spectroscopy and scanning transmission ion microscopy. Our results indicate that the penetration of ultrafine zinc oxide, in a hydrophobic basis gel with 48 h application time, is limited to the stratum corneum layer of the intact skin. Removing the stratum corneum partially or entirely by tape-stripping did not cause the penetration of the particles into the deeper dermal layers; the zinc particles remained on the surface of the skin.

Ultrafine manganese dioxide nanowire network for high-performance supercapacitors.

PubMed

Jiang, Hao; Zhao, Ting; Ma, Jan; Yan, Chaoyi; Li, Chunzhong

2011-01-28

Ultrafine MnO(2) nanowires with sub-10 nm diameters have been synthesized by a simple process of hydrothermal treatment with subsequent calcinations to form networks that exhibit an enhanced specific capacitance (279 F g(-1) at 1 A g(-1)), high rate capability (54.5% retention at 20 A g(-1)) and good cycling stability (1.7% loss after 1000 cycles).

ENHANCED TOXICITY OF CHARGED CARBON NANOTUBES AND ULTRAFINE CARBON BLACK PARTICLES

EPA Science Inventory

Man-made carbonaceous nano-particles such as single and multi-walled carbon nano-tubes (CNT) and ultra-fine carbon black (UFCB) particles are finding increasing applications in industry, but their potential toxic effects is of concern. In aqueous media, these particles cluster in...

A practice of ultra-fine tailings disposal as filling material in a gold mine.

PubMed

Deng, D Q; Liu, L; Yao, Z L; Song, K I-I L; Lao, D Z

2017-07-01

A practice of cemented backfill technology with ultra-fine tailings in a gold mine was comprehensively presented, and a series of tests were conducted in accordance with the peculiar properties of ultra-fine tailings and the mining technology conditions. The test results show that, the tailings from Shuiyindong Gold Mine have a great grinding fineness, with the average particle diameter 22.03 μm, in which the ultra-fine particles with the diameter below 20 μm occupying 66.13%. The analysis results of chemical components of tailings indicate that the content of SiO 2 is relatively low, i.e., 33.08%, but the total content of CaO, MgO and Al 2 O 3 is relatively high i.e., 36.5%. After the settlement of 4-6 h, the tailing slurry with the initial concentration of 40% has the maximum settling concentration of 54.692%, and the corresponding maximum settling unit weight is 1.497 g/cm 3 . During the field application, the ultra-fine tailings and PC32.5 cement were mixed with the cement-tailings ratios of 1:3-1:8, and the slurry concentration of 50 wt% was prepared. Using the slurry pump, the prepared cemented backfill slurries flowed into the goaf, and then the strength of the cemented backfill body met the mining technique requirements in Shuiyindong Gold Mine, where the ore body has a smooth occurrence, with the average thickness of approximately 2 m and the inclination angle ranging from 5 to 10°. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of aging time and temperature of Fe-1wt.%Cu on magnetic Barkhausen noise and FORC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saleh, Muad; Cao, Yue; Edwards, Danny J.

Magnetic Barkhausen noise (MBN), hysteresis measurements, first order reversal curves (FORC), Vickers microhardness, and Transmission Electron Microscopy (TEM) analyses were performed on Fe-1wt.%Cu (Fe-Cu) samples isothermally aged at 700°C for 0.5 – 25 hours to obtain samples with different sized Cu precipitates and dislocation structures. Fe-Cu is used to simulate the thermal and irradiation-induced defects in copper-containing nuclear reactor materials such as cooling system pipes and pressure vessel materials. The sample series showed an initial increase followed by a decrease in hardness and coercivity with aging time, which is explained by Cu precipitates formation and growth as observed by TEMmore » measurements. Further, the MBN envelope showed a continuous decrease in its magnitude and the appearance of a second peak with aging. Also, FORC diagrams showed multiple peaks whose intensity and location changed for different aging time. The changes in FORC diagrams are attributed to combined changes of the magnetic behavior due to Cu precipitate characteristics and dislocation structure. A second series of samples aged at 850°C, which is above the solid solution temperature of Fe-Cu, was studied to isolate the effects of dislocations. These samples showed a continuous decrease in MBN amplitude with aging time although the coercivity and hardness did not change significantly. The decrease of MBN amplitude and the appearance of the second MBN envelope peak are attributed to the changes in dislocation density and structure. This study shows that the effect of dislocations on MBN and FORC of Fe-Cu materials can vary significantly and should be considered in interpreting magnetic signatures.« less

Ultrafine Angelica gigas powder normalizes ovarian hormone levels and has antiosteoporosis properties in ovariectomized rats: particle size effect.

PubMed

Choi, Kyeong-Ok; Lee, Inae; Paik, Sae-Yeol-Rim; Kim, Dong Eun; Lim, Jung Dae; Kang, Wie-Soo; Ko, Sanghoon

2012-10-01

The root of Angelica gigas (Korean angelica) is traditionally used to treat women's ailments that are caused by an impairment of menstrual blood flow and cycle irregularities. This study evaluated the effect particle size of Korean angelica powder on its efficacy for treating estrogen-related symptoms of menopause. Initially, Korean angelica roots were pulverized into ultrafine powder, and orally administered to the rats at a concentration of 500 mg/kg body weight for 8 weeks. The effects of Korean angelica powder particle size on extraction yield, contents of bioactive compounds (decursin and decursinol angelate), levels of serum ovarian hormones (estradiol and progesterone), reproductive hormones (luteinizing hormone and follicle-stimulating hormone), and experimental osteoporosis parameters (mineral density, strength, and histological features) were determined. A significant increase (fivefold) in the contents of decursin and decursinol angelate in the extract of the ultrafine Korean angelica powder was observed compared to coarse Korean angelica powder. Rats were divided into sham-operated or ovariectomized (OVX) groups that were fed coarse (CRS) or ultrafine (UF) ground Korean angelica root. The serum levels of estradiol in the OVX_UF group were 19.2% and 54.1% higher than that of OVX_CRS group. Serum bone-alkaline phosphatase/total-alkaline phosphatase index in the OVX_UF group was half that of the OVX_CRS group. In addition, less trabecular bone loss and thick cortical areas were observed in rats administered ultrafine powder. Therefore, ultrafine grinding may enhance the bioactivity of herbal medicines and be especially useful when their extracted forms lose bioactivity during processing, storage, and oral intake.

Imaging of DNA Ultrafine Bridges in Budding Yeast.

PubMed

Quevedo, Oliver; Lisby, Michael

2018-01-01

DNA ultrafine bridges (UFBs) are a type of chromatin-free DNA bridges that connect sister chromatids in anaphase and pose a threat to genome stability. However, little is known about the origin of these structures, and how they are sensed and resolved by the cell. In this chapter, we review tools and methods for studying UFBs by fluorescence microscopy including chemical and genetic approaches to induce UFBs in the model organism Saccharomyces cerevisiae.

Preservation of amorphous ultrafine material: A proposed proxy for slip during recent earthquakes on active faults

PubMed Central

Hirono, Tetsuro; Asayama, Satoru; Kaneki, Shunya; Ito, Akihiro

2016-01-01

The criteria for designating an “Active Fault” not only are important for understanding regional tectonics, but also are a paramount issue for assessing the earthquake risk of faults that are near important structures such as nuclear power plants. Here we propose a proxy, based on the preservation of amorphous ultrafine particles, to assess fault activity within the last millennium. X-ray diffraction data and electron microscope observations of samples from an active fault demonstrated the preservation of large amounts of amorphous ultrafine particles in two slip zones that last ruptured in 1596 and 1999, respectively. A chemical kinetic evaluation of the dissolution process indicated that such particles could survive for centuries, which is consistent with the observations. Thus, preservation of amorphous ultrafine particles in a fault may be valuable for assessing the fault’s latest activity, aiding efforts to evaluate faults that may damage critical facilities in tectonically active zones. PMID:27827413

Precipitation in Al-Cu-Li alloys: from the kinetics of T1 phase precipitation to microstructure development in friction stir welds

NASA Astrophysics Data System (ADS)

Deschamps, A.; de Geuser, F.; Decreus, B.; Malard, B.

Al-Cu-Li based alloys are experiencing a rapid development for aerospace applications. The main hardening phase of this system (T1-Al2CuLi) forms as thin platelets (1 nm) that can reach diameters of 50 to 100 nm with remarkable stability in temperature. The nucleation, growth and thickening mechanisms of this phase are of crucial importance for the understanding of the microstructures resulting from simple to complex thermo-mechanical treatments, including friction stir welding of such alloys.

Combustion-derived ultrafine particles transport organic toxicants to target respiratory cells.

PubMed

Penn, Arthur; Murphy, Gleeson; Barker, Steven; Henk, William; Penn, Lynn

2005-08-01

Epidemiologic evidence supports associations between inhalation of fine and ultrafine ambient particulate matter [aerodynamic diameter < or = 2.5 microm (PM2.5)] and increases in cardiovascular/respiratory morbidity and mortality. Less attention has been paid to how the physical and chemical characteristics of these particles may influence their interactions with target cells. Butadiene soot (BDS), produced during combustion of the high-volume petrochemical 1,3-butadiene, is rich in polynuclear aromatic hydrocarbons (PAHs), including known carcinogens. We conducted experiments to characterize BDS with respect to particle size distribution, assembly, PAH composition, elemental content, and interaction with respiratory epithelial cells. Freshly generated, intact BDS is primarily (> 90%) PAH-rich, metals-poor (nickel, chromium, and vanadium concentrations all < 1 ppm) PM2.5, composed of uniformly sized, solid spheres (30-50 nm) in aggregated form. Cells of a human bronchial epithelial cell line (BEAS-2B) exhibit sequential fluorescent responses--a relatively rapid (approximately 30 min), bright but diffuse fluorescence followed by the slower (2-4 hr) appearance of punctate cytoplasmic fluorescence--after BDS is added to medium overlying the cells. The fluorescence is associated with PAH localization in the cells. The ultrafine BDS particles move down through the medium to the cell membrane. Fluorescent PAHs are transferred from the particle surface to the cell membrane, cross the membrane into the cytosol, and appear to accumulate in lipid vesicles. There is no evidence that BDS particles pass into the cells. The results demonstrate that uptake of airborne ultrafine particles by target cells is not necessary for transfer of toxicants from the particles to the cells.

Nanocrystallization of Zr-Cu-Ni-Al-Au glassy alloys during severe plastic deformation

NASA Astrophysics Data System (ADS)

Yamada, Masahiro; Kamisato, Ryo; Yamasaki, Tohru; Adachi, Hiroki; Tsuchiya, Koichi; Yokoyama, Yoshihiko

2014-08-01

A study has been carried out into the formation of nanocrystalline grains during high-pressure torsion (HPT) deformation of Zr65Cu17Ni5Al10Au3 bulk alloys prepared using tilt casting. As a preliminary to this, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were carried out on as-cast Zr65+xCu17-xNi5Al10Au3 (x=0~5 at.%) and Zr65Cu20Ni5Al10Au3 alloys, in order to determine the effect on the microstructure of the excess Zr content x and the presence of Au. From the XRD patterns, it was determined that all of the alloys had a metallic glassy nature. For Zr65Cu17Ni5Al10Au3, the DSC results indicated the presence of a wide supercooled liquid region between the glass transition temperature (Tg) of 644 K and the crystallization temperature of 763 K, where the stable body-centered tetragonal Zr2Cu phase was formed. In contrast, for the Zr65+xCu17-xNi5Al10Au3 alloys, precipitation of an icosahedral quasicrystalline phase (I-phase) was observed in the supercooled liquid region at about 715 K. HPT deformation of the Zr65Cu17Ni5Al10Au3 alloys was carried out under a high pressure of 5 GPa. Both as-cast specimens and those annealed at Tg-50 K for 90 min were used. Following a single HPT rotation (N=1), transmission electron microscopy identified the presence of face- centered cubic Zr2Ni precipitates in the as-cast alloy, with a size of about 50 nm. For the annealed alloy, a high density of I-phase precipitates with sizes of less than 10 nm was observed following HPT with N=10, indicating that the combination of severe plastic deformation and annealing is effective at producing extremely small grains.

Process for making ultra-fine ceramic particles

DOEpatents

Stangle, Gregory C.; Venkatachari, Koththavasal R.; Ostrander, Steven P.; Schulze, Walter A.

1995-01-01

A process for producing ultra-fine ceramic particles in which droplets are formed from a ceramic precursor mixture containing a metal cation, a nitrogen-containing fuel, a solvent, and an anion capable of participating in an anionic oxidation-reduction reaction with the nitrogen containing fuel. The nitrogen-containing fuel contains at least three nitrogen atoms, at least one oxygen atom, and at least one carbon atom. The ceramic precursor mixture is dried to remove at least 85 weight percent of the solvent, and the dried mixture is then ignited to form a combusted powder.

Fabrication of ultra-fine grained aluminium tubes by RTES technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarzadeh, H., E-mail: h.jafarzadeh@ut.ac.ir; Abrinia, K.

Recently, repetitive tube expansion and shrinking have been exploited as a means for producing ultra-fine grained and nano-crystalline microstructures for magnesium alloy tubes. This method includes two different half-cycles and was based on pressing a tubular part through an angular channel die with two shear zones. Since the aluminium alloys are the most widely used materials in industries, in this study, repetitive tube expansion and shrinking as a new severe plastic deformation technique was applied to commercially pure aluminium for fabricating ultra-fine grained aluminium tubes for the first time and the ability of this process in significant grain refinement ismore » determined even after single cycle. Transmission electron microscopy and X-ray diffraction were used to evaluate the microstructure of the repetitive tube expansion and shrinking processed materials and the examinations showed ultra-fine grains with the average grain size of 320 nm after one cycle of repetitive tube expansion and shrinking. The yield strength, ultimate tensile strength increased notably by the factor of 2.17 and 1.27 respectively, after one cycle of repetitive tube expansion and shrinking, whereas the elongation to failure as well as the uniform elongation decreased. Furthermore, micro-hardness distribution through the part's section proposed the hardness increasing to ~ 55 HV from the initial value of ~ 28 HV after one cycle of repetitive tube expansion and shrinking. - Highlights: • RTES was introduced for fabricating the UFGed AA1050 tubes for the first time. • Nano-grained AA1050 tube was obtained by RTES process. • Grain size of ~ 320 nm was obtained after two half-cycles of RTES process. • Yield and ultimate strength increased by the factor of 2.17 and 1.27 respectively. • The microhardness increased to ~ 55 HV from the initial value of ~ 28 HV.« less

CARDIOVASCULAR RESPONSES IN UNRESTRAINED WKY-RATS TO INHALED ULTRAFINE CARBON PARTICLES

EPA Science Inventory

Abstract
This study provides evidence for adverse cardiac effects of inhaled ultrafine particles (UFPs) in healthy WKY rats. Short term exposure (24 h) with carbon UFPs (180 ?g?m ?) induced a moderate but significant heart rate increase of 18 bpm (4.8 %) in association with a ...

Precipitation and runoff water quality from an urban parking lot and implications for tree growth

Treesearch

C. H. Pham; H. G. Halverson; G. M. Heisler

1978-01-01

The water quality of precipitation and runoff from a large parking lot in New Brunswick, New Jersey was studied during the early growing season, from March to June 1976. Precipitation and runoff from 10 storms were analyzed. The runoff was higher in all constituents considered except for P, Pb, and Cu. Compared with published values for natural waters, sewage effluent...

Polymer-supported CuPd nanoalloy as a synergistic catalyst for electrocatalytic reduction of carbon dioxide to methane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Sheng; Kang, Peng; Bakir, Mohammed

2015-12-14

Developing sustainable energy strategies based on CO2 reduction is an increasingly important issue given the world’s continued reliance on hydrocarbon fuels and the rise in CO2 concentrations in the atmosphere. An important option is electrochemical or photoelectrochemical CO2 reduction to carbon fuels. We describe here an electrodeposition strategy for preparing highly dispersed, ultrafine metal nanoparticle catalysts on an electroactive polymeric film including nanoalloys of Cu and Pd. Compared with nanoCu catalysts, which are state-of-the-art catalysts for CO2 reduction to hydrocarbons, the bimetallic CuPd nanoalloy catalyst exhibits a greater than twofold enhancement in Faradaic efficiency for CO2 reduction to methane. Themore » origin of the enhancement is suggested to arise from a synergistic reactivity interplay between Pd–H sites and Cu–CO sites during electrochemical CO2 reduction. The polymer substrate also appears to provide a basis for the local concentration of CO2 resulting in the enhancement of catalytic current densities by threefold. The procedure for preparation of the nanoalloy catalyst is straightforward and appears to be generally applicable to the preparation of catalytic electrodes for incorporation into electrolysis devices.« less

Polymer-supported CuPd nanoalloy as a synergistic catalyst for electrocatalytic reduction of carbon dioxide to methane

PubMed Central

Zhang, Sheng; Kang, Peng; Bakir, Mohammed; Lapides, Alexander M.; Dares, Christopher J.; Meyer, Thomas J.

2015-01-01

Developing sustainable energy strategies based on CO2 reduction is an increasingly important issue given the world’s continued reliance on hydrocarbon fuels and the rise in CO2 concentrations in the atmosphere. An important option is electrochemical or photoelectrochemical CO2 reduction to carbon fuels. We describe here an electrodeposition strategy for preparing highly dispersed, ultrafine metal nanoparticle catalysts on an electroactive polymeric film including nanoalloys of Cu and Pd. Compared with nanoCu catalysts, which are state-of-the-art catalysts for CO2 reduction to hydrocarbons, the bimetallic CuPd nanoalloy catalyst exhibits a greater than twofold enhancement in Faradaic efficiency for CO2 reduction to methane. The origin of the enhancement is suggested to arise from a synergistic reactivity interplay between Pd–H sites and Cu–CO sites during electrochemical CO2 reduction. The polymer substrate also appears to provide a basis for the local concentration of CO2 resulting in the enhancement of catalytic current densities by threefold. The procedure for preparation of the nanoalloy catalyst is straightforward and appears to be generally applicable to the preparation of catalytic electrodes for incorporation into electrolysis devices. PMID:26668386

Effect of Heat Treatment on Borides Precipitation and Mechanical Properties of CoCrFeNiAl1.8Cu0.7B0.3Si0.1 High-Entropy Alloy Prepared by Arc-Melting and Laser-Cladding

NASA Astrophysics Data System (ADS)

Zhang, H.; Tang, H.; He, Y. Z.; Zhang, J. L.; Li, W. H.; Guo, S.

2017-11-01

Effects of heat treatment on borides precipitation and mechanical properties of arc-melted and laser-cladded CoCrNiFeAl1.8Cu0.7B0.3Si0.1 high-entropy alloys were comparatively studied. The arc-melted alloy contains lots of long strip borides distributed in the body-centered cubic phase, with a hardness about 643 HV0.5. Laser-cladding can effectively inhibit the boride precipitation and the laser-cladded alloy is mainly composed of a simple bcc solid solution, with a high hardness about 769 HV0.5, indicating the strengthening effect by interstitial boron atoms is greater than the strengthening by borides precipitation. Heat treatments between 800°C and 1200°C can simultaneously improve the hardness and fracture toughness of arc-melted alloys, owing to the boride spheroidization, dissolution, re-precipitation, and hence the increased boron solubility and nano-precipitation in the bcc solid solution. By contrast, the hardness of laser-cladded alloys reduce after heat treatments in the same temperature range, due to the decreased boron solubility in the matrix.

Ultrafine Particles from Traffic Emissions and Children's Health (UPTECH) in Brisbane, Queensland (Australia): study design and implementation.

PubMed

Ezz, Wafaa Nabil; Mazaheri, Mandana; Robinson, Paul; Johnson, Graham R; Clifford, Samuel; He, Congrong; Morawska, Lidia; Marks, Guy B

2015-02-02

Ultrafine particles are particles that are less than 0.1 micrometres (µm) in diameter. Due to their very small size they can penetrate deep into the lungs, and potentially cause more damage than larger particles. The Ultrafine Particles from Traffic Emissions and Children's Health (UPTECH) study is the first Australian epidemiological study to assess the health effects of ultrafine particles on children's health in general and peripheral airways in particular. The study is being conducted in Brisbane, Australia. Continuous indoor and outdoor air pollution monitoring was conducted within each of the twenty five participating school campuses to measure particulate matter, including in the ultrafine size range, and gases. Respiratory health effects were evaluated by conducting the following tests on participating children at each school: spirometry, forced oscillation technique (FOT) and multiple breath nitrogen washout test (MBNW) (to assess airway function), fraction of exhaled nitric oxide (FeNO, to assess airway inflammation), blood cotinine levels (to assess exposure to second-hand tobacco smoke), and serum C-reactive protein (CRP) levels (to measure systemic inflammation). A pilot study was conducted prior to commencing the main study to assess the feasibility and reliably of measurement of some of the clinical tests that have been proposed for the main study. Air pollutant exposure measurements were not included in the pilot study.

Ultrafine Angelica gigas Powder Normalizes Ovarian Hormone Levels and Has Antiosteoporosis Properties in Ovariectomized Rats: Particle Size Effect

PubMed Central

Choi, Kyeong-Ok; Lee, Inae; Paik, Sae-Yeol-Rim; Kim, Dong Eun; Lim, Jung Dae; Kang, Wie-Soo; Ko, Sanghoon

2012-01-01

Abstract The root of Angelica gigas (Korean angelica) is traditionally used to treat women's ailments that are caused by an impairment of menstrual blood flow and cycle irregularities. This study evaluated the effect particle size of Korean angelica powder on its efficacy for treating estrogen-related symptoms of menopause. Initially, Korean angelica roots were pulverized into ultrafine powder, and orally administered to the rats at a concentration of 500 mg/kg body weight for 8 weeks. The effects of Korean angelica powder particle size on extraction yield, contents of bioactive compounds (decursin and decursinol angelate), levels of serum ovarian hormones (estradiol and progesterone), reproductive hormones (luteinizing hormone and follicle-stimulating hormone), and experimental osteoporosis parameters (mineral density, strength, and histological features) were determined. A significant increase (fivefold) in the contents of decursin and decursinol angelate in the extract of the ultrafine Korean angelica powder was observed compared to coarse Korean angelica powder. Rats were divided into sham-operated or ovariectomized (OVX) groups that were fed coarse (CRS) or ultrafine (UF) ground Korean angelica root. The serum levels of estradiol in the OVX_UF group were 19.2% and 54.1% higher than that of OVX_CRS group. Serum bone-alkaline phosphatase/total-alkaline phosphatase index in the OVX_UF group was half that of the OVX_CRS group. In addition, less trabecular bone loss and thick cortical areas were observed in rats administered ultrafine powder. Therefore, ultrafine grinding may enhance the bioactivity of herbal medicines and be especially useful when their extracted forms lose bioactivity during processing, storage, and oral intake. PMID:23039111

UPREGULATION OF TISSUE FACTOR IN HUMAN ENDOTHELIAL CELLS FOLLOWING ULTRAFINE PARTICLE EXPOSURE

EPA Science Inventory

Epidemiology studies have linked the exposure to air pollutant particles with increased cardiovascular mortality and morbidity, but the mechanisms remain unknown. In our laboratory we have tested the hypothesis that the ultrafine fraction of ambient pollutant particles would cau...

