Calcioferrite with composition (Ca3.94Sr0.06Mg1.01(Fe2.93Al1.07(PO46(OH4·12H2O

Directory of Open Access Journals (Sweden)

Barbara Lafuente

2014-03-01

Full Text Available Calcioferrite, ideally Ca4MgFe3+4(PO46(OH4·12H2O (tetracalcium magnesium tetrairon(III hexakis-phosphate tetrahydroxide dodecahydrate, is a member of the calcioferrite group of hydrated calcium phosphate minerals with the general formula Ca4AB4(PO46(OH4·12H2O, where A = Mg, Fe2+, Mn2+ and B = Al, Fe3+. Calcioferrite and the other three known members of the group, montgomeryite (A = Mg, B = Al, kingsmountite (A = Fe2+, B = Al, and zodacite (A = Mn2+, B = Fe3+, usually occur as very small crystals, making their structure refinements by conventional single-crystal X-ray diffraction challenging. This study presents the first structure determination of calcioferrite with composition (Ca3.94Sr0.06Mg1.01(Fe2.93Al1.07(PO46(OH4·12H2O based on single-crystal X-ray diffraction data collected from a natural sample from the Moculta quarry in Angaston, Australia. Calcioferrite is isostructural with montgomeryite, the only member of the group with a reported structure. The calcioferrite structure is characterized by (Fe/AlO6 octahedra (site symmetries 2 and -1 sharing corners (OH to form chains running parallel to [101]. These chains are linked together by PO4 tetrahedra (site symmetries 2 and 1, forming [(Fe/Al3(PO43(OH2] layers stacking along [010], which are connected by (Ca/Sr2+ cations (site symmetry 2 and Mg2+ cations (site symmetry 2; half-occupation. Hydrogen-bonding interactions involving the water molecules (one of which is equally disordered over two positions and OH function are also present between these layers. The relatively weaker bonds between the layers account for the cleavage of the mineral parallel to (010.

Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH(CH3COO2 crystals

Directory of Open Access Journals (Sweden)

KIYOHARA PEDRO K.

2000-01-01

Full Text Available Crystalline aluminium hydroxiacetate was prepared by reaction between aluminium powder (ALCOA 123 and aqueous solution of acetic acid at 96ºC ±1ºC. The white powder of Al(OH(CH3COO2 is constituted by agglomerates of crystalline plates, having size about 10mum. The crystals were fired from 200ºC to 1550ºC, in oxidizing atmosphere and the products characterized by X-ray diffraction, scanning electron microscopy and surface area measurements by BET-nitrogen method. Transition aluminas are formed from heating at the following temperatures: gamma (300ºC; delta (750ºC; alpha (1050ºC. The aluminas maintain the original morphology of the Al(OHAc2 crystal agglomerates, up to 1050ºC, when sintering and coalescence of the alpha-alumina crystals start and proceed up to 1550ºC. High surface area aluminas are formed in the temperature range of 700ºC to 1100ºC; the maximum value of 198m²/g is obtained at 900ºC, with delta-alumina structure. The formation sequence of transition aluminas is similar to the sequence from well ordered boehmite, but with differences in the transition temperatures and in the development of high surface areas. It is suggested that the causes for these diversities between the two sequences from Al(OH Ac2 and boehmite are due to the different particle sizes, shapes and textures of the gamma-Al2O3 which acts as precursor for the sequence gamma- to alpha-Al2O3.

EXOTIC METAL MOLECULES IN OXYGEN-RICH ENVELOPES: DETECTION OF AlOH (X1Σ+) IN VY CANIS MAJORIS

International Nuclear Information System (INIS)

Tenenbaum, E. D.; Ziurys, L. M.

2010-01-01

A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s -1 , as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H 2 was found to be ∼1 x 10 -7 for a source size of 0.26'' or 22 R * . In contrast, AlCl was not detected with f ≤ 5 x 10 -8 . AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is ∼17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

Influence of 8-hydroxyquinoline addition on the corrosion behavior of commercial Al and Al-HO411 alloys in NaOH aqueous media

International Nuclear Information System (INIS)

Soliman, H.N.

2011-01-01

Highlights: → The corrosion of commercial Al alloy is higher than that of Al-HO411 alloy. → The inhibition efficiency increases with the increasing of 8-hydroxyquinoline (8HQ) concentration. → The inhibition efficiencies of Al-HO411 samples are higher than those of commercial Al. → The 8HQ is promising candidate to be added to the coating systems as active anti-corrosive component for corrosion protection of both alloys. - Abstract: The effect of 8-hydroxyquinoline (8HQ) on the corrosion inhibition of commercial Al and Al-HO411 alloys has been investigated in NaOH solutions. Results showed that the inhibition efficiency was increased with increasing concentration of 8HQ. Al-HO411 alloy exhibited higher corrosion resistance and inhibition efficiency than the commercial Al. Examination of both samples was studied by means of optical microscope as well as energy-dispersive X-ray spectrometer. The crystallographic structure of both samples was analyzed by means of X-ray diffractometry. It was observed that protective films are formed on the surfaces that play an essential role in the corrosion inhibition of the alloys under investigation.

Dissolution of targets for the production of Mo-99: Part 1. Influence of NaOH concentration and the addition of NaNO{sub 3} and NaNO{sub 2} on the dissolution time

Energy Technology Data Exchange (ETDEWEB)

Camilo, Ruth L.; Araujo, Izilda da C.; Mindrisz, Ana C.; Forbicini, Christina A.L.G. de O., E-mail: rcamilo@ipen.br, E-mail: icaraujo@ipen.br, E-mail: acmindri@ipen.br, E-mail: cforbici@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN/SP), Sao Paulo, SP (Brazil)

2011-07-01

Faced with global crisis in the production of radioisotope {sup 99}Mo, which product of decay, {sup 99}mTc, is the tracer element most often used in nuclear medicine and accounts for about 80% of all diagnostic procedures in vivo, since September 2008 Brazil is developing the project called Brazilian Multipurpose Reactor (RMB). Within the Brazilian Nuclear Program (PNB) the construction of the RMB, is seen as a long term solution to meet all domestic demand relative to the supply of radioisotopes and radiopharmaceuticals. In the process to be studied to obtain {sup 99}Mo from irradiated UA1{sub x}-A1 LEU targets employing alkaline dissolution, processing time should be minimized, considering the short half life of {sup 99}Mo and {sup 99}mTc, about 66 h and 6 h, respectively. That makes dissolution time a significant factor in the development of the process. This paper presents the results of alkaline dissolution of scraps of Al, used to simulate the dissolution process of UA1{sub x}-A1 targets. Al corresponds to about 79% of the total weight of the UA1{sub x}-A1 target. The effect of NaOH concentration on dissolution time for the interval of 1 to 3.5 mol.L-1 was studied, keeping the molar ratio in 1Al:2.16NaOH and the initial temperature of 88 degree C. The influence of reagent composition over dissolution time was studied using three different solutions: a) 3 mol.L{sup -1} NaOH, b) 3 mol.L{sup -1} NaOH/NaNO{sub 3} and c) 3 mol.L{sup -1} NaOH/NaNO{sub 2}, keeping the same molar ratio and temperature. The results showed that the dissolution time decreases with increasing NaOH concentration and the addition of NaNO{sub 3} or NaNO{sub 2} in the NaOH solution reduces both dissolution time and volume of gases released. (author)

Compatibility of hydrogarnet, Ca3Al2(SiO4)x(OH)4(3−x), with sulfate and carbonate-bearing cement phases: 5–85 °C

International Nuclear Information System (INIS)

Okoronkwo, Monday Uchenna; Glasser, Fredrik Paul

2016-01-01

The stable existence of hydrogarnet in Portland cement compositions cured at temperatures below 55 °C has long been predicted from application of equilibrium thermodynamics. However hydrogarnet is not often reported in hydrated commercial Portland cements. The substitutions (SO 4 –CO 3 –OH) in AFm have previously been shown to stabilise AFm to higher temperatures and raise the temperature at which AFm converts to Si-free hydrogarnet, C 3 AH 6 . But unanswered question remains about the compatibility of AFm and AFm solid solutions with Si-substituted hydrogarnet, Ca 3 Al 2 (SiO 4 ) x (OH) 4(3 − x) . Phase relations of C 3 AH 6 and Ca 3 Al 2 (SiO 4 ) x (OH) 4(3 − x) at sulfate and carbonate activities conditioned respectively by (gypsum and SO 4 -AFt) and (calcite and CO 3 -AFt) have been determined experimentally in the range 5–85 °C. The results confirm the instability of Si-free hydrogarnet with carbonate and sulfate-bearing cement phases, but do indicate that a range of silica-substituted hydrogarnet solid solutions are stable under conditions likely to be encountered in blended cement systems.

SEM, EDS and vibrational spectroscopic study of dawsonite NaAl(CO3)(OH)2

Science.gov (United States)

Frost, Ray L.; López, Andrés; Scholz, Ricardo; Sampaio, Ney Pinheiro; de Oliveira, Fernando A. N.

2015-02-01

In this work we have studied the mineral dawsonite by using a combination of scanning electron microscopy with EDS and vibrational spectroscopy. Single crystals show an acicular habitus forming aggregates with a rosette shape. The chemical analysis shows a phase composed of C, Al, and Na. Two distinct Raman bands at 1091 and 1068 cm-1 are assigned to the CO32- ν1 symmetric stretching mode. Multiple bands are observed in both the Raman and infrared spectra in the antisymmetric stretching and bending regions showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the dawsonite structure. Multiple OH deformation vibrations centred upon 950 cm-1 in both the Raman and infrared spectra show that the OH units in the dawsonite structure are non-equivalent. Raman bands observed at 3250, 3283 and 3295 cm-1 are assigned to OH stretching vibrations. The position of these bands indicates strong hydrogen bonding of the OH units in the dawsonite structure. The formation of the mineral dawsonite has the potential to offer a mechanism for the geosequestration of greenhouse gases.

Exotic Metal Molecules in Oxygen-rich Envelopes: Detection of AlOH (X1Σ+) in VY Canis Majoris

Science.gov (United States)

Tenenbaum, E. D.; Ziurys, L. M.

2010-03-01

A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s-1, as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H2 was found to be ~1 × 10-7 for a source size of 0.26'' or 22 R* . In contrast, AlCl was not detected with f VY CMa is ~17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

Low silicon U(Al,Si)3 stabilization by Zr addition

International Nuclear Information System (INIS)

Pizarro, L.M.; Alonso, P.R.; Rubiolo, G.H.

2009-01-01

Previous knowledge states that (U,Zr)Al 3 and U(Al,Si) 3 phases with Zr and Si content higher than 6 at.% (7.7 wt%) and 4 at.% (1.4 wt%), respectively, does not partially transform to UAl 4 at 600 o C. In this work, four alloys within the quaternary system U-Al-Si-Zr were made with a fixed nominal 0.18 at.% (0.1 wt%) Si content in order to assess the synergetic effect of both Zr and Si alloying elements to the thermodynamic stability of the (U,Zr)(Al,Si) 3 phase. Heat treatments at 600 deg. C were undertaken and samples were analyzed by means of XRD, EPMA and EDS techniques. A remarkable conclusion is that addition of 0.3 at.% Si in the (U,Zr)(Al,Si) 3 phase reduces in 2.7 at.% the necessary Zr content to inhibit its transformation to U(Al,Si) 4 .

Ductility and fracture of single crystaliine Ni3Al with boron additions

International Nuclear Information System (INIS)

Heredia, F.E.; Pope, D.P.

1989-01-01

Low and high temperature tensile tests were performed on single crystals of pure Ni 3 Al and Ni 3 Al+B in order to determine the effect of B additions on the ductility and fracture behavior. Tests were carried out in air at a constant strain rate of 1/3 x 10 -3 s -1 . The orientation tested were [001] for whic the yield stress in tension is always greater than in compression, and those for wich the tension/compression asymmetry is zero ([T=C]) for each particular composition. At room temperature, the results show a positive effect of B additions on both the fracture stress and on the ductility. The ductility at 800K appears to decrease monotonically with B additions. The largest ductilities are found for [T=C] at room temperature where an improvement of about 26% (resolved strain) for an addition of 0.2 at % B was obtained. However, the most dramatic increase in ductility occurs for the [001] oriented samples at room temperature where a 55% improvement was measured over that of pure Ni 3 Al. Fracture surfaces show a combinaton of massive slip, some clevage, and heavily dimpled areas. These observations show that B additions not only increase the ductility of polycrystalline Ni 3 Al, as has been previously observed by many investigators, but also that the already-ductile single crystalline material, indicating that a bulk effect should be added to the grain boundary strengthening effect of B when explaining the improvement in ductility of polycrystalline Ni 3 Al due to B additions

New nighttime retrievals of O(3P) and OH densities in the mesosphere/lower thermosphere using SABER/TIMED observations

Science.gov (United States)

Panka, P.; Kutepov, A. A.; Kalogerakis, K. S.; Janches, D.; Feofilov, A.; Rezac, L.; Marsh, D. R.; Yigit, E.

2017-12-01

We present first retrievals of O(3P) and OH densities in the mesosphere/lower thermosphere (MLT) using SABER/TIMED OH 2.0 and 1.6 μm limb emission observations. Recently, Kaufmann et al. [2014] reported that current SABER O(3P) densities are on average 30% higher compared to other observations. In this study we applied new detailed non-LTE model [Panka et al. 2017] of nighttime OH(v), which accounts for the new mechanism OH(v≥5)+O(3P)→O(1D)+OH(v-5) of energy transfer recently suggested by Sharma et al. [2015] and confirmed through laboratory studies by Kalogerakis et al. [2016]. Based on this model we developed a new self-consistent two channel retrieval approach for O(3P) and OH density. Using this approach, we retrieved O(3P) densities that are 10-40% lower than current SABER O(3P), as well as total OH density which is retrieved for the first time using SABER observations. We compare our retrieveals with the results of other observations and models. As it was recently shown by Panka et al. [2017], the new mechanism of OH quenching produces a significant pumping of CO2 4.3 µm emission. We discuss the effects these new O(3P) and OH retrievals have on the nighttime CO2 density retrievals from the SABER 4.3 µm channel.

Elasticity of phase-Pi (Al3Si2O7(OH)3) - A hydrous aluminosilicate phase

Science.gov (United States)

Peng, Ye; Mookherjee, Mainak; Hermann, Andreas; Bajgain, Suraj; Liu, Songlin; Wunder, Bernd

2017-08-01

Phase-Pi (Al3Si2O7(OH)3) is an aluminosilicate hydrous mineral and is likely to be stable in hydrated sedimentary layers of subducting slabs. Phase-Pi is likely to be stable between the depths of 60 and 200 km and is likely to transport water into the Earth's interior. Here, we use first principles simulations based on density functional theory to explore the crystal structure at high-pressure, equation of state, and full elastic stiffness tensor as a function of pressure. We find that the pressure volume results could be described by a finite strain fit with V0 , K0 , and K0‧ being 310.3 Å3, 133 GPa, and 3.6 respectively. At zero pressure, the full elastic stiffness tensor shows significant anisotropy with the diagonal principal components C11 , C22 , and C33 being 235, 292, 266 GPa respectively, the diagonal shear C44 , C55 , and C66 being 86, 92, and 87 GPa respectively, and the off-diagonal stiffness C12 , C13 , C14 ,C15 , C16 , C23 , C24 , C25 , C26 , C34 , C35 , C36 , C45 , C46 , and C56 being 73, 78, 6, -30, 15, 61, 17, 2, 1, -13, -15, 6, 3, 1, and 3 GPa respectively. The zero pressure, shear modulus, G0 and its pressure derivative, G0 ‧ are 90 GPa and 1.9 respectively. Upon compression, hydrogen bonding in phase-Pi shows distinct behavior, with some hydrogen bonds weakening and others strengthening. The latter eventually undergo symmetrization, at pressure greater (>40 GPa) than the thermodynamic stability of phase-Pi. Full elastic constant tensors indicate that phase-Pi is very anisotropic with AVP ∼22.4% and AVS ∼23.7% at 0 GPa. Our results also indicate that the bulk sound velocity of phase-Pi is slower than that of the high-pressure hydrous aluminosilicate phase, topaz-OH.

Colloidal stability of Ni(OH){sub 2} in water and its dispersion into a ceramic matrix from the reaction media to obtain Ni/Al{sub 2}O{sub 3} materials

Energy Technology Data Exchange (ETDEWEB)

Cabanas-Polo, S.; Ferrari, B.; Sanchez-Herencia, A. J.

2014-07-01

Ni/Al{sub 2}O{sub 3} composites have been fabricated by slip casting of concentrated Ni(OH){sub 2}/Al{sub 2}O{sub 3} suspensions and subsequent in situ reduction to metallic nickel during sintering. For that, the synthesis assisted by ultrasound of both α- and β-Ni(OH){sub 2} polymorphs, as well as their colloidal stability, have been studied. The structural differences between both polymorphs have been thoroughly studied by means of XRD, FTIR, DTA-TG, SSA, SEM and TEM, in order to optimize the starting suspensions. This way, the IEP of both polymorphs have been established (9.7 y 12 for β- and α-Ni(OH){sub 2}, respectively), as well as the optimal content of an anionic dispersant (PAA) to stabilize the particles (0.8 wt. % for beta phase and 3.0 wt. % for alpha phase). Three different Ni/Al{sub 2}O{sub 3} composites, with a high dispersion degree of the metallic phase, have been obtained considering the potential vs. particles distance curve of the Ni(OH){sub 2}, and their structure has been discussed in terms of the strength of the agglomerates and/or aggregates of the Ni(OH){sub 2}. (Author)

Electric conductivity of low-temperature molten electrolyte KF-AlF3 with additions of LiF and Al2O3

International Nuclear Information System (INIS)

Apisarov, A.P.; Kryukovskij, V.A.; Zajkov, Yu.P.; Red'kin, A.A.; Tkacheva, O.Yu.; Khokhlov, V.A.

2007-01-01

Electric conductivity of LiF, Al 2 O 3 doped KF-AlF 3 (Cryolite Ratio CR=1.3) molten electrolytes was estimated on the basis of empiric equations. Specific electric conductivity of KF-AlF 3 , KF-AIF 3 -AI 2 O 3 , KF-AlF 3 -LiF, KF-AlF 3 -LiF-Al 2 0 3 molten mixtures was measured in the range 687-797 Deg C. Cells with the pyrolytic boron nitride capillary and parallel molybdena electrodes were applied for the determination of electric conductivity. Comparison of calculated and experimental data of the specific electric conductivity of cryolite-alumina melts confirms that the offered model of the calculation adequate represents temperature and concentration dependencies, and it permits forecasting its change under the introduction of different additives in electrolyte [ru

Assay of 25-OH vitamin D3

International Nuclear Information System (INIS)

Nayer, P. de; Thalasso, M.; Beckers, C.

1977-01-01

A simplified version of the competitive protein binding assay for 25-OH vit D3 derived from the method of Belsey et al. is presented. The procedure does not include a chromatography step, and is performed on an alcoolic extract of 0.1 ml plasma or serum. Normal rat serum (1:20,000) was used as binding protein. No β-lipoproteins were added to the assay buffer. A 10% displacement of the tracer was observed at 0.04 ng/tube, and 50% at 0.15 ng/tube, allowing for the measurement of 25-OH vit D3 concentrations between 2 ng/ml and 200 ng/ml. Mean values in a normal group was 23.1 +- 6.5 ng/ml (range 16-37 ng/ml, n = 11). (orig.) [de

Statistical evaluation of potential damage to the Al(OH)3 layer on nTiO2 particles in the presence of swimming pool and seawater

International Nuclear Information System (INIS)

Virkutyte, Jurate; Al-Abed, Souhail R.

2012-01-01

Nanosized TiO 2 particles (nTiO 2 ) are usually coated with an Al(OH) 3 layer when used in sunscreen to shield against the harmful effects of free radicals that are generated when these particles are exposed to UV radiation. Therefore, it is vital to insure the structural stability of these particles in the environment where the protective layer may be damaged and adverse health and environmental effects can occur. This study utilized X-ray analysis (SEM–EDS) to provide a qualitative and semi-quantitative assessment of the chemical and physical characteristics of Al(OH) 3 -coated original and damaged nTiO 2 particles (used in sunscreen lotion formulations) in the presence of both swimming pool and seawater. Also, by utilizing statistical tools, a distribution of Al/Ti (%) on the particle surface was determined and evaluated. It was found that 45 min of treatment with swimming pool and seawater significantly induced the redistribution of Al/Ti (%), which changed the surface characteristics of particles and, therefore, may have induced undesired photo-activity and the consequent formation of free radicals.