Pulmonary diseases induced by ambient ultrafine and engineered nanoparticles in twenty-first century.

PubMed

Xia, Tian; Zhu, Yifang; Mu, Lina; Zhang, Zuo-Feng; Liu, Sijin

2016-12-01

Air pollution is a severe threat to public health globally, affecting everyone in developed and developing countries alike. Among different air pollutants, particulate matter (PM), particularly combustion-produced fine PM (PM 2.5 ) has been shown to play a major role in inducing various adverse health effects. Strong associations have been demonstrated by epidemiological and toxicological studies between increases in PM 2.5 concentrations and premature mortality, cardiopulmonary diseases, asthma and allergic sensitization, and lung cancer. The mechanisms of PM-induced toxicological effects are related to their size, chemical composition, lung clearance and retention, cellular oxidative stress responses and pro-inflammatory effects locally and systemically. Particles in the ultrafine range (<100 nm), although they have the highest number counts, surface area and organic chemical content, are often overlooked due to insufficient monitoring and risk assessment. Yet, ample studies have demonstrated that ambient ultrafine particles have higher toxic potential compared with PM 2.5 . In addition, the rapid development of nanotechnology, bringing ever-increasing production of nanomaterials, has raised concerns about the potential human exposure and health impacts. All these add to the complexity of PM-induced health effects that largely remains to be determined, and mechanistic understanding on the toxicological effects of ambient ultrafine particles and nanomaterials will be the focus of studies in the near future.

Pulmonary diseases induced by ambient ultrafine and engineered nanoparticles in twenty-first century

PubMed Central

Xia, Tian; Zhu, Yifang; Mu, Lina; Zhang, Zuo-Feng; Liu, Sijin

2016-01-01

Abstract Air pollution is a severe threat to public health globally, affecting everyone in developed and developing countries alike. Among different air pollutants, particulate matter (PM), particularly combustion-produced fine PM (PM2.5) has been shown to play a major role in inducing various adverse health effects. Strong associations have been demonstrated by epidemiological and toxicological studies between increases in PM2.5 concentrations and premature mortality, cardiopulmonary diseases, asthma and allergic sensitization, and lung cancer. The mechanisms of PM-induced toxicological effects are related to their size, chemical composition, lung clearance and retention, cellular oxidative stress responses and pro-inflammatory effects locally and systemically. Particles in the ultrafine range (<100 nm), although they have the highest number counts, surface area and organic chemical content, are often overlooked due to insufficient monitoring and risk assessment. Yet, ample studies have demonstrated that ambient ultrafine particles have higher toxic potential compared with PM2.5. In addition, the rapid development of nanotechnology, bringing ever-increasing production of nanomaterials, has raised concerns about the potential human exposure and health impacts. All these add to the complexity of PM-induced health effects that largely remains to be determined, and mechanistic understanding on the toxicological effects of ambient ultrafine particles and nanomaterials will be the focus of studies in the near future. PMID:28649460

Grindability of cast Ti-Cu alloys.

PubMed

Kikuchi, Masafumi; Takada, Yukyo; Kiyosue, Seigo; Yoda, Masanobu; Woldu, Margaret; Cai, Zhuo; Okuno, Osamu; Okabe, Toru

2003-07-01

The purpose of the present study was to evaluate the grindability of a series of cast Ti-Cu alloys in order to develop a titanium alloy with better grindability than commercially pure titanium (CP Ti), which is considered to be one of the most difficult metals to machine. Experimental Ti-Cu alloys (0.5, 1.0, 2.0, 5.0, and 10.0 mass% Cu) were made in an argon-arc melting furnace. Each alloy was cast into a magnesia mold using a centrifugal casting machine. Cast alloy slabs (3.5 mm x 8.5 mm x 30.5 mm), from which the hardened surface layer (250 microm) was removed, were ground using a SiC abrasive wheel on an electric handpiece at four circumferential speeds (500, 750, 1000, or 1250 m/min) at 0.98 N (100 gf). Grindability was evaluated by measuring the amount of metal volume removed after grinding for 1min. Data were compared to those for CP Ti and Ti-6Al-4V. For all speeds, Ti-10% Cu alloy exhibited the highest grindability. For the Ti-Cu alloys with a Cu content of 2% or less, the highest grindability corresponded to an intermediate speed. It was observed that the grindability increased with an increase in the Cu concentration compared to CP Ti, particularly for the 5 or 10% Cu alloys at a circumferential speed of 1000 m/min or above. By alloying with copper, the cast titanium exhibited better grindability at high speed. The continuous precipitation of Ti(2)Cu among the alpha-matrix grains made this material less ductile and facilitated more effective grinding because small broken segments more readily formed.

MECHANISMS BY WHICH ULTRAFINE, FINE, AND COARSE PARTICLES CAUSE ADVERSE HEALTH EFFECTS

EPA Science Inventory

A small number of recent studies suggest that different size particles may cause different health effects. There are clearly differences in the chemical makeup of coarse, fine, and ultrafine particles, and this different chemistry may well drive different health responses. The ...

OXIDATIVE STRESS AND LIPID MEDIATORS INDUCED IN ALVEOLAR MACHROPHAGES BY ULTRAFINE PARTICLES

EPA Science Inventory

In ambient aerosols, ultrafine particles (UFP) and their agglomerates are considered to be major factors contributing to adverse health effects. Reactivity of agglomerated UFP of elemental carbon (EC), Printex 90, Printex G, and diesel exhaust particles (DEP) was evaluated by the...

[Ultrafine particles and effects on the body: review of the literature].

PubMed

Pedata, P; Garzillo, E M; Sannolo, N

2010-01-01

The International laws and the technology developments led to a situation where the current levels of environmental pollution are below those that existed at the beginning of the century: however, these pollution levels produce harmful effects to health linked to an increase in morbidity and mortality. Over the years the pollution has changed: following the transformation of heating, motor innovation and emissions reducing, has been a reduction in air concentration of some conventional pollutants (sulfur dioxide, carbon monoxide, benzene), while there wasn't a significant reduction of particulate air pollution. In this work have been questioned several electronic databases of scientific literature based on a selection algorithm that contains expressions for the following topics: "ultrafine particles", "effects on human health", "occupational and environmental exposure". We analyzed 200 articles, progressively reduced to 88, selected for keywords, year of publication and arguments; the main topics covered by the articles were related to chemical and physical UFP properties, UFP exposure, European legislation relating to the values of particle concentrations in the atmosphere, toxicokinetics and effects on various organs such as, in particular, the respiratory system, cardiovascular system, central nervous system and the intracellular mechanism of action. Analysis of the literature showed that ultrafine particles (PM0.1 aerodynamic diameter less than 0.1 microm) are more powerful than the coarse particle fraction (2.5-10 microm) and fine (0.1-2.5 microm) in inducing adverse effects to human health. Unfortunately, the study of mechanisms of action of these particles presents particular difficulties because of the large number of chemical and biological mechanisms that come into play in the body after exposure to ultrafine particles.

Combustion-Derived Ultrafine Particles Transport Organic Toxicants to Target Respiratory Cells

PubMed Central

Penn, Arthur; Murphy, Gleeson; Barker, Steven; Henk, William; Penn, Lynn

2005-01-01

Epidemiologic evidence supports associations between inhalation of fine and ultrafine ambient particulate matter [aerodynamic diameter ≤ 2.5 μm (PM2.5)] and increases in cardiovascular/respiratory morbidity and mortality. Less attention has been paid to how the physical and chemical characteristics of these particles may influence their interactions with target cells. Butadiene soot (BDS), produced during combustion of the high-volume petrochemical 1,3-butadiene, is rich in polynuclear aromatic hydrocarbons (PAHs), including known carcinogens. We conducted experiments to characterize BDS with respect to particle size distribution, assembly, PAH composition, elemental content, and interaction with respiratory epithelial cells. Freshly generated, intact BDS is primarily (> 90%) PAH-rich, metals-poor (nickel, chromium, and vanadium concentrations all < 1 ppm) PM2.5, composed of uniformly sized, solid spheres (30–50 nm) in aggregated form. Cells of a human bronchial epithelial cell line (BEAS-2B) exhibit sequential fluorescent responses—a relatively rapid (~ 30 min), bright but diffuse fluorescence followed by the slower (2–4 hr) appearance of punctate cytoplasmic fluorescence—after BDS is added to medium overlying the cells. The fluorescence is associated with PAH localization in the cells. The ultrafine BDS particles move down through the medium to the cell membrane. Fluorescent PAHs are transferred from the particle surface to the cell membrane, cross the membrane into the cytosol, and appear to accumulate in lipid vesicles. There is no evidence that BDS particles pass into the cells. The results demonstrate that uptake of airborne ultrafine particles by target cells is not necessary for transfer of toxicants from the particles to the cells. PMID:16079063

Graphite to ultrafine nanocrystalline diamond phase transition model and growth restriction mechanism induced by nanosecond laser processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, X. D., E-mail: renxd@mail.ujs.edu.cn; Liu, R.; Zheng, L. M.

2015-10-05

To have a clear insight into nanocrystal growth from graphite to diamond upon high energy pulsed laser irradiation of graphite suspension, synthesis of ultrafine nanocrystalline diamonds with laser energy set up from 0.3 J to 12 J, repetition rate of 10 Hz has been studied. The method allows synthesizing ultrafine nanocrystalline particles continuously at the ambient temperature and normal pressure. The particle size is shown independent of laser energy, which is ultrafine and ranges in 2–6 nm. The theoretical grown size of nano-diamonds is found in well agreement with the experiment results. Four kinds of production were found: nano-diamond, spherical carbon nano-particles, flocculent amorphousmore » carbon, and graphene nano-ribbon rolls. A solid-vapor-plasma-liquid coexistence model describing phase transition from graphite to diamond induced by nanosecond laser processing was proposed. Graphene nano-ribbon rolls might be the intermediate phase in the conversion from graphite to diamond.« less

Preparing ultrafine PbS powders from the scrap lead-acid battery by sulfurization and inert gas condensation

NASA Astrophysics Data System (ADS)

Xia, Huipeng; Zhan, Lu; Xie, Bing

2017-02-01

A novel method for preparing ultrafine PbS powders involving sulfurization combined with inert gas condensation is developed in this paper, which is applicable to recycle Pb from lead paste of spent lead-acid batteries. Initially, the effects of the evaporation and condensation temperature, the inert gas pressure, the condensation distance and substrate on the morphology of as-obtained PbS ultrafine particles are intensively investigated using sulfur powders and lead particles as reagents. Highly dispersed and homogeneous PbS nanoparticles can be prepared under the optimized conditions which are 1223 K heating temperature, 573 K condensation temperature, 100 Pa inert gas pressure and 60 cm condensation distance. Furthermore, this method is successfully applied to recycle Pb from the lead paste of spent lead acid battery to prepare PbS ultrafine powders. This work does not only provide the theoretical fundamental for PbS preparation, but also provides a novel and efficient method for recycling spent lead-acid battery with high added-value products.

A novel film-pore-surface diffusion model to explain the enhanced enzyme adsorption of corn stover pretreated by ultrafine grinding.

PubMed

Zhang, Haiyan; Chen, Longjian; Lu, Minsheng; Li, Junbao; Han, Lujia

2016-01-01

Ultrafine grinding is an environmentally friendly pretreatment that can alter the degree of polymerization, the porosity and the specific surface area of lignocellulosic biomass and can, thus, enhance cellulose hydrolysis. Enzyme adsorption onto the substrate is a prerequisite for the enzymatic hydrolysis process. Therefore, it is necessary to investigate the enzyme adsorption properties of corn stover pretreated by ultrafine grinding. The ultrafine grinding pretreatment was executed on corn stover. The results showed that ultrafine grinding pretreatment can significantly decrease particle size [from 218.50 μm of sieve-based grinding corn stover (SGCS) to 17.45 μm of ultrafine grinding corn stover (UGCS)] and increase the specific surface area (SSA), pore volume (PV) and surface composition (SSA: from 1.71 m(2)/g of SGCS to 2.63 m(2)/g of UGCS, PV: from 0.009 cm(3)/g of SGCS to 0.024 m(3)/g of UGCS, cellulose surface area: from 168.69 m(2)/g of SGCS to 290.76 m(2)/g of UGCS, lignin surface area: from 91.46 m(2)/g of SGCS to 106.70 m(2)/g of UGCS). The structure and surface composition changes induced by ultrafine grinding increase the enzyme adsorption capacity from 2.83 mg/g substrate of SGCS to 5.61 mg/g substrate of UGCS. A film-pore-surface diffusion model was developed to simultaneously predict the enzyme adsorption kinetics of both the SGCS and UGCS. Satisfactory predictions could be made with the model based on high R (2) and low RMSE values (R (2) = 0.95 and RMSE = 0.16 mg/g for the UGCS, R (2) = 0.93 and RMSE = 0.09 mg/g for the SGCS). The model was further employed to analyze the rate-limiting steps in the enzyme adsorption process. Although both the external-film and internal-pore mass transfer are important for enzyme adsorption on the SGCS and UGCS, the UGCS has a lower internal-pore resistance compared to the SGCS. Ultrafine grinding pretreatment can enhance the enzyme adsorption onto corn stover by altering structure and

One-Pot Synthesis of GeAs Ultrafine Particles from Coal Fly Ash by Vacuum Dynamic Flash Reduction and Inert Gas Condensation.

PubMed

Zhang, Lingen; Xu, Zhenming

2017-06-16

Ge-monopnictides (GeAs) plays critical role in high-tech industry, especially in the field of advanced optical devices and infrared. As a secondary material, coal fly ash could be further recycled to retrieve germanium and prepare GeAs material with high added values. Hence, the aim of this paper is to propose a one-pot synthesis that uses vacuum flash reduction and inert-gas consolidation method to prepare GeAs ultrafine particles. Germanium in coal fly ash can be successfully recycled; simultaneously, GeAs ultrafine particles were prepared. Separation principle and feasibility of this process was discussed. Temperature, carrier gas flow rate and system pressure were the major factors on formation, morphology and distribution of particle size of GeAs ultrafine particles. A three steps synthetic mechanism was clarified, namely, thermal rupture of coal fly ash and release of GeO 2 and As 2 O 3 , the gas-solid phase reaction of GeO 2 , As 2 O 3 and coke to generate metallic Ge and As in vacuum flash reduction. Meantime, GeAs were produced in the gas phase reaction. Finally, GeAs ultrafine particles were obtained by carrier gas condensation. In short, this research developed a practical and environment-friendly one-pot synthesis to recycle germanium in coal fly ash and prepare GeAs ultrafine particles with high added values.

Disintegration of the net-shaped grain-boundary phase by multi-directional forging and its influence on the microstructure and properties of Cu-Ni-Si alloy

NASA Astrophysics Data System (ADS)

Zhang, Jinlong; Lu, Zhenlin; Zhao, Yuntao; Jia, Lei; Xie, Hui; Tao, Shiping

2017-09-01

Cu-Ni-Si alloys with 90% Cu content and Ni to Si ratios of 5:1 were fabricated by fusion casting, and severe plastic deformation of the Cu-Ni-Si alloy was carried out by multi-direction forging (MDF). The results showed that the as-cast and homogenized Cu-Ni-Si alloys consisted of three phases, namely the matrix phase α-Cu (Ni, Si), the reticular grain boundary phase Ni31Si12 and the precipitated phase Ni2Si. MDF significantly destroyed the net-shaped grain boundary phase, the Ni31Si12 phase and refined the grain size of the Cu matrix, and also resulted in the dissolving of Ni2Si precipitates into the Cu matrix. The effect of MDF on the conductivity of the solid solution Cu-Ni-Si alloy was very significant, with an average increase of 165.16%, and the hardness of the Cu-Ni-Si alloy also increased obviously.

Atomistic Simulations of Grain Boundary Pinning in CuFe Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zepeda-Ruiz, L A; Gilmer, G H; Sadigh, B

2005-05-22

The authors apply a hybrid Monte Carlo-molecular dynamics code to the study of grain boundary motion upon annealing of pure Cu and Cu with low concentrations of Fe. The hybrid simulations account for segregation and precipitation of the low solubility Fe, together with curvature driven grain boundary motion. Grain boundaries in two different systems, a {Sigma}7+U-shaped half-loop grain and a nanocrystalline sample, were found to be pinned in the presence of Fe concentrations exceeding 3%.

Quantitative description of the T1 morphology and strengthening mechanisms in an age-hardenable Al-Li-Cu alloy

NASA Astrophysics Data System (ADS)

Dorin, Thomas; Deschamps, Alexis; De Geuser, Frédéric; Weyland, Matthew

In the Al-Cu-Li system, the main strengthening precipitate is the T1 phase (Al2CuLi). In order to understand the strengthening related to the formation of this phase, we first present an investigation of the morphology of the T1 phase in an AA2198 alloy using Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC) in relation with the evolution of micro-hardness. In parallel, we present an investigation of the interaction between T1 precipitates and dislocations using High Angle Annular Dark Field (HAADF) imaging in an atomic resolution Scanning Transmission Electron Microscope (STEM). The atomic scale imaging of precipitates makes it possible to quantify the density of shearing events, which turns out to be insufficient to account for the imposed plastic strain. We discuss the implications of this result in terms of precipitate-dislocation interactions.

Ultrafine Particle Metrics and Research Considerations: Review of the 2015 UFP Workshop

EPA Science Inventory

In February 2015, the United States Environmental Protection Agency (EPA) sponsored a workshop in Research Triangle Park, North Carolina, USA to review the current state of the science on emissions, air quality impacts, and health effects associated with exposures to ultrafine pa...

SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES

EPA Science Inventory

SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES
Y.M. Kim, A.G. Lenz, R. Silbajoris, I. Jaspers and J.M. Samet. Department of Environmental Sciences and Engineering and Center for Environmental Medicine, University of North Carolina, ...

Anhydrite pseudomorphs and the origin of stratiform Cu-Co ores in the Katangan Copperbelt (Democratic Republic of Congo)

NASA Astrophysics Data System (ADS)

Muchez, Ph.; Vanderhaeghen, P.; El Desouky, H.; Schneider, J.; Boyce, A.; Dewaele, S.; Cailteux, J.

2008-07-01

The stratiform Cu-Co ore mineralisation in the Katangan Copperbelt consists of dispersed sulphides and sulphides in nodules and lenses, which are often pseudomorphs after evaporites. Two types of pseudomorphs can be distinguished in the nodules and lenses. In type 1 examples, dolomite precipitated first and was subsequently replaced by Cu-Co sulphides and authigenic quartz, whereas in type 2 examples, authigenic quartz and Cu-Co sulphides precipitated prior to dolomite and are coarse-grained. The sulphur isotopic composition of the copper-cobalt sulphides in the type 1 pseudomorphs is between -10.3 and 3.1‰ relative to the Vienna Canyon Diablo Troilite, indicating that the sulphide component was derived from bacterial sulphate reduction (BSR). The generation of {text{HCO}}_3^ - during this process caused the precipitation and replacement of anhydrite by dolomite. A second product of BSR is the generation of H2S, resulting in the precipitation of Cu-Co sulphides from the mineralising fluids. Initial sulphide precipitation occurred along the rim of the pseudomorphs and continued towards the core. Precipitation of authigenic quartz was most likely induced by a pH decrease during sulphide precipitation. Fluid inclusion data from quartz indicate the presence of a high-salinity (8-18 eq. wt.% NaCl) fluid, possibly derived from evaporated seawater which migrated through the deep subsurface. 87Sr/86Sr ratios of dolomite in type 1 nodules range between 0.71012 and 0.73576, significantly more radiogenic than the strontium isotopic composition of Neoproterozoic marine carbonates (87Sr/86Sr = 0.7056-0.7087). This suggests intense interaction with siliciclastic sedimentary rocks and/or the granitic basement. The low carbon isotopic composition of the dolomite in the pseudomorphs (-7.02 and -9.93‰ relative to the Vienna Pee Dee Belemnite, V-PDB) compared to the host rock dolomite (-4.90 and +1.31‰ V-PDB) resulted from the oxidation of organic matter during BSR.

Enhanced Impact Toughness at Ambient Temperatures of Ultrafine-Grained Al-26 wt.% Si Alloy Produced by Equal-Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Jiang, Jinghua; Yuan, Ting; Shi, Jun; Zhang, Lingling; Ma, Aibin; Song, Dan

2018-05-01

Overcoming general brittleness of hypereutectic Al-Si alloys is in urgent need for expanding their application in automotive, aerospace and construction industries. A unique phenomenon was observed that bulk ultrafine-grained Al-26 wt.% Si alloy, produced by severe plastic deformation via equal-channel angular pressing, exhibited higher toughness at the impact temperature of - 196 100 °C than the coarse-grained casting alloy. The improvement in impact toughness at all testing temperatures was mainly due to the homogeneous ultrafine-grained structure with the breakage of brittle primary silicon crystals, which generated more and deeper fracture dimples that consumed much higher fracture energy. It indicates the advantage of bulk ultrafine-grained Al-Si alloys and spurs their application interest at various ambient temperatures.

Enhanced Impact Toughness at Ambient Temperatures of Ultrafine-Grained Al-26 wt.% Si Alloy Produced by Equal-Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Jiang, Jinghua; Yuan, Ting; Shi, Jun; Zhang, Lingling; Ma, Aibin; Song, Dan

2018-04-01

Overcoming general brittleness of hypereutectic Al-Si alloys is in urgent need for expanding their application in automotive, aerospace and construction industries. A unique phenomenon was observed that bulk ultrafine-grained Al-26 wt.% Si alloy, produced by severe plastic deformation via equal-channel angular pressing, exhibited higher toughness at the impact temperature of - 196 100 °C than the coarse-grained casting alloy. The improvement in impact toughness at all testing temperatures was mainly due to the homogeneous ultrafine-grained structure with the breakage of brittle primary silicon crystals, which generated more and deeper fracture dimples that consumed much higher fracture energy. It indicates the advantage of bulk ultrafine-grained Al-Si alloys and spurs their application interest at various ambient temperatures.

Effect of Boron Doping on Cellular Discontinuous Precipitation for Age-Hardenable Cu–Ti Alloys

PubMed Central

Semboshi, Satoshi; Ikeda, Jun; Iwase, Akihiro; Takasugi, Takayuki; Suzuki, Shigeru

2015-01-01

The effects of boron doping on the microstructural evolution and mechanical and electrical properties of age-hardenable Cu–4Ti (at.%) alloys are investigated. In the quenched Cu–4Ti–0.03B (at.%) alloy, elemental B (boron) is preferentially segregated at the grain boundaries of the supersaturated solid-solution phase. The aging behavior of the B-doped alloy is mostly similar to that of conventional age-hardenable Cu–Ti alloys. In the early stage of aging at 450 °C, metastable β′-Cu4Ti with fine needle-shaped precipitates continuously form in the matrix phase. Cellular discontinuous precipitates composed of the stable β-Cu4Ti and solid-solution laminates are then formed and grown at the grain boundaries. However, the volume fraction of the discontinuous precipitates is lower in the Cu–4Ti–0.03B alloy than the Cu–4Ti alloy, particularly in the over-aging period of 72–120 h. The suppression of the formation of discontinuous precipitates eventually results in improvement of the hardness and tensile strength. It should be noted that minor B doping of Cu–Ti alloys also effectively enhances the elongation to fracture, which should be attributed to segregation of B at the grain boundaries.