Ab initio calculations for the substitutions of Al(OH)4- and SO42- with Si tetrahedra

International Nuclear Information System (INIS)

Rahman, Md.Mazibur; Tanaka, Satoru; Nagasaki, Shinya

2001-01-01

We have studied the interaction phenomena for the substitutions of Al(OH) 4 - and SO 4 2- with both paired and bridging Si tetrahedra likely to be occurred in C-S-H gel coexisting with ettringite system. Gaussian 94 program has been used to obtain the total energy of the molecule in the optimized structure employing HF/3-21G level of theory. It has been investigated that the net charge on the substitution site causes the modification of the original structure during the substitution. The substitutions of Al(OH) 4 - with Si tetrahedra were found to be thermodynamically possible in both paired and bridging Si tetrahedra at chemical equilibrium. The substitutions of SO 4 2- with Si tetrahedra were found to be thermodynamically possible at the limited positions as well. It this work, these possibilities are also discussed with the estimated activated energies for the substitutions of Al(OH) 4 - and SO 4 2- with paired Si tetrahedra. (author)

The Recovery of Uranium From The Rejected Fuel Plate Dispersion Type of U3O8-Al and U3Si2Al by NaOH

International Nuclear Information System (INIS)

Widodo, G; Aji, D

1998-01-01

The recovery of uranium from the rejected fuel plate dispersion type of U 3 O 8 -AI And U 3 Si 2 -AI with a dissolution has been performed.Each of 5 fragment of fuel plate dispersion of U 3 O 8 -AI or U 3 Si 2 Al of 1x4 cm size was put in the distilled glass content of 250 ml NaOH solution whit The concentration variation 10,15,20,25,and 30%,and than was heated at temperature of 102 o C and was stirred constantly by magnetic stirred.Uranium in the form of U 3 O 8 or U 3 Si 2 was separated by filtration and Either residu and filtrate was analyzed by potentiometry using modified Devies Gray method. From the experiment data it was found in the residu that presentation of uranium was 83.99-84.05% and 84.67-86.556% while in filtrate it was found 53.90 ppm and 69.3 ppm

Effects of additives on the sintering of UO2.Gd2O3 nuclear fuel

International Nuclear Information System (INIS)

Pagano Junior, Luciano

2009-01-01

The addition of 0.5wt% TiO 2 , Nb 2 O 5 , SiO 2 , Fe 2 O 3 and Al(OH) 3 in the UO 2 ·7%Gd 2 O 3 nuclear fuel and the effect on its sintering kinetics under a 99.999% H 2 atmosphere were investigated by stepwise isothermal dilatometry. This fuel, used as burnable poison in nuclear power plants, presents a diffusion barrier around 1573 K that impairs densification. The aid of the sintering additives TiO 2 , Al(OH) 3 , Nb 2 O 5 and Fe 2 O 3 turned out to be effective to obtain the required final density, unlike the effect observed for the SiO 2 -doped composition. The activation energy for the intermediate sintering stage was calculated by stepwise isothermal dilatometry method and a positive correlation with the sintered body density was found. The method was valid for part of the intermediate sintering stage, in the range from 1200 K to 1700 K for the doped compositions and with no additive, except for the SiO 2 -doped one, whose validity range was between 1500 K and 1900 K. The energy-density correlation was not valid for the SiO 2 -doped composition, whose effect was to reduce the final density. This anomalous behavior may be attributed to the intense loss of Si mass, probably due to lower oxides volatilization, during the initial sintering stage at temperatures lower than 1173 K. Similar loss, but no so intense, was observed for the Al(OH) 3 -doped composition in the temperature interval from 1173 K to 1573 K. The Si concentration decrease to residual values of dozens of parts per million may explain its anomalous behavior. The positive correlation between activation energy and sintered body density may be explained by the inhibitor role played by the TiO 2 , Nb 2 O 5 , Fe 2 O 3 and Al(OH) 3 additives on the diffusion mechanisms that enhance the coarsening regime. As a consequence, the densification mechanisms are favored in the competition for the surface free energy. The coarsening-densification transition temperature model, originally suggested for the UO 2

An i.r. investigation on some calcium aluminate hydrates, Ca2Al(OH)6+X-.yH2O (= 3CaO.Al2O3.CaX2.nH2O, X- = univalent anion)

NARCIS (Netherlands)

Houtepen, C.J.M.; Stein, H.N.

1976-01-01

The i.r. spectra of some hydrated and dehydrated calcium aluminate hydrates of the type Ca2Al(OH)6+X-·yH2O with X- = Cl-, Br-, J-, ClO3-, NO3-, ClO4- (y = 2) and X- = BrO3-, JO3- (2

Exotic Metal Molecules in Oxygen-Rich Envelopes: Detection of AlOH (X1Σ^+) in VY Canis Majoris

Science.gov (United States)

Tenenbaum, E. D.; Ziurys, L. M.

2010-06-01

A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris, an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope (SMT), while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H_2 was found to be 1x10-7 for a source size of 0.26'' or 22 R_*. AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry, and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is ˜17. LTE calculations predict the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides.

Atom-radical reaction dynamics of O(3P)+C3H5→C3H4+OH: Nascent rovibrational state distributions of product OH

Science.gov (United States)

Park, Jong-Ho; Lee, Hohjai; Kwon, Han-Cheol; Kim, Hee-Kyung; Choi, Young-Sang; Choi, Jong-Ho

2002-08-01

The reaction dynamics of ground-state atomic oxygen [O(3P)] with allyl radicals (C3H5) has been investigated by applying a combination of crossed beams and laser induced fluorescence techniques. The reactants O(3P) and C3H5 were produced by the photodissociation of NO2 and the supersonic flash pyrolysis of precursor allyl iodide, respectively. A new exothermic channel of O(3P)+C3H5→C3H4+OH was observed and the nascent internal state distributions of the product OH (X 2Π:υ″=0,1) showed substantial bimodal internal excitations of the low- and high-N″ components without Λ-doublet and spin-orbit propensities in the ground and first excited vibrational states. With the aid of the CBS-QB3 level of ab initio theory and Rice-Ramsperger-Kassel-Marcus calculations, it is predicted that on the lowest doublet potential energy surface the major reaction channel of O(3P) with C3H5 is the formation of acrolein (CH2CHCHO)+H, which is consistent with the previous bulk kinetic experiments performed by Gutman et al. [J. Phys. Chem. 94, 3652 (1990)]. The counterpart C3H4 of the probed OH product in the title reaction is calculated to be allene after taking into account the factors of reaction enthalpy, barrier height and the number of intermediates involved along the reaction pathway. On the basis of population analyses and comparison with prior calculations, the statistical picture is not suitable to describe the reactive atom-radical scattering processes, and the dynamics of the title reaction is believed to proceed through two competing dynamical pathways. The major low N″-components with significant vibrational excitation may be described by the direct abstraction process, while the minor but extraordinarily hot rotational distribution of high N″-components implies that some fraction of reactants is sampled to proceed through the indirect short-lived addition-complex forming process.

Effect of 24,25-dihydroxyvitamin D3 on 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] metabolism in vitamin D-deficient rats infused with 1,25-(OH)2D3

International Nuclear Information System (INIS)

Yamato, H.; Matsumoto, T.; Fukumoto, S.; Ikeda, K.; Ishizuka, S.; Ogata, E.

1989-01-01

Previous studies revealed that administration of 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3] to calcium (Ca)-deficient rats causes a dose-dependent reduction in markedly elevated serum 1,25-(OH)2D3 level. Although the results suggested that the metabolism of 1,25-(OH)2D3 was accelerated by 24,25-(OH)2D3, those experiments could not define whether the enhanced metabolism of 1,25-(OH)2D3 played a role in the reduction in the serum 1,25-(OH)2D3 level. In the present study, in order to address this issue more specifically, serum 1,25-(OH)2D3 was maintained solely by exogenous administration through miniosmotic pumps of 1,25-(OH)2D3 into vitamin D-deficient rats. Thus, by measuring the serum 1,25-(OH)2D3 concentration, the effect of 24,25-(OH)2D3 on the MCR of 1,25-(OH)2D3 could be examined. Administration of 24,25-(OH)2D3 caused a dose-dependent enhancement in the MCR of 1,25-(OH)2D3, and 1 microgram/100 g rat.day 24,25-(OH)2D3, which elevated serum 24,25-(OH)2D3 to 8.6 +/- 1.3 ng/ml, significantly increased MCR and suppressed serum levels of 1,25-(OH)2D3. The effect of 24,25-(OH)2D3 on 1,25-(OH)2D3 metabolism developed with a rapid time course, and the recovery of iv injected [1 beta-3H]1,25-(OH)2D3 in blood was significantly reduced within 1 h. In addition, there was an increase in radioactivity in the water-soluble fraction of serum as well as in urine, suggesting that 1,25-(OH)2D3 is rapidly degraded to a water-soluble metabolite(s). Furthermore, the reduction in serum 1,25-(OH)2D3 was associated with a reduction in both serum and urinary Ca levels. Because the conversion of [3H]24,25-(OH)2D3 to [3H]1,24,25-(OH)2D3 or other metabolites was minimal in these rats, 24,25-(OH)2D3 appears to act without being converted into other metabolites. These results demonstrate that 24,25-(OH)2D3 rapidly stimulates the metabolism of 1,25-(OH)2D3 and reduces its serum level

Water-n-BuOH solvothermal synthesis of ZnAl-LDHs with different morphologies and its calcined product in efficient dyes removal.

Science.gov (United States)

Huang, Gailing; Sun, Yingying; Zhao, Chencong; Zhao, Yifei; Song, Zhaoyuan; Chen, Junli; Ma, Shulan; Du, Junping; Yin, Zhigang

2017-05-15

In this study, water-n-BuOH mixed solvents were used to synthesize the ZnAl-layered double hydroxides (ZnAl-LDHs) via hydrothermal method. The XRD, FT-IR, SEM, ICP and CHN analyses revealed that the type of intercalated anions, the layer Zn/Al ratios, and morphologies of the LDHs depended on the ratio of V(water)/V(n-BuOH) in the mixed solvents. When the ratio of V(water)/V(n-BuOH) is 3 or 0.3, the as-prepared LDHs had 3D "silk flowers" (ZnAl-LDH-3) or "Sedimentary rock" morphology (ZnAl-LDH-0.3). Adsorption properties of dyes on calcined LDHs were studied. Compared with ZnAl-LDO-0.3 and ZnAl-LDO-w (calcined from the LDHs obtained in pure water), ZnAl-LDO-3 showed much better adsorption efficiency for anionic dyes thanks to its much larger BET-specific surface area. The sorption kinetics for dyes was appropriately described by the pseudo-second-order model and sorption isotherms can be fitted more satisfactorily by the Langmuir model. With the increasing concentrations of dyes from 10mg/L to 400mg/L, the maximum absorption capacities of ZnAl-LDO-3 were 1540mg/g (2.21mmol/g) for congo red, 1153mg/g (3.52mmol/g) for methyl orange and 390mg/g (0.63mmol/g) for active red (X-3B), respectively. The adsorption dyes onto the external surface is still the main mechanism for LDO adsorbents. The ZnAl-LDO-3 was a potential adsorbent for dyeing wastewater treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Chemical failure modes of AlQ3-based OLEDs: AlQ3 hydrolysis.

Science.gov (United States)

Knox, John E; Halls, Mathew D; Hratchian, Hrant P; Schlegel, H Bernhard

2006-03-28

Tris(8-hydroxyquinoline)aluminum(III), AlQ3, is used in organic light-emitting diodes (OLEDs) as an electron-transport material and emitting layer. The reaction of AlQ3 with trace H2O has been implicated as a major failure pathway for AlQ3-based OLEDs. Hybrid density functional calculations have been carried out to characterize the hydrolysis of AlQ3. The thermochemical and atomistic details for this important reaction are reported for both the neutral and oxidized AlQ3/AlQ3+ systems. In support of experimental conclusions, the neutral hydrolysis reaction pathway is found to be a thermally activated process, having a classical barrier height of 24.2 kcal mol(-1). First-principles infrared and electronic absorption spectra are compared to further characterize AlQ3 and the hydrolysis pathway product, AlQ2OH. The activation energy for the cationic AlQ3 hydrolysis pathway is found to be 8.5 kcal mol(-1) lower than for the neutral reaction, which is significant since it suggests a role for charge imbalance in promoting chemical failure modes in OLED devices.

Effect of additives in sintering UO2-7wt%Gd2O3 fuel pellets

International Nuclear Information System (INIS)

Santos, L.R.; Riella, H.G.

2009-01-01

Gadolinium has been used as burnable poison for reactivity control in modern PWRs. The incorporation of Gd 2 O 3 powder directly into the UO 2 powder enables longer fuel cycles and optimized fuel utilization. Nevertheless, processing by this method leads to difficulties while obtaining sintered pellets with the minimum required density. The process for manufacturing UO 2 - Gd 2 O 3 generates scraps that should be reused. The main scraps are green and sintered pellets, which must be calcined to U 3 O 8 to return to the fabrication process. Also, the incorporation of Gd 2 O 3 in UO 2 requires the use of an additive to improve the sintering process, in order to achieve the physical properties specified for the mixed fuel, mainly density and microstructure. This paper describes the effect of the addition of fabrication scraps on the properties of the UO 2 -Gd 2 O 3 fuel. Aluminum hydroxide Al(OH) 3 was also incorporated to the fuel as a sintering aid. The results shown that the use of 2000 ppm of Al(OH) 3 as additive allow to fabricate good pellets with up to 10 wt% of recycled scraps. (author)

The use of CH3OH additive to NaOH for etching alpha particle tracks in a CR-39 plastic nuclear track detector

International Nuclear Information System (INIS)

Ashry, A.H.; Abdalla, A.M.; Rammah, Y.S.; Eisa, M.; Ashraf, O.

2014-01-01

Fast detection of alpha particles in CR-39 detectors was investigated using a new chemical etchant. 252 Cf and 241 Am sources were used for irradiating samples of CR-39 SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8 ml of 10N NaOH+1 ml CH 3 OH) at 60 °C to detect alpha particle in short time in CR-39 detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 2.73 μm/h. Both the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution. Pure NaOH was used as a control to compare with the result from etching in NaOH with different concentrations of CH 3 OH. The etching efficiency is determined and compared with conventional aqueous solution of 6.25N NaOH at 70 °C for etching time equals 5 h. In this study, the obtained etching efficiency shows a considerable agreement with the previous work. - Highlights: • The value of bulk etching rate is equal to 2.73 μm/h. • Fast detection of alpha particles in CR-39 detectors. • Samples of CR-39 have been irradiated with fission fragments. • Etching efficiency was determined

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH3OH+OH reaction

DEFF Research Database (Denmark)

Rasmussen, Christian Lund; Wassard, K.H.; Dam-Johansen, Kim

2008-01-01

The oxidation of methanol in a flow reactor has been studied experimentally under diluted, fuel-lean conditions at 650-1350 K, over a wide range of O-2 concentrations (1%-16%), and with and without the presence of nitric oxide. The reaction is initiated above 900 K, with the oxidation rate...... decreasing slightly with the increasing O-2 concentration. Addition of NO results in a mutually promoted oxidation of CH3OH and NO in the 750-1100 K range. The experimental results are interpreted in terms of a revised chemical kinetic model. Owing to the high sensitivity of the mutual sensitization of CH3OH...... and NO oxidation to the partitioning of CH3O and CH2OH, the CH3OH + OH branching fraction could be estimated as alpha = 0.10 +/- 0.05 at 990 K. Combined with low-temperature measurements, this value implies a branching fraction that is largely independent of temperature. It is in good agreement with recent...

Roymillerite, Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, a new mineral: mineralogical characterization and crystal chemistry

Science.gov (United States)

Chukanov, Nikita V.; Jonsson, Erik; Aksenov, Sergey M.; Britvin, Sergey N.; Rastsvetaeva, Ramiza K.; Belakovskiy, Dmitriy I.; Van, Konstantin V.

2017-11-01

The new mineral roymillerite Pb24Mg9(Si9AlO28)(SiO4)(BO3)(CO3)10(OH)14O4, related to britvinite and molybdophyllite, was discovered in a Pb-rich assemblage from the Kombat Mine, Grootfontein district, Otjozondjupa region, Namibia, which includes also jacobsite, cerussite, hausmannite, sahlinite, rhodochrosite, barite, grootfonteinite, Mn-Fe oxides, and melanotekite. Roymillerite forms platy single-crystal grains up to 1.5 mm across and up to 0.3 mm thick. The new mineral is transparent, colorless to light pink, with a strong vitreous lustre. Cleavage is perfect on (001). Density calculated using the empirical formula is equal to 5.973 g/cm3. Roymillerite is optically biaxial, negative, α = 1.86(1), β ≈ γ = 1.94(1), 2 V (meas.) = 5(5)°. The IR spectrum shows the presence of britvinite-type tetrahedral sheets, {CO}3^{2 - }, {BO}3^{3 - }, and OH- groups. The chemical composition is (wt%; electron microprobe, H2O and CO2 determined by gas chromatography, the content of B2O3 derived from structural data): MgO 4.93, MnO 1.24, FeO 0.95, PbO 75.38, B2O3 0.50, Al2O3 0.74, CO2 5.83, SiO2 7.90, H2O 1.8, total 99.27. The empirical formula based on 83 O atoms pfu (i.e. Z = 1) is Pb24.12Mg8.74Mn1.25Fe0.94B1.03Al1.04C9.46Si9.39H14.27O83. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is triclinic, space group P \\bar{1}, with a = 9.315(1), b = 9.316(1), c = 26.463(4) Å, α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°, V = 1971.2(6) Å3. The crystal structure of roymillerite is based built by alternating pyrophyllite-type TOT-modules Mg9(OH)8[(Si,Al)10O28] and I-blocks Pb24(OH)6O4(CO3)10(BO3,SiO4). The strongest lines of the powder X-ray diffraction pattern [ d, Å (I, %) ( hkl)] are: 25.9 (100) (001), 13.1 (11) (002), 3.480 (12) (017, 107, -115, 1-15), 3.378 (14) (126, 216), 3.282 (16) (-2-15, -1-25), 3.185 (12) (-116, 1-16), 2.684 (16) (031, 301, 030, 300, 332, -109, 0-19, 1-18), 2.382 (11) (0.0.-11). Roymillerite is

Statistical Evaluation of Potential Damage to the Al(OH)3 Layer on nTiO2 Particles in the Presence of Swimming Pool and Seawater

Science.gov (United States)

Nanosized TiO2 particles (nTiO2) are usually coated with an Al(OH)3 layer when used in sunscreen to shield against the harmful effects of free radicals that are generated when these particles are exposed to UV radiation. Therefore, it is vital to ...

Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The performance of Al-Ti-C master alloy in refining Al-10Mg and A1-5Cu alloys was studied by using electron probe micro-analyzer (EPMA) and X-ray diffractometer (XRD) analysis.The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds.Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading.However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti(Al, Cu)2, which is responsible for the refinement fading in Al-5Cu alloy.These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.

The Influence of Backwater Al3+ on Diaspore Bauxite Flotation

Directory of Open Access Journals (Sweden)

Chaojun Fang

2017-10-01

Full Text Available The effect of Al3+ in backwater on the flotation of diaspore bauxite was investigated by micro-flotation tests and the underlying mechanisms were investigated by inductively coupled plasma (ICP measurement, zeta potential measurements, solution chemistry analyses, and synchrotron near edge X-ray absorption fine structure (NEXAFS analyses. The ICP measurement results show the concentration of Al3+ in backwater was up to 1 × 10−4 mol/L. The micro-flotation results indicated that backwater Al3+ reduced the flotation recovery of diaspore and improved the flotation recovery of kaolinite at pH 9, which was the pH value used in the industrial flotation. The adsorption of Al3+ species changed the zeta potential, the Al atomic abundance, and the number of active sites on the mineral surface. In particular, the result of solution chemistry analyses and synchrotron NEXAFS analyses show that the Al3+ in backwater was adsorbed on the mineral surface in the form of Al(OH3 (s, and the bond of –Al–O–Al–(OH2 or –Al/Si–O–Al–(OH2 was formed at pH 9. It changed the intensity of hydrogen bond force between minerals and collectors, and resulted in the depression of diaspore flotation and the activation of kaolinite flotation. This study can be used to guide the application of backwater in the flotation of diaspore bauxite in industry.

A highly sensitive, single selective, fluorescent sensor for Al3+ detection and its application in living cell imaging

International Nuclear Information System (INIS)

Ye, Xing-Pei; Sun, Shao-bo; Li, Ying-dong; Zhi, Li-hua; Wu, Wei-na; Wang, Yuan

2014-01-01

A new o-aminophenol-based fluorogenic chemosensor methyl 3,5-bis((E)-(2-hydroxyphenylimino)methyl)-4-hydroxybenzoate 1 have been synthesized by Schiff base condensation of methyl 3,5-diformyl-4-hydroxybenzoate with o-aminophenol, which exhibits high selectivity and sensitivity toward Al 3+ . Fluorescence titration studies of receptors 1 with different metal cations in CH 3 OH medium showed highly selective and sensitive towards Al 3+ ions even in the presence of other commonly coexisting metal ions. The detection limit of Al 3+ ions is at the parts per billion level. Interestingly, the Al(III) complex of 1 offered a large Stokes shift (>120 nm), which can miximize the selfquenching effect. In addition, possible utilization of this receptor as bio-imaging fluorescent probe to detect Al 3+ in human cervical HeLa cancer cell lines was also investigated by confocal fluorescence microscopy. - Highlights: • A new Schiff base chemosensor is reported. • The sensor for Al 3+ offers large Stokes shift. • The detection limit of Al 3+ in CH 3 OH solution is at the parts per billion level. • The utilization of sensor for the monitoring of Al 3+ levels in living cells was examined

First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

DEFF Research Database (Denmark)

Saadi, Souheil; Hinnemann, Berit; Appel, Charlotte C.

2011-01-01

We investigate the structure and surface composition of the γ′-Ni3Al(111) and β-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel–aluminum alloys are protected...... by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni3Al and NiAl surfaces, the conditions under which CO and OH...... adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH...

Effect of Ga2O3 addition on the properties of Y2O3-doped AlN ceramics

Directory of Open Access Journals (Sweden)

Shin H.

2015-01-01

Full Text Available Effect Ga2O3 addition on the densification and properties of Y2O3-doped AlN ceramics was investigated under the constraint of total sintering additives (Y2O3 and Ga2O3 of 4.5 wt%. Ga was detected in the AlN grain as well as the grain boundary phases. YAlO3 and Y4Al2O9 were observed as the secondary crystalline phases in all of the investigated compositions. As the substitution of Ga2O3 for Y2O3 increased, the quantity of the Y4Al2O9 phase decreased while that of YAlO3 was more or less similar. Neither additional secondary phases was identified, nor was the sinterability inhibited by the Ga2O3 addition; the linear shrinkage and apparent density were above 20 percent and 3.34-3.37 g/cm3, respectively. However, the optical reflectance and the elastic modulus generally decreased whereas the Poisson ratio increased significantly. The dielectric constant and the loss tangent of 4.0Y2O3-0.5Ga2O3-95.5Y2O3 at the resonant frequency of 8.22 GHz were 8.63 and 0.003, respectively.

Statistical evaluation of potential damage to the Al(OH){sub 3} layer on nTiO{sub 2} particles in the presence of swimming pool and seawater

Energy Technology Data Exchange (ETDEWEB)

Virkutyte, Jurate [Pegasus Technical Services, Inc (United States); Al-Abed, Souhail R., E-mail: al-abed.souhail@epa.gov [U.S. Environmental Protection Agency, National Risk Management Research Laboratory (United States)

2012-03-15

Nanosized TiO{sub 2} particles (nTiO{sub 2}) are usually coated with an Al(OH){sub 3} layer when used in sunscreen to shield against the harmful effects of free radicals that are generated when these particles are exposed to UV radiation. Therefore, it is vital to insure the structural stability of these particles in the environment where the protective layer may be damaged and adverse health and environmental effects can occur. This study utilized X-ray analysis (SEM-EDS) to provide a qualitative and semi-quantitative assessment of the chemical and physical characteristics of Al(OH){sub 3}-coated original and damaged nTiO{sub 2} particles (used in sunscreen lotion formulations) in the presence of both swimming pool and seawater. Also, by utilizing statistical tools, a distribution of Al/Ti (%) on the particle surface was determined and evaluated. It was found that 45 min of treatment with swimming pool and seawater significantly induced the redistribution of Al/Ti (%), which changed the surface characteristics of particles and, therefore, may have induced undesired photo-activity and the consequent formation of free radicals.

Comparative effect of Al, Se, and Mo toxicity on NO3(-) assimilation in sunflower (Helianthus annuus L.) plants.

Science.gov (United States)

Ruiz, Juan M; Rivero, Rosa M; Romero, Luis

2007-04-01

Here, we study the effect caused by three trace elements--Al, Se, and Mo--applied at the same concentration (100 microM) and in their oxyanionic forms--NaAl(OH)(4), Na(2)SeO(4), and Na(2)MoO(4)--on NO(3)(-) assimilation (NO(3)(-), nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) activities, and concentrations of amino acids and proteins) in sunflower (Helianthus annuus L. var. Kasol) plants. The most harmful element for sunflower plants proved to be selenate, followed by aluminate. On the contrary, the application of molybdate had no negative effect on the growth of this plant, suggesting the possibility of using sunflower for the phytoremediation of this metal, mainly in agricultural zones used for grazing where the excess of this element can provoke problems of molybdenosis in ruminants (particularly in cattle). In addition, we found that the alteration of NO(3)(-) assimilation by SeO(4)(2-) and Al(OH)(4)(-) directly influences the growth and development of plants, foliar inhibition of NR activity by SeO(4)(2-) being more harmful than the decrease in foliar availability of NO(3)(-) provoked by Al(OH)(4)(-).

Attikaite, Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O, a new mineral species

Science.gov (United States)

Chukanov, N. V.; Pekov, I. V.; Zadov, A. E.

2007-12-01

Attikaite, a new mineral species, has been found together with arsenocrandalite, arsenogoyazite, conichalcite, olivenite, philipsbornite, azurite, malachite, carminite, beudantite, goethite, quartz, and allophane at the Christina Mine No. 132, Kamareza, Lavrion District, Attiki Prefecture (Attika), Greece. The mineral is named after the type locality. It forms spheroidal segregations (up to 0.3 mm in diameter) consisting of thin flexible crystals up to 3 × 20 × 80 μm in size. Its color is light blue to greenish blue, with a pale blue streak. The Mohs’ hardness is 2 to 2.5. The cleavage is eminent mica-like parallel to {001}. The density is 3.2(2) g/cm3 (measured in heavy liquids) and 3.356 g/cm3 (calculated). The wave numbers of the absorption bands in the infrared spectrum of attikaite are (cm-1; sh is shoulder; w is a weak band): 3525 sh, 3425, 3180, 1642, 1120 w, 1070 w, 1035 w, 900 sh, 874, 833, 820, 690 w, 645 w, 600 sh, 555, 486, 458, and 397. Attikaite is optically biaxial, negative, α = 1.642(2), β = γ = 1.644(2) ( X = c) 2 V means = 10(8)°, and 2 V calc = 0°. The new mineral is microscopically colorless and nonpleochroic. The chemical composition (electron microprobe, average over 4 point analyses, wt %) is: 0.17 MgO, 17.48 CaO, 0.12 FeO, 16.28 CuO, 10.61 Al2O3, 0.89 P2O5, 45.45 As2O5, 1.39 SO3, and H2O (by difference) 7.61, where the total is 100.00. The empirical formula calculated on the basis of (O,OH,H2O)22 is: Ca2.94Cu{1.93/2+} Al1.97Mg0.04Fe{0.02/2+} [(As3.74S0.16P0.12)Σ4.02O16.08](OH)3.87 · 2.05H2 O. The simplified formula is Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O. Attikaite is orthorhombic, space group Pban, Pbam or Pba2; the unit-cell dimensions are a = 10.01(1), b = 8.199(5), c = 22.78(1) Å, V = 1870(3) Å3, and Z = 4. In the result of the ignition of attikaite for 30 to 35 min at 128 140°, the H2O bands in the IR spectrum disappear, while the OH-group band is not modified; the weight loss is 4.3%, which approximately corresponds to two H2O

Pharmacokinetics of 1,25(OH)(2)D(3) and 1alpha(OH)D(3) in normal and uraemic men

DEFF Research Database (Denmark)

Brandi, Lisbet; Egfjord, Martin; Olgaard, Klaus

2002-01-01

,25(OH)(2)D(3) (n=6) protocol. RESULTS: After oral administration of 1,25(OH)(2)D(3) the bioavailability of 1,25(OH)(2)D(3) was 70.6+/-5.8/72.2+/-4.8% in healthy volunteers/uraemic patients (n.s.). After i.v. administration the volume of distribution of 1,25(OH)(2)D(3) was similar, 0.49+/-0.14 vs 0...

A schiff-base receptor based naphthalimide derivative: Highly selective and colorimetric fluorescent turn-on sensor for Al{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Kang, Lei; Liu, Ya-Tong; Li, Na-Na; Dang, Qian-Xi [Department of Applied Chemistry, College of Science, Northeast Agricultural University, Harbin 150030 (China); Xing, Zhi-Yong, E-mail: zyxing@neau.edu.cn [Department of Applied Chemistry, College of Science, Northeast Agricultural University, Harbin 150030 (China); Li, Jin-Long; Zhang, Yu [College of Heilongjiang Province Key Laboratory of Fine Chemicals, Qiqihar University, Qiqihar 161006 (China)

2017-06-15

A new schiff-base receptor L based on naphthalimide had been investigated as a selective and sensitive chemosensor for Al{sup 3+} in CH{sub 3}OH. Upon addition of Al{sup 3+}, L showed a 39-fold enhancement at 508 nm with colorimetric and fluorometric dual-signaling response which might be induced by the integration of ICT and CHEF. A 1:1 stoichiometry for the L-Al{sup 3+} complex was formed with an association constant of 1.62×10{sup 4} M{sup −1}, and the limit of detection for Al{sup 3+} was determined as 7.4 nM. In addition, the potential utility of L in sensing Al{sup 3+} was also examined in real water samples.

Photodissociation thresholds of OH produced from CH sub 3 OH in solid neon and argon

CERN Document Server

Cheng, B M; Lo, W J; Lee, Y P

2001-01-01

Photodissociation thresholds of OH from CH sub 3 OH in solid Ne and Ar were determined via photolysis of CH sub 3 OH/Ne and CH sub 3 OH/Ar (1/200) samples in situ at 4 K. The samples were irradiated with VUV synchrotron radiation after dispersion by a Seya-Namioka monochromator. The OH photo-product was detected by means of laser-induced fluorescence technique. The increase of fluorescent intensity of OH was monitored and recorded after the matrix sample was irradiated at different wavelengths for 3-5 min. Photodissociation threshold energies of 7.13+-0.02 eV (174.0+-0.5 nm) and 7.08+-0.04 eV (175.0+-1.0 nm) were measured for OH production of CH sub 3 OH in solid Ne and Ar, respectively.

The Effectiveness of Additional Literacy Support (ALS) in Years 3 and 4

Science.gov (United States)

Bunn, Tim

2008-01-01

This study compared the progress in reading and spelling of 256 children in 11 classes in 9 English primary schools in Years 3 and 4, and a partially overlapping sample of 126 children who received additional help with literacy during 1 year. Teachers and teaching assistants used either Additional Literacy Support (ALS), a highly structured set of…

Completing the Heterocubane Family [Cp*AlE]4 (E = O, S, Se, and Te) by Selective Oxygenation and Sulfuration of [Cp*Al]4: Density Functional Theory Calculations of [Cp*AlE]4 and Reactivity of [Cp*AlO]4 toward Hydrolysis.

Science.gov (United States)

Stelzer, Adrian C; Hrobárik, Peter; Braun, Thomas; Kaupp, Martin; Braun-Cula, Beatrice

2016-05-16

The subvalent aluminum compound [Cp*Al]4 (1) reacts with dioxygen, N2O, or sulfur to yield the heterocubane complexes [Cp*AlX]4 [X = O (2) and S (3)]. Treatment of [Cp*AlO]4 (2) with (tBuO)3SiOH gave [(tBuO)3SiOAlO]4 (6) and Cp*H. The structures and spectroscopic data of the Al clusters are supported by density functional theory (DFT) calculations, which also demonstrate the importance of noncovalent interactions (NCI) in oligomeric Al(I) complexes as well as in [Cp*AlS]4 and the heavier homologues of Se and Te. The computed (27)Al NMR shifts indicate a deshielding at the Al centers with increasing electronegativity of the chalcogen atom as well as significant spin-orbit shielding effects within the heavier heterocubane [Al4E4] cores. Further hydrolysis of 6 with an additional amount of silanol in the presence of water resulted in the formation of [Al4(OH)6(OH2)2(OSiOtBu3)6] (7), which shows a structural motif found in boehmite and diaspore.

Fabrication and properties of highly luminescent materials from Tb(OH)3-SiO2 and Tb(OH)3-SiO2:Eu3+ nanotubes

International Nuclear Information System (INIS)

Tran Thu Huong; Tran Kim Anh; Le Quoc Minh

2009-01-01

Luminescent nanomaterials with one-dimensional (1D) structures have attracted much attention due to their unique properties and potential applications in nanophotonics and nanobiophotonics. In this paper, we report a synthesis of terbium - hydroxide - at - silica Tb(OH) 3 -SiO 2 and Tb(OH) 3 -SiO 2 :Eu 3+ nanotubes. Terbium - hydroxide tubes were synthesized by soft template method. The size of the tubes can be controlled precisely and have outer diameters ranging from 80 to 120 nm, wall thickness of about 30 nm, and lengths ranging from 300 to 800 nm. To fabricate core/shell materials, the seed growth method is used. FESEM, X-ray diffraction, Raman spectra of Tb(OH) 3 and Tb(OH) 3 -SiO 2 nanotubes were investigated. The photoluminescence (PL) spectrum of Tb(OH) 3 under 325 nm excitation consists of four main peaks at 488, 542, 582, and 618 nm. Furthermore, a preliminary suggestion for the mechanism of growth of the Tb(OH) 3 nanotubes using the soft - template synthesis technique has been proposed. The PL intensity from Tb(OH) 3 -SiO 2 or Tb(OH) 3 -SiO 2 :Eu 3+ nanotubes is much stronger than that of Tb(OH) 3 .

Continuous Flow Aerobic Alcohol Oxidation Reactions Using a Heterogeneous Ru(OH)x/Al2O3 Catalyst

Science.gov (United States)

2015-01-01

Ru(OH)x/Al2O3 is among the more versatile catalysts for aerobic alcohol oxidation and dehydrogenation of nitrogen heterocycles. Here, we describe the translation of batch reactions to a continuous-flow method that enables high steady-state conversion and single-pass yields in the oxidation of benzylic alcohols and dehydrogenation of indoline. A dilute source of O2 (8% in N2) was used to ensure that the reaction mixture, which employs toluene as the solvent, is nonflammable throughout the process. A packed bed reactor was operated isothermally in an up-flow orientation, allowing good liquid–solid contact. Deactivation of the catalyst during the reaction was modeled empirically, and this model was used to achieve high conversion and yield during extended operation in the aerobic oxidation of 2-thiophene methanol (99+% continuous yield over 72 h). PMID:25620869

A highly sensitive, single selective, fluorescent sensor for Al{sup 3+} detection and its application in living cell imaging

Energy Technology Data Exchange (ETDEWEB)

Ye, Xing-Pei [Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Sun, Shao-bo; Li, Ying-dong [Institute of Integrated Traditional and Western Medicine, Gansu University of Traditional Chinese Medicine, Lanzhou 730000 (China); Zhi, Li-hua [Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Wu, Wei-na, E-mail: wuwn08@hpu.edu.cn [Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Wang, Yuan, E-mail: wangyuan08@hpu.edu.cn [Department of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China)

2014-11-15

A new o-aminophenol-based fluorogenic chemosensor methyl 3,5-bis((E)-(2-hydroxyphenylimino)methyl)-4-hydroxybenzoate 1 have been synthesized by Schiff base condensation of methyl 3,5-diformyl-4-hydroxybenzoate with o-aminophenol, which exhibits high selectivity and sensitivity toward Al{sup 3+}. Fluorescence titration studies of receptors 1 with different metal cations in CH{sub 3}OH medium showed highly selective and sensitive towards Al{sup 3+} ions even in the presence of other commonly coexisting metal ions. The detection limit of Al{sup 3+} ions is at the parts per billion level. Interestingly, the Al(III) complex of 1 offered a large Stokes shift (>120 nm), which can miximize the selfquenching effect. In addition, possible utilization of this receptor as bio-imaging fluorescent probe to detect Al{sup 3+} in human cervical HeLa cancer cell lines was also investigated by confocal fluorescence microscopy. - Highlights: • A new Schiff base chemosensor is reported. • The sensor for Al{sup 3+} offers large Stokes shift. • The detection limit of Al{sup 3+} in CH{sub 3}OH solution is at the parts per billion level. • The utilization of sensor for the monitoring of Al{sup 3+} levels in living cells was examined.

Tiberiobardiite, Cu9Al(SiO3OH2(OH12(H2O6(SO41.5·10H2O, a New Mineral Related to Chalcophyllite from the Cretaio Cu Prospect, Massa Marittima, Grosseto (Tuscany, Italy: Occurrence and Crystal Structure

Directory of Open Access Journals (Sweden)

Cristian Biagioni

2018-04-01

Full Text Available The new mineral species tiberiobardiite, ideally Cu9Al(SiO3OH2(OH12(H2O6(SO41.5·10H2O, has been discovered in the Cretaio Cu prospect, Massa Marittima, Grosseto, Tuscany, Italy, as very rare, light green, vitreous, tabular {0001}, pseudo-hexagonal crystals, up to 200 μm in size and 5 μm in thickness, associated with brochantite. Electron microprobe analysis gave (in wt %, average of 5 spot analyses: SO3 10.37, P2O5 3.41, As2O5 0.05, SiO2 8.13, Al2O3 5.54, Fe2O3 0.74, CuO 62.05, and ZnO 0.03, for a total of 90.32. Based on an idealized O content of 42 atoms per formula unit, assuming the presence of 16 H2O groups and 13.5 cations (without H, the empirical formula of tiberiobardiite is (Cu8.69Al0.21Fe0.10Σ9.00Al1.00(Si1.51P0.54Σ2.05S1.44O12.53(OH13.47·16H2O. The main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity]: 9.4 (s, 4.67 (s, 2.576 (m, 2.330 (m, and 2.041 (mw. The crystal structure study revealed tiberiobardiite to be trigonal, space group R 3 ¯ , with unit-cell parameters a = 10.6860(4, c = 28.3239(10 Å, V = 2801.0(2 Å3, and Z = 3. The crystal structure was refined to a final R1 = 0.060 for 1747 reflections with Fo > 4σ (Fo and 99 refined parameters. Tiberiobardiite is the Si-analogue of chalcophyllite, with Si4+ replacing As5+ through the coupled substitution As5+ + O2− = Si4+ + (OH−. The name tiberiobardiite honors Tiberio Bardi (b. 1960 for his contribution to the study of the mineralogy of Tuscany.

Enhanced emission of encaged-OH--free Ca12(1-x)Sr12xAl14O33:0.1%Gd3+ conductive phosphors via tuning the encaged-electron concentration for low-voltage FEDs.

Science.gov (United States)

Zhang, Meng; Liu, Yuxue; Yang, Jian; Zhu, Hancheng; Yan, Duanting; Zhang, Xinyang; Liu, Chunguang; Xu, Changshan; Zhang, Hong

2017-05-24

Encaged-OH - -free Ca 12(1-x) Sr 12x Al 14 O 33 :0.1%Gd 3+ conductive phosphors were prepared through a melt-solidification process in combination with a subsequent heat treatment. Absorption spectra showed that the maximum encaged-electron concentration was increased to 1.08 × 10 21 cm -3 through optimizing the doping amount of Sr 2+ (x = 0.005). Meanwhile, FTIR and Raman spectra indicated that pure Ca 11.94 Sr 0.06 Al 14 O 33 :0.1%Gd 3+ conductive phosphor without encaged OH - and C 2 2- anions was acquired. For the conductive powders heat-treated in air for different times, the encaged-electron concentrations were tuned from 1.02 × 10 21 to 8.3 × 10 20 cm -3 . ESR, photoluminescence, and luminescence kinetics analyses indicated that the emission at 312 nm mainly originated from Gd 3+ ions surrounded by encaged O 2- anions, while Gd 3+ ions surrounded by encaged electrons had a negative contribution to the UV emission due to the existence of an energy transfer process. Under low-voltage electron-beam excitation (3 kV), enhanced cathodoluminescence (CL) of the conductive phosphors could be achieved by tuning the encaged-electron concentrations. In particular, for the encaged-OH - -free conductive phosphor, the emission intensity of the CL was about one order of magnitude higher than that of the conductive phosphor containing encaged OH - anions. Our results suggested that the encaged-OH - -free conductive phosphors have potential application in low-voltage FEDs.

Comprehensive Theoretical Studies on the Reaction of 1-Bromo-3,3,3-trifluoropropene with OH Free Radicals

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Yan Tian

2013-07-01

Full Text Available The potential energy surfaces (PES for the reaction of 1-bromo-3,3,3-trifluoropropene (CF3CHCBrH with hydroxyl (OH free radicals is probed theoretically at the CCSD/aug-cc-pVDZ//B3LYP/6-311++G(d,p level of theory. All the possible stationary and first-order saddle points along the reaction paths were verified by the vibrational analysis. The calculations account for all the product channels. Based on the calculated CCSD/aug-cc-pVDZ potential energy surface, the possible reaction mechanism is discussed. Six distinct reaction pathways of 1-bromo-3,3,3-trifluoropropene (BTP with OH are investigated. The geometries, reaction enthalpies and energy barriers are determined. Canonical transition-state theory with Wigner tunneling correction was used to predict the rate constants for the temperature range of 290–3,000 K without any artificial adjustment, and the computed rate constants for elementary channels can be accurately fitted with three-parameter Arrhenius expressions. OH addition reaction channel and the H atom abstraction channels related to the carbon-carbon double bond are found to be the main reaction channels for the reaction of 1-bromo-3,3,3-trifluoropropene (CF3CHCBrH with hydroxyl (OH free radicals while the products leading to CF3CHCH + BrOH and COHF2CHCBrH + F play a negligible role.

Synthesis of Hydroxysodalite From Paper Sludge Ash Using NaOH-LiOH Mixtures

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Takaaki Wajima

2017-06-01

Full Text Available Hydroxysodalite zeolite was synthesized at 90 oC from paper sludge ash, which is industrial wastes in paper manufacturing, using NaOH-LiOH mixed solution. Paper sludge ash was discharged from paper making plant as industrial wastes, and the amount is increasing annually. The new utilization of paper sludge ash is desired. Hydroxysodalite can be used to remove HCl gas at high temperature, and there are papers for hydroxysodalite synthesis from various ashes, for example, coal fly ash. In my previous study, hydroxysodalite can be synthesized from paper sludge ash. However, little information can be available on the synthesis of hydroxysodalite from paper sludge ash. Therefore, we attempted to examine the synthesis of hydroxysodalite from paper sludge ash using NaOH-LiOH mixtures. Hydroxysodalite [Na6Al6Si6O24‧8H2O] was obtained in the mixed solution with Li / (Li + Na ratios smaller than 0.25, while katoite [Ca3Al2(SiO4(OH8] was formed in the mixed solutions with the other molar ratios, due to the dissolution of gehlenite [Ca2Al2SiO7]. The observed concentrations of Si and Al in the solution during the reaction explain the synthesis of reaction products, which depends on alkali species.

Processing simulated high-level liquid waste by heat treatment with addition of TiN and AlN or Al2O3

International Nuclear Information System (INIS)

Uno, Masayoshi; Kinoshita, Hajime; Sakai, Etsuro; Ikeda, Akira; Matsumoto, Y.; Yamanaka, Shinsuke

1999-01-01

The present study aims to decrease the melting temperature of the oxide phase by the addition of the mixture of TiN and AlN or Al 2 O 3 for reduction of the treatment temperature of super high temperature method. The addition of the mixture of TiN and AlN or Al 2 O 3 with the atomic ratio of Al to Ti of 1:9 caused the melting of both the alloy phase and oxide phase at 1673 K. The measured values of density and hardness for thus obtained oxide phase were same as those for the oxide phase obtained at 1873 K without Al. Thus, above mentioned method is achieved at 1673 K without degradation of the properties of the oxide phase as an waste. (author)

Formation pathways of DMSO(2) in the addition channel of the OH-initiated DMS oxidation: A theoretical study.

Science.gov (United States)

Ramírez-Anguita, Juan M; González-Lafont, Angels; Lluch, José M

2009-07-15

The production of dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO(2)) in the dimethyl sulfide (DMS) degradation scheme initiated by the hydroxyl (OH) radical has been shown to be very sensitive to nitrogen oxides (NO(x)) levels. In the present work we have explored the potential energy surfaces corresponding to several reaction pathways which yield DMSO(2) from the CH(3)S(O)(OH)CH(3) adduct [including the formation of CH(3)S(O)(OH)CH(3) from the reaction of DMSO with OH] and the reaction channels that yield DMSO or/and DMSO(2) from the CH(3)S(O(2))(OH)CH(3) adduct are also studied. The formation of the CH(3)S(O(2))(OH)CH(3) adduct from CH(3)S(OH)CH(3) (DMS-OH) and O(2) was analyzed in our previous work. All these pathways due to the presence of NO(x) (NO and NO(2)) and also due to the reactions with O(2), OH and HO(2) are compared with the objective of inferring their kinetic relevance in the laboratory experiments that measure DMSO(2) (and DMSO) formation yields. In particular, our theoretical results clearly show the existence of NO(x)-dependent pathways leading to the formation of DMSO(2), which could explain some of these experimental results in comparison with experimental measurements carried out in NO(x)-free conditions. Our results indicate that the relative importance of the addition channel in the DMS oxidation process can be dependent on the NO(x) content of chamber experiments and of atmospheric conditions. (c) 2008 Wiley Periodicals, Inc.