Trace metals in bulk precipitation and throughfall in a suburban area of Japan

NASA Astrophysics Data System (ADS)

Hou, H.; Takamatsu, T.; Koshikawa, M. K.; Hosomi, M.

Throughfall and bulk precipitation samples were collected monthly for 1.5 years over bare land and under canopies of Japanese cedar ( Cryptomeria japonica), Japanese red pine ( Pinus densiflora), Japanese cypress ( Chamaecyparis obtusa), and bamboo-leafed oak ( Quercus myrsinaefolia) in a suburban area of Japan. Samples were analyzed for dissolved Al, Mn, Fe, Cu, Zn, Ag, In, Sn, Sb and Bi by ICP-AES and ICP-MS. The metal concentrations were higher in throughfall, especially that of C. japonica, than bulk precipitation. Enrichment ratios (ERs: ratios of metal concentrations in throughfall to those in bulk precipitation) ranged from 2.5 (Zn) to 5.3 (Ag) (3.9 on average), and ERs for slightly soluble metals were generally higher than those for easily soluble metals. Concentrations of Mn, Fe, Cu, and Zn accounted for 99% of the total concentration of heavy metals in rainwater, whereas those of rare metals such as Ag, In, Sn, and Bi totaled <0.23%. Average concentrations of rare metals were 0.002 and 0.010 μg l -1 for Ag, 0.001 and 0.005 μg l -1 for In, 0.062 and 0.21 μg l -1 for Sn, and 0.006 and 0.023 μg l -1 for Bi in bulk precipitation and throughfall, respectively. The metal concentrations in rainwater were negatively correlated to the volume of rainwater, indicating that washout is the main mechanism that incorporates metals into rainwater. From the enrichment factors, that is, (X/Al) rain/(X/Al) crust, metals other than Fe were shown to be more enriched in rainwater than in the Earth's crust, including those present as a result of leaching from soil dust (Mn) and from anthropogenic sources (Cu, Zn, Ag, In, Sn, Sb, and Bi).

Electrolysis treatment of trichiasis by using ultra-fine needle.

PubMed

Sakarya, Yasar; Sakarya, Rabia; Yildirim, Aydin

2010-01-01

To determine the safety and efficacy of electrolysis treatment of trichiasis by using ultrafine needle. The medical records of 24 lids of 24 patients who underwent electrolysis treatment for trichiasis by the same surgeon (Y.S.) during the period from May 2006 through December 2008 were reviewed. The average age of the 24 patients was 59.2 years (range, 43 to 76 years). Thirteen of the patients were women. The results were considered satisfactory if no recurrence of trichiasis occurred for at least 6 months after the last electrolysis procedure. Sixteen of the 24 patients (66.6%) had a satisfactory result with 1 treatment. Of the 8 patients (33.3%) who had an unsatisfactory result, while 5 (20.8%) responded well to 1 additional electrolysis, 3 (12.5%) responded well to 2 additional electrolyses to the recurrent cilia. The procedure was well tolerated by the patients. All eyelids healed within 2 weeks after treatment without any scarring. Faint hypopigmentation was visible in 2 patients (8.3%). Mild notching of eyelid occurred in 4 patients (16.6%). Electrolysis treatment by using ultrafine (55-microm thickness) needle is an effective and safe method for treatment of trichiasis with many advantages over other recognized modalities of therapy.

Transparent, flexible, and high-performance supercapacitor based on ultrafine nickel cobaltite nanospheres

NASA Astrophysics Data System (ADS)

Liu, Xinyue; Wang, Jianxing; Yang, Guowei

2017-07-01

There has been growing interest in transparent and flexible electronic devices such as wrist watch, cell phone, and so on. These devices need the power sources which also have transparent and flexible features. Here, we demonstrate a transparent and flexible energy storage device with outstanding electrochemical performance, high energy density, and super-long life based on ultrafine NiCo2O4 nanospheres which are synthesized by an innovative method concerning laser ablation in liquid and hydrothermal process. The ultrafine NiCo2O4 nanospheres provide high electrochemical activity and the synthesized colloidal solution is suitable for transparent devices. The transparent and flexible device shows a high specific capacitance of 299.7 F/g at the scan rate of 1 mV/s and a long cycling life of 90.4% retention rate after 10,000 cycles at a scan rate of 10 mV/s, which is superior to that of previously reported transparent and flexible energy storage device. In addition, an optical transmittance up to 55% at the wavelength of 550 nm is obtained, and the bending test shows that the bending angle makes no difference to the specific capacitance of the device. In addition, it shows an outstanding energy density of 10.41 Wh/kg. The integrated electrochemical performances of the device are good based on NiCo2O4 nanospheres. These findings make the ultrafine NiCo2O4 nanospheres being promising electrode materials for transparent and flexible energy storage devices.

Application of the discrete generalized multigroup method to ultra-fine energy mesh in infinite medium calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, N. A.; Forget, B.

2012-07-01

The Discrete Generalized Multigroup (DGM) method uses discrete Legendre orthogonal polynomials to expand the energy dependence of the multigroup neutron transport equation. This allows a solution on a fine energy mesh to be approximated for a cost comparable to a solution on a coarse energy mesh. The DGM method is applied to an ultra-fine energy mesh (14,767 groups) to avoid using self-shielding methodologies without introducing the cost usually associated with such energy discretization. Results show DGM to converge to the reference ultra-fine solution after a small number of recondensation steps for multiple infinite medium compositions. (authors)

The preliminary result of the δ65Cu and δ34S values of major ore minerals in the Erdenetiin-Ovoo Cu-Mo porphyry deposit, Northern Mongolia

NASA Astrophysics Data System (ADS)

KIM, Y.; Lee, I.; Oyungerel, S.; Jargal, L.; Tsedenbal, T.; Ryu, J. S.

2016-12-01

The copper isotope (δ65Cu) and sulfur isotope (δ34S) compositions of major ore minerals from the Erdenetiin-Ovoo Cu-Mo porphyry deposit were measured to trace sources of copper and sulfur, and to evaluate the precipitation environment of ore minerals. The major ore minerals are pyrite, chalcopyrite, molybdenite and chalcocite developed in the QSP (Quartz-Sericite-Pyrite) alteration zone. The sulfide minerals such as sphalerite and covellite, and carbonate ore minerals like malachite, azurite are also identified. The copper isotope ratios (65Cu/63Cu) of copper ore minerals (chalcopyrite, chalcocite, malachite, azurite, covellite and chrysocolla) were analyzed by the MC-ICPMS in KBSI located in Ochang, South Korea. The measured δ65Cu values relative to NIST 976 range from -1.01 ‰ to 5.76 ‰. The average δ65Cu values of sulfide minerals such as chalcopyrite (1.03 ‰), chalcocite (0.62 ‰) and covellite (0.51 ‰) seem to be relatively lower than those of carbonate and silicate Cu minerals such as malachite (0.24 ‰), azurite (2.17 ‰) and chrysocolla (5.76 ‰). The sulfur isotope ratios (34S/32S) of major sulfide minerals were measured by EA-CF-IRMS (Elemental Analyzer - Continuous Flow - Isotope Ratio Mass Spectrometer) in NCIRF, Seoul National University. The average δ34SV-CDT value is -1.1 ‰ indicating the magmatic signature of sulfur. There is the difference of δ34S values between sulfide minerals. While the δ34S values of pyrite, chalcopyrite and molybdenite range from -0.9 to 0.8 ‰, the δ34S values of chalcocite range from -2.6 ‰ to -1.4 ‰. These lower values might be attributed to the sulfur isotope fractionation during its precipitation.

Method for producing ultrafine-grained materials using repetitive corrugation and straightening

DOEpatents

Zhu, Yuntian T.; Lowe, Terry C.; Jiang, Honggang; Huang, Jianyu

2001-01-01

A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH) in Brisbane, Queensland (Australia): Study Design and Implementation

PubMed Central

Ezz, Wafaa Nabil; Mazaheri, Mandana; Robinson, Paul; Johnson, Graham R.; Clifford, Samuel; He, Congrong; Morawska, Lidia; Marks, Guy B.

2015-01-01

Ultrafine particles are particles that are less than 0.1 micrometres (µm) in diameter. Due to their very small size they can penetrate deep into the lungs, and potentially cause more damage than larger particles. The Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH) study is the first Australian epidemiological study to assess the health effects of ultrafine particles on children’s health in general and peripheral airways in particular. The study is being conducted in Brisbane, Australia. Continuous indoor and outdoor air pollution monitoring was conducted within each of the twenty five participating school campuses to measure particulate matter, including in the ultrafine size range, and gases. Respiratory health effects were evaluated by conducting the following tests on participating children at each school: spirometry, forced oscillation technique (FOT) and multiple breath nitrogen washout test (MBNW) (to assess airway function), fraction of exhaled nitric oxide (FeNO, to assess airway inflammation), blood cotinine levels (to assess exposure to second-hand tobacco smoke), and serum C-reactive protein (CRP) levels (to measure systemic inflammation). A pilot study was conducted prior to commencing the main study to assess the feasibility and reliably of measurement of some of the clinical tests that have been proposed for the main study. Air pollutant exposure measurements were not included in the pilot study. PMID:25648226

Synthesis and characterization of Chitosan-CuO-MgO polymer nanocomposites

NASA Astrophysics Data System (ADS)

Praffulla, S. R.; Bubbly, S. G.

2018-05-01

In the present work, we have synthesized Chitosan-CuO-MgO nanocomposites by incorporating CuO and MgO nanoparticles in chitosan matrix. Copper oxide and magnesium oxide nanoparticles synthesized by precipitation method were characterized by X-ray diffraction and the diffraction patterns confirmed the monoclinic and cubic crystalline structures of CuO and MgO nanoparticles respectively. Chitosan-CuO-MgO composite films were prepared using solution- cast method with different concentrations of CuO and MgO nanoparticles (15 - 50 wt % with respect to chitosan) and characterized by XRD, FTIR and UV-Vis spectroscopy. The X-ray diffraction pattern shows that the crystallinity of the chitosan composite increases with increase in nanoparticle concentration. FTIR spectra confirm the chemical interaction between chitosan and metal oxide nanoparticles (CuO and MgO). UV absorbance of chitosan nanocomposites were up to 17% better than pure chitosan, thus confirming its UV shielding properties. The mechanical and electrical properties of the prepared composites are in progress.

Development of Cu-bearing bake-hardenable steel sheets for automotive exposed panels

NASA Astrophysics Data System (ADS)

Hong, Moon-Hi; Cho, Noi-Ha; Kim, Sung-Il; Kwon, Ohjoon; Lim, Sung-Hwan; Moon, Won-Jin

2010-12-01

Recently, newly developed bake-hardenable (BH) steel sheets strengthened by copper sulfide (CuS) have been successfully employed in commercial production lines that supply automotive outer panels. The metallurgical concepts governing fabrication of these new BH steel sheets require keeping carbon content as low as 0.0015 wt.% without any additional amount of titanium and/or niobium for solute carbon scavenging. The role of CuS precipitates has turned out to raise the yield strength acting as a barrier against dislocation movement. In this paper, we studied the effects of chemical compositions and manufacturing process variables on the microstructure and mechanical properties of newly developed BH steel sheets. We found that the control of carbon and nitrogen showed a good balance between bake-hardenability (BH) and yield point elongation (YP-El). We identified the crystallographic relationship between the nano-size CuS precipitates and the ferrite matrix of (001)sulfide//(001)α-Fe and [001]sulfide//[001]α-Fe. We also found that the BH and YP-El were affected by the formation of aluminium nitride (AlN) and the annealing temperature.

Ultrafine Particulate Matter Increases Cardiac Ischemia/Reperfusion Injury via Mitochondrial Permeability Transition Pore.

EPA Science Inventory

Ultrafine Particulate Matter (UFP) has been associated with increased cardiovascular morbidity and mortality. However, the mechanisms that drive PM associated cardiovascular disease and dysfunction remain unclear. We examined the impact of intratracheal instillation of 100 g UFP...

Variation of the uniaxial tensile behavior of ultrafine-grained pure aluminum after cyclic pre-deformation

NASA Astrophysics Data System (ADS)

Yan, Ying; Chen, Li-jia; Zhang, Guo-qiang; Han, Dong; Li, Xiao-wu

2018-06-01

To explore the influence of cyclic pre-deformation on the mechanical behavior of ultrafine-grained (UFG) materials with a high stacking fault energy (SFE), UFG Al processed by equal-channel angular pressing (ECAP) was selected as a target material and its tensile behavior at different pre-cyclic levels D ( D = N i / N f, where N i and N f are the applied cycles and fatigue life at a constant stress amplitude of 50 MPa, respectively) along with the corresponding microstructures and deformation features were systematically studied. The cyclic pre-deformation treatment on the ECAPed UFG Al led to a decrease in flow stress, and a stress quasi-plateau stage was observed after yielding for all of the different-state UFG Al samples. The yield strength σ YS, ultimate tensile strength σ UTS, and uniform strain ɛ exhibited a strong dependence on D when D ≤ 20%; however, when D was in the range from 20% to 50%, no obvious change in mechanical properties was observed. The micro-mechanism for the effect of cyclic pre-deformation on the tensile properties of the ECAPed UFG Al was revealed and compared with that of ECAPed UFG Cu through the observations of deformation features and microstructures.

Ultrafine particles cause cytoskeletal dysfunctions in macrophages: role of intracellular calcium

PubMed Central

Möller, Winfried; Brown, David M; Kreyling, Wolfgang G; Stone, Vicki

2005-01-01

Background Particulate air pollution is reported to cause adverse health effects in susceptible individuals. Since most of these particles are derived form combustion processes, the primary composition product is carbon with a very small diameter (ultrafine, less than 100 nm in diameter). Besides the induction of reactive oxygen species and inflammation, ultrafine particles (UFP) can cause intracellular calcium transients and suppression of defense mechanisms of alveolar macrophages, such as impaired migration or phagocytosis. Methods In this study the role of intracellular calcium transients caused by UFP was studied on cytoskeleton related functions in J774A.1 macrophages. Different types of fine and ultrafine carbon black particles (CB and ufCB, respectively), such as elemental carbon (EC90), commercial carbon (Printex 90), diesel particulate matter (DEP) and urban dust (UD), were investigated. Phagosome transport mechanisms and mechanical cytoskeletal integrity were studied by cytomagnetometry and cell viability was studied by fluorescence microscopy. Macrophages were exposed in vitro with 100 and 320 μg UFP/ml/million cells for 4 hours in serum free medium. Calcium antagonists Verapamil, BAPTA-AM and W-7 were used to block calcium channels in the membrane, to chelate intracellular calcium or to inhibit the calmodulin signaling pathways, respectively. Results Impaired phagosome transport and increased cytoskeletal stiffness occurred at EC90 and P90 concentrations of 100 μg/ml/million cells and above, but not with DEP or UD. Verapamil and W-7, but not BAPTA-AM inhibited the cytoskeletal dysfunctions caused by EC90 or P90. Additionally the presence of 5% serum or 1% bovine serum albumin (BSA) suppressed the cytoskeletal dysfunctions. Cell viability showed similar results, where co-culture of ufCB together with Verapamil, W-7, FCS or BSA produced less cell dead compared to the particles only. PMID:16202162

Effect of loading orientations on the microstructure and property of Al−Cu single crystal during stress aging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jiqiang; Chen, Zhiguo, E-mail: zgchen@mail.csu.edu.cn; Hunan University of Humanities, Science and Technology, Loudi 417000

The precipitation behavior and property of Al−Cu alloy during stress aging under various loading orientations were investigated using single crystals. The resulting microstructures and the strength property were examined by transmission electron microscope (TEM) and compression test, respectively, and the effect of the distribution of θ′-plates on strength property were discussed. The results show that the precipitation distribution of θ′ was significantly affected by the loading orientation during stress aging of Al−Cu single crystals. Loading along close to 〈011〉{sub Al} directions provided more uniform precipitation distribution of θ′ as compared to loading along close to 〈001〉{sub Al} directions, and thereforemore » provided higher strengthening stress of the θ′-plates for the stress aging sample. The results suggested that regulating the distribution of θ′ and therefore improving strength property are possible via controlling the loading orientation during stress aging. - Highlights: • We studied the effect of loading directions on stress aging of Al−Cu single crystal. • Precipitation distribution of θ′ was noticeably affected by the loading direction. • Loading along close to 〈011〉{sub Al} directions reduced the stress-orienting effect. • The strength property is closely related to the precipitation distribution of θ′. • It is possible to regulate the distribution of θ′ and improve strength property.« less

Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

NASA Astrophysics Data System (ADS)

Wang, Zexuan; Ju, Jinyun; Wang, Jinzhi; Yin, Wenzong; Chen, Renjie; Li, Ming; Jin, Chaoxiang; Tang, Xu; Lee, Don; Yan, Aru

2016-12-01

Ultrafine-grained die-upset Nd-Fe-B magnets are of importance because they provide a wide researching space to redesign the textured structures. Here is presented a route to obtain a new die-upset magnet with substantially improved magnetic properties. After experiencing the optimized heat treatment, both the coercivity and remanent magnetization of the Dy-Cu press injected magnets increased substantially in comparison with those of the annealed reference magnets, which is distinct from the reported experimental results on heavy rare-earth diffusion. To study the mechanism, we analyzed the texture evolution in high-temperature annealed die-upset magnets, which had significant impact on the improvement of remanent magnetization. On basis of the results, we find that the new structures are strongly interlinked with the initial structures. With injecting Dy-Cu eutectic alloy, an optimized initial microstructure was achieved in the near-surface diffused regions, which made preparations for the subsequent texture improvement. Besides, the Dy gradient distribution of near-surface regions of the Dy-Cu press injected magnets was also investigated. By controlling the initial microstructure and subsequent diffusion process, a higher performance magnet is expected to be obtained.

Magnetic Properties Improvement of Die-upset Nd-Fe-B Magnets by Dy-Cu Press Injection and Subsequent Heat Treatment

PubMed Central

Wang, Zexuan; Ju, Jinyun; Wang, Jinzhi; Yin, Wenzong; Chen, Renjie; Li, Ming; Jin, Chaoxiang; Tang, Xu; Lee, Don; Yan, Aru

2016-01-01

Ultrafine-grained die-upset Nd-Fe-B magnets are of importance because they provide a wide researching space to redesign the textured structures. Here is presented a route to obtain a new die-upset magnet with substantially improved magnetic properties. After experiencing the optimized heat treatment, both the coercivity and remanent magnetization of the Dy-Cu press injected magnets increased substantially in comparison with those of the annealed reference magnets, which is distinct from the reported experimental results on heavy rare-earth diffusion. To study the mechanism, we analyzed the texture evolution in high-temperature annealed die-upset magnets, which had significant impact on the improvement of remanent magnetization. On basis of the results, we find that the new structures are strongly interlinked with the initial structures. With injecting Dy-Cu eutectic alloy, an optimized initial microstructure was achieved in the near-surface diffused regions, which made preparations for the subsequent texture improvement. Besides, the Dy gradient distribution of near-surface regions of the Dy-Cu press injected magnets was also investigated. By controlling the initial microstructure and subsequent diffusion process, a higher performance magnet is expected to be obtained. PMID:27922060

Soot, organics and ultrafine ash from air- and oxy-fired coal combustion

EPA Science Inventory

This paper is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practically relevant s...

Soot, organics, and ultrafine ash from air- and oxy-fired coal combustion

EPA Science Inventory

This paper/presentation is concerned with determining the effects of oxy-combustion of coal on the composition of the ultrafine fly ash. To this end, a 10 W externally heated entrained flow furnace was modified to allow the combustion of pulverized coal in flames under practicall...

Fine and ultrafine particle emissions from microwave popcorn.

PubMed

Zhang, Q; Avalos, J; Zhu, Y

2014-04-01

This study characterized fine (PM2.5 ) and ultrafine particle (UFP, diameter < 100 nm) emissions from microwave popcorn and analyzed influential factors. Each pre-packed popcorn bag was cooked in a microwave oven enclosed in a stainless steel chamber for 3 min. The number concentration and size distribution of UFPs and PM2.5 mass concentration were measured inside the chamber repeatedly for five different flavors under four increasing power settings using either the foil-lined original package or a brown paper bag. UFPs and PM2.5 generated by microwaving popcorn were 150-560 and 350-800 times higher than the emissions from microwaving water, respectively. About 90% of the total particles emitted were in the ultrafine size range. The emitted PM concentrations varied significantly with flavor. Replacing the foil-lined original package with a brown paper bag significantly reduced the peak concentration by 24-87% for total particle number and 36-70% for PM2.5 . A positive relationship was observed between both UFP number and PM2.5 mass and power setting. The emission rates of microwave popcorn ranged from 1.9 × 10(10) to 8.0 × 10(10) No./min for total particle number and from 134 to 249 μg/min for PM2.5 . © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Microstructure and mechanical properties of an ultrafine Ti–Si–Nb alloy

DOE PAGES

Cao, G. H.; Jian, G. Y.; Liu, N.; ...

2015-08-19

In this study, Nb-modified ultrafine Ti–Si eutectic alloy was made by cold crucible levitation melting, tested in compression at room temperature, and characterized by electron microscopy. Compression tests of (Ti 86.5Si 13.5) 97Nb 3 specimens measured an ultimate compressive strength of 1180 MPa and a compressive plastic strain of 12%, both of which are higher than in eutectic Ti 86.5Si 13.5 alloy. Electron microscopy showed that the Ti–Si–Nb alloy had a bimodal microstructure with micrometer-scale primary α-Ti dendrites distributed in an ultrafine eutectic (α-Ti + Ti 5Si 3) matrix. The enhanced ductility is attributed to the morphology of the phase constituents and to the larger lattice mismatches between α-Ti and Ti 5Si 3 phases caused by the Nb addition. The crystallographic orientation relationship of Ti 5Si 3 with α-Ti is (more » $$1\\bar{1}00$$)[$$\\overline{11}$$26]Ti 5Si 3∥($$01\\bar{1}1$$)[5$$\\overline{143}$$] α–Τi.« less

Comparison of detonation spreading in pressed ultra-fine and nano-TATB

NASA Astrophysics Data System (ADS)

Olles, Joseph; Wixom, Ryan; Knepper, Robert; Yarrington, Cole; Patel, Rajen; Stepanov, Victor

2017-06-01

Detonation spreading behavior in insensitive high explosives is an important performance characteristic for initiation-train design. In the past, several variations of the floret test have been used to study this phenomenon. Commonly, dent blocks or multi-fiber optical probes were employed for reduced cost and complexity. We devised a floret-like test, using minimal explosive material, to study the detonation spreading in nano-TATB as compared to ultra-fine TATB. Our test uses a streak camera, combined with photonic Doppler velocimetry, to image the breakout timing and quantify the output particle velocity. The TATB acceptor pellets are initiated using an explosively-driven aluminum flyer with a well characterized velocity. We characterized the two types of TATB by assessing purity, particle morphology, and the microstructure of the consolidated pellets. Our results align with published data for ultra-fine TATB, however the nano-TATB shows a distinct difference where output has a strong dependence on density. The results indicate that control over pellet pore size and pressing density may be used to optimize detonation spreading behavior.