Hydrogen-bonding behavior of various conformations of the HNO3…(CH3OH)2 ternary system.

Science.gov (United States)

Özsoy, Hasan; Uras-Aytemiz, Nevin; Balcı, F Mine

2017-12-21

Nine minima were found on the intermolecular potential energy surface for the ternary system HNO 3 (CH 3 OH) 2 at the MP2/aug-cc-pVDZ level of theory. The cooperative effect, which is a measure of the hydrogen-bonding strength, was probed in these nine conformations of HNO 3 …(CH 3 OH) 2 . The results are discussed here in terms of structures, energetics, infrared vibrational frequencies, and topological parameters. The cooperative effect was observed to be an important contributor to the total interaction energies of the cyclic conformers of HNO 3 …(CH 3 OH) 2 , meaning that it cannot be neglected in simulations in which the pair-additive potential is applied. Graphical abstract The H-bonding behavior of various conformations of the HNO 3 (CH 3 OH) 2 trimer was investigated.

Evaluation of liquid-phase sintering SiC using as additive the system Al2O3/DyO3

International Nuclear Information System (INIS)

Oliveira, M.R.; Atilio, I.; Garcia, G.C.R.; Ribeiro, S.

2012-01-01

The objective of this work was to study the liquid-phase sintering SiC with additives that has not been studied yet, Al 2 O 3 /Dy 2 O 3 , with 10% in volume. The powders were mixed, dried, and pressed in uniaxial and isostatic pressing. It was studied the melting temperature of the additives and bars were sintered at temperatures of 1900, 1950 e 2000 deg C, with averaged linear shrinkage of 17%, phase transformations of β-SiC into α-SiC and formation of Dy 3 Al 5 O 12 at all temperatures. The results showed that for further densification, the temperature of 1950 deg C is enough for a higher densification, with a low wetting angle, transformations of SiC and formation of Dy 3 Al 5 O 12 . (author)

MERLIN observations of the OH/IR stars OH 53.6-0.2, OH 138.0+7.2 and OH 141.7+3.5

International Nuclear Information System (INIS)

Chapman, J.; Cohen, R.J.; Norris, R.P.; Diamond, P.J.; Booth, R.S.

1984-01-01

OH maser emission from the three OH/IR stars OH 53.6-0.2, OH 138.0+7.2 and OH 141.7+3.5 has been mapped with an angular resolution of 0.28 arcsec and a velocity resolution of 0.7 km s -1 using the Jodrell Bank MERLIN array. Maps are presented of the 1612-MHz OH emission over individual velocity ranges. The maps are consistent with a uniform expanding shell model, and by fitting such models to the data the angular diameters of the shells have been estimated to an accuracy of approx. 25 per cent. (author)

Crystal structure and stability of LiAlD4 with TiF3 additive

International Nuclear Information System (INIS)

Brinks, H.W.; Fossdal, A.; Fonnelop, J.E.; Hauback, B.C.

2005-01-01

LiAlD 4 samples with TiF 3 additives have been investigated by synchrotron X-ray diffraction, neutron diffraction and a Sieverts-type apparatus. Directly after ball milling there are no signs of any Ti-containing phases, and the unit-cell of LiAlD 4 and Al give no indication of any solid solutions. Hence it is concluded that the Ti is in an amorphous state directly after ball milling. Furthermore, no LiF was observed in the samples. Based on Sieverts-type measurements the plateau pressure at 80 deg C has been proved to be higher than 85 bar. Samples stored in a glove box are slowly desorbed, and after 6 months for a LiAlD 4 + TiF 3 sample, the reaction to LiD + Al is nearly finished

Theoretical study of the oxidation mechanisms of naphthalene initiated by hydroxyl radicals: the OH-addition pathway.

Science.gov (United States)

Shiroudi, Abolfazl; Deleuze, Michael S; Canneaux, Sébastien

2014-07-03

The oxidation mechanisms of naphthalene by OH radicals under inert (He) conditions have been studied using density functional theory along with various exchange-correlation functionals. Comparison has been made with benchmark CBS-QB3 theoretical results. Kinetic rate constants were correspondingly estimated by means of transition state theory and statistical Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Comparison with experiment confirms that, on the OH-addition reaction pathway leading to 1-naphthol, the first bimolecular reaction step has an effective negative activation energy around -1.5 kcal mol(-1), whereas this step is characterized by an activation energy around 1 kcal mol(-1) on the OH-addition reaction pathway leading to 2-naphthol. Effective rate constants have been calculated according to a steady state analysis upon a two-step model reaction mechanism. In line with experiment, the correspondingly obtained branching ratios indicate that, at temperatures lower than 410 K, the most abundant product resulting from the oxidation of naphthalene by OH radicals must be 1-naphthol. The regioselectivity of the OH(•)-addition onto naphthalene decreases with increasing temperatures and decreasing pressures. Because of slightly positive or even negative activation energies, the RRKM calculations demonstrate that the transition state approximation breaks down at ambient pressure (1 bar) for the first bimolecular reaction steps. Overwhelmingly high pressures, larger than 10(5) bar, would be required for restoring to some extent (within ∼5% accuracy) the validity of this approximation for all the reaction channels that are involved in the OH-addition pathway. Analysis of the computed structures, bond orders, and free energy profiles demonstrate that all reaction steps involved in the oxidation of naphthalene by OH radicals satisfy Leffler-Hammond's principle. Nucleus independent chemical shift indices and natural bond orbital analysis also show that the computed

Vitamina D y cáncer: acción antineoplásica de la 1α, 25(OH2 -vitamina D3 Vitamin D and cancer: antineoplastic effects of 1α,25(OH2-vitamin D3

Directory of Open Access Journals (Sweden)

Verónica González Pardo

2012-04-01

Full Text Available La forma hormonalmente activa de la vitamina D, 1α,25(OH2-vitamina D3 (1α,25(OH2D3, además de desempeñar un rol crucial en el mantenimiento de la homeostasis de calcio en el cuerpo, también regula el crecimiento y la diferenciación de diferentes tipos celulares, incluyendo células cancerosas. Actualmente hay numerosos estudios que investigan los efectos de la hormona en estas células, debido al interés en el uso terapéutico del 1α,25(OH2D3 y de análogos con menor actividad calcémica para el tratamiento o prevención del cáncer. En este trabajo de revisión se describe el sistema endocrino de la vitamina D, su mecanismo de acción, su acción antineoplásica y se provee información sobre los últimos avances en el estudio de nuevos análogos de la hormona con menos actividad calcémica para el tratamiento del cáncer.The hormonal form of vitamin D, 1α,25(OH2-vitamin D3 (1α,25(OH2D3, in addition of playing a central role in the control of calcium homeostasis in the body, regulates the growth and differentiation of different cell types, including cancer cells. At present several epidemiologic and clinical studies investigate the effect of the hormone in these cells due to the interest in the therapeutic use of 1α,25(OH2D3 and analogues with less calcemic activity for prevention or treatment of cancer. This review describes vitamin D endocrine system, its mechanism of action, its antineoplastic activity and provides information about the latest advances in the study of new hormone analogues with less calcemic activity for cancer treatment.

A novel method to fabricate TiAl intermetallic alloy 3D parts using additive manufacturing

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J.J.S. Dilip

2017-04-01

Full Text Available The present work explores the feasibility of fabricating porous 3D parts in TiAl intermetallic alloy directly from Ti–6Al–4V and Al powders. This approach uses a binder jetting additive manufacturing process followed by reactive sintering. The results demonstrate that the present approach is successful for realizing parts in TiAl intermetallic alloy.

Nitrate-assisted photocatalytic efficiency of defective Eu-doped Pr(OH)3 nanostructures.

Science.gov (United States)

Aškrabić, S; Araújo, V D; Passacantando, M; Bernardi, M I B; Tomić, N; Dojčinović, B; Manojlović, D; Čalija, B; Miletić, M; Dohčević-Mitrović, Z D

2017-12-06

Pr(OH) 3 one-dimensional nanostructures are a less studied member of lanthanide hydroxide nanostructures, which recently demonstrated an excellent adsorption capacity for organic pollutant removal from wastewater. In this study, Pr 1-x Eu x (OH) 3 (x = 0, 0.01, 0.03, and 0.05) defective nanostructures were synthesized by a facile and scalable microwave-assisted hydrothermal method using KOH as an alkaline metal precursor. The phase and surface composition, morphology, vibrational, electronic and optical properties of the as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Raman, infrared (IR), photoluminescence (PL), and diffuse reflectance spectroscopy (DRS). It was deduced that the incorporation of Eu 3+ ions promoted the formation of oxygen vacancies in the already defective Pr(OH) 3 , subsequently changing the Pr(OH) 3 nanorod morphology. The presence of KNO 3 phase was registered in the Eu-doped samples. The oxygen-deficient Eu-doped Pr(OH) 3 nanostructures displayed an improved photocatalytic activity in the removal of reactive orange (RO16) dye under UV-vis light irradiation. An enhanced photocatalytic activity of the Eu-doped Pr(OH) 3 nanostructures was caused by the synergetic effect of oxygen vacancies and Eu 3+ (NO 3 - ) ions present on the Pr(OH) 3 surface, the charge separation efficiency and the formation of the reactive radicals. In addition, the 3% Eu-doped sample exhibited very good adsorptive properties due to different morphology and higher electrostatic attraction with the anionic dye. Pr 1-x Eu x (OH) 3 nanostructures with the possibility of tuning their adsorption/photocatalytic properties present a great potential for wastewater treatment.

Natural Rosin-based Phosphate Diester Surfactant Assisted One-step Synthesis of 3D Flowerlikeβ-Ni(OH)2/γ-Ni(OH)2 Composite Nano-microspheres

Institute of Scientific and Technical Information of China (English)

BoShi Wu; Juan Li; ChunRui Han; Feng Xu

2018-01-01

Self-assembled uniform 3Dflowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres with hollow interiors were successfully synthesized via a facile aqueous-ethanol mixed solvothermal method, using nickel sulfate as a precursor, urea as a precipitant, and dehydroabietic based phosphate diester sodium (DDPDS) as a surfactant. The prepared 3D flowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres were tested as supercapacitors in a two-electrode cell with 6 mol/L KOH electrolyte. In addition, the influence of DDPDS concentration on the morphology and size of 3Dflowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres was studied at 180℃. X-ray diffraction (XRD), scanning electron microscopy (SEM), BET(Brunauer, Emmett and Teller)techniques, and equity default swap (EDS) were used to characterize the structure, morphology, and size of the as-prepared samples. Moreover, a possible formation mechanism of the 3Dflowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres was proposed based on the effects of DDPDS concentrationand reaction time. The surfactant micelles were used as soft templates to induce the self-assembly of nanosheets. The crystallinity of the 3D flowerlikeβ-Ni(OH)2/g-Ni(OH)2composite nano-microspheres improved with the increase of DDPDS concentration, and the morphology and size of synthetic nano-microspheres could be controlled.

13C, 18O, and D Fractionation Effects in the Reactions of CH3OH Isotopologues with Cl andOH Radicals

DEFF Research Database (Denmark)

Feilberg, Karen; Gruber-Stadler, Margaret; Johnson, Matthew Stanley

2008-01-01

A relative rate experiment is carried out for six isotopologues of methanol and their reactions with OH and Cl radicals. The reaction rates of CH2DOH, CHD2OH, CD3OH, 13CH3OH, and CH3 18OH with Cl and OH radicals are measured by long-path FTIR spectroscopy relative to CH3OH at 298 ( 2 K and 1013...... with measured high-resolution infrared spectra as references. The relative reaction rates defined as R ) klight/kheavy are determined to be: kOH + CH3OH/kOH + 13CH3OH ) 1.031 ( 0.020, kOH + CH3OH/kOH + CH3 18OH ) 1.017 ( 0.012, kOH + CH3OH/kOH + CH2DOH ) 1.119 ( 0.045, kOH + CH3OH/kOH + CHD2OH ) 1.326 ( 0...... reactions with CH3OH were further investigated using canonical variational transition state theory with small curvature tunneling and compared to experimental measurements as well as to those observed in CH4 and several other substituted methane species. Udgivelsesdato: 16 August 2008...

Addition and elimination kinetics in OH radical induced oxidation of phenol and cresols in acidic and alkaline solutions

International Nuclear Information System (INIS)

Roder, M.; Wojnarovits, L.; Foeldiak, G.; Emmi, S.S.; Beggiato, G.; D'Angelantonio, M.

1999-01-01

The rates of the two consecutive reactions, OH radical addition and H 2 O/OH - elimination, were studied by pulse radiolysis in highly acidic (pH=1.3-1.9) and alkaline (pH∼11) solutions, respectively, for phenol and for the three cresol isomers. The rate coefficient of the addition as measured by the build-up of phenoxyl radical absorbance and by a competitive method is the same (1.4±0.1)x10 10 mol -1 dm 3 s -1 both in acidic and alkaline solution. The rate coefficient of the H 2 O elimination in acidic solution is (1.6±0.2)x10 6 s -1 , whereas the coefficient of the OH - elimination in alkaline solutions is 6-8 times higher. The kinetics of the phenoxyl radical formation was described by the two-exponential equation of the consecutive reactions: the first exponential is related to the pseudo-first-order addition, while the second to the elimination reaction. No considerable structure dependence was found in the rate coefficients, indicating that the methyl substitutent in these highly acidic or alkaline solutions influences neither the addition nor the elimination rate

Effect of molybdenum and chromium additions on the mechanical properties of Fe3Al-based alloys

International Nuclear Information System (INIS)

Sun Yangshan; Xue Feng; Mei Jianping; Yu Xingquan; Zhang Lining

1995-01-01

Iron aluminides based on Fe 3 Al offer excellent oxidation and sulfidation resistance, with lower material cost and density than stainless steels. However, their potential use as structural material has been hindered by limited ductility and a sharp drop in strength above 600 C. Recent development efforts have indicated that adequate engineering ductility of 10--20% and tensile yield strength of as high as 500 MPa can be achieved through control of composition and microstructure. These improved tensile properties make Fe 3 Al-based alloys more competitive against conventional austenic and ferritic steels. The improvement of high temperature mechanical properties has been achieved mainly by alloying processes. Molybdenum has been found to be one of the most important alloying elements for strengthening Fe 3 Al-based alloys at high temperatures. However, the RT(room temperature) ductility decreases with the increase of a molybdenum addition. On the other hand, a chromium addition to Fe 3 Al-based alloys is very efficient for improving RT ductility but not beneficial to yield strength at temperatures to 800 C. The purpose of the present paper is to report the effects of combined additions of molybdenum and chromium on mechanical properties at ambient temperature and high temperature of 600 C

Grain refinement of Ca addition in a twin-roll-cast Mg-3Al-1Zn alloy

Energy Technology Data Exchange (ETDEWEB)

Jiang Bin, E-mail: jiangbinrong@cqu.edu.cn [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030 (China); College of Materials Science and Engineering, Chongqing University, Chongqing 400030 (China); Liu Wenjun [College of Materials Science and Engineering, Chongqing University, Chongqing 400030 (China); Qiu Dong; Zhang Mingxing [Division of Materials, School of Mechanical and Mining Engineering, University of Queensland, St Lucia, QLD 4072 (Australia); Pan Fusheng [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030 (China)

2012-04-16

Highlights: Black-Right-Pointing-Pointer Grain refinement of Ca addition in a twin-roll-cast Mg-3Al-1Zn alloy was investigated. Black-Right-Pointing-Pointer Addition of 0.08 wt% Ca into Mg melts can significantly reduce the grain size to 30 {mu}m from 100 {mu}m. Black-Right-Pointing-Pointer Al{sub 2}Ca intermetallic particles have high potency to act as heterogeneous nucleation sites for {alpha}-Mg. - Abstract: Addition of 0.08 wt% Ca into AZ31 melts significantly reduces the average grain size of thin strips produced by twin-roll-cast to 30 {mu}m from 100 {mu}m. Like Zr, due to the high chemical activity, the Ca added into the melts reacts with Al and forms Al{sub 2}Ca intermetallic compound. X-ray diffraction result approves the existence of Al{sub 2}Ca in the thin strips, which formed in the melts. Crystallographic examination of relationship between Al{sub 2}Ca and Mg using the edge-to-edge matching model indicates that Al{sub 2}Ca particles are effective inoculants for heterogeneous nucleation of Mg. It is considered that Al{sub 2}Ca is a potential and effective grain refiner for Mg alloys and the grain refinement through addition of Ca in the AZ31 alloy is attributed to the inoculation effect of Al{sub 2}Ca particles formed in the melts.

The dehydrogenation performance and reaction mechanisms of Li{sub 3}AlH{sub 6} with TiF{sub 3} additive

Energy Technology Data Exchange (ETDEWEB)

Liu, Shu-Sheng [Materials and Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Yao; Sun, Li-Xian; Zhang, Jian; Zhao, Jun-Ning [Materials and Thermochemistry Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Xu, Fen [Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Huang, Feng-Lei [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

2010-05-15

For Li{sub 3}AlH{sub 6} prepared by mechanical milling method, the dissociation reaction enthalpy and activation energy are calculated to be 22.1 kJ mol{sup -1} H{sub 2} and 133.7 {+-} 2.7 kJ mol{sup -1}, respectively. The dehydrogenation performance of Li{sub 3}AlH{sub 6} is greatly enhanced by TiF{sub 3} additive, especially in the kinetic behaviors. For the Li{sub 3}AlH{sub 6} + 10 mol% TiF{sub 3} sample, the starting temperature of dehydrogenation is obviously decreased by 60 C from that of pure Li{sub 3}AlH{sub 6} (190 C), and 3.0 wt.% H{sub 2} may be released within 1000 s at 120 C under an initial vacuum. With the amount of TiF{sub 3} increasing, the starting temperature decreases and the kinetics improves due to the decrease in the activation energy. The X-ray diffraction (XRD) together with thermogravimetric analysis (TGA) results show that there are three mechanochemical reactions involved during milling: i) Li{sub 3}AlH{sub 6} + TiF{sub 3} {yields} 3 LiF + Al + Ti + 3H{sub 2}, ii) Ti + H{sub 2} {yields} TiH{sub 2}, iii) 3 Al + Ti {yields} Al{sub 3}Ti. The in-situ formed Ti species (TiH{sub 2} and Al{sub 3}Ti) co-catalyze the thermal dehydrogenation of Li{sub 3}AlH{sub 6}. (author)

Thermoluminescent properties of polycrystalline carbon doped LaAlO3/La(OH)3 crystals synthesized by solid state reaction for application in UV dosimetry

International Nuclear Information System (INIS)

Alves, N.; Oliveira de F, L.; Barbosa F, W.

2017-10-01

It is well known that UV radiation can induce certain deleterious effects, such as erythema, painful inflammation of the membrane of the eye and skin cancer. Therefore, it has been pushing the research for producing new and high performance UV sensitive Tl materials. There is an increasing interest in the development of new Tl materials for ultraviolet (UV) dosimetry purposes, owing to simplicity of the sample readout compared to other techniques. In this paper, thermoluminescence and dosimetric characteristics of pure and carbon doped lanthanum aluminate and hydroxide lanthanum crystals, irradiated with different UV doses, were studied and discussed. All samples studied were produced by solid state reaction method with different mixing methodologies. Characterization of sintered powders by X-ray diffraction, UV-Vis spectrophotometry and Ftir spectroscopy were performed. XRD data confirmed the LaAlO 3 and La(OH) 3 crystalline phases. The thermoluminescent study revealed that all compositions presented high UV sensibility. The sample which was grown by first sintering La 2 O 3 together carbon atoms and then sintering again in order to obtain La 2 O 3 :C together Al 2 O 3 , presented the best linear dose response over UV doses ranging from 0.042 to 0.63 mJ/cm 2 , with correlation coefficients equal to 0.99931. The synthesis methodology used was very efficient to obtain crystals with high Tl output intensities for low exposure rate UV R fields. (Author)

Remelting of aluminium with the addition of AlTi5B1 and AlTi3C0,15 grain refiners

Directory of Open Access Journals (Sweden)

Dobešrek, M.

2008-04-01

Full Text Available It was found that concentration of boron in aluminium with the addition of AlTi5B1 grain refiner is decreasing during remelting as a consequence of TiB2 particles settling down due to gravity. TiB2 particles remained in aluminium after four remelts shows lower effect of grain refinement compared to non-remelted samples with the same TiB2 content. It was also found that TiC particles are still present in aluminium with the addition of AlTi3C0,15 grain refiner after four remelts and they probably participate in nucleation of α-Al grains.

Mechanical properties of Fe3Al-based alloys with addition of carbon, niobium and titanium

International Nuclear Information System (INIS)

Zhang Zhengrong; Liu Wenxi

2006-01-01

Several Fe 3 Al-based iron aluminides with the addition of alloying elements carbon, niobium and titanium were produced by vacuum induction melting (VIM) and hot spinning forging. Analytic techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used in studying the microstructure and fracture manner of these alloys. The results show that due to the addition of alloying elements, the superlattice dislocations tend towards multiple slipping, leaving behind on their slip plane ribbons of square-shaped slip-induced antiphase boundaries. The elongation of Fe 3 Al in tension at room temperature increased to about 10% by the addition of suitable alloying elements, the usage of thermo-mechanical processing that has the function of refining grains and substructures, and subsequent annealing

Properties of B4C–PbO–Al(OH)3-epoxy nanocomposite prepared by ultrasonic dispersion approach for high temperature neutron shields

International Nuclear Information System (INIS)

Lee, M.K.; Lee, J.K.; Kim, J.W.; Lee, G.J.

2014-01-01

High functional epoxy nanocomposites with three different filler materials, i.e., B 4 C, PbO, and Al(OH) 3 , were fabricated using an effective fabrication method consisting of an ultrasonic dispersion of nanoparticles in low-viscosity hardener and a subsequent mixing of a hardener-nanoparticle colloid with epoxy resins. It was confirmed that this approach provided not only an uniform dispersion but also an excellent wetting with enhanced interfacial adhesion of nano-particulate fillers within the matrix. By incorporating those three fillers, a synergistic effect was verified in multiple properties such as mechanical strength properties, thermal degradation, flame retardancy, and radiation shielding performance

Investigation of the C-3-epi-25(OH)D3 of 25-hydroxyvitamin D3 in urban schoolchildren.