Size evolution of ultrafine particles: Differential signatures of normal and episodic events.

PubMed

Joshi, Manish; Khan, Arshad; Anand, S; Sapra, B K

2016-01-01

The effect of fireworks on the aerosol number characteristics of atmosphere was studied for an urban mega city. Measurements were made at 50 m height to assess the local changes around the festival days. Apart from the increase in total number concentration and characteristic accumulation mode, short-term increase of ultrafine particle concentration was noted. Total number concentration varies an order of magnitude during the measurement period in which peak occurs at a frequency of approximately one per day. On integral scale, it seems not possible to distinguish an episodic (e.g. firework bursting induced aerosol emission) and a normal (ambient atmospheric changes) event. However these events could be differentiated on the basis of size evolution analysis around number concentration peaks. The results are discussed relative to past studies and inferences are drawn towards aerosol signatures of firework bursting. The short-term burst in ultrafine particle concentration can pose an inhalation hazard. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparison between electrocoagulation and chemical precipitation for metals removal from acidic soil leachate.

PubMed

Meunier, Nathalie; Drogui, Patrick; Montané, Camille; Hausler, Robert; Mercier, Guy; Blais, Jean-François

2006-09-01

This paper provides a quantitative comparison between electrocoagulation and chemical precipitation based on heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) removal from acidic soil leachate (ASL) at the laboratory pilot scale. Chemical precipitation was evaluated using either calcium hydroxide or sodium hydroxide, whereas electrocoagulation was evaluated via an electrolytic cell using mild steel electrodes. Chemical precipitation was as effective as electrocoagulation in removing metals from ASL having low contamination levels (30 mg Pbl(-1) and 18 mg Znl(-1)). For ASL enriched with different metals (each concentration of metals was initially adjusted to 100 mg l(-1)), the residual Cr, Cu, Pb and Zn concentrations at the end of the experiments were below the acceptable level recommended for discharge in sewage urban works (more than 99.8% of metal was removed) using either electrocoagulation or chemical precipitation. Cd was more effectively removed by electrochemical treatment, whereas Ni was easily removed by chemical treatment. The cost for energy, chemicals and disposal of metallic residue of electrocoagulation process ranged from USD 8.83 to 13.95 tds(-1), which was up to five times lower than that recorded using chemical precipitation. Highly effective electrocoagulation was observed as the ASL was specifically enriched with high concentration of Pb (250-2000 mg Pbl(-1)). More than 99.5% of Pb was removed regardless of the initial Pb concentration imposed in ASL and, in all cases, the residual Pb concentrations (0.0-1.44 mg l(-1)) were below the limiting value (2.0 mg l(-1)) for effluent discharge in sewage works.

Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement.

PubMed

Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Tan, Piqiang; Yao, Di; Hu, Wei; Li, Peng; Ren, Jin; Chen, Changhong

2012-01-01

This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) x 10(8) cm(-3). The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 x 10(6) cm(-3) and 2.7 x 10(7) cm(-3) under decelerating and idling operations and as high as 5.0 x 10(8) cm(-3) under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

Studies of concentration and temperature dependences of precipitation kinetics in iron-copper alloys using kinetic Monte Carlo and stochastic statistical simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khromov, K. Yu.; Vaks, V. G., E-mail: vaks@mbslab.kiae.ru; Zhuravlev, I. A.

2013-02-15

The previously developed ab initio model and the kinetic Monte Carlo method (KMCM) are used to simulate precipitation in a number of iron-copper alloys with different copper concentrations x and temperatures T. The same simulations are also made using an improved version of the previously suggested stochastic statistical method (SSM). The results obtained enable us to make a number of general conclusions about the dependences of the decomposition kinetics in Fe-Cu alloys on x and T. We also show that the SSM usually describes the precipitation kinetics in good agreement with the KMCM, and using the SSM in conjunction withmore » the KMCM allows extending the KMC simulations to the longer evolution times. The results of simulations seem to agree with available experimental data for Fe-Cu alloys within statistical errors of simulations and the scatter of experimental results. Comparison of simulation results with experiments for some multicomponent Fe-Cu-based alloys allows making certain conclusions about the influence of alloying elements in these alloys on the precipitation kinetics at different stages of evolution.« less

Ultrafine particle and fiber production in micro-gravity

NASA Technical Reports Server (NTRS)

Webb, George W.

1987-01-01

The technique of evaporation and condensation of material in an inert gas is investigated for the purpose of preparing ultrafine particles (of order 10 nm in diameter) with a narrow distribution of sizes. Gravity-driven convection increases the rate of coalescence of the particles, leading to larger sizes and a broader distribution. Analysis and experimental efforts to investigate coalescence of particles are presented. The possibility of reducing coalescence in microgravity is discussed. An experimental test in reduced gravity to be performed in a KC135 aircraft is described briefly.

Microstructure and Properties of Ternary Cu-Ti-Sn Alloy

NASA Astrophysics Data System (ADS)

Wang, Xianhui; Chen, Chunyu; Guo, Tingting; Zou, Juntao; Yang, Xiaohong

2015-07-01

The effect of Sn addition and heat treatment on the microstructure and properties of Cu-3Ti and Cu-2Ti alloys was studied. The microstructure and phase constituents were characterized by an optical microscope, x-ray diffractometer, and transmission electron microscope, and the electrical conductivity and hardness were determined as well. The results show that the as-cast microstructure of Cu-Ti-Sn alloys consists of α-Cu(Ti,Sn) and primary CuSn3Ti5 intermetallic compound. CuSn3Ti5 phase has a hexagonal structure with the lattice parameters a = 0.81737 nm, b = 0.81737 nm, and c = 0.55773 nm. With the increase of aging time, the electrical conductivity progressively increases, while the hardness increases and then decreases. After aging at 450 °C for 8 h, Cu-3Ti-2Sn alloy has an electrical conductivity of 23.1 MS/m and a hardness of 134.5 HV, and the electrical conductivity and hardness of Cu-2Ti-2Sn alloy are 21.5 MS/m and 119.3 HV, respectively. An appropriate aging is beneficial for the precipitation of coherent metastable β'-Cu4Ti phase, which can strengthen Cu-3Ti-2Sn and Cu-2Ti-2Sn alloys. However, a prolonged aging time results in the decrease of hardness due to the formation of incoherent equilibrium β-Cu3Ti phase. The presence of CuSn3Ti5 phase reduces the solute Ti content in the copper matrix and, thus, gives rise to the increase of the electrical conductivity of Cu-Ti-Sn alloys.

TRANSLOCATION AND POTENTIAL NEUROLOGICAL EFFECTS OF FINE AND ULTRAFINE PARTICLES: A CRITICAL UPDATE

EPA Science Inventory

This proceedings book is a collection of seminars presented in a symposium organized by by Munich's GSF-National Research Center for Environment and Health. Research presented at this symposium indicated inhaled ultrafine particulate matter quickly exits the lungs and target...

Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry.

PubMed

Kero, Ida Teresia; Jørgensen, Rikke Bramming

2016-09-01

The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPI(TM)), a Fast Mobility Particle Sizer (FMPS(TM)), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification.

Comparison of Three Real-Time Measurement Methods for Airborne Ultrafine Particles in the Silicon Alloy Industry

PubMed Central

Kero, Ida Teresia; Jørgensen, Rikke Bramming

2016-01-01

The aim of this study was to compare the applicability and the correlation between three commercially available instruments capable of detection, quantification, and characterization of ultrafine airborne particulate matter in the industrial setting of a tapping area in a silicon alloy production plant. The number concentration of ultrafine particles was evaluated using an Electric Low Pressure Impactor (ELPITM), a Fast Mobility Particle Sizer (FMPSTM), and a Condensation Particle Counter (CPC). The results are discussed in terms of particle size distribution and temporal variations linked to process operations. The instruments show excellent temporal covariation and the correlation between the FMPS and ELPI is good. The advantage of the FMPS is the excellent time- and size resolution of the results. The main advantage of the ELPI is the possibility to collect size-fractionated samples of the dust for subsequent analysis by, for example, electron microscopy. The CPC does not provide information about the particle size distribution and its correlation to the other two instruments is somewhat poor. Nonetheless, the CPC gives basic, real-time information about the ultrafine particle concentration and can therefore be used for source identification. PMID:27598180

Effect of Cu content on exfoliation corrosion and electrochemical corrosion of A7N01 aluminum alloy in EXCO solution

NASA Astrophysics Data System (ADS)

He, Yaling; Wang, Xiaomin; Hu, Jie; Zhou, Qiang; Chen, Hui

2017-07-01

The exfoliation corrosion (EXCO) sensitivities and electrochemical corrosions of A7N01 aluminum (Al) alloys with 0.074% and 0.136% Cu contents were investigated in EXCO solution. The exfoliation corrosion developed more rapidly for the alloy with 0.136% Cu by expressing higher exfoliation rate and deeper corrosion pits as observed by SEM and laser confocal scanning microscopy (LCSM). In EXCO solution, the alloy with 0.136% Cu content showed lower open-circuit potential (OCP) than the alloy with 0.074% Cu content. The alloy with 0.136% Cu content had bigger “hysteresis loop” in cyclic polarization curve which meant lower self-passivation ability. In electrochemical impedance spectroscopy plot, its curvature radius and capacitance index were lower. The electrochemical test results revealed that the alloy with 0.136% Cu content showed more severe electrochemical corrosion than the alloy with 0.074% Cu content, consistent with the exfoliation corrosion results. The microstructures of two alloys were observed through optical microscopy (OM) and transmission electron microscopy (TEM). The continuous distribution of the equilibrium precipitate η-MgZn2 on grain boundaries, the decreasing of the width of precipitate-free zone (PFZ) and the coarse Cu-Fe-Si-rich phase were responsible for the higher corrosion sensitivity of the Al alloy with 0.136% Cu than that of Al alloy with 0.074% Cu content in EXCO solution.

Patterning of alloy precipitation through external pressure

NASA Astrophysics Data System (ADS)

Franklin, Jack A.

Due to the nature of their microstructure, alloyed components have the benefit of meeting specific design goals across a wide range of electrical, thermal, and mechanical properties. In general by selecting the correct alloy system and applying a proper heat treatment it is possible to create a metallic sample whose properties achieve a unique set of design requirements. This dissertation presents an innovative processing technique intended to control both the location of formation and the growth rates of precipitates within metallic alloys in order to create multiple patterned areas of unique microstructure within a single sample. Specific experimental results for the Al-Cu alloy system will be shown. The control over precipitation is achieved by altering the conventional heat treatment process with an external surface load applied to selected locations during the quench and anneal. It is shown that the applied pressures affect both the rate and directionality of the atomic diffusion in regions close to the loaded surfaces. The control over growth rates is achieved by altering the enthalpic energy required for successful diffusion between lattice sites. Changes in the local chemical free energy required to direct the diffusion of atoms are established by introducing a non-uniform elastic strain energy field within the samples created by the patterned surface pressures. Either diffusion rates or atomic mobility can be selected as the dominating control process by varying the quench rate; with slower quenches having greater control over the mobility of the alloying elements. Results have shown control of Al2Cu precipitation over 100 microns on mechanically polished surfaces. Further experimental considerations presented will address consistency across sample ensembles. This includes repeatable pressure loading conditions and the chemical interaction between any furnace environments and both the alloy sample and metallic pressure loading devices.

Microscopy and microanalysis of complex nanosized strengthening precipitates in new generation commercial Al-Cu-Li alloys.

PubMed

Guinel, M J-F; Brodusch, N; Sha, G; Shandiz, M A; Demers, H; Trudeau, M; Ringer, S P; Gauvin, R

2014-09-01

Precipitates (ppts) in new generation aluminum-lithium alloys (AA2099 and AA2199) were characterised using scanning and transmission electron microscopy and atom probe tomography. Results obtained on the following ppts are reported: Guinier-Preston zones, T1 (Al2 CuLi), β' (Al3 Zr) and δ' (Al3 Li). The focus was placed on their composition and the presence of minor elements. X-ray energy-dispersive spectrometry in the electron microscopes and mass spectrometry in the atom probe microscope showed that T1 ppts were enriched in zinc (Zn) and magnesium up to about 1.9 and 3.5 at.%, respectively. A concentration of 2.5 at.% Zn in the δ' ppts was also measured. Unlike Li and copper, Zn in the T1 ppts could not be detected using electron energy-loss spectroscopy in the transmission electron microscope because of its too low concentration and the small sizes of these ppts. Indeed, Monte Carlo simulations of EEL spectra for the Zn L2,3 edge showed that the signal-to-noise ratio was not high enough and that the detection limit was at least 2.5 at.%, depending on the probe current. Also, the simulation of X-ray spectra confirmed that the detection limit was exceeded for the Zn Kα X-ray line because the signal-to-noise ratio was high enough in that case, which is in agreement with our observations. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Exposure to ultrafine particles, intracellular production of reactive oxygen species in leukocytes and altered levels of endothelial progenitor cells.

PubMed

Jantzen, Kim; Møller, Peter; Karottki, Dorina Gabriela; Olsen, Yulia; Bekö, Gabriel; Clausen, Geo; Hersoug, Lars-Georg; Loft, Steffen

2016-06-01

Exposure to particles in the fine and ultrafine size range has been linked to induction of low-grade systemic inflammation, oxidative stress and development of cardiovascular diseases. Declining levels of endothelial progenitor cells within systemic circulation have likewise been linked to progression of cardiovascular diseases. The objective was to determine if exposure to fine and ultrafine particles from indoor and outdoor sources, assessed by personal and residential indoor monitoring, is associated with altered levels of endothelial progenitor cells, and whether such effects are related to leukocyte-mediated oxidative stress. The study utilized a cross sectional design performed in 58 study participants from a larger cohort. Levels of circulating endothelial progenitor cells, defined as either late (CD34(+)KDR(+) cells) or early (CD34(+)CD133(+)KDR(+) cells) subsets were measured using polychromatic flow cytometry. We additionally measured production of reactive oxygen species in leukocyte subsets (lymphocytes, monocytes and granulocytes) by flow cytometry using intracellular 2',7'-dichlorofluoroscein. The measurements encompassed both basal levels of reactive oxygen species production and capacity for reactive oxygen species production for each leukocyte subset. We found that the late endothelial progenitor subset was negatively associated with levels of ultrafine particles measured within the participant residences and with reactive oxygen species production capacity in lymphocytes. Additionally, the early endothelial progenitor cell levels were positively associated with a personalised measure of ultrafine particle exposure and negatively associated with both basal and capacity for reactive oxygen species production in lymphocytes and granulocytes, respectively. Our results indicate that exposure to fine and ultrafine particles derived from indoor sources may have adverse effects on human vascular health. Copyright © 2016 The Authors. Published by Elsevier

Children exposure to indoor ultrafine particles in urban and rural school environments.

PubMed

Cavaleiro Rufo, João; Madureira, Joana; Paciência, Inês; Slezakova, Klara; Pereira, Maria do Carmo; Aguiar, Lívia; Teixeira, João Paulo; Moreira, André; Oliveira Fernandes, Eduardo

2016-07-01

Extended exposure to ultrafine particles (UFPs) may lead to consequences in children due to their increased susceptibility when compared to older individuals. Since children spend in average 8 h/day in primary schools, assessing the number concentrations of UFPs in these institutions is important in order to evaluate the health risk for children in primary schools caused by indoor air pollution. Thus, the purpose of this study was to assess and determine the sources of indoor UFP number concentrations in urban and rural Portuguese primary schools. Indoor and outdoor ultrafine particle (UFP) number concentrations were measured in six urban schools (US) and two rural schools (RS) located in the north of Portugal, during the heating season. The mean number concentrations of indoor UFPs were significantly higher in urban schools than in rural ones (10.4 × 10(3) and 5.7 × 10(3) pt/cm(3), respectively). Higher UFP levels were associated with higher squared meters per student, floor levels closer to the ground, chalk boards, furniture or floor covering materials made of wood and windows with double-glazing. Indoor number concentrations of ultrafine-particles were inversely correlated with indoor CO2 levels. In the present work, indoor and outdoor concentrations of UFPs in public primary schools located in urban and rural areas were assessed, and the main sources were identified for each environment. The results not only showed that UFP pollution is present in augmented concentrations in US when compared to RS but also revealed some classroom/school characteristics that influence the concentrations of UFPs in primary schools.

Coalescence growth mechanism of ultrafine metal particles

NASA Astrophysics Data System (ADS)

Kasukabe, S.

1990-01-01

Ultrafine particles produced by a gas-evaporation technique show clear-cut crystal habits. The convection of an inert gas makes distinct growth zones in a metal smoke. The coalescence stages of hexagonal plates and multiply twinned particles are observed in the outer zone of a smoke. A model of the coalescence growth of particles with different crystal habits is proposed. Size distributions can be calculated by counting the ratio of the number of collisions by using the effective cross section of collisions and the existence probability of the volume of a particle. This simulation model makes clear the effect on the growth rate of coalescence growth derived from crystal habit.

Coercivity enhancement in Mn-Al-Cu flakes produced by surfactant-assisted milling

NASA Astrophysics Data System (ADS)

Saravanan, P.; Hsu, Jen-Hwa; Vinod, V. T. P.; Černík, Miroslav; Kamat, S. V.

2015-11-01

We herein report the achievement of exceptionally high coercivity (Hc) values: 9.92 and 5.86 kOe at 5 and 300 K, respectively, for Mn55Al43Cu2 flakes produced by surfactant-assisted milling process without employing any heat-treatment. The use of surfactants such as oleic acid and oleylamine during milling yielded high-aspect ratio flakes for the Mn-Al-Cu alloy. Structural studies confirmed the presence of τ- and β-phases as the major constituents in the Mn-Al-Cu flakes. The observed Hc enhancement is due to the increase in anisotropy field and structural defects, which is hypothesized to originate from the domain-wall pinning as a consequence of precipitation of fine Cu-particles present at the grain boundaries.

Empirical force field-based kinetic Monte Carlo simulation of precipitate evolution and growth in Al-Cu alloys

NASA Astrophysics Data System (ADS)

Joshi, Kaushik; Chaudhuri, Santanu

2016-10-01

Ability to accelerate the morphological evolution of nanoscale precipitates is a fundamental challenge for atomistic simulations. Kinetic Monte Carlo (KMC) methodology is an effective approach for accelerating the evolution of nanoscale systems that are dominated by so-called rare events. The quality and accuracy of energy landscape used in KMC calculations can be significantly improved using DFT-informed interatomic potentials. Using newly developed computational framework that uses molecular simulator LAMMPS as a library function inside KMC solver SPPARKS, we investigated formation and growth of Guiner-Preston (GP) zones in dilute Al-Cu alloys at different temperature and copper concentrations. The KMC simulations with angular dependent potential (ADP) predict formation of coherent disc-shaped monolayers of copper atoms (GPI zones) in early stage. Such monolayers are then gradually transformed into energetically favored GPII phase that has two aluminum layers sandwiched between copper layers. We analyzed the growth kinetics of KMC trajectory using Johnson-Mehl-Avrami (JMA) theory and obtained a phase transformation index close to 1.0. In the presence of grain boundaries, the KMC calculations predict the segregation of copper atoms near the grain boundaries instead of formation of GP zones. The computational framework presented in this work is based on open source potentials and MD simulator and can predict morphological changes during the evolution of the alloys in the bulk and around grain boundaries.

Cardiovascular Effects in Adults with Metabolic Syndrome Exposed to Concentrated Ultrafine Air Pollution Particles

EPA Science Inventory

RATIONALE: Epidemiologic studies report associations between ambient air pollution particulate matter (PM) and various indices of cardiopulmonary morbidity and mortality. A leading hypothesis contends that smaller ultrafine (UF) particles induce a greater physiologic response bec...

Cobalt doped CuMnOx catalysts for the preferential oxidation of carbon monoxide

NASA Astrophysics Data System (ADS)

Dey, Subhashish; Dhal, Ganesh Chandra; Mohan, Devendra; Prasad, Ram; Gupta, Rajeev Nayan

2018-05-01

Carbon monoxide (CO) is a poisonous gas, recognized as a silent killer for the 21st century. It is produced from the partial oxidation of carbon containing compounds. The catalytic oxidation of CO receives a huge attention due to its applications in different fields. In the present work, hopcalite (CuMnOx) catalysts were synthesized using a co-precipitation method for CO oxidation purposes. Also, it was doped with the cobalt by varying concentration from 1 to 5wt%. It was observed that the addition of cobalt into the CuMnOx catalyst (by the deposition-precipitation method) improved the catalytic performance for the low-temperature CO oxidation. CuMnOx catalyst doped with 3wt% of cobalt exhibited most active performance and showed the highest activity than other cobalt concentrations. Different analytical tools (i.e. XRD, FTIR, BET, XPS and SEM-EDX) were used to characterize the as-synthesized catalysts. It was expected that the introduction of cobalt will introduce new active sites into the CuMnOx catalyst that are associated with the cobalt nano-particles. The order of calcination strategies based on the activity for cobalt doped CuMnOx catalysts was observed as: Reactive calcinations (RC) > flowing air > stagnant air. Therefore, RC (4.5% CO in air) route can be recommended for the synthesis of highly active catalysts. The catalytic activity of doped CuMnOx catalysts toward CO oxidation shows a correlation among average oxidation number of Mn and the position and the nature of the doped cobalt cation.

[Worker exposure to ultrafine particles during carbon black treatment].

PubMed

Mikołajczyk, Urszula; Bujak-Pietrek, Stella; Szadkowska-Stańczyk, Irena

2015-01-01

The aim of the project was to assess the exposure of workers to ultrafine particles released during handling and packing of carbon black. The assessment included the results of the measurements performed in a carbon black handling plant before, during, and after work shift. The number concentration of particles within the dimension range 10-1000 nm and 10-100 nm was assayed by a condensation particle counter (CPC). The mass concentration of particles was determined by a DustTrak II DRX aerosol concentration monitor. The surface area concentration of the particles potentially deposited in the alveolar (A) and tracheo-bronchial (TB) regions was estimated by an AeroTrak 9000 nanoparticle monitor. An average mass concentration of particles during the process was 6-fold higher than that before its start, while a 3-fold increase in the average number concentration of particles within the dimension range 10-1000 nm and 10-100 nm was observed during the process. At the same time a 4-fold increase was found in the surface area concentration of the particles potentially deposited in the A and TB regions. During the process of carbon black handling and packing a significantly higher values of each of the analysed parameters, characterizing the exposure to ultrafine particles, were noted. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects

PubMed Central

Liu, Chen; Fu, Xuekun; Pan, Haobo; Wan, Peng; Wang, Lei; Tan, Lili; Wang, Kehong; Zhao, Ying; Yang, Ke; Chu, Paul K.