Science.gov (United States)

Berger, Samantha E; Van Rompay, Maria I; Gordon, Catherine M; Goodman, Elizabeth; Eliasziw, Misha; Holick, Michael F; Sacheck, Jennifer M

2018-03-01

The physiological relevance C-3 epimer of 25-hydroxyvitamin D (3-epi-25(OH)D) is not well understood among youth. The objective of this study was to assess whether demographic/physiologic characteristics were associated with 3-epi-25(OH)D 3 concentrations in youth. Associations between 3-epi-25(OH)D 3 and demographics and between 3-epi-25(OH)D 3 , total 25-hydroxyvitamin (25(OH)D) (25(OH)D 2 + 25(OH)D 3 ), total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides were examined in racially/ethnically diverse schoolchildren (n = 682; age, 8-15 years) at Boston-area urban schools. Approximately 50% of participants had detectable 3-epi-25(OH)D 3 (range 0.95-3.95 ng/mL). The percentage of 3-epi-25(OH)D 3 of total 25(OH)D ranged from 2.5% to 17.0% (median 5.5%). Males were 38% more likely than females to have detectable 3-epi-25(OH)D 3 concentrations. Both Asian and black race/ethnicity were associated with lower odds of having detectable 3-epi-25(OH)D 3 compared with non-Hispanic white children (Asian vs. white, odds ratio (OR) 0.28, 95% confidence interval (CI) 0.14-0.53; black vs. white, OR 0.38, 95%CI 0.23-0.63, p 30 ng/mL) 25(OH)D concentration was associated with higher odds of having detectable 3-epi-25(OH)D 3 than having an inadequate (<20 ng/mL) concentration (OR 4.78, 95%CI 3.23-6.94 or OR 14.10, 95%CI 7.10-28.0, respectively). There was no association between 3-epi-25(OH)D 3 and blood lipids. However, when considering 3-epi-25(OH)D 3 as a percentage of total 25(OH)D, total cholesterol was lower in children with percent 3-epi-25(OH)D 3 above the median (mean difference -7.1 mg/dL, p = 0.01). In conclusion, among schoolchildren, sex, race/ethnicity, and total serum 25(OH)D concentration is differentially associated with 3-epi-25(OH)D. The physiological relevance of 3-epi-25(OH)D 3 may be related to the 3-epi-25(OH)D 3 as a percentage of total 25(OH)D and should be considered in future investigations.

OH-point defects in quartz in B- and Li-bearing systems and their application to pegmatites

Science.gov (United States)

Baron, M. A.; Stalder, R.; Konzett, J.; Hauzenberger, C. A.

2015-01-01

OH incorporation in quartz in Al-, B- and Li-bearing systems (granitic systems containing tourmaline or spodumene) was studied experimentally in order to investigate the effect of pressure, temperature and chemical impurities on the generation of OH-defects. High-pressure experiments were carried out at pressures between 5 and 25 kbar and temperatures between 800 and 900 °C, and OH-contents in quartz were calculated from IR absorption spectra measured on oriented quartz crystals. IR absorption features were assigned to impurity substitutions, such as AlOH (3,420, 3,379 and 3,315 cm-1) and BOH (3,595 cm-1), LiOH (3,483 cm-1), and hydrogarnet substitution (4H)Si defects (3,583 cm-1). Results indicate a negative correlation of incorporated Al-specific OH-defect content versus pressure (630 ± 130 wt ppm H2O at 5 kbar to 102 ± 6 wt ppm H2O at 25 kbar), but no clear correlation of B-specific OH-defects with pressure. In runs initially containing spodumene, virtually OH-free quartzes were observed at pressures ≥10 kbar, where impurity cations compensate each other forming an anhydrous eucryptite-defect component. In contrast, at 5 kbar, both Li- ad Al-specific OH-defects are observed (corresponding to 470 ± 75 wt ppm H2O). Results from this study may therefore be used to monitor formation conditions of quartz in terms of pressure and trace metal saturation of the crystallizing petrological system. IR spectra obtained from natural quartz grains from a tourmaline-bearing pegmatite exhibit B- and Al-related OH-bands. The B-related OH-band is also exhibited in quartz from a tourmaline + spodumene-bearing pegmatite. Li- and Al-related OH-bands, however, are subordinate or not observed at all in the spodumene-bearing system, which suggests that OH-vibrations do not reflect absolute Li-contents in quartz due to efficient coupled substitution involving Al. Data from experimental runs and natural specimens indicate that the B-related OH-band can be used as a rough proxy for

Microstructural Characterization of Water-Rich Boehmite (AlO(OH)): TEM Correlation of Apparently Divergent XRD and TGA Results

International Nuclear Information System (INIS)

Allard, L.F.; Anovitz, L.M.; Benezeth, P.; Coffey, D.W.; Palmer, D.A.; Porter, W.D.; Wesolowski, D.J.

1999-01-01

An understanding of the solid-phase thermodynamics and aqueous speciation of aluminum is critical to our ability to understand and predict processes in a wide variety of geologic and industrial settings. Boehmite (AIO(OH)) is an important phase in the system Al 2 O 3 -H 2 O that has been the subject of a number of structural and thermodynamic studies since its initial synthesis [l] and discovery in nature [2]. Unfortunately, it has long been recognized that thermogravimetric analysis (TGA) of both synthetic and natural boehmite samples (that appear well crystallized by powder XRD methods) yields significant excess water - typically losing 16-16.5 wt. % on heating as compared with a nominal expected weight loss of 15.0 wt. % [3,4]. The boehmite used in our experiments was synthesized hydrothermally from acid-washed gibbsite (Al(OH) 3 ) at 200C. Powder XRD and SEM examination showed no evidence of the presence a contaminant phase. The TGA patterns do not suggest that this is due to adsorbed water, so a structural source is likely. We therefore undertook to examine this material by TEM to clarify this phenomenon

SMA OBSERVATIONS OF THE W3(OH) COMPLEX: PHYSICAL AND CHEMICAL DIFFERENTIATION BETWEEN W3(H{sub 2}O) AND W3(OH)

Energy Technology Data Exchange (ETDEWEB)

Qin, Sheng-Li [Department of Astronomy, Yunnan University, and Key Laboratory of Astroparticle Physics of Yunnan Province, Kunming, 650091 (China); Schilke, Peter; Sánchez-Monge, Álvaro [Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany); Wu, Jingwen [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Wu, Yuefang [Department of Astronomy, Peking University, Beijing, 100871 (China); Liu, Tie [Korea Astronomy and Space Science Institute 776, Daedeokdaero, Yuseong-gu, Daejeon, Korea 305-348 (Korea, Republic of); Liu, Ying, E-mail: slqin@bao.ac.cn [Department of Physics and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Shijiazhuang 050024 (China)

2015-04-10

We report on the Submillimeter Array (SMA) observations of molecular lines at 270 GHz toward the W3(OH) and W3(H{sub 2}O) complex. Although previous observations already resolved the W3(H{sub 2}O) into two or three sub-components, the physical and chemical properties of the two sources are not well constrained. Our SMA observations clearly resolved the W3(OH) and W3(H{sub 2}O) continuum cores. Taking advantage of the line fitting tool XCLASS, we identified and modeled a rich molecular spectrum in this complex, including multiple CH{sub 3}CN and CH{sub 3}OH transitions in both cores. HDO, C{sub 2}H{sub 5}CN, O{sup 13}CS, and vibrationally excited lines of HCN, CH{sub 3}CN, and CH{sub 3}OCHO were only detected in W3(H{sub 2}O). We calculate gas temperatures and column densities for both cores. The results show that W3(H{sub 2}O) has higher gas temperatures and larger column densities than W3(OH) as previously observed, suggesting physical and chemical differences between the two cores. We compare the molecular abundances in W3(H{sub 2}O) to those in the Sgr B2(N) hot core, the Orion KL hot core, and the Orion Compact Ridge, and discuss the chemical origin of specific species. An east–west velocity gradient is seen in W3(H{sub 2}O), and the extension is consistent with the bipolar outflow orientation traced by water masers and radio jets. A north–south velocity gradient across W3(OH) is also observed. However, with current observations we cannot be assured whether the velocity gradients are caused by rotation, outflow, or radial velocity differences of the sub-components of W3(OH)

Construction of g-C_3N_4/Al_2O_3 hybrids via in-situ acidification and exfoliation with enhanced photocatalytic activity

International Nuclear Information System (INIS)

Wang, Xiao-jing; Liu, Chao; Li, Xu-li; Li, Fa-tang; Li, Yu-pei; Zhao, Jun; Liu, Rui-hong

2017-01-01

Highlights: • Ultrathin g-C_3N_4/Al_2O_3 hybrids are prepared via in-situ reaction. • The structure modification role of in-situ formed HNO_3 for g-C_3N_4 is found. • The ultrathin g-C_3N_4 nanosheets are formed by the acidified melamine and Al(OH)_3. • In-situ calcination of melamine and Al(OH)_3 benefits the contact of C_3N_4 and Al_2O_3. • The activity of g-C_3N_4/Al_2O_3 is 16.6 times that of pristine g-C_3N_4 in degrading RhB. - Abstract: Homogeneous ultrathin g-C_3N_4 nanosheets/Al_2O_3 heterojunctions are synthesized using melamine and Al(NO_3)_3 via in-situ reaction and the following thermal polymerization approach. The in-situ reaction between melamine and Al(NO_3)_3 results in the existence of HNO_3-acidified melamine and Al(OH)_3 aggregates via the hydrolysis of Al(NO_3)_3. After thermal polymerization, the aggregates are converted to g-C_3N_4/Al_2O_3 composites. The thermal polymerization of acidified melamine and the support effect of aluminum hydroxide for g-C_3N_4 during the calcination process lead to highly dispersed amrophous Al_2O_3 on ultrathin g-C_3N_4 nanosheets, which is beneficial for the separation of photogenerated electron-hole pairs in the heterojunction. The degradation rate for Rhodamine B (RhB) over the most activie sample is 16.6 times than that of pristine g-C_3N_4 under visible light irradiation, which can be attributed to the high specific surface area, highly dispersion of amorphous Al_2O_3 on ultrathin g-C_3N_4 nanosheet, and the effective electrons transfer from g-C_3N_4 to the amorphous Al_2O_3.

Atomic-scale microstructures of Zr2Al3C4 and Zr3Al3C5 ceramics

International Nuclear Information System (INIS)

Lin, Z.J.; Zhuo, M.J.; He, L.F.; Zhou, Y.C.; Li, M.S.; Wang, J.Y.

2006-01-01

The microstructures of bulk Zr 2 Al 3 C 4 and Zr 3 Al 3 C 5 ceramics have been investigated using transmission electron microscopy and scanning transmission electron microscopy. These two carbides were determined to have a point group 6/mmm and a space group P6 3 /mmc using selected-area electron diffraction and convergent beam electron diffraction. The atomic-scale microstructures of Zr 2 Al 3 C 4 and Zr 3 Al 3 C 5 were investigated through high-resolution imaging and Z-contrast imaging. Furthermore, intergrowth between Zr 2 Al 3 C 4 and Zr 3 Al 3 C 5 was identified. Stacking faults in Zr 3 Al 3 C 5 were found to result from the insertion of an additional Zr-C layer. Cubic ZrC was occasionally identified to be incorporated in elongated Zr 3 Al 3 C 5 grains. In addition, Al may induce a twinned ZrC structure and lead to the formation of ternary zirconium aluminum carbides

Formation and characterization of nanotubes of La(OH)3 obtained using porous alumina membranes

International Nuclear Information System (INIS)

Gonzalez-Rovira, L; Sanchez-Amaya, J M; Botana, F J; Lopez-Haro, M; Hungria, A B; Boukha, Z; Bernal, S

2008-01-01

An electrodeposition process is used to synthesize nanotubes of a lanthanum-containing phase, employing porous alumina membranes as templates. This method should lead to the formation of La(OH) 3 nanowires, according to the previous results presented by Bocchetta et al (2007 Electrochem. Commun. 9 683-8), which can be decomposed to La 2 O 3 , as the latter shows more interest for different applications. The results obtained by means of different electron microscopy techniques indicate that this method leads to the formation of nanotubes of about 200 nm in diameter and 30-40 μm in length, instead of the nanowires proposed in the literature. Additionally, the chemical characterization demonstrates that the material synthesized is composed of lanthanum hydroxycarbonate. The presence of carbonates is found to be crucial in determining the conditions for the preparation of La 2 O 3 from the nanotubes here obtained.

Formation and characterization of nanotubes of La(OH)3 obtained using porous alumina membranes

Science.gov (United States)

González-Rovira, L.; Sánchez-Amaya, J. M.; López-Haro, M.; Hungria, A. B.; Boukha, Z.; Bernal, S.; Botana, F. J.

2008-12-01

An electrodeposition process is used to synthesize nanotubes of a lanthanum-containing phase, employing porous alumina membranes as templates. This method should lead to the formation of La(OH)3 nanowires, according to the previous results presented by Bocchetta et al (2007 Electrochem. Commun. 9 683-8), which can be decomposed to La2O3, as the latter shows more interest for different applications. The results obtained by means of different electron microscopy techniques indicate that this method leads to the formation of nanotubes of about 200 nm in diameter and 30-40 µm in length, instead of the nanowires proposed in the literature. Additionally, the chemical characterization demonstrates that the material synthesized is composed of lanthanum hydroxycarbonate. The presence of carbonates is found to be crucial in determining the conditions for the preparation of La2O3 from the nanotubes here obtained.

Canted antiferromagnetism in KNi3[PO3(F,OH)]2[PO2(OH)2]F2 with a stair-case Kagomé lattice

Science.gov (United States)

Liu, Li-Chen; Ren, Wei-Jian; Huang, Ya-Xi; Pan, Yuanming; Mi, Jin-Xiao

2017-10-01

A new nickel phosphate KNi3[PO3(F,OH)]2[PO2(OH)2]F2 has been synthesized using a modified hydrothermal method. Structural characterizations show that it adopts a 3D framework structure with 2D layers of Ni octahedra in a stair-case Kagomé lattice. The Ni2 octahedron at the inversion center shares two trans-faces with Ni1 octahedra to form a linear trimer (Ni3O8F6) as the basic structural unit. The Ni-trimers are linked between themselves by sharing F-corners and to [PO3(F,OH)] tetrahedral groups by sharing O-corners to form 2D stair-case Kagomé layers, which are parallel to the (100) plane and are stacked along the a-axis. Successive Kagomé layers are combined together by [PO2(OH)2] tetrahedral groups and interstice cations K+. Magnetic measurements reveal that KNi3[PO3(F,OH)]2[PO2(OH)2]F2 exhibits a canted antiferromagnetic ordering with a ferromagnetic component at low temperatures.

Crystallization of mordenite zeolite with seed addition in reaction mixtures with different SiO{sub 2}/Al{sub 2}O{sub 3} ratios; Cristalizacao da zeolita mordenita com adicao de sementes em meio reacionais com diferentes razoes SiO{sub 2}/Al{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Cysneiros, O.M.S.; Silva, B.J.B.; Silva, A.O.S.; Alencar, S.L.; Santos, R.B.; Soares, P.F.M.; Mendonca, T.R.D.; Sousa Junior, L.V.; Santos, J.R., E-mail: brunojbarros@hotmail.com [Universidade Federal de Alagoas (UFAL), Maceio (Brazil). Departamento de Engenharia Quimica. Laboratorio de Sintese de Catalisadores

2016-04-15

The synthesis of samples of mordenite were performed using the hydrothermal method using two different types of crystallization seed (mordenite and ferrierite), where they were exploited to change some parameters of the synthesis, such as SiO{sub 2}/Al{sub 2}O{sub 3} = 20, 60 and 100 and the ratio OH/SiO{sub 2} = 0.2, 0.3 and 0.4, at different times of crystallization, at a temperature of 170 °C. The samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA/DTA), nitrogen adsorption at -196 °C (BET) and temperature programmed desorption of ammonia (NH{sub 3}-TPD). It was found that the use of the ratio OH/SiO{sub 2} = 0.4, together with the seeds of the most MOR and FER crystalline samples were obtained, demonstrating the critical role of mineralizing agent OH{sup -} in the middle. (author)

Effect of phosphorus addition on the hydrotreating activity of NiMo/Al{sub 2}O{sub 3} carbide catalyst

Energy Technology Data Exchange (ETDEWEB)

Sundaramurthy, V.; Dalai, A.K. [Catalysis and Chemical Reaction Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9 (Canada); Adjaye, J. [Syncrude Edmonton Research Centre, Edmonton, AB T6N 1H4 (Canada)

2007-07-30

A series of phosphorus promoted {gamma}-Al{sub 2}O{sub 3} supported NiMo carbide catalysts with 0-4.5 wt.% P, 13 wt.% Mo and 2.5 wt.% Ni were synthesized and characterized by elemental analysis, pulsed CO chemisorption, BET surface area measurement, X-ray diffraction, near-edge X-ray absorption fine structure, DRIFT spectroscopy of CO adsorption and H{sub 2} temperature programmed reduction. X-ray diffraction patterns and CO uptake showed the P addition to NiMo/{gamma}-Al{sub 2}O{sub 3} carbide, increased the dispersion of {beta}-Mo{sub 2}C particles. DRIFT spectra of adsorbed CO revealed that P addition to NiMo/{gamma}-Al{sub 2}O{sub 3} carbide catalyst not only increases the dispersion of Ni-Mo carbide phase, but also changes the nature of surface active sites. The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) activities of these P promoted NiMo/{gamma}-Al{sub 2}O{sub 3} carbide catalysts were performed in trickle bed reactor using light gas oil (LGO) derived from Athabasca bitumen and model feed containing quinoline and dibenzothiophene at industrial conditions. The P added NiMo/{gamma}-Al{sub 2}O{sub 3} carbide catalysts showed enhanced HDN activity compared to the NiMo/{gamma}-Al{sub 2}O{sub 3} catalysts with both the feed stocks. The P had almost no influence on the HDS activity of NiMo/{gamma}-Al{sub 2}O{sub 3} carbide with LGO and dibenzothiophene. P addition to NiMo/{gamma}-Al{sub 2}O{sub 3} carbide accelerated C-N bond breaking and thus increased the HDN activity. (author)

Effect of AlF3 Production Waste on the Properties of Hardened Cement Paste

Directory of Open Access Journals (Sweden)

Danutė VAIČIUKYNIENĖ

2012-06-01

Full Text Available The possibility to use by-product SiO2·nH2O (often called AlF3 production waste in cement casting has been attracting the interest of researchers for many years, although high content of fluorine makes the use of amorphous SiO2 problematic. Finding the way of utilizing waste products is a very important research topic at the moment. In this study AlF3 production waste was investigated as the basic ingredient of a new pozzolanic material. The goal of this study is to investigate the possibilities of using AlF3 production waste, washed in ammonia solution, in cement stone specimens. Chemically treated silica gel additive was proved to reduce the amount of Ca(OH2 and CaCO3 in hardened cement paste samples. Experimental research has revealed that the density in hydrated samples reduces from 2220 kg/m3 to 2030 kg/m3 with the increase of silica gel content from 0 % to 35 %. The compressive strength of samples containing 10 % of silica gel additive increased by 8.04 % compared to the samples without the additive. SiO2 additive used at 10 % and 20 % increased the maximum hydration temperature. In this case, the additive modifies the hydration kinetics.DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1925

Influence of silver addition on the microstructure and mechanical properties of squeeze cast Mg-6Al-1Sn-0.3Mn-0.3Ti

International Nuclear Information System (INIS)

Acikgoez, Sehzat; Sevik, Hueseyin; Kurnaz, S.Can

2011-01-01

Graphical abstract: Highlights: → X-ray diffractometry reveals that the main phases are α-Mg, α-Ti, β-Mg 17 Al 12 and Al 8 Mn 5 in the base alloy. → With addition of silver, Al 81 Mn 19 phase was found. → The mechanical properties of the base alloy are improved with addition of silver. → The fracture surface of base alloy shows relatively deeper and more amount of dimples than that of alloys containing silver. - Abstract: In this study, the effect of silver (0, 0.2, 0.5, and 1 wt.%) on the microstructure and mechanical properties of a magnesium-based alloy (Mg-Al 6 wt.%-Sn 1 wt.%-Mn 0.3 wt.%-Ti 0.3 wt.%) were investigated. The alloys were produced under a controlled atmosphere by a squeeze-casting process. X-ray diffractometry revealed that the main phases are α-Mg, α-Ti, β-Mg 17 Al 12 and Al 8 Mn 5 in the all of alloys. In addition to, Al 81 Mn 19 phase was found with Ag additive. Besides, the amount of β-Mg 17 Al 12 phase was decreased with increasing the amount of Ag. The strength of the base alloy was increased by solid solution mechanism and decreasing the amount of β-Mg 17 Al 12 phase with addition of Ag. Furthermore, existence of Al 81 Mn 19 phase can be acted an important role in the increase on the mechanical properties of the alloys.