2016-01-01

A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications. PMID:27271057

CuO/CeO2 catalysts for glycerol selective conversion to lactic acid.

PubMed

Palacio, Ruben; Torres, Sebastian; Royer, Sébastien; Mamede, Anne Sophie; López, Diana; Hernández, Diana

2018-03-26

Ceria supported copper oxide catalysts were produced by a deposition-precipitation method, at a high copper loading (up to >25 wt%). These materials demonstrated excellent properties for glycerol selective conversion to lactic acid, with a conversion reaching up to 87% with a selectivity to lactic acid of 74% (8 h reaction, 220 °C, under N2 pressure). These catalysts also exhibited high stability upon 5 successive reaction cycles. The formation of a crystalline CuO phase was demonstrated in the nanocomposites at a high Cu loading, with elongated shaped particles formed on the cerium oxide surface. Such particles were however, not observed at low Cu loadings. XPS analysis revealed that Cu(ii) was the main Cu species on the fresh catalyst, and that this species was reduced to Cu(i) during the reaction. Complementary characterization over the spent catalyst clearly showed the morphological modifications of the CuO phase, however, did not impact significantly either glycerol conversion or selectivity to lactic acid upon recycling. For instance, apparently, the catalytic activity of CuO largely depends on the Cu(ii) species.

Benign joining of ultrafine grained aerospace aluminum alloys using nanotechnology.

PubMed

Longtin, Rémi; Hack, Erwin; Neuenschwander, Jürg; Janczak-Rusch, Jolanta

2011-12-22

Ultrafine grained aluminum alloys have restricted applicability due to their limited thermal stability. Metalized 7475 alloys can be soldered and brazed at room temperature using nanotechnology. Reactive foils are used to release heat for milliseconds directly at the interface between two components leading to a metallurgical joint without significantly heating the bulk alloy, thus preserving its mechanical properties. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A dislocation density based micromechanical constitutive model for Sn-Ag-Cu solder alloys

NASA Astrophysics Data System (ADS)

Liu, Lu; Yao, Yao; Zeng, Tao; Keer, Leon M.

2017-10-01

Based on the dislocation density hardening law, a micromechanical model considering the effects of precipitates is developed for Sn-Ag-Cu solder alloys. According to the microstructure of the Sn-3.0Ag-0.5Cu thin films, intermetallic compounds (IMCs) are assumed as sphere particles embedded in the polycrystalline β-Sn matrix. The mechanical behavior of polycrystalline β-Sn matrix is determined by the elastic-plastic self-consistent method. The existence of IMCs not only impedes the motion of dislocations but also increases the overall stiffness. Thus, a dislocation density based hardening law considering non-shearable precipitates is adopted locally for single β-Sn crystal, and the Mori-Tanaka scheme is applied to describe the overall viscoplastic behavior of solder alloys. The proposed model is incorporated into finite element analysis and the corresponding numerical implementation method is presented. The model can describe the mechanical behavior of Sn-3.0Ag-0.5Cu and Sn-1.0Ag-0.5Cu alloys under high strain rates at a wide range of temperatures. Furthermore, the overall Young’s modulus changes due to different contents of IMCs is predicted and compared with experimental data. Results show that the proposed model can describe both elastic and inelastic behavior of solder alloys with reasonable accuracy.

Time-Temperature-Precipitation Behavior in Al-Li Alloy 2195

NASA Technical Reports Server (NTRS)

Chen, P. S.; Bhat, B. N.

2002-01-01

Transmission electron microscopy was used to study time-temperature-precipitation (TTP) behavior in aluminum-lithium (Al-Li) 2195 alloy. Al-Li 2195 (nominally Al + 4 percent Cu + 1 percent Li + 0.3 percent Ag + 0.3 percent Mg + 0.1 percent Zr) was initially solutionized for 1 hr at 950 F and then stretched 3 percent. Heat treatments were conducted for up to 100 hr at temperatures ranging from 200 to 1,000 F. TTP diagrams were determined for both matrix and subgrain boundaries. Depending upon heat treatment conditions, precipitate phases (such as GP zone, theta'', theta', theta, delta', T1, TB, and T2) were found in the alloy. The TTP diagrams were applied as a guide to avoid T1 precipitation at subgrain boundaries, as part of an effort to improve the alloy's cryogenic fracture toughness (CFT). New understanding of TTP behavior was instrumental in the development of a two-step artificial aging treatment that significantly enhanced CFT in Al-Li 2195.

Effect of CeLa addition on the microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Jiandi

Development of high strength lithium battery shell alloy is highly desired for new energy automobile industry. The microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy with different CeLa additions were investigated through optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rietveld refinement and tensile testing. Experimental results indicate that Al{sub 8}Cu{sub 4}Ce and Al{sub 6}Cu{sub 6}La phases formed due to CeLa addition. Addition of 0.25 wt.% CeLa could promote the formation of denser precipitation of Al{sub 20}Cu{sub 2}Mn{sub 3} and Al{sub 6}(Mn, Fe) phases, which improved the mechanical properties of the alloy at room temperature.more » However, up to 0.50 wt.% CeLa addition could promote the formation of coarse Al{sub 8}Cu{sub 4}Ce phase, Al{sub 6}Cu{sub 6}La phase and Al{sub 6}(Mn, Fe) phase, which resulted in weakened mechanical properties. - Highlights: •Al-Cu-Mn-Mg-Fe alloys with different CeLa addition were fabricated through casting and rolling. •Al{sub 8}Cu{sub 4}Ce and Al{sub 6}Cu{sub 6}La phases formed after CeLa addition. •Addition of 0.25 wt.% CeLa promoted formation of denser precipitates of Al{sub 20}Cu{sub 2}Mn{sub 3} and Al{sub 6}(Mn, Fe). •Mechanical properties of the alloy was improved after 0.25 wt.% CeLa addition.« less

Grindability of dental cast Ti-Ag and Ti-Cu alloys.

PubMed

Kikuchi, Masafumi; Takahashi, Masatoshi; Okabe, Toru; Okuno, Osamu

2003-06-01

Experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were cast into magnesia molds using a dental casting machine, and their grindability was investigated. At the lowest grinding speed (500 m min(-1)), there were no statistical differences among the grindability values of the titanium and titanium alloys. The grindability of the alloys increased as the grinding speed increased. At the highest grinding speed (1500 m x min(-1)), the grindability of the 20% Ag, 5% Cu, and 10% Cu alloys was significantly higher than that of titanium. It was found that alloying with silver or copper improved the grindability of titanium, particularly at a high speed. It appeared that the decrease in elongation caused by the precipitation of small amounts of intermetallic compounds primarily contributed to the favorable grindability of the experimental alloys.

Combustion of PTFE: The effects of gravity on ultrafine particle generation

NASA Technical Reports Server (NTRS)

McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

1996-01-01

The objective of this project is to obtain an understanding of the effect of gravity on the toxicity of ultrafine particle and gas phase materials produced when fluorocarbon polymers are thermally degraded or burned. The motivation for the project is to provide a basic technical foundation on which policies for spacecraft health and safety with regard to fire and polymers can be formulated.

Size-resolved ultrafine particle composition analysis 1. Atlanta

NASA Astrophysics Data System (ADS)

Rhoads, K. P.; Phares, D. J.; Wexler, A. S.; Johnston, M. V.

2003-04-01

During August 1999 as part of the Southern Oxidants Study Supersite Experiment, our group collected size-resolved measurements of the chemical composition of single ambient aerosol particles with a unique real-time laser desorption/ionization mass spectrometry technique. The rapid single-particle mass spectrometry instrument is capable of analyzing "ultrafine" particles with aerodynamic diameters ranging from 0.01 to 1.5 μm. Under the heaviest loading observed in Atlanta, particles were analyzed at a rate of roughly one per second in sizes ranging from 0.1 to 0.2 μm. Nearly 16,000 individual spectra were recorded over the course of the month during both daytime and nighttime sampling periods. Evaluation of the data indicates that the composition of the ultrafine (less than 100 nm) particles is dominated by carbon-containing compounds. Larger particles show varied compositions but typically appeared to have organic carbon characteristics mixed with an inorganic component (e.g., crustal materials, metals, etc.). During the experiment, 70 composition classes were identified. In this paper we report the average spectra and correlations with various meteorological parameters for all major compound classes and a number of minor ones. The major composition classes are identified from the primary peaks in their spectra as organic carbon (about 74% of the particles), potassium (8%), iron (3%), calcium (2%), nitrate (2%), elemental carbon (1.5%), and sodium (1%). Many of these compound classes appeared in repeatable size ranges and quadrants of the wind rose, indicating emission from specific sources.

SOURCE STRENGTHS OF ULTRAFINE AND FINE PARTICLES DUE TO COOKING WITH A GAS STOVE

EPA Science Inventory

Cooking, particularly frying, is an important source of particles indoors. Few studies have measured a full range of particle sizes, including ultrafine particles, produced during cooking. In this study, semicontinuous instruments with fine size discriminating ability were us...

Spatial Pattern of Copper Phosphate Precipitation Involves in Copper Accumulation and Resistance of Unsaturated Pseudomonas putida CZ1 Biofilm.

PubMed

Chen, Guangcun; Lin, Huirong; Chen, Xincai

2016-12-28

Bacterial biofilms are spatially structured communities that contain bacterial cells with a wide range of physiological states. The spatial distribution and speciation of copper in unsaturated Pseudomonas putida CZ1 biofilms that accumulated 147.0 mg copper per g dry weight were determined by transmission electron microscopy coupled with energy dispersive X-ray analysis, and micro-X-ray fluorescence microscopy coupled with micro-X-ray absorption near edge structure (micro-XANES) analysis. It was found that copper was mainly precipitated in a 75 μm thick layer as copper phosphate in the middle of the biofilm, while there were two living cell layers in the air-biofilm and biofilm-medium interfaces, respectively, distinguished from the copper precipitation layer by two interfaces. The X-ray absorption fine structure analysis of biofilm revealed that species resembling Cu₃(PO₄)₂ predominated in biofilm, followed by Cu-Citrate- and Cu-Glutathione-like species. Further analysis by micro-XANES revealed that 94.4% of copper were Cu₃(PO₄)₂-like species in the layer next to the air interface, whereas the copper species of the layer next to the medium interface were composed by 75.4% Cu₃(PO₄)₂, 10.9% Cu-Citrate-like species, and 11.2% Cu-Glutathione-like species. Thereby, it was suggested that copper was initially acquired by cells in the biofilm-air interface as a citrate complex, and then transported out and bound by out membranes of cells, released from the copper-bound membranes, and finally precipitated with phosphate in the extracellular matrix of the biofilm. These results revealed a clear spatial pattern of copper precipitation in unsaturated biofilm, which was responsible for the high copper tolerance and accumulation of the biofilm.

[Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

PubMed

Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

2014-09-01

Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

Mammalian cell-transforming potential of traffic-linked ultrafine particulate matter PM0.056 in urban roadside atmosphere.

PubMed

Verma, Mukesh K; Poojan, Shiv; Sultana, Sarwat; Kumar, Sushil

2014-09-01

We examined the clastogenic and cell-transforming potential of ultrafine particulate matter fraction PM0.056 of urban ambient aerosol using mammalian cells. PM1.0, PM0.56 and PM0.056 fractions were sampled from roadside atmosphere of an urban area using the cascade impactor MOUDI-NR-110. The potential to induce cytotoxicity, DNA damage and micronuclei formation was examined at the test concentrations of 3, 6, 12.5, 25, 50 and 100 μg/ml using the 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, the plasmid relaxation assay and the C3H10T1/2 (10T1/2) cells. The cell-transforming potential was investigated in vitro using 10T1/2 cell transformation assay and the soft agar assay. PM1, PM0.56 and PM0.056 fractions were found to be toxic in dose-dependent manner. These induced cytotoxicity at five test concentrations, the ultrafine particle fraction PM0.056 showed greater cytotoxic potential. PM0.056 induced micronucleus formation in 10T1/2 cells. The effect was statistically significant. The DNA-damaging potential was measured in a plasmid relaxation assay. Both fine and ultrafine particle fraction PM0.56 and PM0.056 displayed greater effect as compared to larger PM1 fraction. DNA damage was found to be dependent on particulate matter intrinsic pro-oxidant chemicals. The ability of the ultrafine particle fraction PM0.056 to induce morphological cell transformation was demonstrated by significant and dose-dependent increases in type III focus formation by morphologically transformed cells in culture flasks and their clonal expansion in soft agar. It is concluded that the traffic-linked ultrafine particle fraction PM0.056 in the atmosphere by the roadside of an urban area is clastogenic and able to induce morphological transformation of mammalian cells. © The Author 2014. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions

Corona-assisted flame synthesis of ultrafine titania particles

NASA Astrophysics Data System (ADS)

Vemury, Srinivas; Pratsinis, Sotiris E.

1995-06-01

Synthesis of ultrafine titania particles is investigated in a diffusion flame aerosol reactor in the presence of a gaseous electric discharge (corona) created by two needle electrodes. The corona wind flattens the flame and reduces the particle residence time at high temperatures, resulting in smaller primary particle sizes and lower level of crystallinity. Increasing the applied potential from 5 to 8 kV reduces the particle size from 50 to 25 nm and the rutile content from 20 to 8 wt %. Coronas provide a clean and simple technique that facilitates gas phase synthesis of nanosized materials with controlled size and crystallinity.

A novel ultrafine-grained Fe−22Mn−0.6C TWIP steel with superior strength and ductility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Y.Z., E-mail: yztian@imr.ac.cn

A fully recrystallized ultrafine-grained (UFG) Fe−22wt.%Mn−0.6wt.%C twinning-induced plasticity (TWIP) steel with mean grain size of 576 nm was fabricated by cold rolling and annealing process. Tensile test showed that this UFG steel possessed high yield strength of 785 MPa, and unprecedented uniform elongation of 48%. The Hall-Petch relationship was verified from the coarse-grained (CG) regime to the ultrafine-grained (UFG) regime. The microstructures at specified tensile strains were characterized by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The microstructures and strain hardening behavior of the UFG TWIP steel were compared with the CG counterpart. The strong strain hardening capabilitymore » of the UFG steel is supposed to be responsible for the high strength and good ductility. - Highlights: • A fully recrystallized Fe−22Mn−0.6C TWIP steel with mean grain size of 576 nm was fabricated. • The ultrafine-grained (UFG) steel exhibits strong strain-hardening capability, excellent strength and ductility. • The Hall-Petch relationship is fitted well from the CG regime to the UFG regime.« less

Daily trends and source apportionment of ultrafine particulate mass (PM0.1) over an annual cycle in a typical California city.

PubMed

Kuwayama, Toshihiro; Ruehl, Chris R; Kleeman, Michael J

2013-12-17

Toxicology studies indicate that inhalation of ultrafine particles (Dp < 0.1 μm) causes adverse health effects, presumably due to their large surface area-to-volume ratio that can drive heterogeneous reactions. Epidemiological associations between ultrafine particles and health effects, however, have been difficult to identify due to the lack of appropriate long-term monitoring and exposure data. The majority of the existing ultrafine particle epidemiology studies are based on exposure to particle number, although an independent analysis suggests that ultrafine particle mass (PM0.1) correlates better with particle surface area. More information is needed to characterize PM0.1 exposure to fully evaluate the health effects of ultrafine particles using epidemiology. The present study summarizes 1 year of daily PM0.1 chemistry and source apportionment at Sacramento, CA, USA. Positive matrix factorization (PMF) was used to resolve PM0.1 source contributions from old-technology diesel engines, residential wood burning, rail, regional traffic, and brake wear/road dust. Diesel PM0.1 and total PM0.1 concentrations were reduced by 97 and 26%, respectively, as a result of the adoption of cleaner diesel technology. The strong linear correlation between PM0.1 and particle surface area in central California suggests that the adoption of clean diesel engines reduced particle surface area by similar amounts. PM0.1 sulfate reduction occurred as a result of reduced primary particle surface area available for sulfate condensation. The current study demonstrates the capability of measuring PM0.1 source contributions over a 12 month period and identifies the extended benefits of emissions reduction efforts for diesel engines on ambient concentrations of primary and secondary PM0.1.

Effect of reductant and PVP on morphology and magnetic property of ultrafine Ni powders prepared via hydrothermal route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jun, E-mail: j-zhang@126.com; Wang, Xiucai; Li, Lili

2013-10-15

Graphical abstract: The ultrafine Ni powders with the shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using different reductants. Their saturation magnetization, remanent magnetization and coercivity sequentially increase, and the coercivity of hexagonal sheet-like Ni powders increases by 25% compared with the Ni bulk counterpart. - Highlights: • The ultrafine Ni powders with various shapes of sphere, fish-bone, hexagonal sheet, etc. • Facile and one-step hydrothermal reduction using three reductants and PVP additive was developed. • Magnetic properties of the ultrafine Ni powders with different shapes were measured. • Compared with bulkmore » Ni material, coercivity of hexagonal sheet Ni increases by 25%. • The formation mechanism of the shapes was suggested. - Abstract: The ultrafine nickel particles with different shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using hydrazine hydrate, sodium hypophosphite and ethylene glycol as reductants, polyvinylpyrrolidone as structure-directing agent. It has been verified with the characterization of X-ray powder diffraction and transmission/scanning electronic microscopy that as-prepared products belong to face-centered cubic structure of nickel microcrystals with high purity and fine dispersity. The magnetic hysteresis loops measured at room temperature reveal that the values of saturation magnetization, remanent magnetization and coercivity rise sequentially from silknet, sphere to hexagonal sheet. In comparison with nickel bulk counterpart, the coercivity of the hexagonal sheet nickel powders increases by 25%.« less

TL-OSL study of Li3PO4: Mg, Cu phosphor

NASA Astrophysics Data System (ADS)

Rahangdale, S. R.; Wankhede, S. P.; Dhabekar, B. S.; Palikundwar, U. A.; Moharil, S. V.

2015-08-01

In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li3PO4 phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li3PO4 shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

PULMONARY AND CARDIAC GENE EXPRESSION FOLLOWING ACUTE ULTRAFINE CARBON PARTICLE INHALATION IN HYPERTENSIVE RATS

EPA Science Inventory

Inhalation of ultrafine carbon particles (ufCP) causes cardiac physiological changes without marked pulmonary injury or inflammation. We hypothesized that acute ufCP exposure of 13 months old Spontaneously Hypertensive (SH) rats will cause differential effects on the lung and hea...

DEPOSITION DISTRIBUTION OF NANO AND ULTRAFINE PARTICLES IN HUMAN LUNGS DURING CONTROLLED MOUTH BREATHING

EPA Science Inventory

Nano and ultrafine particles are abundant in the atmosphere and the level of human exposure to these tiny particles is expected to increase markedly as industrial activities increase manufacturing nano-sized materials. Exposure-dose relationships and site-specific internal dose a...

Increased ultrafine particles and carbon monoxide concentrations are associated with asthma exacerbation among urban children.

PubMed

Evans, Kristin A; Halterman, Jill S; Hopke, Philip K; Fagnano, Maria; Rich, David Q

2014-02-01

Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1-7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. We conducted a pilot study using data from 3 to 10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088p/cm(3); OR=1.27; 95% CI=0.90-1.79) and 7-day mean carbon monoxide (interquartile range=0.17ppm; OR=1.63; 95% CI=1.03-2.59). Relative odds

Increased ultrafine particles and carbon monoxide concentrations are associated with asthma exacerbation among urban children

PubMed Central

Evans, Kristin A.; Halterman, Jill S.; Hopke, Philip K.; Fagnano, Maria; Rich, David Q.

2014-01-01

Objectives Increased air pollutant concentrations have been linked to several asthma-related outcomes in children, including respiratory symptoms, medication use, and hospital visits. However, few studies have examined effects of ultrafine particles in a pediatric population. Our primary objective was to examine the effects of ambient concentrations of ultrafine particles on asthma exacerbation among urban children and determine whether consistent treatment with inhaled corticosteroids could attenuate these effects. We also explored the relationship between asthma exacerbation and ambient concentrations of accumulation mode particles, fine particles (≤ 2.5 micrograms [μm]; PM2.5), carbon monoxide, sulfur dioxide, and ozone. We hypothesized that increased 1 to 7 day concentrations of ultrafine particles and other pollutants would be associated with increases in the relative odds of an asthma exacerbation, but that this increase in risk would be attenuated among children receiving school-based corticosteroid therapy. Methods We conducted a pilot study using data from 3–10 year-old children participating in the School-Based Asthma Therapy trial. Using a time-stratified case-crossover design and conditional logistic regression, we estimated the relative odds of a pediatric asthma visit treated with prednisone (n=96 visits among 74 children) associated with increased pollutant concentrations in the previous 7 days. We re-ran these analyses separately for children receiving medications through the school-based intervention and children in a usual care control group. Results Interquartile range increases in ultrafine particles and carbon monoxide concentrations in the previous 7 days were associated with increases in the relative odds of a pediatric asthma visit, with the largest increases observed for 4-day mean ultrafine particles (interquartile range=2088 p/cm3; OR=1.27; 95% CI=0.90–1.79) and 7-day mean carbon monoxide (interquartile range=0.17 ppm; OR=1.63; 95

Ultrafine particles (UFPs) from domestic wood stoves: genotoxicity in human lung carcinoma A549 cells.

PubMed

Marabini, Laura; Ozgen, Senem; Turacchi, Silvia; Aminti, Stefania; Arnaboldi, Francesca; Lonati, Giovanni; Fermo, Paola; Corbella, Lorenza; Valli, Gianluigi; Bernardoni, Vera; Dell'Acqua, Manuela; Vecchi, Roberta; Becagli, Silvia; Caruso, Donatella; Corrado, Galli L; Marinovich, Marina

2017-08-01

In this paper, results on the potential toxicity of ultrafine particles (UFPs d<100nm) emitted by the combustion of logwood and pellet (hardwood and softwood) are reported. The data were collected during the TOBICUP (TOxicity of BIomass COmbustion generated Ultrafine Particles) project, carried out by a team composed of interdisciplinary research groups. The genotoxic evaluation was performed on A549 cells (human lung carcinomacells) using UFPs whose chemical composition was assessed by a suite of analytical techniques. Comet assay and γ-H2AX evaluation show a significant DNA damage after 24h treatment. The interpretation of the results is based on the correlation among toxicological results, chemical-physical properties of UFPs, and the type and efficiency conditions in residential pellet or logwood stoves. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrafine particles, and PM 2.5 generated from cooking in homes

NASA Astrophysics Data System (ADS)

Wan, Man-Pun; Wu, Chi-Li; Sze To, Gin-Nam; Chan, Tsz-Chun; Chao, Christopher Y. H.

2011-11-01

Exposure to airborne particulate matters (PM) emitted during cooking can lead to adverse health effects. An understanding of the exposure to PM during cooking at home provides a foundation for the quantification of possible health risks. The concentrations of airborne particles covering the ultrafine (14.6-100 nm) and accumulation mode (100-661.2 nm) size ranges and PM 2.5 (airborne particulate matters smaller than 2.5 μm in diameter) during and after cooking activities were measured in 12 naturally ventilated, non-smoking homes in Hong Kong, covering a total of 33 cooking episodes. The monitored homes all practiced Chinese-style cooking. Cooking elevated the average number concentrations of ultrafine particles (UFPs) and accumulation mode particles (AMPs) by 10 fold from the background level in the living room and by 20-40 fold in the kitchen. PM 2.5 mass concentrations went up to the maximum average of about 160 μg m -3 in the kitchen and about 60 μg m -3 in the living room. Cooking emitted particles dispersed quickly from the kitchen to the living room indicating that the health impact is not limited to occupants in the kitchen. Particle number and mass concentrations remained elevated for 90 min in the kitchen and for 60 min in the living room after cooking. Particles in cooking emissions were mainly in the ultrafine size range in terms of the number count while AMPs contributed to at least 60% of the surface area concentrations in the kitchen and 73% in the living room. This suggests that AMPs could still be a major health concern since the particle surface area concentration is suggested to have a more direct relationship with inhalation toxicity than with number concentration. Particle number concentration (14.6-661.2 nm) in the living room was about 2.7 times that in the outdoor environment, suggesting that better ventilation could help reduce exposure.

Effect of the Thermomechanical Treatment on Structural and Phase Transformations in Cu-14Al-3Ni Shape Memory Alloy Subjected to High-Pressure Torsion

NASA Astrophysics Data System (ADS)

Lukyanov, A. V.; Pushin, V. G.; Kuranova, N. N.; Svirid, A. E.; Uksusnikov, A. N.; Ustyugov, Yu. M.; Gunderov, D. V.

2018-04-01

The possibilities of controlling the structure and properties of a Cu-Al-Ni shape memory alloy due to the use of different schemes of the thermomechanical treatment, including forging, homogenizing in the austenitic state and subsequent quenching, and high-pressure torsion have been found. For the first time, an ultrafine-grain structure has been produced in this alloy via severe plastic deformation using high-pressure torsion. It has been detected that high-pressure torsion using ten revolutions of the anvils leads to the formation of a nanocrystalline structure with a grain size of less than 100 nm. The subsequent short-term heating of the alloy to 800°C (10 s) in the temperature region of the existence of the homogeneous β phase made it possible to form an ultrafine-grain structure with predominant sizes of recrystallized grains of 1 and 8 μm. The quenching after heating prevented the decomposition of the solid solution. The refinement of the grain structure changed the deformation behavior of the alloy, having provided the possibility of the significant plastic deformation upon mechanical tensile tests. The coarse-grained hot-forged quenched alloy was brittle, and fracture occurred along the boundaries of former austenite grains and martensite packets. The highstrength ultrafine-grained alloy also experienced mainly the intercrystalline fracture along the high-angle boundaries of elements of the structure, the grain size of which was less by two orders than that in the initial alloy. This determined an increase in its relative elongation upon mechanical tests.

Synthesis and magnetic properties of bacterial cellulose—ferrite (MFe2O4, M  =  Mn, Co, Ni, Cu) nanocomposites prepared by co-precipitation method

NASA Astrophysics Data System (ADS)

Sriplai, Nipaporn; Mongkolthanaruk, Wiyada; Pinitsoontorn, Supree

2017-09-01

The magnetic nanocomposites based on bacterial cellulose (BC) matrix and ferrite (MFe2O4, M  =  Mn, Co, Ni and Cu) nanoparticles (NPs) were fabricated. The never-dried and freeze-dried BC nanofibrils were used as templates and a co-precipitation method was applied for NPs synthesis. The nanocomposites were either freeze-dried or annealed before subjected to characterization. The x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy showed that only MnFe2O4 and CoFe2O4 NPs could be successfully incorporated in the BC nanostructures. The results also indicated that the BC template should be freeze-dried prior to the co-precipitation process. The magnetic measurement by a vibrating sample magnetometer (VSM) showed that the strongest ferromagnetic signal was found for BC-CoFe2O4 nanocomposites. The morphological investigation by a scanning electron microscope (SEM) showed the largest volume fraction of NPs in the BC-CoFe2O4 sample which was complimentary to the magnetic property measurement. Annealing resulted in the collapse of the opened nanostructure of the BC composites. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

[Health effects of ambient ultrafine particles--the project UFIREG].

PubMed

Dostál, Miroslav; Pastorková, Anna; Lanzinger, Stefanie; Schneider, Alexandra; Bastian, Susanne; Senghaas, Monika; Erzen, Ziva; Novák, Jiří; Kolodnitska, Teťana; Šrám, Radim J; Peters, Annette

2015-01-01

The project "Ultrafine particles--an evidence based contribution to the development of regional and European environmental and health policy" (UFIREG) started in July 2011 and ended in December 2014. It was implemented through the Central Europe Programme and co-financed by the European Regional Development Fund. Five cities in four Central European countries participated in the study: Augsburg (Germany), Chernivtsi (Ukraine), Dresden (Germany), Ljubljana (Slovenia) and Prague (Czech Republic). The aim of the UFIREG project was to improve the knowledge base on possible health effects of ambient ultrafine particles (UFP) and to raise overall awareness of environmental and health care authorities and the population. Epidemiological studies in the frame of the UFIREG project have assessed the short-term effects of UFP on human mortality and morbidity, especially in relation to cardiovascular and respiratory diseases. Official statistics were used to determine the association between air pollution concentration and daily (cause-specific: respiratory and cardiovascular) hospital admissions and mortality. Associations of UFP levels and health effects were analysed for each city by use of Poisson regression models adjusting for a number of confounding factors. Results on morbidity and mortality effects of UFP were heterogeneous across the five European cities investigated. Overall, an increase in respiratory hospital admissions and mortality could be detected for increases in UFP concentrations. Results on cardiovascular health were less conclusive. Further multi-centre studies such as UFIREG are needed preferably investigating several years in order to produce powerful results.

Middle atmosphere NO/x/ production due to ion propulsion induced radiation belt proton precipitation

NASA Technical Reports Server (NTRS)

Aikin, A. C.; Jackman, C. H.

1980-01-01

The suggestion that keV Ar(+) resulting from ion propulsion operations during solar power satellite construction could cause energetic proton precipitation from the inner radiation belt is examined to determine if such precipitation could cause significant increases in middle atmosphere nitric oxide concentrations thereby adversely affecting stratospheric ozone. It is found that the initial production rate of NO (mole/cu cm-sec) at 50 km is 130 times that due to nitrous oxide reacting with excited oxygen. However, since the time required to empty the inner belt of protons is about 1 sec and short compared to the replenishment time due to neutron decay, precipitation of inner radiation belt protons will have no adverse atmospheric environmental effect.

Identification of strengthening phases in Al-Cu-Li alloy Weldalite 049

NASA Technical Reports Server (NTRS)

Langan, T. J.; Pickens, J. R.

1989-01-01

The tensile properties in the peak-strength T8 temper for Weldalite 049, a family of ultrahigh-strength weldable Al-Cu-Li-based alloys with a Li content ranging from 0 to 1.9 wt percent, are investigated, and strengthening precipitates at selected Li levels are identified. Relatively small amounts of Ag and Mg were found to be extremely effective in stimulating precipitation in Weldalite 049, resulting in a homogeneous distribution of fine, platelike precipitates with a 111-type habit plane in the peak-aged, T8 temper. The yield and tensile strengths are strongly dependent on Li content, with a peak in the range of 1.1 to 1.4 wt percent Li. At above 1.4 wt percent Li, strength decreases rapidly, which is associated with delta-prime precipitation. For high-resolution TEM, the structure of T(1)-type precipitates in Weldalite 049 is similar to that of T(1) platelets in 2090.

Recent exposure to ultrafine particles in school children alters miR-222 expression in the extracellular fraction of saliva.

PubMed

Vriens, Annette; Nawrot, Tim S; Saenen, Nelly D; Provost, Eline B; Kicinski, Michal; Lefebvre, Wouter; Vanpoucke, Charlotte; Van Deun, Jan; De Wever, Olivier; Vrijens, Karen; De Boever, Patrick; Plusquin, Michelle

2016-07-26

Ultrafine particles (<100 nm) are ubiquitous present in the air and may contribute to adverse cardiovascular effects. Exposure to air pollutants can alter miRNA expression, which can affect downstream signaling pathways. miRNAs are present both in the intracellular and extracellular environment. In adults, miR-222 and miR-146a were identified as associated with particulate matter exposure. However, there is little evidence of molecular effects of ambient air pollution in children. This study examined whether exposure to fine and ultrafine particulate matter (PM) is associated with changes in the extracellular content of miR-222 and miR-146a of children. Saliva was collected from 80 children at two different time points, circa 11 weeks apart and stabilized for RNA preservation. The extracellular fraction of saliva was obtained by means of differential centrifugation and ultracentrifugation. Expression levels of miR-222 and miR-146a were profiled by qPCR. We regressed the extracellular miRNA expression against recent exposure to ultrafine and fine particles measured at the school site using mixed models, while accounting for sex, age, BMI, passive smoking, maternal education, hours of television use, time of the day and day of the week. Exposure to ultrafine particles (UFP) at the school site was positively associated with miR-222 expression in the extracellular fraction in saliva. For each IQR increase in particles in the class room (+8504 particles/cm(3)) or playground (+28776 particles/cm(3)), miR-222 was, respectively 23.5 % (95 % CI: 3.5 %-41.1 %; p = 0.021) or 29.9 % (95 % CI:10.6 %-49.1 %; p = 0.0027) higher. No associations were found between miR-146a and recent exposure to fine and ultrafine particles. Our results suggest a possible epigenetic mechanism via which cells respond rapidly to small particles, as exemplified by miR-222 changes in the extracellular fraction of saliva.

Production of Ultrafine, High-purity Ceramic Powders Using the US Bureau of Mines Developed Turbomill

NASA Technical Reports Server (NTRS)

Hoyer, Jesse L.

1993-01-01

Turbomilling, an innovative grinding technology developed by the U.S. Bureau of Mines in the early 1960's for delaminating filler-grade kaolinitic clays, has been expanded into the areas of particle size reduction, material mixing, and process reaction kinetics. The turbomill, originally called an attrition grinder, has been used for particle size reduction of many minerals, including natural and synthetic mica, pyrophyllite, talc, and marble. In recent years, an all-polymer version of the turbomill has been used to produce ultrafine, high-purity, advanced ceramic powders such as SiC, Si3N4, TiB2, and ZrO2. In addition to particle size reduction, the turbomill has been used to produce intimate mixtures of high surface area powders and whiskers. Raw materials, TiN, AlN, and Al2O3, used to produce a titanium nitride/aluminum oxynitride (TiN/AlON) composite, were mixed in the turbomill, resulting in strength increases over samples prepared by dry ball milling. Using the turbomill as a leach vessel, it was found that 90.4 pct of the copper was extracted from the chalcopyrite during a 4-hour leach test in ferric sulfate versus conventional processing which involves either roasting of the ore for Cu recovery or leaching of the ore for several days.

Toxicity of boehmite nanoparticles: impact of the ultrafine fraction and of the agglomerates size on cytotoxicity and pro-inflammatory response.

PubMed

Forest, Valérie; Pailleux, Mélanie; Pourchez, Jérémie; Boudard, Delphine; Tomatis, Maura; Fubini, Bice; Sennour, Mohamed; Hochepied, Jean-François; Grosseau, Philippe; Cottier, Michèle

2014-08-01

Boehmite (γ-AlOOH) nanoparticles (NPs) are used in a wide range of industrial applications. However, little is known about their potential toxicity. This study aimed at a better understanding of the relationship between the physico-chemical properties of these NPs and their in vitro biological activity. After an extensive physico-chemical characterization, the cytotoxicity, pro-inflammatory response and oxidative stress induced by a bulk industrial powder and its ultrafine fraction were assessed using RAW264.7 macrophages. Although the bulk powder did not trigger a significant biological activity, pro-inflammatory response was highly enhanced with the ultrafine fraction. This observation was confirmed with boehmite NPs synthesized at the laboratory scale, with well-defined and tightly controlled physico-chemical features: toxicity was increased when NPs were dispersed. In conclusion, the agglomerates size of boehmite NPs has a major impact on their toxicity, highlighting the need to study not only raw industrial powders containing NPs but also the ultrafine fractions representative of respirable particles.

The Structure and Mechanical Properties of High-Strength Bulk Ultrafine-Grained Cobalt Prepared Using High-Energy Ball Milling in Combination with Spark Plasma Sintering

PubMed Central

Marek, Ivo; Vojtěch, Dalibor; Michalcová, Alena; Kubatík, Tomáš František

2016-01-01

In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as the compressive yield strength, the ultimate compressive strength, the maximum compressive deformation and the Vickers hardness were studied and compared with those of a coarse-grained as-cast cobalt reference sample. The bulk ultrafine-grained sample showed an ultra-high compressive yield strength that was greater than 1 GPa, which is discussed with respect to the preparation technique and a structural investigation. PMID:28773514

Translocation and potential neurological effects of fine and ultrafine particles a critical update

PubMed Central

Peters, Annette; Veronesi, Bellina; Calderón-Garcidueñas, Lilian; Gehr, Peter; Chen, Lung Chi; Geiser, Marianne; Reed, William; Rothen-Rutishauser, Barbara; Schürch, Samuel; Schulz, Holger

2006-01-01

Particulate air pollution has been associated with respiratory and cardiovascular disease. Evidence for cardiovascular and neurodegenerative effects of ambient particles was reviewed as part of a workshop. The purpose of this critical update is to summarize the evidence presented for the mechanisms involved in the translocation of particles from the lung to other organs and to highlight the potential of particles to cause neurodegenerative effects. Fine and ultrafine particles, after deposition on the surfactant film at the air-liquid interface, are displaced by surface forces exerted on them by surfactant film and may then interact with primary target cells upon this displacement. Ultrafine and fine particles can then penetrate through the different tissue compartments of the lungs and eventually reach the capillaries and circulating cells or constituents, e.g. erythrocytes. These particles are then translocated by the circulation to other organs including the liver, the spleen, the kidneys, the heart and the brain, where they may be deposited. It remains to be shown by which mechanisms ultrafine particles penetrate through pulmonary tissue and enter capillaries. In addition to translocation of ultrafine particles through the tissue, fine and coarse particles may be phagocytized by macrophages and dendritic cells which may carry the particles to lymph nodes in the lung or to those closely associated with the lungs. There is the potential for neurodegenerative consequence of particle entry to the brain. Histological evidence of neurodegeneration has been reported in both canine and human brains exposed to high ambient PM levels, suggesting the potential for neurotoxic consequences of PM-CNS entry. PM mediated damage may be caused by the oxidative stress pathway. Thus, oxidative stress due to nutrition, age, genetics among others may increase the susceptibility for neurodegenerative diseases. The relationship between PM exposure and CNS degeneration can also be

Translocation and potential neurological effects of fine and ultrafine particles a critical update.

PubMed

Peters, Annette; Veronesi, Bellina; Calderón-Garcidueñas, Lilian; Gehr, Peter; Chen, Lung Chi; Geiser, Marianne; Reed, William; Rothen-Rutishauser, Barbara; Schürch, Samuel; Schulz, Holger

2006-09-08

Particulate air pollution has been associated with respiratory and cardiovascular disease. Evidence for cardiovascular and neurodegenerative effects of ambient particles was reviewed as part of a workshop. The purpose of this critical update is to summarize the evidence presented for the mechanisms involved in the translocation of particles from the lung to other organs and to highlight the potential of particles to cause neurodegenerative effects. Fine and ultrafine particles, after deposition on the surfactant film at the air-liquid interface, are displaced by surface forces exerted on them by surfactant film and may then interact with primary target cells upon this displacement. Ultrafine and fine particles can then penetrate through the different tissue compartments of the lungs and eventually reach the capillaries and circulating cells or constituents, e.g. erythrocytes. These particles are then translocated by the circulation to other organs including the liver, the spleen, the kidneys, the heart and the brain, where they may be deposited. It remains to be shown by which mechanisms ultrafine particles penetrate through pulmonary tissue and enter capillaries. In addition to translocation of ultrafine particles through the tissue, fine and coarse particles may be phagocytized by macrophages and dendritic cells which may carry the particles to lymph nodes in the lung or to those closely associated with the lungs. There is the potential for neurodegenerative consequence of particle entry to the brain. Histological evidence of neurodegeneration has been reported in both canine and human brains exposed to high ambient PM levels, suggesting the potential for neurotoxic consequences of PM-CNS entry. PM mediated damage may be caused by the oxidative stress pathway. Thus, oxidative stress due to nutrition, age, genetics among others may increase the susceptibility for neurodegenerative diseases. The relationship between PM exposure and CNS degeneration can also be

Relative abundance of chemical forms of Cu(II) and Cd(II) on soybean roots as influenced by pH, cations and organic acids

PubMed Central

Zhou, Qin; Liu, Zhao-dong; Liu, Yuan; Jiang, Jun; Xu, Ren-kou

2016-01-01

Little information is available on chemical forms of heavy metals on integrate plant roots. KNO3 (1 M), 0.05M EDTA at pH6 and 0.01 M HCl were used sequentially to extract the exchangeable, complexed and precipitated forms of Cu(II) and Cd(II) from soybean roots and then to investigate chemical form distribution of Cu(II) and Cd(II) on soybean roots. Cu(II) and Cd(II) adsorbed on soybean roots were mainly exchangeable form, followed by complexed form, while their precipitated forms were very low under acidic conditions. Soybean roots had a higher adsorption affinity to Cu(II) than Cd(II), leading to higher toxic of Cu(II) than Cd(II). An increase in solution pH increased negative charge on soybean and thus increased exchangeable Cu(II) and Cd(II) on the roots. Ca2+, Mg2+ and NH4+ reduced exchangeable Cu(II) and Cd(II) levels on soybean roots and these cations showed greater effects on Cd(II) than Cu(II) due to greater adsorption affinity of the roots to Cu(II) than Cd(II). L-malic and citric acids decreased exchangeable and complexed Cu(II) on soybean roots. In conclusion, Cu(II) and Cd(II) mainly existed as exchangeable and complexed forms on soybean roots. Ca2+ and Mg2+ cations and citric and L-malic acids can potentially alleviate Cu(II) and Cd(II) toxicity to plants. PMID:27805020

Effect of thermal treatment on the bio-corrosion and mechanical properties of ultrafine-grained ZK60 magnesium alloy.

PubMed

Choi, H Y; Kim, W J

2015-11-01

The combination of solid solution heat treatments and severe plastic deformation by high-ratio differential speed rolling (HRDSR) resulted in the formation of an ultrafine-grained microstructure with high thermal stability in a Mg-5Zn-0.5Zr (ZK60) alloy. When the precipitate particle distribution was uniform in the matrix, the internal stresses and dislocation density could be effectively removed without significant grain growth during the annealing treatment (after HRDSR), leading to enhancement of corrosion resistance. When the particle distribution was non-uniform, rapid grain growth occurred in local areas where the particle density was low during annealing, leading to development of a bimodal grain size distribution. The bimodal grain size distribution accelerated corrosion by forming a galvanic corrosion couple between the fine-grained and coarse-grained regions. The HRDSR-processed ZK60 alloy with high thermal stability exhibited high corrosion resistance, high strength and high ductility, and excellent superplasticity, which allow the fabrication of biodegradable magnesium devices with complicated designs that have a high mechanical integrity throughout the service life in the human body. Copyright © 2015 Elsevier Ltd. All rights reserved.

The General Isothermal Oxidation Behavior of Cu-8Cr-4Nb

NASA Technical Reports Server (NTRS)

Thomas-Ogbuji, L. U.; Gray, Hugh R. (Technical Monitor)

2002-01-01

Oxidation kinetics of Cu-8Cr-4Nb was investigated by TGA (thermogravimetric) exposures between 500 and 900-C (at 25-50 C intervals) and the oxide scale morphologies examined by microscopy and micro-analysis. Because Cu-8Cr-4Nb is comprised of fine Cr2Nb precipitates in a Cu matrix, the results were interpreted by comparison with the behavior of copper (OFHC) and 'NARloy-Z' (a rival candidate material for thrust cell liner applications in advanced rocket engines) under the same conditions. While NARloy-Z and Cu exhibited identical oxidation behavior, Cu-8Cr-4Nb differed markedly in several respects: below approx. 700 C its oxidation rates were significantly lower than those of Cu; At higher temperatures its oxidation rates fell into two categories: an initial rate exceeding that of Cu, and a terminal rate comparable to that of Cu. Differences in oxide morphologies paralleled the kinetic differences at higher temperature: While NARloy-Z and Cu produced a uniform oxide scale of Cu2O inner layer and CuO outer layer, the inner (Cu2O) layer on Cu-8Cr-4Nb was stratified, with a highly porous/spongy inner stratum (responsible for the fast initial kinetics) and a dense/blocky outer stratum (corresponding to the slow terminal kinetics). Single and spinel oxides of Nb and Cr were found at the interface between the oxide scale and Cu-8Cr-4Nb substrate and it appears that these oxides were responsible for its suppressed oxidation rates at the intermediate temperatures. No difference was found between Cu-8Cr-4Nb oxidation in air and in oxygen at 1.0 atm.

Structural and optical properties of co-precipitated copper doped zinc oxide

NASA Astrophysics Data System (ADS)

Pandey, Devendra K.; Modi, Anchit; Pandey, Padmini; Gaur, N. K.

2018-05-01

We have synthesized pure and copper doped zinc oxide Zn1-xO:Cux (x = 0, 0.03) powder by wet chemical co-precipitation method followed by sintering of the co-precipitated amorphous phase powder at 450°C for 4 hours. The experiment is performed to recognize the effect of nominal doping of transition metal over the structural, morphological and optical properties. The structural parameters are observed by using Rietveld refinement of X-ray diffraction data which clearly represents that Cu ion is perfectly incorporated at the Zn site with minimal distortions within the lattice. The crystallite size is estimated by Debye-Scherrer and Hall-Williamson formulation. The particle morphology and size is determined with scanning electron microscopic (SEM) technique. The band gap and optical measurements are carried out with UV-visible absorption and photoluminescence (PL) spectroscopic technique, respectively. Enhanced PL spectral response is observed for ZnO:Cu along with non-radiative transitions from conduction band to valence band. The energy levels near the conduction band that are commonly involved in the optoelectronic transitions in the UV-region are traced by using absorption and luminescence spectral graphs.

Fatigue Behavior of Ultrafine-Grained 5052 Al Alloy Processed Through Different Rolling Methods

NASA Astrophysics Data System (ADS)

Yogesha, K. K.; Joshi, Amit; Jayaganthan, R.