UO2-7%Gd2O3 fuel process development by mechanical blending with reprocessing of waste products and usage of densification additive

International Nuclear Information System (INIS)

Santos, Lauro Roberto dos

2009-01-01

In the nuclear fuel cycle, reprocessing and storage of 'burned' fuels, either temporary or permanent, demand high investments and, in addition, can potentially generate environmental problems. A strategy to decrease these problems is to adopt measures to reduce the amount of waste generated. The usage of integrated burnable poison based on gadolinium is a measure that contributes to achieve this goal. The reason to use burnable poison is to control the neutron population in the reactor during the early life of the fresh reactor core or the beginning of each recharging fuel cycle, extending its cycle duration. Another advantage of using burnable poison is to be able to operate the reactor with higher burning rate, optimizing the usage of the fuel. The process of manufacturing UO 2 -Gd 2 O 3 integrated burnable fuel poison generates waste that, as much as possible, needs to be recycled. Blending of Gd 2 O 3 in UO 2 powder requires the usage of a special additive to achieve the final fuel pellet specified density. The objective of this work is to develop the process of obtaining UO 2 - 7% Gd 2 O 3 integrated burnable poison using densification additives, aluminum hydroxide (Al(OH)3), and reprocessing manufacturing waste products by mechanical blending. The content of 7%- Gd 2 O 3 is based on commercial PWR reactor fuels - Type Angra 2. The results show that the usage of Al(OH) 3 as an additive is a very effective choice that promotes the densification of fuel pellets with recycle up to 10%. Concentrations of 0,20 % of Al(OH) 3 were found to be the indicated amount on an 7 industrial scale, specially when the recycled products come from U 3 O 8 obtained by calcination of sintered pellets. This is particularly interesting because it is following the steps of sintering and rectifying of the pellets, which is generating the largest amounts of recycled material. (author)

UO2-7%Gd2O3 fuel process development by mechanical blending with reprocessing of waste products and usage of densification additive

International Nuclear Information System (INIS)

Santos, Lauro Roberto dos

2009-01-01

In the nuclear fuel cycle, reprocessing and storage of 'burned' fuels, either temporary or permanent, demand high investments and, in addition, can potentially generate environmental problems. A strategy to decrease these problems is to adopt measures to reduce the amount of waste generated. The usage of integrated burnable poison based on gadolinium is a measure that contributes to achieve this goal. The reason to use burnable poison is to control the neutron population in the reactor during the early life of the fresh reactor core or the beginning of each recharging fuel cycle, extending its cycle duration. Another advantage of using burnable poison is to be able to operate the reactor with higher burning rate, optimizing the usage of the fuel. The process of manufacturing UO 2 -Gd 2 O 3 integrated burnable fuel poison generates waste that, as much as possible, needs to be recycled. Blending of Gd 2 O 3 in UO 2 powder requires the usage of a special additive to achieve the final fuel pellet specified density. The objective of this work is to develop the process of obtaining UO 2 - 7% Gd 2 O 3 integrated burnable poison using densification additives, aluminum hydroxide (Al(OH) 3 ), and reprocessing manufacturing waste products by mechanical blending. The content of 7%- Gd 2 O 3 is based on commercial PWR reactor fuels - Type Angra 2. The results show that the usage of Al(OH) 3 as an additive is a very effective choice that promotes the densification of fuel pellets with recycle up to 10%. Concentrations of 0,20 % of Al(OH) 3 were found to be the indicated amount on an industrial scale, specially when the recycled products come from U 3 O 8 obtained by calcination of sintered pellets. This is particularly interesting because it is following the steps of sintering and rectifying of the pellets, which is generating the largest amounts of recycled material. (author)

Measurement of casting parameters in ZnAlCu3 molds created by additive technology

Directory of Open Access Journals (Sweden)

S. Medić

2016-10-01

Full Text Available This paper examines the parameters of casting ZnAl4Cu3 alloy (volume, castability, density and occupancy of the mold in mold made additive technology. Molds made by additive technology are: cheaper in production of a small number of castings, geometrically more accurate and faster made. From obtained results of this paper it is clearly seen that printed mold must be protected with thermal coating because liquid adhesive of powder otherwise evaporates during casting and creates additional moisture in the mold, as it was noted.

Thermoluminescent properties of polycrystalline carbon doped LaAlO{sub 3}/La(OH){sub 3} crystals synthesized by solid state reaction for application in UV dosimetry

Energy Technology Data Exchange (ETDEWEB)

Alves, N.; Oliveira de F, L. [Federal University of the State of Minas Gerais, Department of Nuclear Engineering, Av. Pres. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Barbosa F, W., E-mail: neire.radiologia@yahoo.com.br [Nuclear Technology Development Center, 941, 30161-970 Belo Horizonte, Minas Gerais (Brazil)

2017-10-15

It is well known that UV radiation can induce certain deleterious effects, such as erythema, painful inflammation of the membrane of the eye and skin cancer. Therefore, it has been pushing the research for producing new and high performance UV sensitive Tl materials. There is an increasing interest in the development of new Tl materials for ultraviolet (UV) dosimetry purposes, owing to simplicity of the sample readout compared to other techniques. In this paper, thermoluminescence and dosimetric characteristics of pure and carbon doped lanthanum aluminate and hydroxide lanthanum crystals, irradiated with different UV doses, were studied and discussed. All samples studied were produced by solid state reaction method with different mixing methodologies. Characterization of sintered powders by X-ray diffraction, UV-Vis spectrophotometry and Ftir spectroscopy were performed. XRD data confirmed the LaAlO{sub 3} and La(OH){sub 3} crystalline phases. The thermoluminescent study revealed that all compositions presented high UV sensibility. The sample which was grown by first sintering La{sub 2}O{sub 3} together carbon atoms and then sintering again in order to obtain La{sub 2}O{sub 3}:C together Al{sub 2}O{sub 3}, presented the best linear dose response over UV doses ranging from 0.042 to 0.63 mJ/cm{sup 2}, with correlation coefficients equal to 0.99931. The synthesis methodology used was very efficient to obtain crystals with high Tl output intensities for low exposure rate UV R fields. (Author)

Crystal structure and stability of LiAlD{sub 4} with TiF{sub 3} additive

Energy Technology Data Exchange (ETDEWEB)

Brinks, H.W. [Department of Physics, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway)]. E-mail: hwbrinks@ife.no; Fossdal, A. [Department of Physics, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway); Fonnelop, J.E. [Department of Physics, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway); Hauback, B.C. [Department of Physics, Institute for Energy Technology, P.O. Box 40, Kjeller NO-2027 (Norway)

2005-07-19

LiAlD{sub 4} samples with TiF{sub 3} additives have been investigated by synchrotron X-ray diffraction, neutron diffraction and a Sieverts-type apparatus. Directly after ball milling there are no signs of any Ti-containing phases, and the unit-cell of LiAlD{sub 4} and Al give no indication of any solid solutions. Hence it is concluded that the Ti is in an amorphous state directly after ball milling. Furthermore, no LiF was observed in the samples. Based on Sieverts-type measurements the plateau pressure at 80 deg C has been proved to be higher than 85 bar. Samples stored in a glove box are slowly desorbed, and after 6 months for a LiAlD{sub 4} + TiF{sub 3} sample, the reaction to LiD + Al is nearly finished.

Effect of Rapid Solidification and Addition of Cu3P on the Mechanical Properties of Hypereutectic Al-Si Alloys

OpenAIRE

Suárez-Rosales,Miguel Ángel; Pinto-Segura,Raúl; Palacios-Beas,Elia Guadalupe; Hernández-Herrera,Alfredo; Chávez-Alcalá,José Federico

2016-01-01

The combined processes; rapid solidification, addition of Cu3P compound and heat treatments to improve the mechanical properties of the hypereutectic Al-13Si, Al-20Si and Al-20Si-1.5Fe-0.7Mn alloys (in wt. %) was studied. Optical microscopy and scanning electron microscopy were used to characterize the microstructures. The mechanical properties were evaluated by tensile tests. It was found that the cooling rate (20-50°C/s) used to solidify the alloys plus the addition of Cu3P compound favored...

Equilibrium aluminium hydroxo-oxalate phases during initial clay formation; H +-Al 3+-oxalic acid-Na + system

Science.gov (United States)

Bilinski, Halka; Horvath, Laszlo; Ingri, Nils; Sjöberg, Staffan

1986-09-01

The conditions necessary for initial clay formation have been studied in different model systems comprising different organic acids besides Si and Al. In the present paper the solid phases and the precipitation boundary characterizing the subsystem H +-Al 3+-oxalic acid (H 2L) are discussed. pH and tyndallometric measurements were performed in an ionic medium of 0.6 M Na(Cl) at 25 °C. The two phases Al 3(OH) 7(C 2O 4) · 3H 2O (phase I) and NaAl(OH) 2(C 2O 4) · 3H 2O (phase II) determine the precipitation boundary. The following formation constants for the two phases were deduced: lgβ1 = lg([ Al3+] -3[ H2C2O4] -1[ H+] 9 = -21.87 ± 0.08 and lgβ11 = lg([ Al3+] -1[ H2C2O4] -1[ H+] 4 = -5.61 ± 0.06. Phase I exists in the range [ Al] tot≥ 10 -4.4moldm-3,[ H2C2O4] tot ≥ 10 -4.9moldm-3 and at pH oxalic-rich natural waters. The more soluble sodium phase is unlikely to exist in natural waters. The two phases are metastable relative to crystalline gibbsite and may be considered as the first precipitation step in the transition from aqueous Al oxalates down to stable Al hydroxide. Model calculations illustrating these competing hydrolysis-complexation reactions are discussed in terms of predominance and speciation diagrams. The solid phases have been characterized by X-ray analysis of powders, TGA and IR spectra, and tentative structures are proposed. Phase I seems to be an octahedral layer structure, in which 3/5 of the octahedral sites between two close packed oxygen sheets are occupied by Al 3+ and the oxalate ion acts as a bridge ligand between two aluminium atoms. Phase II forms a more open sheet structure and has ion exchange properties. Powder data for a phase crystallized from the studied solution after a year are also presented. This phase, Na 4Al 2(OH) 2(C 2O 4) 4 · 10H 2O, supports the results from the equilibrium analysis of recent solution data by SJöBERG and ÖHMAN (1985), who have found the dinuclear complex Al 2(OH) 2(C 2O 4) 44- to exist in a

Investigation into isomolar series of Al(NO3)3, Na3VO4 solution mixture and composition of solid phases

International Nuclear Information System (INIS)

Chernysh, L.F.; Nakhodnova, A.P.; Makarova, R.A.

1979-01-01

Conducted is investigation of properties of isomolar series of aluminium nitrate and sodiUm vanadate solutions at pH of the latter 12.5; 10.0; 7.0 and the temperature of 25 deg C using the methods of pH-metry, conductometry, ''seeming'' volume of precipitations, residual concentration of aluminium and vanadium. It is shown, that the composition property diagram of the system investigated does not reflect the true composition of solid-phase products of the reaction, which depends on the component ratio in solution. Bottom phases of isomolar series are mainly heterogeneous. At the excess of sodium vanadate solution and its high pH values conditions for the basic salt formation are created. At pH of the Na 3 VO 4 solution of 12.5 and 10.0 and Al(NO 3 ) 3 : Na 3 VO 4 ratios 4:6 and 3:7 respectively obtained are the basic aluminium vanadates of the (AlOH) 3 (VO 4 ) 2 x 7.5H 2 O and (AlOH) 2 V 2 O 7 x5H 2 O composition, some of their physicochemical properties being investigated

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

International Nuclear Information System (INIS)

Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

2014-01-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )]·H 2 O (α-, β-RbUAs) and the anhydrous phase Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions. - Graphical abstract: Three different layer geometries observed in the structures of Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )] and α- and β- Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )]·H 2 O. Two different coordination environments of uranium polyhedra (types I and II) are shown schematically on the top of the figure. - Highlights: • Three new uranyl arsenates were synthesized from the hydrothermal reactions. • The phases consist of the topologically identical but geometrically different layers. • Topotactic transitions were observed in the processes of mono-hyrates dehydration

High-performance cobalt carbonate hydroxide nano-dot/NiCo(CO3)(OH)2 electrode for asymmetric supercapacitors

Science.gov (United States)

Lee, Damin; Xia, Qi Xun; Yun, Je Moon; Kim, Kwang Ho

2018-03-01

Binder-free mesoporous NiCo(CO3)(OH)2 nanowire arrays were grown using a facile hydrothermal technique. The Co2(CO3)(OH)2 in NiCo(CO3)(OH)2 nanowire arrays was well-decorated as nano-dot scale (a few nanometer). In addition, increasing cobalt content in nickel compound matrix, NiCo(CO3)(OH)2 nanowire arrays were separately uniformly grown without agglomeration on Ni foam, providing a high specific surface area to help electrolyte access and ion transfer. The enticing composition and morphology of the NiCo(CO3)(OH)2 nanowire exhibit a superior specific capacity of 1288.2 mAh g-1 at a current density of 3 A g-1 and excellent cycling stability with the capacity retention of 80.7% after 10,000 cycles. Furthermore, an asymmetric supercapacitor composed of the NiCo(CO3)(OH)2 composite as a positive electrode and the graphene as a negative electrode presented a high energy density of 35.5 W h kg-1 at a power density of 2555.6 W kg-1 and satisfactory cycling stability with 71.3% capacity retention after 10,000 cycles. The great combination of the active nano-dot Co2(CO3)(OH)2 and the individually grown NiCo(CO3)(OH)2 nanowires made it a promising electrode material for asymmetric supercapacitors. A well-developed nanoarchitecture of the nano-dot Co2(CO3)(OH)2 decorated NiCo(CO3)(OH)2 composite could pave the way for an excellent electrode design for high-performance supercapacitors.

The Influence of oxide additives on Ni/Al2O3 catalysts in low temperature methane steam reforming

International Nuclear Information System (INIS)

Lazar, Mihaela; Dan, Monica; Mihet, Maria; Almasan, Valer

2009-01-01

Hydrogen is industrially produced by methane steam reforming. The process is catalytic and the usual catalyst is based on Ni as the active element. The main problem of this process is its inefficiency. It requires high temperatures at which Ni also favors the formation of graphite, which deactivates the catalysts. Ni has the advantage of being much cheaper than noble metal catalysts, so many researches are done in order to improve the properties of supported Ni catalysts and to decrease the temperature at which the process is energetically efficient. In order to obtain catalysts with high activity and stability, it is essential to maintain the dispersion of the active phase (Ni particles) and the stability of the support. Both properties can be improved by addition of a second oxide to the support. In this paper we present the results obtained in preparation and characterization of Ni/Al 2 O 3 catalysts modified by addition of CeO 2 and La 2 O 3 to alumina support. The following catalysts were prepared by impregnation method: Ni/Al 2 O 3 , Ni/CeO 2 -Al 2 O 3 and Ni/La 2 O 3 -Al 2 O 3 (10 wt.% Ni and 6 wt.% additional oxide). The catalytic surface was characterized by N 2 adsorption - desorption isotherms. The hydrogen - surface bond was characterized by Thermo-Programmed-Desorption (TPD) method. All catalysts were tested in steam reforming reaction of methane in the range of 600 - 700 deg. C, at atmospheric pressure working with CH 4 :H 2 O ratio of 1:3. The modified catalysts showed a better catalytic activity and selectivity for H 2 and CO 2 formation, at lower temperatures than the simple Ni/Al 2 O 3 catalyst. (authors)

In vitro and in vivo antitumor activity of the halogenated boroxine dipotassium-trioxohydroxytetrafluorotriborate (K2[B3O3F4OH]).

Science.gov (United States)

Ivankovic, Sinisa; Stojkovic, Ranko; Galic, Zoran; Galic, Borivoj; Ostojic, Jelena; Marasovic, Maja; Milos, Mladen

2015-06-01

Dipotassium-trioxohydroxytetrafluorotriborate K2[B3O3F4OH] was listed as a promising new therapeutic for cancer diseases. For in vitro and in vivo investigation of its antitumor effects 4T1 mammary adenocarcinoma, B16F10 melanoma and squamous cell carcinoma SCCVII were used. The detailed in vitro investigation undoubtedly showed that K2[B3O3F4OH] affects the growth of cancer cells. The proliferation of cells depends on the concentration so that aqueous solution of K2[B3O3F4OH], the concentrations of 10(-4) M and less, does not affect cell growth, but the concentrations of 10(-3) M or more, significantly slows cells growth. B16F10 and SCCVII cells show higher sensitivity to the cytotoxic effects of K2[B3O3F4OH] compared to 4T1 cells. Under in vivo conditions, K2[B3O3F4OH] slows the growth of all three tumors tested compared to the control, and the inhibitory effect was most pronounced during the application of the substance. There is almost no difference if K2[B3O3F4OH] was applied intraperitoneally, intratumor, peroral or as ointment. Addition of 5-FU did not further increase the antitumor efficacy of K2[B3O3F4OH].

The Effect of Nb Addition on the Microstructure and the High-Temperature Strength of Fe3Al Aluminide

Science.gov (United States)

Kratochvíl, Petr; Švec, Martin; Král, Robert; Veselý, Jozef; Lukáč, Pavel; Vlasák, Tomáš

2018-02-01

The microstructural and high-temperature mechanical properties of Fe-26Al-xNb (x = 3 and 5 at. pct) are compared. The alloys were investigated "as cast" and after hot rolling at 1473 K (1200 °C). Scanning electron microscopes equipped with EDS and EBSD were used for the microstructure and phase identification. The addition of 3 at. pct of Nb into the Fe3Al matrix leads to the formation of C14 λ—Laves phase (Fe,Al)2Nb (LP) particles spread in the Fe3Al matrix, while an eutectic with thin lamellae of LP C14 λ—Laves phase (Fe,Al)2Nb and matrix is also formed in the iron aluminide with 5 at. pct of Nb. The presence of incoherent precipitates is connected with the enhancement of the high-temperature strength and creep resistance.

EXAFS Characterization of Dendrimer-Derived Pt/γ-Al2O3

International Nuclear Information System (INIS)

Siani, A.; Alexeev, O. S.; Williams, C. T.; Ploehn, H. J.; Amiridis, M. D.

2007-01-01

The various steps involved in the preparation of a Pt/γ-Al2O3 material using hydroxyl-terminated generation four (G4OH) PAMAM dendrimers as templates were monitored by EXAFS. The results indicate that Cl ligands in the Pt precursors (H2PtCl6 and K2PtCl4) were partially replaced by aquo ligands upon hydrolysis to form [PtCl3(H2O)3]+ and [PtCl2(H2O)2] species. After interaction of such species with G4OH, Cl ligands from the first coordination shell of Pt were further replaced by nitrogen atoms from the dendrimer interior, indicating the complexation of Pt with the dendrimer. This process was accompanied by a transfer of the electron density from the dendrimer to Pt, indicating that the former plays the role of a ligand. Following treatment of the H2PtCl6/G4OH and K2PtCl4/G4OH composites with NaBH4, no substantial changes were detecteded in the electronic or coordination environment of Pt, and no formation of metal nanoparticles was observed. However, when the reduction treatment was performed with H2, the formation of extremely small Pt clusters incorporating no more than 4 Pt atoms was observed. These Pt species remained strongly bonded to the dendrimer and their nuclearity depends on the length of the H2 treatment. Formation of Pt nanoparticles with an average diameter of approximately 10 A was finally observed after the deposition of H2PtCl6/G4OH on γ-Al2O3 and drying, suggesting that their formation may be related to the collapse of the dendrimer structure. The Pt nanoparticles formed appear to have high mobility, since subsequent thermal treatment in O2/H2 led to further sintering

Characterization of hydroxyapatite coatings deposited by hydrothermal electrochemical method on NaOH immersed Ti6Al4V

International Nuclear Information System (INIS)

He, Daihua; Liu, Ping; Liu, Xinkuan; Ma, Fengcang; Chen, Xiaohong; Li, Wei; Du, Jiandi; Wang, Pu; Zhao, Jun

2016-01-01

The hydrothermal electrochemical method was used to deposit hydroxyapatite coating on Ti6Al4V. In order to improve the bonding strength between the coating and substrate, the substrates were modified by 8 M NaOH solution before the deposition. The effects of immersing time on the substrate, on the hydroxyapatite coating, and on the bonding strength were studied. X-Ray Diffraction, Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy and Drop Shape Analysis Method were applied. And the crystallinity of hydroxyapatite coating was calculated. The results show that immersing treatment effects the phase compositions, the microstructure and the wettability of the substrate surface. A porous, three-dimensional network structure is formed on the Ti6Al4V surface through the NaOH immersion. The pore size and depth increase with the increase of immersing time from 12 to 48 h. The surface microstructure of Ti6Al4V with 60 h′ immersion time was different from the others. The modification treatment can improve the bonding strength between hydroxyapatite coating and the substrate obviously. The value of the bonding strength with the substrate immersed for 48 h is larger than those of the others. A bone-like apatite layer forms on the coating after 3 days of soaking in SBF, implying with good bioactivity of the hydroxyapatite coatings deposited by the method. The surface characteristics of the sample immersed with 48 h are more conductive to the deposition of hydroxyapatite and to the improvement of the bonding strength. The formation mechanism of hydroxyapatite coating deposited by hydrothermal electrochemical method was discussed. - Highlights: • Immerse Ti6Al4V alloy with NaOH solution for different immersing time. • We deposit hydroxyapatite coating by hydrothermal electrochemical method. • We examine changes of composition, microstructure, bonding strength and bioactivity of the hydroxyapatite coating. • 48 h is the optimal immersing time. • We

Antidepressants differentially related to 1,25-(OH)(2) vitamin D(3) and 25-(OH) vitamin D(3) in late-life depression

NARCIS (Netherlands)

Oude Voshaar, R.C.; Derks, W.J.; Comijs, H.C.; Schoevers, R.A.; Borst, M.H. de; Marijnissen, R.M.

2014-01-01

A low plasma 25-OH vitamin D3 level is a universal risk factor for a wide range of diseases and has also been implicated in late-life depression. It is currently unknown whether the biologically active form of vitamin D, that is, 1,25-(OH)2 vitamin D3, is also decreased in late-life depression, or

Antidepressants differentially related to 1,25-(OH)(2) vitamin D-3 and 25-(OH) vitamin D-3 in late-life depression

NARCIS (Netherlands)

Oude Voshaar, R C; Derks, W J; Comijs, H C; Schoevers, R A; de Borst, M H; Marijnissen, R M

2014-01-01

A low plasma 25-OH vitamin D-3 level is a universal risk factor for a wide range of diseases and has also been implicated in late-life depression. It is currently unknown whether the biologically active form of vitamin D, that is, 1,25-(OH)(2) vitamin D-3, is also decreased in late-life depression,

Total OH Reactivity Measurements in the Boreal Forest

Science.gov (United States)

Praplan, A. P.; Hellén, H.; Hakola, H.; Hatakka, J.