2017-05-01

In the present study, 5052 Al alloy was processed through different rolling methods to obtain ultrafine grains and its high-cycle fatigue behavior were investigated. The solution-treated Al-Mg alloys (AA 5052) were deformed through different methods such as cryorolling (CR), cryo groove rolling (CGR) and cryo groove rolling followed by warm rolling (CGW), up to 75% thickness reduction. The deformed samples were subjected to mechanical testing such as hardness, tensile and high-cycle fatigue (HCF) test at stress control mode. The CGW samples exhibit better HCF strength when compared to other conditions. The microstructure of the tested samples was characterized by optical microscopy, SEM fractography and TEM to understand the deformation behavior of deformed Al alloy. The improvement in fatigue life of CR and CGR samples is due to effective grain refinement, subgrain formations, and high dislocation density observed in the heavily deformed samples at cryogenic condition as observed from SEM and TEM analysis. However, in case of CGW samples, formation of nanoshear bands accommodates the applied strain during cyclic loading, thereby facilitating dislocation accumulation along with subgrain formations, leading to the high fatigue life. The deformed or broken impurity phase particles found in the deformed samples along with the precipitates that were formed during warm rolling also play a prominent role in enhancing the fatigue strength. These tiny particles hindered the dislocation movement by effectively pinning it at grain boundaries, thereby improving the resistance of crack propagation under cyclic load.

Microstructure and Mechanical Properties of Ultrafine-Grained Al-6061 Prepared Using Intermittent Ultrasonic-Assisted Equal-Channel Angular Pressing

NASA Astrophysics Data System (ADS)

Lu, Jianxun; Wu, Xiaoyu; Wu, Zhaozhi; Liu, Zhiyuan; Guo, Dengji; Lou, Yan; Ruan, Shuangchen

2017-10-01

Equal-channel angular pressing (ECAP) is an efficient technique to achieve grain refinement in a wide range of materials. However, the extrusion process requires an excessive extrusion force, the microstructure of ECAPed specimens scatters heterogeneously because of considerable fragmentation of the structure and strain heterogeneity, and the resultant ultrafine grains exhibit poor thermal stability. The intermittent ultrasonic-assisted ECAP (IU-ECAP) approach was proposed to address these issues. In this work, ECAP and IU-ECAP were applied to produce ultrafine-grained Al-6061 alloys, and the differences in their mechanical properties, microstructural characteristics, and thermal stability were investigated. Mechanical testing demonstrated that the necessary extrusion force for IU-ECAP was significantly reduced; even more, the microhardness and ultimate tensile strength were strengthened. In addition, the IU-ECAPed Al alloy exhibited a smaller grain size with a more homogeneous microstructure. X-ray diffraction analysis indicated that the intensities of the textures were weakened using IU-ECAP, and a more homogeneous microstructure and larger dislocation densities were obtained. Investigation of the thermal stability revealed that the ultrafine-grained materials produced using IU-ECAP recrystallized at higher temperature or after longer time; the materials thus exhibited improved thermal stability.

Positron Annihilation Spectroscopy and Small Angle Neutron Scattering Characterization of Nanostructural Features in Irradiated Fe-Cu-Mn Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wirth, B D; Asoka-Kumar, P; Howell, R H

2001-01-01

Radiation embrittlement of nuclear reactor pressure vessel steels results from a high number density of nanometer sized Cu-Mn-Ni rich precipitates (CRPs) and sub-nanometer matrix features, thought to be vacancy-solute cluster complexes (VSC). However, questions exist regarding both the composition of the precipitates and the defect character and composition of the matrix features. We present results of positron annihilation spectroscopy (PAS) and small angle neutron scattering (SANS) characterization of irradiated and thermally aged Fe-Cu and Fe-Cu-Mn alloys. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of CRPs andmore » VSCs in both alloys. The CRPs are coarser in the Fe-Cu alloy and the number densities of CRP and VSC increase with the addition of Mn. The PAS involved measuring both the positron lifetimes and the Doppler broadened annihilation spectra in the high momentum region to provide elemental sensitivity at the annihilation site. The spectra in Fe-Cu-Mn specimens thermally aged to peak hardness at 450 C and irradiated at 288 C are nearly identical to elemental Cu. Positron lifetime and spectrum measurements in Fe-Cu specimens irradiated at 288 C clearly show the existence of long lifetime ({approx}500 ps) open volume defects, which also contain Cu. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of CRPs and VSCs and tend to discount high Fe concentrations in the CRPs.« less

Artifacts introduced by ion milling in Al-Li-Cu alloys.

PubMed

Singh, A K; Imam, M A; Sadananda, K

1988-04-01

Ion milling is commonly used to prepare specimens for observation under transmission electron microscope (TEM). This technique sometimes introduces artifacts in specimens contributing to misleading interpretation of TEM results as observed in the present investigation of Al-Li-Cu alloys. This type of alloy, in general, contains several kinds of precipitates, namely delta', T1, and theta'. It is found that ion milling even for a short time produces drastic changes in the precipitate characteristics as compared to standard electropolishing methods of specimen preparation for TEM. Careful analysis of selected area diffraction patterns and micrographs shows that after ion milling delta' precipitates are very irregular, whereas other precipitates coarsen and they are surrounded by misfit dislocations. In situ hot-stage TEM experiments were performed to relate the microstructure to that observed in the ion-milled specimen. Results and causes of ion milling effects on the microstructure are discussed in relation to standard electropolishing techniques and in situ hot-stage experiment.

Oxidized nanocrystalline Fe-Cu pseudoalloy subjected to high pressure and electrodischarge pulses: Mössbauer and x-ray investigations

NASA Astrophysics Data System (ADS)

Gavriliuk, A. G.; Voitkovsky, V. S.; Sidorov, V. A.; Filonenko, V. P.; Tsiok, O. B.; Khvostantsev, L. G.

1998-05-01

Nanocrystalline Fe15Cu85 pseudoalloy has been subjected to pulsed heating up to 1500 K at high pressure (8 GPa). Two regimes were studied: the direct heating using electrodischarge through the sample and indirect heating with the use of cylindrical heater around the sample. The temperature and time conditions in both types of experiments were adjusted to be equivalent. The discharge parameters (stored energy, discharge time, and magnitude of current pulse) were sufficient to move defects by conduction electrons, but insufficient to melt the sample. The properties of treated samples were studied using Mössbauer absorption spectra and x-ray diffraction for three types of samples: (a) primary powder treated by high pressure up to 8 GPa, (b) powder subjected to indirect pulsed heating at 8 GPa, (c) powder treated by electrical pulses at 8 GPa. The x-ray diffraction pattern of primary powder exhibits peaks of copper, iron, and copper oxide (CuO). The Mössbauer spectrum of primary powder exhibits six peaks of alpha iron and some peaks near zero velocity due to the small iron clusters in the copper matrix and ultrafine clusters of paramagnetic phase x-Fe2O3. The transformation of CuO to Cu2O takes place in the course of indirect heating, the Mössbauer spectrum being almost unchanged. The direct electrodischarge heating causes the appearance of new magnetic phase with the magnetic field on iron nucleus 505 kOe, which corresponds to α-Fe2O3. The formation of α-Fe2O3 was confirmed by x-ray diffraction. At the same time the transformation of CuO to Cu2O is incomplete. These experiments demonstrate that high density current pulses, causing the electron wind, can be a useful tool to influence the structure of nanocrystalline powder.

Method for the production of ultrafine particles by electrohydrodynamic micromixing

DOEpatents

DePaoli, David W.; Hu, Zhong Cheng; Tsouris, Constantinos

2001-01-01

The present invention relates to a method for the rapid production of homogeneous, ultrafine inorganic material via liquid-phase reactions. The method of the present invention employs electrohydrodynamic flows in the vicinity of an electrified injector tube placed inside another tube to induce efficient turbulent mixing of two fluids containing reactive species. The rapid micromixing allows liquid-phase reactions to be conducted uniformly at high rates. This approach allows continuous production of non-agglomerated, monopispersed, submicron-sized, sphere-like powders.

Orientation influence on grain size-effects in ultrafine-grained magnesium

DOE PAGES

Fan, Haidong; Aubry, Sylvie; Arsenlis, A.; ...

2014-11-08

The mechanical behavior of ultrafine-grained magnesium was studied by discrete dislocation dynamics (DDD) simulations. Our results show basal slip yields a strong size effect, while prismatic and pyramidal slips produce a weak one. We developed a new size-strength model that considers dislocation transmission across grain boundaries. Good agreement between this model, current DDD simulations and previous experiments is observed. These results reveal that the grain size effect depends on 3 factors: Peierls stress, dislocation source strength and grain boundary strength.

UP-REGULATION OF TISSUE FACTOR IN HUMAN PULMONARY ARTERY ENDOTHELIAL CELLS AFTER ULTRAFINE PARTICLE EXPOSURE

EPA Science Inventory

Background: Epidemiology studies have linked exposure to pollutant particles to

increased cardiovascular mortality and morbidity, but the mechanisms remain unknown.

Objectives: We tested the hypothesis that the ultrafine fraction of ambient pollutant

particle...

Enhancement in light harvesting ability of photoactive layer P3HT: PCBM using CuO nanoparticles

NASA Astrophysics Data System (ADS)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Pukhrambam; Chandel, Tarun

2018-05-01

In this paper, we have synthesized CuO nanoparticles via precipitation method and incorporated CuO nanoparticles in the P3HT-poly (3-hexyl) thiophene: PCBM-[6, 6]-phenyl-C61-butyric acid methyl ester heterogeneous blend. The ratio of P3HT to CuO in the blend was varied, while maintaining the fixed ratio of PCBM. The UV-visible absorption spectra of P3HT: PCBM photoactive layer containing different weight percentages of CuO nanoparticles showed a clear enhancement in the photo absorption of the active layer. The absorption band starts from 310 nm to 750 nm for P3HT: CuO (NPs):PCBM (0.5:0.5:1). This shows that incorporation of CuO nanoparticles leads to larger absorption band. In addition, the X-ray diffraction (XRD) shows improvement in P3HT crystallinity and the better formation of CuO nanostructures.

Optically stimulated luminescence in Cu+ doped lithium orthophosphate

NASA Astrophysics Data System (ADS)

Barve, R. A.; Patil, R. R.; Moharil, S. V.; Bhatt, B. C.; Kulkarni, M. S.

2015-02-01

Optically stimulated luminescence (OSL) in Cu+ doped Li3PO4 synthesized by co-precipitation technique using different phosphorus precursors was studied. Changes in the luminescent properties were observed with change in the phosphorus precursors. All the synthesized phosphors showed intense fading but the OSL sensitivity was comparable to that of the commercially available Al2O3:C (Landauer Inc.). In general, BSL (blue stimulated luminescence) decay was very fast but the GSL (green stimulated luminescence) decay was comparable to that of Al2O3:C phosphor. Phosphors with fast decay, good sensitivity and intense fading are suitable for real-time dosimetry. Therefore, Cu-doped Li3PO4 could be developed for real-time dosimetry using a fiber optic based OSL reader system.

Ultrafine particles are not major carriers of carcinogenic PAHs and their genotoxicity in size-segregated aerosols.

PubMed

Topinka, Jan; Milcova, Alena; Schmuczerova, Jana; Krouzek, Jiri; Hovorka, Jan

2013-06-14

Some studies suggest that genotoxic effects of combustion-related aerosols are induced by carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) and their derivatives, which are part of the organic fraction of the particulate matter (PM) in ambient air. The proportion of the organic fraction in PM is known to vary with particle size. The ultrafine fraction is hypothesized to be the most important carrier of c-PAHs, since it possesses the highest specific surface area of PM. To test this hypothesis, the distribution of c-PAHs in organic extracts (EOMs) was compared for four size fractions of ambient-air aerosols: coarse (1ultrafine particles (dae<0.17). High-volume aerosol samples were collected consecutively in four localities that differed in the level of environmental pollution. The genotoxicity of EOMs was measured by analysis of DNA adducts induced in an a cellular assay consisting of calf thymus DNA with/without rat liver microsomal S9 fraction coupled with (32)P-postlabelling. The upper accumulation fraction was the major size fraction in all four localities, forming 37-46% of the total PM mass. Per m(3) of sampled air, this fraction also bound the largest amount of c-PAHs. Correspondingly, the upper accumulation fraction induced the highest DNA-adduct levels. Per PM mass itself, the lower accumulation fraction is seen to be the most efficient in binding DNA-reactive organic compounds. Interestingly, the results suggest that the fraction of ultrafine particles of various ambient-air samples is neither a major carrier of c-PAHs, nor a major inducer of their genotoxicity, which is an important finding that is relevant to the toxicity and health effects of ultrafine particles, which are so extensively discussed these days. Copyright © 2013. Published by Elsevier B.V.

Kinetics of cellular dissolution in a Cu-Cd alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakkalil, R.; Gupta, S.P.

1989-07-01

Dissolution of the cellular precipitate by cell boundary migration has been studied in a Cu-2 at.% Cd alloy in the temperature range 777--878 K. Microstructural observations have revealed that the process of dissolution begins at the original position of the grain boundary as well as the cell boundary. The steady state rate of cell boundary migration decreased with decreasing temperature of dissolution and became zero at approximately 770 K, which is about 30 K below the equilibrium solves temperature. The boundary diffusivities were determined at a number of temperatures by using the theory of Petermann and Hornbogen modified for dissolution.more » The diffusivity values calculated from the experimental data are seven orders of magnitude higher than the corresponding volume diffusivities. From the temperature dependence of the diffusivity, an activation energy of 157 kJ mol{sup {minus} 1} is obtained, which is bout three-quarters of the activation energy for the bulk diffusion of Cd into Cu. From the diffusivity and activation energy values, it is concluded that the diffusion of Cd along the migrating grain boundaries control the dissolution of the cellular precipitate in this alloy.« less

Effect of Natural Aging and Cold Working on Microstructures and Mechanical Properties of Al-4.6Cu-0.5Mg-0.5Ag alloy

NASA Astrophysics Data System (ADS)

Chen, Yu-Te; Lee, Sheng-Long; Bor, Hui-Yun; Lin, Jing-Chie

2013-06-01

This research investigates the effects of natural aging and cold working prior to artificial aging on microstructures and mechanical properties of Al-4.6Cu-0.5Mg-0.5Ag alloy. Mechanical properties relative to microstructure variations were elucidated by the observations of the optical microscope (OM), differential scanning calorimeter (DSC), electrical conductivity meter (pct IACS), and transmission electron microscopy (TEM). The results showed that natural aging treatment has little noticeable benefit on the quantity of precipitation strengthening phases and mechanical properties, but it increases the precipitation strengthening rate at the initial stage of artificial aging. Cold working brings more lattice defects which suppress Al-Cu (GP zone) and Mg-Ag clustering, and therefore the precipitation of Ω phase decreases. Furthermore, more dislocations are formed, leading to precipitate the more heterogeneous nucleation of θ' phase. The above-mentioned precipitation phenomena and strain hardening effect are more obvious with higher degrees of cold working.

DESIGN AND CHARACTERIZATION OF AN ULTRAFINE COAL ASH AEROSOL GENERATOR FOR DIRECT ANIMAL EXPOSURE STUDIES

EPA Science Inventory

Primary ultrafine particulate matter (PM) is produced during pulverized coal combustion by the nucleation and heterogeneous condensation of vapor-phase species. This differs from the mechanisms that control the formation of the supermicron fly ash that is heavily influenced by t...

Divacancy complexes induced by Cu diffusion in Zn-doped GaAs

NASA Astrophysics Data System (ADS)

Elsayed, M.; Krause-Rehberg, R.; Korff, B.; Ratschinski, I.; Leipner, H. S.

2013-08-01

Positron annihilation spectroscopy was applied to investigate the nature and thermal behavior of defects induced by Cu diffusion in Zn-doped p-type GaAs crystals. Cu atoms were intentionally introduced in the GaAs lattice through thermally activated diffusion from a thin Cu capping layer at 1100 °C under defined arsenic vapor pressure. During isochronal annealing of the obtained Cu-diffused GaAs in the temperature range of 450-850 K, vacancy clusters were found to form, grow and finally disappear. We found that annealing at 650 K triggers the formation of divacancies, whereas further increasing in the annealing temperature up to 750 K leads to the formation of divacancy-copper complexes. The observations suggest that the formation of these vacancy-like defects in GaAs is related to the out-diffusion of Cu. Two kinds of acceptors are detected with a concentration of about 1016 - 1017 cm-3, negative ions and arsenic vacancy copper complexes. Transmission electron microscopy showed the presence of voids and Cu precipitates which are not observed by positron measurements. The positron binding energy to shallow traps is estimated using the positron trapping model. Coincidence Doppler broadening spectroscopy showed the presence of Cu in the immediate vicinity of the detected vacancies. Theoretical calculations suggested that the detected defect is VGaVAs-2CuGa.

Effects of Thermal and Mechanical Processing on Microstructures and Desired Properties of Particle-Strengthened Cu-Cr-Nb Alloys

NASA Technical Reports Server (NTRS)

Anderson, Kenneth Reed

2000-01-01

Ternary Cu-Cr-Nb alloys, particularly Cu-8 Cr-4 Nb (in at.%), have demonstrated good thermal stability as well as high strength and conductivity at elevated temperatures. The initial powder material has a bimodal size distribution of Cr2Nb precipitates. Primary Cr2Nb precipitates are approx. 1 micron, and secondary Cr2Nb particles are 30-200 nm. The particle coarsening was analyzed and found to follow LSW-type behavior, This study provides a detailed examination of the stability and strengthening effects of Cr2Nb particles. This investigation also revealed that the primary particles provide direct grain boundary pinning and indirect grain boundary strengthening but virtually no Orowan strengthening. The secondary particles found within grains do provide Orowan strengthening. For extruded material, grain bound-ary strengthening (Hall-Petch effect) accounts for two-thirds of the strength with Orowan effects contributing the remainder. The proven advantages of Cu-Cr-Nb were the motivation to improve these attributes via microstructural refinement. Mechanical milling (MM) of Cu- 4 Cr-2 Nb and Cu-8 Cr-2 Nb produced an increase in hot pressed Vickers hardness of 122% and 96%, respectively. The increase in hardness was more due to Cu grain-size refinement than to Cr,,Nb refinement. This study also demonstrated enhanced stability of MM Cu-4 Cr-2 Nb. Hot pressed 4 h milled Cu-4 Cr-2 Nb experienced only a 22% drop in hardness when annealed at 1273 K for 50 h versus a 30% drop for extruded Cu-8 Cr-4 Nb. The goal of improving the strength and stability of Cu-4 Cr-2 Nb to better than such properties for as- extruded Cu-8 Cr-4 Nb has been met. In addition, a figure-of-merit (FOM) coupling hardness and thermal conductivity was maximized for the case of 4 h milled Cu-4 Cr-2 Nb material. Overall, Cu-Cr-Nb alloys not only possess high strength, conductivity and thermal stability but also can be further developed to improve strength and stability.

Ultrafine-grained mineralogy and matrix chemistry of olivine-rich chondritic interplanetary dust particles

NASA Technical Reports Server (NTRS)

Rietmeijer, F. J. M.

1989-01-01

Olivine-rich chondritic interplanetary dust particles (IDPs) are an important subset of fluffy chondritic IDPs collected in the earth's stratosphere. Particles in this subset are characterized by a matrix of nonporous, ultrafine-grained granular units. Euhedral single crystals, crystals fragments, and platey single crystals occur dispersed in the matrix. Analytical electron microscopy of granular units reveals predominant magnesium-rich olivines and FeNi-sulfides embedded in amorphous carbonaceous matrix material. The variable ratio of ultrafine-grained minerals vs. carbonaceous matrix material in granular units support variable C/Si ratios, and some fraction of sulfur is associated with carbonaceous matrix material. The high Mg/(Mg+Fe) ratios in granular units is similar to this distribution in P/Comet Halley dust. The chondritic composition of fine-grained, polycrystalline IDPs gradually breaks down into nonchondritic, and ultimately, single mineral compositions as a function of decreased particle mass. The relationship between particle mass and composition in the matrix of olivine-rich chondritic IDPs is comparable with the relationship inferred for P/Comet Halley dust.

Fast photocatalytic degradation of sulforhodamine B using ZnO:Cu nanorods

NASA Astrophysics Data System (ADS)

Raji, R.; Gopchandran, K. G.

2018-02-01

In this work, ZnO:Cu nanorods with tunable Cu content were successfully synthesized via co-precipitation method and investigations were made on the use of these nanorods as photocatalyst by observing the photodegradation of a representative dye pollutant of sulforhodamine B (SRB) under sunlight. The X-ray diffraction analysis and high resolution transmission electron microscopy showed that ZnO:Cu nanorods possess wurtzite phase with preferential growth along (101) plane. The formation of additional defect levels in these nanorods on doping with Cu and its dependence on the concentration of Cu were studied using photoluminescence and X-ray photoelectron spectroscopy. ZnO:Cu nanorods results in faster degradation of dye as compared to the undoped ZnO and is found that Cu doping enhances the photodegradation activity significantly and is highly sensitive to Cu doping level. The fast photocatalytic degradation is attributed to the fact that Cu ions promote the interfacial charge transfer and favors the effective charge separation of photogenerated electrons and holes generated during sunlight irradiation, increasing the rate of production of reactive oxygen species needed for the degradation of the dye. The chemical oxygen demand analysis of the dye solution after sunlight irradiation indicates that rate of mineralization is slower than the decoloration. The possible mechanism for degradation of dye under sunlight irradiation is described with a schematic. Additionally, the photostability of the ZnO:Cu nanorods was also tested through three repetitive cycles. This work suggest that the prepared ZnO:Cu nanorods are suitable for cost-effective water purification.

Deposition of ultrafine (nano) particles in the human lung.

PubMed

Asgharian, Bahman; Price, Owen T

2007-10-01

Increased production of industrial devices constructed with nanostructured materials raises the possibility of environmental and occupational human exposure with consequent adverse health effects. Ultrafine (nano) particles are suspected of having increased toxicity due to their size characteristics that serve as carrier transports. For this reason, it is critical to refine and improve existing deposition models in the nano-size range. A mathematical model of nanoparticle transport by airflow convection, axial diffusion, and convective mixing (dispersion) was developed in realistic stochastically generated asymmetric human lung geometries. The cross-sectional averaged convective-diffusion equation was solved analytically to find closed-form solutions for particle concentration and losses per lung airway. Airway losses were combined to find lobar, regional, and total lung deposition. Axial transport by diffusion and dispersion was found to have an effect on particle deposition. The primary impact was in the pulmonary region of the lung for particles larger than 10 nm in diameter. Particles below 10 nm in diameter were effectively removed from the inhaled air in the tracheobronchial region with little or no penetration into the pulmonary region. Significant variation in deposition was observed when different asymmetric lung geometries were used. Lobar deposition was found to be highest in the left lower lobe. Good agreement was found between predicted depositions of ultrafine (nano) particles with measurements in the literature. The approach used in the proposed model is recommended for more realistic assessment of regional deposition of diffusion-dominated particles in the lung, as it provides a means to more accurately relate exposure and dose to lung injury and other biological responses.

Real-Time Ultrafine Aerosol Measurements from Wastewater Treatment Facilities.

PubMed

Piqueras, P; Li, F; Castelluccio, V; Matsumoto, M; Asa-Awuku, A

2016-10-18

Airborne particle emissions from wastewater treatment plants (WWTP) have been associated with health repercussions but particulate quantification studies are scarce. In this study, particulate matter (PM) number concentrations and size distributions in the ultrafine range (7-300 nm) were measured from two different sources: a laboratory-scale aerobic bioreactor and the activated sludge aeration basins at Orange County Sanitation District (OCSD). The relationships between wastewater parameters (total organic carbon (TOC), chemical oxygen demand (COD), and total suspended solids (TSS)), aeration flow rate and particle concentrations were also explored. A significant positive relationship was found between particle concentration and WWTP variables (COD: r(10) = 0.876, p <.001, TOC: r(10) = 0.664, p <.05, TSS: r(10) = 0.707, p <.05, aeration flow rate: r(8) = 0.988, p <.0001). A theoretical model was also developed from empirical data to compare real world WWTP aerosol number emission fluxes with laboratory data. Aerosol number fluxes at OCSD aerated basins (9.8 × 10 4 lbs/min·cm 2 ) and the bioreactor (7.95 × 10 4 lbs/min·cm 2 ) were calculated and showed a relatively small difference (19%). The ultrafine size distributions from both systems were consistent, with a mode of ∼48 nm. The average mass concentration (7.03 μg/cm 3 ) from OCSD was relatively small compared to other urban sources. However, the in-tank average number concentration of airborne particles (14 480 lbs/cm 3 ) was higher than background ambient concentrations.

Long-term assessment of ultrafine particles on major roadways in Las Vegas, Nevada and Detroit, Michigan

EPA Science Inventory

This is a presentation at the National Air Monitoring conference, given at the request of OAQPS partners. The presentation will cover ultrafine particle data collected at three locations - Las Vegas, Detroit, and Research Triangle Park.

Optical absorption and thermal stability study of Cu doped NiO nanoparticles

NASA Astrophysics Data System (ADS)

Varunkumar, K.; Ethiraj, Anita Sagadevan; Kechiantz, Ara

2018-05-01

This work reports variation of Cu doping concentration in NiO nanoparticles (NiO:Cu NPs) synthesized via chemical co-precipitation from solution by using NiCl2.6H2O as precursor, CuSO4.5H2O as dopant and NaOH as surfactant. We studied optical and thermal stability of prepared NiO:Cu NPs by UV-Vis absorbance, Diffuse Reflectance Spectroscopy (DRS), Atomic Absorption Spectroscopy (AAS), and Thermo Gravimetric/Differential Scanning Calorimetry (TGA/DSC) analyses. Optical absorption data of NiO:Cu NPs indicated strong absorption peaks shifted towards blue with respect to the peak of undoped NiO NPs due to quantum confinement effect. The bandgap estimated via Tauc plot first increased from 3.32eV (undoped NiO NPs) to 3.37 eV (8 at % of Cu in NiO NPs) and further increase of Cu doping to 10 at% reduced the bandgap to 3.35 eV. Such behavior of the bandgap clearly indicates that the size of NiO NPs first reduces with Cu doping up to 8 at % and then increases with further Cu doping to 10 at %. This behavior of reduction in particle size with increased doping can be attributed to the dislocation density and microstrain developed in NiO:Cu NPs. Thermal stability analysis demonstrated that in addition undoped NiO NPs, all NiO:Cu nanoparticle samples exhibited good thermal stability.

Removal of Cu(II) from acidic electroplating effluent by biochars generated from crop straws.

PubMed

Tong, Xuejiao; Xu, Renkou

2013-04-01

The removal efficiency of copper (Cu(II)) from an actual acidic electroplating effluent by biochars generated from canola, rice, soybean and peanut straws was investigated. The biochars simultaneously removed Cu(II) from the effluent, mainly through the mechanisms of adsorption and precipitation, and neutralized its acidity. The removal efficiency of Cu(II) by the biochars followed the order: peanut straw char > soybean straw char > canola straw char > rice straw char > a commercial activated carbonaceous material, which is consistent with the alkalinity of the biochars. The pH of the effluent was a key factor determining the removal efficiency of Cu(II) by biochars. Raising the initial pH of the effluent enhanced the removal of Cu(II) from it. The optimum pyrolysis temperature was 400 degrees C for producing biochar from crop straws for acidic wastewater treatment, and the optimum reaction time was 8 hr.

The Effects of Vegetation Barriers on Near-road Ultrafine Particle Number and Carbon Monoxide Concentrations

EPA Science Inventory

Numerous studies have shown that people living in near-roadway communities (within 100 m of the road) are exposed to high ultrafine particle (UFP) number concentrations, which may be associated with adverse health effects. Vegetation barriers have been shown to affect pollutant t...

Maskless localized patterning of biomolecules on carbon nanotube microarray functionalized by ultrafine atmospheric pressure plasma jet using biotin-avidin system

NASA Astrophysics Data System (ADS)

Abuzairi, Tomy; Okada, Mitsuru; Purnamaningsih, Retno Wigajatri; Poespawati, Nji Raden; Iwata, Futoshi; Nagatsu, Masaaki

2016-07-01

Ultrafine plasma jet is a promising technology with great potential for nano- or micro-scale surface modification. In this letter, we demonstrated the use of ultrafine atmospheric pressure plasma jet (APPJ) for patterning bio-immobilization on vertically aligned carbon nanotube (CNT) microarray platform without a physical mask. The biotin-avidin system was utilized to demonstrate localized biomolecule patterning on the biosensor devices. Using ±7.5 kV square-wave pulses, the optimum condition of plasma jet with He/NH3 gas mixture and 2.5 s treatment period has been obtained to functionalize CNTs. The functionalized CNTs were covalently linked to biotin, bovine serum albumin (BSA), and avidin-(fluorescein isothiocyanate) FITC, sequentially. BSA was necessary as a blocking agent to protect the untreated CNTs from avidin adsorption. The localized patterning results have been evaluated from avidin-FITC fluorescence signals analyzed using a fluorescence microscope. The patterning of biomolecules on the CNT microarray platform using ultrafine APPJ provides a means for potential application of microarray biosensors based on CNTs.

Bimetallic Cu-Ni nanoparticles supported on activated carbon for catalytic oxidation of benzyl alcohol

NASA Astrophysics Data System (ADS)

Kimi, Melody; Jaidie, Mohd Muazmil Hadi; Pang, Suh Cem

2018-01-01

A series of bimetallic copper-nickel (CuNix, x = 0.1, 0.2, 0.5 and 1) nanoparticles supported on activated carbon (AC) were prepared by deposition-precipitation method for the oxidation of benzyl alcohol to benzaldehyde using hydrogen peroxide as oxidising agent. Analyses by means of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) confirmed that Cu and Ni was successfully added on the surface of activated carbon. CuNi1/AC showed the best catalytic activity for the oxidation of benzyl alcohols to the corresponding aldehyde within a short reaction period at 80 °C. The catalytic performance is significantly enhanced by the addition of equal amount of Ni as compared to the monometallic counterpart. This result indicates the synergistic effect between Ni and Cu particles in the catalytic oxidation reaction.

Microstructure, Mechanical Properties, and Age-Hardening Behavior of an Al-Si-Fe-Mn-Cu-Mg Alloy Produced by Spray Deposition

NASA Astrophysics Data System (ADS)

Feng, Wang; Jishan, Zhang; Baiqing, Xiong; Yongan, Zhang

2011-02-01

It has been recognized generally that the spray-deposited process is an innovative technique of rapid solidification. In this paper, Al-20Si-5Fe-3Mn-3Cu-1Mg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray-deposited alloy were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and tensile tests. It is observed that the microstructure of spray-deposited Al-20Si-5Fe-3Mn-3Cu-1Mg alloy is composed of the α-Al,Si and the particle-like Al15(FeMn)3Si2 compounds. The aging process of the alloy was investigated by microhardness measurement, differential scanning calorimetry analysis, and TEM observations. The results indicate that the two types of precipitates, S-Al2CuMg and σ-Al5Cu6Mg2 precipitate from matrix and improve the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300 °C).

Mechanical Behavior of Nanostructured and Ultrafine Grained Materials under Shock Wave Loadings. Experimental Data and Results of Computer Simulation.

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir

2011-06-01

Features of mechanical behavior of nanostructured (NS) and ultrafine grained (UFG) metal and ceramic materials under quasistatic and shock wave loadings are discussed in this report. Multilevel models developed within the approach of computational mechanics of materials were used for simulation mechanical behavior of UFG and NS metals and ceramics. Comparisons of simulation results with experimental data are presented. Models of mechanical behavior of nanostructured metal alloys takes into account a several structural factors influencing on the mechanical behavior of materials (type of a crystal lattice, density of dislocations, a size of dislocation substructures, concentration and size of phase precipitation, and distribution of grains sizes). Results show the strain rate sensitivity of the yield stress of UFG and polycrystalline alloys is various in a range from 103 up to 106 1/s. But the difference of the Hugoniot elastic limits of a UFG and coarse-grained alloys may be not considerable. The spall strength, the yield stress of UFG and NS alloys are depend not only on grains size, but a number of factors such as a distribution of grains sizes, a concentration and sizes of voids and cracks, a concentration and sizes of phase precipitation. Some titanium alloys with grain sizes from 300 to 500 nm have the quasi-static yield strength and the tensile strength twice higher than that of coarse grained counterparts. But the spall strength of the UFG titanium alloys is only 10 percents above than that of coarse grained alloys. At the same time it was found the spall strength of the bulk UFG aluminium and magnesium alloys with precipitation strengthening is essentially higher in comparison of coarse-grained counterparts. The considerable decreasing of the strain before failure of UFG alloys was predicted at high strain rates. The Hugoniot elastic limits of oxide nanoceramics depend not only on the porosity, but also on sizes and volume distribution of voids.

Thermal stability of Cu-Cr-Zr alloy processed by equal-channel angular pressing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abib, Khadidja

Thermal stability of a Cu-Cr-Zr alloy processed by equal-channel angular pressing up to16 passes was investigated using isochronal annealing ranging from 250 to 850 °C for 1 h. The microstructure, crystallographic texture and micro hardness of samples were characterized through electron back scatter diffraction and Vickers micro hardness measurements. The recrystallized grain size was stable between 250 °C and 500 °C then increased quickly. The achieved mean grain size, after 1, 4 and 16 ECAP passes, was around 5.5 μm. A discontinuous mode of recrystallization was found to occur and a Particle Simulated Nucleation mechanism was evidenced. The evolution ofmore » the high angle grain boundary fraction increased notably after annealing above 550 °C. The crystallographic texture after isochronal annealing was similar to that of ECAP simple shear, no change of the texture during annealing was observed but only slight intensity variations. Micro hardness of all Cu–Cr–Zr samples showed a hardening with two peaks at 400 and 500 °C associated with precipitation of Cu cluster and Cu{sub 5}Zr phase respectively, followed by a subsequent softening upon increasing the annealing temperature due to recrystallization. - Highlight: •The Cu-1Cr-0.1Zr alloy shows a very good thermal stability up to 550 °C after ECAP. •A discontinuous recrystallization was found to occur and PSN mechanism was evidenced. •The annealing texture was found weak and some new components appear. •Hardening is attributed to the Cr clustering followed by the Cu{sub 51}Zr{sub 14} precipitation. •Softening is a result of recrystallization and grain growth progressing.« less

Fine and ultrafine particle exposures on 73 trips by car to 65 non-smoking restaurants in the San Francisco Bay Area.

PubMed

Ott, W R; Wallace, L A; McAteer, J M; Hildemann, L M

2017-01-01

A number of studies indicate cooking is a major source of exposure to particulate matter, but few studies have measured indoor air pollution in restaurants, where cooking predominates. We made 73 visits by car to 65 different non-smoking restaurants in 10 Northern California towns while carrying portable continuous monitors that unobtrusively measured ultrafine (down to 10 nm) and fine (PM 2.5 ) particles to characterize indoor restaurant exposures, comparing them with exposures in the car. The mean ultrafine number concentrations in the restaurants on dinner visits averaging 1.4 h was 71 600 particles/cm 3 , or 4.3 times the mean concentration on car trips, and 12.3 times the mean background concentration in the residence. Restaurants that cooked dinner in the same room as the patrons had higher ultrafine concentrations than restaurants with separate kitchens. Restaurant PM 2.5 mass concentrations averaged 36.3 μg/m 3 , ranging from 1.5 to 454 μg/m 3 , but were relatively low on most visits: 43% of the indoor means were below 10 μg/m 3 and 66% were below 20 μg/m 3 , with 5.5% above 100 μg/m 3 . Exposure to fine and ultrafine particles when visiting a restaurant exceeded the exposure a person received while traveling by car to and from the restaurant. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Thermochemical process for recovering Cu from CuO or CuO.sub.2

DOEpatents

Richardson, deceased, Donald M.; Bamberger, Carlos E.

1981-01-01

A process for producing hydrogen comprises the step of reacting metallic Cu with Ba(OH).sub.2 in the presence of steam to produce hydrogen and BaCu.sub.2 O.sub.2. The BaCu.sub.2 O.sub.2 is reacted with H.sub.2 O to form Cu.sub.2 O and a Ba(OH).sub.2 product for recycle to the initial reaction step. Cu can be obtained from the Cu.sub.2 O product by several methods. In one embodiment the Cu.sub.2 O is reacted with HF solution to provide CuF.sub.2 and Cu. The CuF.sub.2 is reacted with H.sub.2 O to provide CuO and HF. CuO is decomposed to Cu.sub.2 O and O.sub.2. The HF, Cu and Cu.sub.2 O are recycled. In another embodiment the Cu.sub.2 O is reacted with aqueous H.sub.2 SO.sub.4 solution to provide CuSO.sub.4 solution and Cu. The CuSO.sub.4 is decomposed to CuO and SO.sub.3. The CuO is decomposed to form Cu.sub.2 O and O.sub.2. The SO.sub.3 is dissolved to form H.sub.2 SO.sub.4. H.sub.2 SO.sub.4, Cu and Cu.sub.2 O are recycled. In another embodiment Cu.sub.2 O is decomposed electrolytically to Cu and O.sub.2. In another aspect of the invention, Cu is recovered from CuO by the steps of decomposing CuO to Cu.sub.2 O and O.sub.2, reacting the Cu.sub.2 O with aqueous HF solution to produce Cu and CuF.sub.2, reacting the CuF.sub.2 with H.sub.2 O to form CuO and HF, and recycling the CuO and HF to previous reaction steps.

Effect of Ag and Cu Contents on the Age Hardning Behavior of Al-Zn-Mg Alloys

NASA Astrophysics Data System (ADS)

Watanabe, Katsumi; Kawabata, Tokimasa; Ikeno, Susumu; Yoshida, Tomoo; Murakami, Satoshi; Matsuda, Kenji

Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg-Si alloy, were prepared to compare the effect of the additional elements on the aging behavior. The content of Ag and Cu were 0.2 at.% and 0.2at.%, respectively. The age-hardening behavior and microstructures of those alloys were investigated by hardness measurement, high resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED) technique. Ag or Cu added alloy showed higher peak hardness than Ag or Cu free alloy. According to addition of Ag or Cu, the number density of the precipitates increased than Ag or Cu free alloy.

Novel Fe-based nanocrystalline powder cores with excellent magnetic properties produced using gas-atomized powder

NASA Astrophysics Data System (ADS)

Chang, Liang; Xie, Lei; Liu, Min; Li, Qiang; Dong, Yaqiang; Chang, Chuntao; Wang, Xin-Min; Inoue, Akihisa

2018-04-01

FeSiBPNbCu nanocrystalline powder cores (NPCs) with excellent magnetic properties were fabricated by cold-compaction of the gas-atomized amorphous powder. Upon annealing at the optimum temperature, the NPCs showed excellent magnetic properties, including high initial permeability of 88, high frequency stability up to 1 MHz with a constant value of 85, low core loss of 265 mW/cm3 at 100 kHz for Bm = 0.05 T, and superior DC-bias permeability of 60% at a bias field of 100 Oe. The excellent magnetic properties of the present NPCs could be attributed to the ultrafine α-Fe(Si) phase precipitated in the amorphous matrix and the use of gas-atomized powder coated with a uniform insulation layer.

Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into human skin affected by atopic dermatitis

NASA Astrophysics Data System (ADS)

Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Borbíró, I.; Angyal, A.; Csedreki, L.; Furu, E.; Szoboszlai, Z.; Kiss, Á. Z.; Hunyadi, J.

2011-10-01

Skin penetration is one of the potential routes for nanoparticles to gain access into the human body. Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the particle size smaller than 200 nm makes the product more transparent compared to formulations containing coarser particles. The present study continues the work carried out in the frame of the NANODERM: “Quality of skin as a barrier to ultrafine particles” European project and complements our previous investigations on human skin with compromised barrier function. Atopic dermatitis (a type of eczema) is an inflammatory, chronically relapsing, non-contagious skin disease. It is very common in children but may occur at any age. The exact cause of atopic dermatitis is unknown, but is likely due to a combination of impaired barrier function together with a malfunction in the body's immune system. In this study, skin samples were obtained from two patients suffering from atopic dermatitis. Our results indicate that the ultrafine zinc oxide particles, in a hydrophobic basis gel with an application time of 2 days or 2 weeks, have penetrated deeply into the stratum corneum in these patients. On the other hand, penetration into the stratum spinosum was not observed even in the case of the longer application time.

Lead acetate trihydrate precursor route to synthesize novel ultrafine lead oxide from spent lead acid battery pastes

NASA Astrophysics Data System (ADS)

Sun, Xiaojuan; Yang, Jiakuan; Zhang, Wei; Zhu, Xinfeng; Hu, Yuchen; Yang, Danni; Yuan, Xiqing; Yu, Wenhao; Dong, Jinxin; Wang, Haifeng; Li, Lei; Vasant Kumar, R.; Liang, Sha

2014-12-01

A novel green recycling process is investigated to prepare lead acetate trihydrate precursors and novel ultrafine lead oxide from spent lead acid battery pastes. The route contains the following four processes. (1) The spent lead pastes are desulphurized by (NH4)2CO3. (2) The desulphurized pastes are converted into lead acetate solution by leaching with acetic acid solution and H2O2; (3) The Pb(CH3COO)2·3H2O precursor is crystallized and purified from the lead acetate solution with the addition of glacial acetic acid; (4) The novel ultrafine lead oxide is prepared by the calcination of lead acetate trihydrate precursor in N2 or air at 320-400 °C. Both the lead acetate trihydrate and lead oxide products are characterized by TG-DTA, XRD, and SEM techniques. The calcination products are mainly α-PbO, β-PbO, and a small amount of metallic Pb. The particle size of the calcination products in air is significantly larger than that in N2. Cyclic voltammetry measurements of the novel ultrafine lead oxide products show good reversibility and cycle stability. The assembled batteries using the lead oxide products as cathode active materials show a good cyclic stability in 80 charge/discharge cycles with the depth of discharge (DOD) of 100%.

Role of copper in precipitation hardening of high-alloy Cr-Ni cast steels

NASA Astrophysics Data System (ADS)

Gajewski, Mirosław

2006-02-01

The mechanism of strengthening with second-phase particles that results from heat treatment, i.e., precipitate hardening, plays an important role in modern alloys. The strengthening effect of such particles can result from their coherence with the matrix, inhibition of dislocation slip, inhibition of grain boundary slip, as well as hampering recovery processes due to dislocation network pinning. The results of investigations into high-alloy Cr-Ni-Cu cast steels precipitate hardened with highly dispersed ɛ phase particles are presented within. The influence of heat treatment on changes in microstructure, mechanical properties, and morphology of fracture surfaces obtained under loading have been analyzed. It has been demonstrated that, with the appropriate selection of heat treatment parameters, it is possible to control the precipitation of the hardening ɛ phase and, thus, to change the final mechanical and functional properties.

Comparison of GRCop-84 to Other High Thermal Conductive Cu Alloys

NASA Technical Reports Server (NTRS)

deGroh, Henry C., III; Ellis, David L.; Loewenthal, William S.

2007-01-01

The mechanical properties of five copper alloys (GRCop-84, AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, Cu-0.9Cr) competing in high temperature, high heat flux applications such as rocket nozzles, were compared. Tensile, creep, thermal expansion, and compression tests are presented. Tests were done on as-received material, and on material which received a simulated brazing heat treatment at 935 C. The 935 C heat treatment weakened AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr, and the strength of as-received AMZIRC dropped precipitously as test temperatures exceeded 500 C. The properties of GlidCop Al-15 and GRCop-84 were not significantly affected by the 935 C heat treatment. Thus GRCop-84 is better than AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr at temperatures greater than 500 C. Ductility was lowest in GlidCop Al-15 and Cu-0.9Cr. The creep properties of GRCop-84 were superior to those of brazed AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr. At equivalent rupture life and stress, GRCop-84 had a 150 C temperature advantage over brazed AMZIRC; for equivalent rupture life and temperature GRCop-84 was two times stronger. The advantages of GRCop-84 over GlidCop Al-15 associated with ease of processing were confirmed by GlidCop s marginal ductility. In the post brazed condition, GRCop-84 was found to be superior to the other alloys due to its greater strength and creep resistance (compared to AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr) and ductility (compared to GlidCop Al-15)

Associations between short-term exposure to particulate matter and ultrafine particles and myocardial infarction in Augsburg, Germany.

PubMed

Wolf, Kathrin; Schneider, Alexandra; Breitner, Susanne; Meisinger, Christa; Heier, Margit; Cyrys, Josef; Kuch, Bernhard; von Scheidt, Wolfgang; Peters, Annette

2015-08-01

Short-term exposure to increased particulate matter (PM) concentration has been reported to trigger myocardial infarction (MI). However, the association with ultrafine particles remains unclear. We aimed to assess the effects of short-term air pollution and especially ultrafine particles on registry-based MI events and coronary deaths in the area of Augsburg, Germany. Between 1995 and 2009, the MONICA/KORA myocardial infarction registry recorded 15,417 cases of MI and coronary deaths. Concentrations of PM<10μm (PM10), PM<2.5μm (PM2.5), particle number concentration (PNC) as indicator for ultrafine particles, and meteorological parameters were measured in the study region. Quasi-Poisson regression adjusting for time trend, temperature, season, and weekday was used to estimate immediate, delayed and cumulative effects of air pollutants on the occurrence of MI. The daily numbers of total MI, nonfatal and fatal events as well as incident and recurrent events were analysed. We observed a 1.3% risk increase (95%-confidence interval: [-0.9%; 3.6%]) for all events and a 4.4% [-0.4%; 9.4%] risk increase for recurrent events per 24.3μg/m(3) increase in same day PM10 concentrations. Nonfatal events indicated a risk increase of 3.1% [-0.1%; 6.5%] with previous day PM10. No association was seen for PM2.5 which was only available from 1999 on. PNC showed a risk increase of 6.0% [0.6%; 11.7%] for recurrent events per 5529 particles/cm(3) increase in 5-day average PNC. Our results suggested an association between short-term PM10 concentration and numbers of MI, especially for nonfatal and recurrent events. For ultrafine particles, risk increases were notably high for recurrent events. Thus, persons who already suffered a MI seemed to be more susceptible to air pollution. Copyright © 2015 Elsevier GmbH. All rights reserved.

Microwave Observations of Precipitation and the Atmosphere