2015-12-01

INTRODUCTION Atmospheric total OH reactivity (Rtotal) can be measured (Kovacs and Brune, 2001; Sinha et al., 2008) or it can be calculated according to Rtotal = ∑i kOH+X_i [Xi] where kOH+X_i corresponds to the reaction rate coefficient for the reaction of OH with a given compound Xi and [Xi] its concentration. Studies suggest that in some environments a large fraction of missing reactivity, comparing calculated Rtotal with ambient total OH reactivity measurements (Di Carlo et al., 2004; Hofzumahaus et al., 2009). In this study Rtotal has been measured using the Comparative Reactivity Method (Sinha et al., 2008). Levels of the reference compound (pyrrole, C4H5N) are monitored by gas chromatography every 2 minutes and Rtotal is derived from the difference of reactivity between zero and ambient air. RESULTS Around 36 hours of preliminary total OH reactivity data (30 May until 2 June 2015) are presented in Fig. 1. Its range matches previous studies for this site (Nölscher et al., 2012; Sinha et al., 2010) and is similar to values in another pine forest (Nakashima et al., 2014). The setup used during the period presented here has been updated and more recent data will be presented, as well as a comparison with calculated OH reactivity from measured individual species. ACKNOWLEDGEMENTS This work was supported by Academy of Finland (Academy Research Fellowship No. 275608). The authors acknowledge Juuso Raine for technical support. REFERENCES Di Carlo et al. (2004). Science 304, 722-725.Hofzumahaus et al. (2009). Science 324, 1702-1704.Kovacs and Brune (2001). J. Atmos. Chem. 39, 105-122.Nakashima et al. (2014). Atmos. Env. 85, 1-8.Nölscher et al. (2012). Atmos. Chem. Phys. 12, 8257-8270.Sinha et al. (2008). Atmos. Chem. Phys. 8, 2213-2227.Sinha et al. (2010). Environ. Sci. Technol. 44, 6614-6620.

Room temperature atomic layer deposited Al2O3 on CH3NH3PbI3 characterized by synchrotron-based X-ray photoelectron spectroscopy

Science.gov (United States)

Kot, Małgorzata; Das, Chittaranjan; Henkel, Karsten; Wojciechowski, Konrad; Snaith, Henry J.; Schmeisser, Dieter

2017-11-01

An ultrathin Al2O3 film deposited on methylammonium lead triiodide (CH3NH3PbI3) perovskite has the capability to suppress the carrier recombination process and improve the perovskite solar cells efficiency and stability. However, annealing at temperatures higher than 85 °C degrades the CH3NH3PbI3 perovskite film. The X-ray photoelectron spectroscopy study performed in this work indicates that it is possible to grow Al2O3 by atomic layer deposition on the perovskite at room temperature, however, besides pure Al2O3 some OH groups are found and the creation of lead and iodine oxides at the Al2O3/CH3NH3PbI3 interface takes place.

Simple synthesis of Al{sub 2}O{sub 3} sphere composite from hybrid process with improved thermal stability for catalytic applications

Energy Technology Data Exchange (ETDEWEB)

Santos, Regina C.R., E-mail: reginaclaudiasantos@yahoo.com.br [Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceará, Campus of Pici, Fortaleza, CE, CEP: 60440-554 (Brazil); Pinheiro, Antônio N.; Leite, Edson R. [Department of Chemistry, Federal University of São Carlos, São Carlos, SP, CEP: 13560-905 (Brazil); Freire, Valder N. [Department of Physics, Federal University of Ceará, Campus of Pici, Fortaleza, CE, CEP: 60440-554 (Brazil); Longhinotti, Elisane; Valentini, Antoninho [Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceará, Campus of Pici, Fortaleza, CE, CEP: 60440-554 (Brazil)

2015-06-15

Aluminium oxide spheres were synthesized by the hybrid process applying the biopolymer chitosan. After the calcination process the porous spheres were characterized by Chemical elemental analysis (XRF), X-ray diffraction (XRD), Scanning electron microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), N{sub 2} adsorption–desorption isotherms, infrared spectroscopy (IR), and CO{sub 2} temperature programmed desorption (CO{sub 2}-TPD). The effect of thermal treatment on surface properties of the oxide spheres was also evaluated by the catalytic ethanol dehydration reaction. The hybrid method produced interesting results related to the thermal stability against sintering process and consequently low decreases of surface area. The hybrid spheres calcination at 900 and 1200 °C produced a metastable phases of alumina with a high surface area, and nanometric crystallites. Additionally, the spheres of mixed silica-alumina synthesized by this method reveal the formation of porous spheres with highly acidic OH groups, which was suggested by the catalytic performance. - Highlights: • Al and Si/Al oxide spheres with promising properties are synthesized by hybrid method. • Al{sub 2}O{sub 3} spheres show high thermal stability and resistance the loss surface area. • The SiO{sub 2} addition plays an important role in the structure and porosity of the spheres. • Al{sub 2}O{sub 3} and SiO{sub 2}/Al{sub 2}O{sub 3} spheres presented a good activity to conversion ethanol. • The activity is related to the surface area and density of OH groups on surface.

Variability of OH(3-1) and OH(6-2) emission altitude and volume emission rate from 2003 to 2011

Science.gov (United States)

Teiser, Georg; von Savigny, Christian

2017-08-01

In this study we report on variability in emission rate and centroid emission altitude of the OH(3-1) and OH(6-2) Meinel bands in the terrestrial nightglow based on spaceborne nightglow measurements with the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on the Envisat satellite. The SCIAMACHY observations cover the time period from August 2002 to April 2012 and the nighttime observations used in this study are performed at 10:00 p.m. local solar time. Characterizing variability in OH emission altitude - particularly potential long-term variations - is important for an appropriate interpretation of ground-based OH rotational temperature measurements, because simultaneous observations of the vertical OH volume emission rate profile are usually not available for these measurements. OH emission altitude and vertically integrated emission rate time series with daily resolution for the OH(3-1) band and monthly resolution for the OH(6-2) band were analyzed using a standard multilinear regression approach allowing for seasonal variations, QBO-effects (Quasi-Biennial Oscillation), solar cycle (SC) variability and a linear long-term trend. The analysis focuses on low latitudes, where SCIAMACHY nighttime observations are available all year. The dominant sources of variability for both OH emission rate and altitude are the semi-annual and annual variations, with emission rate and altitude being highly anti-correlated. There is some evidence for a 11-year solar cycle signature in the vertically integrated emission rate and in the centroid emission altitude of both the OH(3-1) and OH(6-2) bands.

Influence of the precursors in the chemical preparation of {gamma} - Al{sub 2}O{sub 3} in reactions of alcohols dehydration; Influencia de los precursores en la preparacion quimica de {gamma} - Al{sub 2}O{sub 3} en reacciones de deshidratacion de alcoholes

Energy Technology Data Exchange (ETDEWEB)

Salmones, J.; Limon, M.T.; Mayagoitia, V.; Rojas, F.; Kornhauser, I.; Morales, J.; Acosta, D. [Instituto Mexicano del Petroleo, Subdireccion General de Investigacion Aplicada, Apartado Postal 14-805, 07730, Mexico D.F. (Mexico)

1998-12-31

A chemical method for the synthesis of alumina substrates based on a microscopic morphological control, is presented. The influence of the precursor alcohol used for the synthesis of Al(OR){sub 3} is studied too. This latter compound is the raw material to synthesize the alumina materials treated here. The effects of alcohols such as ethanol, isopropanol and ter butanol are analyzed. Results show that an early formation (i.e. at low temperature) of the porous structure is reached in the case of {gamma} -Al{sub 2}O{sub 3} synthesized from ethanol. On the other hand, pore formation for alumina obtained from isopropanol and ter butanol, occurs until appearance of the {gamma} phase (at approximately 500 Centigrade). The different alumina substrates were used as catalysts in dehydration reactions of primary, secondary and tertiary alcohols. Decreasing catalytic activity corresponds to the sequence: (R-OH){sub 3} < (R-OH){sub 2} < (R-OH) in the case of ethanol; while for isopropanol and ter butanol the sequence is: (R-OH) < (R-OH){sub 2} < (R-OH){sub 3}. These results are explained by means of a reaction mechanism which is associated with the textural properties of the catalysts. (Author)

Facile fabrication of flower like self-assembled mesoporous hierarchical microarchitectures of In(OH){sub 3} and In{sub 2}O{sub 3}: In(OH){sub 3} micro flowers with electron beam sensitive thin petals

Energy Technology Data Exchange (ETDEWEB)

Arul Prakasam, Balasubramaniam, E-mail: arul7777@yahoo.com [Laboratory of Green Chemistry, School of Engineering Science, Lappeenranta University of Technology, Sammonkatu 12, FI-50130, Mikkeli (Finland); Lahtinen, Manu; Peuronen, Anssi [Department of Chemistry, Laboratories of Inorganic and Analytical Chemistry, P.O. Box 35, FI-40014, University of Jyväskylä (Finland); Muruganandham, Manickavachagam [Department of Civil and Environmental Engineering, Temple University, Philadelphia, PA, 19122 (United States); Sillanpää, Mika [Laboratory of Green Chemistry, School of Engineering Science, Lappeenranta University of Technology, Sammonkatu 12, FI-50130, Mikkeli (Finland)

2016-12-01

A template and capping-reagent free facile fabrication method for mesoporous hierarchical microarchitectures of flower-like In(OH){sub 3} particles under benign hydrothermal conditions is reported. Calcination of In(OH){sub 3} to In{sub 2}O{sub 3} with the retention of morphology is also described. Both In(OH){sub 3} and In{sub 2}O{sub 3} microstructures were analyzed with SEM, EDX, TEM and powder X-ray diffraction. The crystal sizes for In(OH){sub 3} and In{sub 2}O{sub 3} were calculated using the Scherrer equation. In In(OH){sub 3} the thin flakes at the periphery of micro flowers were electron beam sensitive. The mechanism of self-assembly process was analyzed as well. - Highlights: • Hydrothermal fabrication In(OH){sub 3} self-assembled porous hierarchical architectures. • Induced dehydration in beam sensitive In(OH){sub 3} micro flowers. • Calcination of In(OH){sub 3} to In{sub 2}O{sub 3} with the retention of flower like morphology. • Phase pure synthesis of In{sub 2}O{sub 3} with the average crystal size of ∼37 nm.

Atmospheric chemistry of CF3CH2CH2OH

DEFF Research Database (Denmark)

Hurley, Michael D.; Misner, Jessica A.; Ball, James C.

2005-01-01

Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with CF3CH2C(O)H and CF3CH2CH2OH in 700 Torr of N-2 or air diluent at 296 2 K. The rate constants determined were k(Cl+CF3CH2C(O)H) = (1.81 +/- 0.27) x 10(-11), k(OH+CF3CH2C(O)H) = (2.57 +/- 0.44...

Influence of Al{sub 2}O{sub 3} addition on microstructure and mechanical properties of 3YSZ-Al{sub 2}O{sub 3} composites

Energy Technology Data Exchange (ETDEWEB)

Abden, Md. Jaynul [International Islamic Univ., Chittagong (Bangladesh). Dept. of Electrical and Electronic Engineering; Afroze, Jannatul Dil [Noakhali Science and Technology Univ. (Bangladesh). Faculty of Science and Engineering; Gafur, Md. Abdul [Bangladesh Council of Scientific and Industrial Research, Dhaka (Bangladesh). Pilot Plant and Process Development Centre; Chowdhury, Faruque-Uz-Zaman [Chittagong University of Engineering and Technology (Bangladesh). Dept. of Physics

2015-07-01

The effect of the amount of Al{sub 2}O{sub 3} content on microstructure, tetragonal phase stability and mechanical properties of 3YSZ-Al{sub 2}O{sub 3} composites are investigated in this study. The ceramic composites are obtained by means of uniaxial compacting at 210 MPa and green compacts are sintered at 1550 C for 3 h in air. The monoclinic zirconia (m-ZrO{sub 2}) phase has completely been transformed into tetragonal zirconia (t-ZrO{sub 2}) phase with corresponding higher Al{sub 2}O{sub 3} content. The t-ZrO{sub 2} grains induce transgranular fracture mode that has contribution in improvement of fracture toughness. The maximum flexural strength of 340 MPa, Vickers hardness value of 14.31 GPa and fracture toughness of 5.1 MPa x m{sup 1/2} in the composition containing 40 wt.-% Al{sub 2}O{sub 3} is attributed to the microstructure with t-ZrO{sub 2} grains as inter- and intragranular particles in the Al{sub 2}O{sub 3} grains, which makes it suitable for dental applications.

Effects of heating atmosphere on formation of crystalline citrate-derived LaAlO3 nanoparticles

International Nuclear Information System (INIS)

Yu, Hsuan-Fu; Guo, Yu-Man

2011-01-01

Research highlights: → LaAlO 3 can be crystallized at 550 deg. C in an oxygen-enriched atmosphere. → Calcining the citrate precursor in oxygen atmosphere lowers the reaction temperatures to form crystalline LaAlO 3 . → In oxygen atmosphere, pure citrate-derived LaAlO 3 nanoparticles can be produced at 700 deg. C. - Abstract: Crystalline LaAlO 3 nanoparticles were synthesized at relative low temperatures, using a citrate-precursor technique. La(NO 3 ) 3 , Al(NO 3 ) 3 , and C 3 H 4 (OH)(COOH) 3 , in a molar ratio of 1:1:1, were dissolved in deionized water. NH 4 OH was used to adjust the aqueous solution to pH 7. After drying, the citrate precursors were charred at 350 deg. C, followed by calcination at different temperatures, in air or oxygen atmosphere. The thermochemical properties of the resultant particles were analyzed using thermogravimetric and differential thermal analysis, X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Effects of calcination temperature and heating atmosphere on the formation of crystalline LaAlO 3 nanoparticles were investigated. In O 2 atmosphere, clacining the citrate-derived charred solid precursor at 700 deg. C for 3 h can decompose all intermediates to produce pure LaAlO 3 nanoparticles (particle sizes ≤ 100 nm) with an average crystallite size of about 24 nm and possessing high sinterability.

The effect of NaOH and KOH on the characterization of meso porous AlOOH nano structures in the hydrothermal route

International Nuclear Information System (INIS)

Haghnazari, N.; Abdollahifar, M.; Jahani, F.

2014-01-01

Meso porous AlOOH was synthesized by hydrothermal treatment from aluminium nitrate and NaOH or KOH. The effect of NaOH and KOH as precipitating agents on the characterization of samples were investigated. XRD, Ftir, FESEM and N 2 adsorption-desorption analytical techniques were used to characterize the products. Our results showed that using KOH as precipitating agent was favour-able for the formation of meso porous and crystalline AlOOH with high Bet-specific surface area of 98 m 2 /g. (Author)

The effect of NaOH and KOH on the characterization of meso porous AlOOH nano structures in the hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

Haghnazari, N.; Abdollahifar, M.; Jahani, F., E-mail: abdollahifar@gmail.com [Islamic Azad University, Kermanshah Branch, Department of Chemical Engineering, 67131 Kermanshah (Iran, Islamic Republic of)

2014-10-01

Meso porous AlOOH was synthesized by hydrothermal treatment from aluminium nitrate and NaOH or KOH. The effect of NaOH and KOH as precipitating agents on the characterization of samples were investigated. XRD, Ftir, FESEM and N{sub 2} adsorption-desorption analytical techniques were used to characterize the products. Our results showed that using KOH as precipitating agent was favour-able for the formation of meso porous and crystalline AlOOH with high Bet-specific surface area of 98 m{sup 2}/g. (Author)

Construction of g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} hybrids via in-situ acidification and exfoliation with enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiao-jing [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu, Chao [College of Gemmology and Material Technics, Hebei GEO University, Shijiazhuang 050031 (China); Li, Xu-li [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Fa-tang, E-mail: lifatang@126.com [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Li, Yu-pei [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Zhao, Jun [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China); State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Liu, Rui-hong [College of Science, Hebei University of Science and Technology, Shijiazhuang 050018 (China)

2017-02-01

Highlights: • Ultrathin g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} hybrids are prepared via in-situ reaction. • The structure modification role of in-situ formed HNO{sub 3} for g-C{sub 3}N{sub 4} is found. • The ultrathin g-C{sub 3}N{sub 4} nanosheets are formed by the acidified melamine and Al(OH){sub 3}. • In-situ calcination of melamine and Al(OH){sub 3} benefits the contact of C{sub 3}N{sub 4} and Al{sub 2}O{sub 3}. • The activity of g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} is 16.6 times that of pristine g-C{sub 3}N{sub 4} in degrading RhB. - Abstract: Homogeneous ultrathin g-C{sub 3}N{sub 4} nanosheets/Al{sub 2}O{sub 3} heterojunctions are synthesized using melamine and Al(NO{sub 3}){sub 3} via in-situ reaction and the following thermal polymerization approach. The in-situ reaction between melamine and Al(NO{sub 3}){sub 3} results in the existence of HNO{sub 3}-acidified melamine and Al(OH){sub 3} aggregates via the hydrolysis of Al(NO{sub 3}){sub 3}. After thermal polymerization, the aggregates are converted to g-C{sub 3}N{sub 4}/Al{sub 2}O{sub 3} composites. The thermal polymerization of acidified melamine and the support effect of aluminum hydroxide for g-C{sub 3}N{sub 4} during the calcination process lead to highly dispersed amrophous Al{sub 2}O{sub 3} on ultrathin g-C{sub 3}N{sub 4} nanosheets, which is beneficial for the separation of photogenerated electron-hole pairs in the heterojunction. The degradation rate for Rhodamine B (RhB) over the most activie sample is 16.6 times than that of pristine g-C{sub 3}N{sub 4} under visible light irradiation, which can be attributed to the high specific surface area, highly dispersion of amorphous Al{sub 2}O{sub 3} on ultrathin g-C{sub 3}N{sub 4} nanosheet, and the effective electrons transfer from g-C{sub 3}N{sub 4} to the amorphous Al{sub 2}O{sub 3}.

Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO2(ν3) and OH(ν) emission models

Science.gov (United States)

Panka, Peter A.; Kutepov, Alexander A.; Kalogerakis, Konstantinos S.; Janches, Diego; Russell, James M.; Rezac, Ladislav; Feofilov, Artem G.; Mlynczak, Martin G.; Yiğit, Erdal

2017-08-01

In the 1970s, the mechanism of vibrational energy transfer from chemically produced OH(ν) in the nighttime mesosphere to the CO2(ν3) vibration, OH(ν) ⇒ N2(ν) ⇒ CO2(ν3), was proposed. In later studies it was shown that this "direct" mechanism for simulated nighttime 4.3 µm emissions of the mesosphere is not sufficient to explain space observations. In order to better simulate these observations, an additional enhancement is needed that would be equivalent to the production of 2.8-3 N2(1) molecules instead of one N2(1) molecule in each quenching reaction of OH(ν) + N2(0). Recently a new "indirect" channel of the OH(ν) energy transfer to N2(ν) vibrations, OH(ν) ⇒ O(1D) ⇒ N2(ν), was suggested and then confirmed in a laboratory experiment, where its rate for OH(ν = 9) + O(3P) was measured. We studied in detail the impact of the "direct" and "indirect" mechanisms on CO2(ν3) and OH(ν) vibrational level populations and emissions. We also compared our calculations with (a) the SABER/TIMED nighttime 4.3 µm CO2 and OH 1.6 and 2.0 µm limb radiances of the mesosphere-lower thermosphere (MLT) and (b) with ground- and space-based observations of OH(ν) densities in the nighttime mesosphere. We found that the new "indirect" channel provides a strong enhancement of the 4.3 µm CO2 emission, which is comparable to that obtained with the "direct" mechanism alone but assuming an efficiency that is 3 times higher. The model based on the "indirect" channel also produces OH(ν) density distributions which are in good agreement with both SABER limb OH emission observations and ground and space measurements. This is, however, not true for the model which relies on the "direct" mechanism alone. This discrepancy is caused by the lack of an efficient redistribution of the OH(ν) energy from higher vibrational levels emitting at 2.0 µm to lower levels emitting at 1.6 µm. In contrast, the new  indirect  mechanism efficiently removes at least five quanta in each

In vivo evaluation of the 3-carboranyl thymidine analogue (3-CTA), N5-2OH, for neutron capture therapy

International Nuclear Information System (INIS)

Barth, Rolf F.; Yang, Weilian; Wu, Gong; Byun, Youngjoo; Tjarks, Werner; Eriksson, Staffan; Binns, Peter J.; Riley, Kent J.

2006-01-01

The purpose of the present study was to evaluate a 3 CTA, designated N5-2OH, as a boron delivery agent for NCT. Target validation was established using the thymidine kinase 1 (+) wild type L929 cell line and its TK1(-) counterpart, which were implanted subcutaneously into NIH nu/nu mice. 10 B-enriched N5-2OH, solubilized in DMSO (50μg 10 B in 15μl), was administered by 2 intratumoral (i.t.) injections at 2 h intervals. Two hours later the animals were irradiated at the MITR-II Research Reactor, following which tumor volumes were determined over a period of 30 days. Mice bearing TK1(+) wild type tumors, which had received N5-2OH, had a 15 fold inhibition in tumor growth compared to TK1(-) controls (247 versus 3,603 mm 3 ). Based on these data, biodistribution and therapy studies were initiated in F98 glioma bearing rats. Animals received 500μg of N5-2OH, administered intracerebrally (i.c.) by convection enhanced delivery (CED) using ALZET pumps (8μl/h for 24 h). The tumor boron concentration was 17.3μg/g compared to undetectable amounts in normal brain and blood. BNCT was carried out 14 d following i.c. implantation of 10 3 F98 glioma cells and 24 h following CED of N5-2OH (500μg/200μl). The mean survival time (MST) of these animals was 38 d compared to 31 d and 25 d, respectively, for irradiated and untreated controls. Studies are planned to optimize the delivery and formulation of N5-2OH and additional therapy studies will be carried out using N5-2OH in combination with BPA and BSH. (author)

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

Science.gov (United States)

Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

2014-07-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O (α-, β-RbUAs) and the anhydrous phase Rb[UO2(AsO3OH)(AsO2(OH)2)] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions.

Antimicrobial activity study of a μ3-oxo bridged [Fe3O(PhCO2)6(MeOH)3](NO3)(MeOH)2] cluster

Science.gov (United States)

Pathak, Sayantan; Jana, Barun; Mandal, Manab; Mandal, Vivekananda; Ghorai, Tanmay K.

2017-11-01

Synthesis, characterization and antimicrobial activity of a tri-nuclear μ3-Oxobridged Fe(III) cluster [Fe3O(PhCO2)6(MeOH)3](NO3)(MeOH)2(1) is reported. Cluster 1 is synthesized in a single pot reaction among Fe(NO3)3·9H2O, C6H5COOH, NaN3 (1:4:1) in MeOH. Single crystal X-ray diffraction studies of the isolated crystals show that it is μ3-Oxo bridged trimeric assembly of three Fe atoms via bridging benzoate anions. Furthermore, BVS calculations show that all three Fe atoms in complex 1 are in +3 oxidation state and are surrounded by benzoate anions and methanol in octahedral environment. The oxidation state of iron is also confirmed from the cyclic voltamogram. FT-IR spectroscopy and CHN analysis of the isolated crystals further supports the functional group attached to the periphery of the complex. The nanomolecular size of complex 1 is 1.29 nm. The antimicrobial efficiency studies of the complex 1 show significant inhibition of the growth of the organisms, viz. B. cereus MTCC 1272, S. epidermidis MTCC 3086 and S. typhimurium MTCC 98 and produced 23 ± 1.93 mm, 16 ± 1.77 mm and 12 ± 2.42 mm inhibition zones respectively. However, it shows zero inhibition to the strain of E. coli MTCC 723.

Analysis of the co-deposition of Al2O3 particles with nickel by an electrolytic route: The influence of organic additives presence and Al2O3 concentration

Science.gov (United States)

Temam, H. B.; Temam, E. G.

2016-04-01

Alloy coatings were prepared by co-deposition of Al2O3 particles in Ni matrix on carbon steel substrate from nickel chloride bath in which metallic powders were held in suspension. The influence of metal powder amount in the bath on chemical composition, morphology, thickness, microhardness and corrosion behavior of obtained coatings, has been investigated. It was shown that the presence of Al2O3 particles in deposit greatly improves the hardness and the wear resistance of alloy coatings. Characterization by microanalysis (EDX) of the various deposits elaborated confirms that the rate of particles incorporated increases as the concentration of solid particles increasing. The results showed that the presence of organic additives in Ni-Al2O3 electrolyte deposition led to an increase in the hardness and corrosion resistance of the deposits.

THE c2d SPITZER SPECTROSCOPIC SURVEY OF ICES AROUND LOW-MASS YOUNG STELLAR OBJECTS. IV. NH3 AND CH3OH

International Nuclear Information System (INIS)

Bottinelli, Sandrine; Van Dishoeck, Ewine F.; Lahuis, Fred; Boogert, A. C. Adwin; Bouwman, Jordy; Beckwith, Martha; Oeberg, Karin I.; Linnartz, Harold; Pontoppidan, Klaus M.; Blake, Geoffrey A.; Evans, Neal J.

2010-01-01

NH 3 and CH 3 OH are key molecules in astrochemical networks leading to the formation of more complex N- and O-bearing molecules, such as CH 3 CN and CH 3 OCH 3 . Despite a number of recent studies, little is known about their abundances in the solid state. This is particularly the case for low-mass protostars, for which only the launch of the Spitzer Space Telescope has permitted high-sensitivity observations of the ices around these objects. In this work, we investigate the ∼8-10 μm region in the Spitzer IRS (InfraRed Spectrograph) spectra of 41 low-mass young stellar objects (YSOs). These data are part of a survey of interstellar ices in a sample of low-mass YSOs studied in earlier papers in this series. We used both an empirical and a local continuum method to correct for the contribution from the 10 μm silicate absorption in the recorded spectra. In addition, we conducted a systematic laboratory study of NH 3 - and CH 3 OH-containing ices to help interpret the astronomical spectra. We clearly detect a feature at ∼9 μm in 24 low-mass YSOs. Within the uncertainty in continuum determination, we identify this feature with the NH 3 ν 2 umbrella mode and derive abundances with respect to water between ∼2% and 15%. Simultaneously, we also revisited the case of CH 3 OH ice by studying the ν 4 C-O stretch mode of this molecule at ∼9.7 μm in 16 objects, yielding abundances consistent with those derived by Boogert et al. based on a simultaneous 9.75 and 3.53 μm data analysis. Our study indicates that NH 3 is present primarily in H 2 O-rich ices, but that in some cases, such ices are insufficient to explain the observed narrow FWHM. The laboratory data point to CH 3 OH being in an almost pure methanol ice, or mixed mainly with CO or CO 2 , consistent with its formation through hydrogenation on grains. Finally, we use our derived NH 3 abundances in combination with previously published abundances of other solid N-bearing species to find that up to 10%-20% of

Sintering behavior and property of bioglass modified HA-Al2O3 composite

Directory of Open Access Journals (Sweden)

Wang Li-li

2012-01-01

Full Text Available The bioglass modified HA-Al2O3 composites were successfully fabricated by mixing HA, synthesized by wet chemical method between precursor materials H3PO4 and Ca(OH2, with 25wt% Al2O3 and different content of bioglass (5%, 25%, 45%, 65wt% respectively, with a mole fraction of 53.9%SiO2, 22.6%Na2O, 21.8%CaO, and 1.7wt%P2O5, sintered in air at various temperatures (750-950°C for 2h. when the content of bioglass is below 45wt% in the composite, HA decomposes completely and transforms to β-TCP. The main phase in this case are β-TCP, Al2O3 and Ca3(AlO32.When the content of bioglass is above 45wt% in the composite, the decomposition of HA to β-TCP is suppressed and the main phases in this case are Al2O3 and HA, DCP□CaHPO4□ and β-TCP, which almost have the same chemical composition, forming ternary-glass phase, and have better bioactive than pure HA. It can also be found that at the certain addition of bioglass, the higher sintered temperature, the bigger volume density and flexural strength of the composite are, but when the sintered temperature reaches 950°C, they decrease. This modified HA-Al2O3 composites by calcium silicate glass have a much lower sintering temperature and decrease the production cost much.

Solid-state 27Al and 29Si NMR characterization of hydrates formed in calcium aluminate-silica fume mixtures

International Nuclear Information System (INIS)

Pena, P.; Rivas Mercury, J.M.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

2008-01-01

Partially deuterated Ca 3 Al 2 (SiO 4 ) y (OH) 12-4y -Al(OH) 3 mixtures, prepared by hydration of Ca 3 Al 2 O 6 (C 3 A), Ca 12 Al 14 O 33 (C 12 A 7 ) and CaAl 2 O 4 (CA) phases in the presence of silica fume, have been characterized by 29 Si and 27 Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca 3 Al 2 (OH) 12 and Al(OH) 3 phases were detected. From the quantitative analysis of 27 Al NMR signals, the Al(OH) 3 /Ca 3 Al 2 (OH) 12 ratio was deduced. The incorporation of Si into the katoite structure, Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x , was followed by 27 Al and 29 Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of 27 Al MAS-NMR components associated with Al(OH) 6 and Al(OSi)(OH) 5 environments. The 29 Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From 29 Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures. - Graphical abstract: Transmission electron micrograph of CaAl 2 O 4 -microsilica mixture hydrated at 90 deg. C for 31 days showing a cubic Ca 3 Al 2.0±0.2 (SiO 4 ) 0.9±0.2 (OH) 1.8 crystal surrounded by unreacted amorphous silica spheres

1 IN TR ODU CT ION Gibbsite (7-Al(OH)3) and boehmite (7-AlOOH ...

African Journals Online (AJOL)

2005-07-10

Jul 10, 2005 ... of A-B-B-A-A-B-B-A-A-B in the direction perpen- dicular to the planes. On dehydroxylation, boehmite and gibbsite do not go directly to the thermodynamically stable a-. Al2O3 phase. Initially the long range crystalline order is destroyed to give 'transition aluminas' or. 'activated aluminas' (Misra, 1 986, Ingram ...

Microstructural and strength improvements through the use of Na{sub 2}CO{sub 3} in a cementless Ca(OH){sub 2}-activated Class F fly ash system

Energy Technology Data Exchange (ETDEWEB)

Jeon, Dongho; Jun, Yubin; Jeong, Yeonung; Oh, Jae Eun, E-mail: ohjaeeun@unist.ac.kr

2015-01-15

This study explores the beneficial effects of Na{sub 2}CO{sub 3} as an additive for microstructural and strength improvements in a Ca(OH){sub 2}-activated fly ash system. NaOH-activated fly ash samples were also tested to compare the effect of Na{sub 2}CO{sub 3}. Compressive strength testing, XRD, SEM/BSE/EDS, {sup 29}Si/{sup 27}Al MAS-NMR, MIP and TGA were performed. The testing results indicate that the use of Na{sub 2}CO{sub 3} for Ca(OH){sub 2}-activation led to a noticeable improvement in strength and microstructure, primarily due to (1) more dissolution of raw fly ash at an early age, (2) more formation of C–S–H [or C–S–H(I)], (3) porosity reduction, and (4) pore-size refinement. We also found that (1) an early high alkalinity from the NaOH formation was not a major cause of strength, (2) geopolymer was not formed despite the early NaOH formation, and (3) no visible pore-filling action of CaCO{sub 3} was observed. However, Na{sub 2}CO{sub 3} did not produce any improvement in strength for NaOH-activated fly ash. -- Highlights: •The use of Na{sub 2}CO{sub 3} significantly improved strength and microstructure. •The use of Na{sub 2}CO{sub 3} induced more dissolution of raw fly ash at early ages. •The use of Na{sub 2}CO{sub 3} promoted more C–S–H [or C–S–H(I)] formation. •The use of Na{sub 2}CO{sub 3} reduced total porosity and refined pore-size distribution. •The use of Na{sub 2}CO{sub 3} produced neither geopolymer formations nor pore-filling actions from CaCO{sub 3}.

Application of the Akinfiev-Diamond equation of state to neutral hydroxides of metalloids (B(OH)3, Si(OH)4, As(OH)3) at infinite dilution in water over a wide range of the state parameters, including steam conditions

Science.gov (United States)

Akinfiev, Nikolay N.; Plyasunov, Andrey V.

2014-02-01

treatment of data, see Table 1. The fitting procedure to evaluate the parameters of the Akinfiev-Diamond model also included the values of ΔfGo and S° of Si(OH)4 in ideal gas state at standard state conditions.First, to fit the EoS parameters, the dataset for g2∞ (Si(OH)4(aq)) has been generated using accepted experimental data on quartz solubility in water according to the reaction SiO2(quartz) + 2H2O = Si(OH)4(aq), as g2∞(SiOH(aq)(T,P)=g(quartz)(T,P)+2g(HO)(T,P)-RTlnm, where mSi corresponds to the molality of silica in the solution. Thermodynamic properties of quartz were adopted from SUPCRT database (Johnson et al., 1992), while g(H2O)(T, P) was computed using the Hill (1990) and/or Wagner and Pruß (2002) formulations.The fitting procedure was organized as described below. It is known that partial molar properties of dilute solutes close to the critical point of water are governed by the Krichevskii parameter, AKr (Levelt Sengers, 1991). Plyasunov (2012) recommended for Si(OH)4AKr = -190 ± 10 MPa evaluated from the available relevant data. We have used this value as an anchor while fitting. So, the fitting procedure was iterative. After any initial approximation for ξ, values of the a, b parameters of the EoS together with ΔfGo298(g) and So298(g) of Si(OH)4 were determined by a linear regression of the available g2∞ (Si(OH)4(aq)) experimental data. Then the ξ parameter was modified in compliance with the adopted AKr value (Eq. A7), and the fitting cycle was repeated until ξ ceased changing.The finally retrieved values for gaseous Si(OH)4 are ΔfGo298 = -1239.66 ± 1.7 kJ mol-1, So298 = 346.37 ± 3.5 J mol-1 K-1, and the EoS parameters are ξ = -1.8933; a = 0.9285 ± 1.1 cm3 g-1; b = -0.9409 ± 0.97 cm3 K0.5 g-1 (2σ confidence) (Table 1). Evaluated in this work values of ΔfGo298 and So298 for Si(OH)4 in the ideal gas state are very close to the data given in Plyasunov (2011b) on the basis of the analysis of the solubility amorphous silica and quartz in low

Development of Al2O3 carrier-Ru composite catalyst for hydrogen generation from alkaline NaBH4 hydrolysis

International Nuclear Information System (INIS)

Huang, Yao-Hui; Su, Chia-Chi; Wang, Shu-Ling; Lu, Ming-Chun

2012-01-01

A recyclable and reusable Ru/Al 2 O 3 catalyst is prepared for hydrogen generation from the hydrolysis process of alkaline sodium borohydride (NaBH 4 ) solution. The hydrogen generation rate by the hydrolysis and methanolysis of alkaline NaBH 4 was explored as a function of NaOH concentration. Meantime, the byproducts derived from the spent alkaline NaBH 4 solution were characterized by X-ray diffraction (XRD), scanning electro microscope/energy dispersive spectrometer (SEM/EDS) and NMR (Nuclear Magnetic Resonance). The effect of NaOH concentration on the hydrogen generation from the hydrolysis of NaBH 4 significantly depends on the type of catalysts. With increasing NaOH concentration, the hydrogen generation rates decrease when using ruthenium (Ru) composite as a catalyst. The hydrogen generation rate of the methanolysis of NaBH 4 is significantly inhibited in the presence of NaOH as compared with the hydrolysis of NaBH 4 . The durability test of the Ru/Al 2 O 3 catalyst shows that the hydrogen generation rate decreases with recycling and reuse. The XRD and NMR analysis results show that the borate hydrate (NaBO 2 H 2 O) was derived from the hydrolysis of 20 wt% and 30 wt% NaBH 4 . -- Highlights: ► A recyclable Ru/Al 2 O 3 catalyst was synthesized for hydrogen generation. ► Ru/Al 2 O 3 significantly promotes the hydrogen generation rate from alkaline NaBH 4 solution. ► The prepared Ru/Al 2 O 3 catalyst can easily collect from the spent alkaline NaBH 4 solution.

Electron-microscopy studies of NaAlH{sub 4} with TiF{sub 3} additive: hydrogen-cycling effects

Energy Technology Data Exchange (ETDEWEB)

Andrei, C.M.; Holmestad, R. [Norwegian University of Science and Technology, Department of Physics, Trondheim (Norway); Walmsley, J.C. [SINTEF Materials and Chemistry, Trondheim (Norway); Brinks, H.W.; Hauback, B.C. [Institute for Energy Technology, P.O. Box 40, Kjeller (Norway); Srinivasan, S.S.; Jensen, C.M. [University of Hawaii, Department of Chemistry, Honolulu, HI (United States)

2005-02-01

NaAlH{sub 4} is a promising candidate material for hydrogen storage. Ti additives are effective in reducing the reaction temperatures and improving kinetics. In this work, the microstructure of NaAlH{sub 4} with 2% TiF{sub 3} has been studied in different conditions using a combination of transmission electron microscopy and scanning electron microscopy, both with energy-dispersive spectroscopic X-ray analysis. The effect of the additive on particle and grain size was examined after the initial ball-milling process and after 15 cycles. The additive has an uneven distribution in the sample after ball milling. Selected-area diffraction and high-resolution imaging confirmed the presence of TiF{sub 3}. This phase accounts for most of the Ti in the material at this stage and showed limited mixing with the alanate. The grain size within particles for TiF{sub 3} is larger than for the alanate particles. Diffraction from the latter was dominated by metallic aluminium. After cycling, the TiF{sub 3} has decomposed and energy-dispersive spectroscopic X-ray analysis maps showed some combination of Ti with the alanate phase. There is no significant change in the measurable grain size of the Al-containing alanate particles between the ball-milled and the 15-cycled samples, but more cycles result in agglomeration of the material. (orig.)

Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO2(ν3 and OH(ν emission models

Directory of Open Access Journals (Sweden)

P. A. Panka

2017-08-01

Full Text Available In the 1970s, the mechanism of vibrational energy transfer from chemically produced OH(ν in the nighttime mesosphere to the CO2(ν3 vibration, OH(ν ⇒ N2(ν ⇒ CO2(ν3, was proposed. In later studies it was shown that this "direct" mechanism for simulated nighttime 4.3 µm emissions of the mesosphere is not sufficient to explain space observations. In order to better simulate these observations, an additional enhancement is needed that would be equivalent to the production of 2.8–3 N2(1 molecules instead of one N2(1 molecule in each quenching reaction of OH(ν + N2(0. Recently a new "indirect" channel of the OH(ν energy transfer to N2(ν vibrations, OH(ν ⇒ O(1D ⇒ N2(ν, was suggested and then confirmed in a laboratory experiment, where its rate for OH(ν = 9 + O(3P was measured. We studied in detail the impact of the "direct" and "indirect" mechanisms on CO2(ν3 and OH(ν vibrational level populations and emissions. We also compared our calculations with (a the SABER/TIMED nighttime 4.3 µm CO2 and OH 1.6 and 2.0 µm limb radiances of the mesosphere–lower thermosphere (MLT and (b with ground- and space-based observations of OH(ν densities in the nighttime mesosphere. We found that the new "indirect" channel provides a strong enhancement of the 4.3 µm CO2 emission, which is comparable to that obtained with the "direct" mechanism alone but assuming an efficiency that is 3 times higher. The model based on the "indirect" channel also produces OH(ν density distributions which are in good agreement with both SABER limb OH emission observations and ground and space measurements. This is, however, not true for the model which relies on the "direct" mechanism alone. This discrepancy is caused by the lack of an efficient redistribution of the OH(ν energy from higher vibrational levels emitting at 2.0 µm to lower levels emitting at 1.6 µm. In contrast, the new  indirect  mechanism

Redetermination of Ce[B5O8(OH(H2O]NO3·2H2O

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Ya-Xi Huang

2012-05-01

Full Text Available The crystal structure of Ce[B5O8(OH(H2O]NO3·2H2O, cerium(III aquahydroxidooctaoxidopentaborate nitrate dihydrate, has been redetermined from single-crystal X-ray diffraction data. In contrast to the previous determination [Li et al. (2003. Chem. Mater. 15, 2253–2260], the present study reveals the location of all H atoms, slightly different fundamental building blocks (FBBs of the polyborate anions, more reasonable displacement ellipsoids for all non-H atoms, as well as a model without disorder of the nitrate anion. The crystal structure is built from corrugated polyborate layers parallel to (010. These layers, consisting of [B5O8(OH(H2O]2− anions as FBBs, stack along [010] and are linked by Ce3+ ions, which exhibit a distorted CeO10 coordination sphere. The layers are additionally stabilized via O—H...O hydrogen bonds between water molecules and nitrate anions, located at the interlayer space. The [BO3(H2O]-group shows a [3 + 1] coordination and is considerably distorted from a tetrahedral configuration. Bond-valence-sum calculation shows that the valence sum of boron is only 2.63 valence units (v.u. when the contribution of the water molecule (0.49 v.u. is neglected.

OH vibrational activation and decay dynamics of CH4-OH entrance channel complexes

International Nuclear Information System (INIS)

Wheeler, Martyn D.; Tsiouris, Maria; Lester, Marsha I.; Lendvay, Gyoergy

2000-01-01

Infrared spectroscopy has been utilized to examine the structure and vibrational decay dynamics of CH 4 -OH complexes that have been stabilized in the entrance channel to the CH 4 +OH hydrogen abstraction reaction. Rotationally resolved infrared spectra of the CH 4 -OH complexes have been obtained in the OH fundamental and overtone regions using an IR-UV (infrared-ultraviolet) double-resonance technique. Pure OH stretching bands have been identified at 3563.45(5) and 6961.98(4) cm-1 (origins), along with combination bands involving the simultaneous excitation of OH stretching and intermolecular bending motions. The infrared spectra exhibit extensive homogeneous broadening arising from the rapid decay of vibrationally activated CH 4 -OH complexes due to vibrational relaxation and/or reaction. Lifetimes of 38(5) and 25(3) ps for CH 4 -OH prepared with one and two quanta of OH excitation, respectively, have been extracted from the infrared spectra. The nascent distribution of the OH products from vibrational predissociation has been evaluated by ultraviolet probe laser-induced fluorescence measurements. The dominant inelastic decay channel involves the transfer of one quantum of OH stretch to the pentad of CH 4 vibrational states with energies near 3000 cm-1. The experimental findings are compared with full collision studies of vibrationally excited OH with CH 4 . In addition, ab initio electronic structure calculations have been carried out to elucidate the minimum energy configuration of the CH 4 -OH complex. The calculations predict a C 3v geometry with the hydrogen of OH pointing toward one of four equivalent faces of the CH 4 tetrahedron, consistent with the analysis of the experimental infrared spectra. (c) 2000 American Institute of Physics

Solid-state 27Al and 29Si NMR investigations on Si-substituted hydrogarnets

International Nuclear Information System (INIS)

Rivas Mercury, J.M.; Pena, P.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

2007-01-01

Partially deuterated Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x hydrates prepared by a reaction in the presence of D 2 O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The 29 Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x was followed by 27 Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH) 6 and Al(OSi)(OH) 5 environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data

Gas phase kinetics of the OH + CH3CH2OH reaction at temperatures of the interstellar medium (T = 21-107 K).

Science.gov (United States)

Ocaña, A J; Blázquez, S; Ballesteros, B; Canosa, A; Antiñolo, M; Albaladejo, J; Jiménez, E

2018-02-21

Ethanol, CH 3 CH 2 OH, has been unveiled in the interstellar medium (ISM) by radioastronomy and it is thought to be released into the gas phase after the warm-up phase of the grain surface, where it is formed. Once in the gas phase, it can be destroyed by different reactions with atomic and radical species, such as hydroxyl (OH) radicals. The knowledge of the rate coefficients of all these processes at temperatures of the ISM is essential in the accurate interpretation of the observed abundances. In this work, we have determined the rate coefficient for the reaction of OH with CH 3 CH 2 OH (k(T)) between 21 and 107 K by employing the pulsed and continuous CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, which means Reaction Kinetics in a Uniform Supersonic Flow) technique. The pulsed laser photolysis technique was used for generating OH radicals, whose time evolution was monitored by laser induced fluorescence. An increase of approximately 4 times was observed for k(21 K) with respect to k(107 K). With respect to k(300 K), the OH-reactivity at 21 K is enhanced by two orders of magnitude. The obtained T-expression in the investigated temperature range is k(T) = (2.1 ± 0.5) × 10 -11 (T/300 K) -(0.71±0.10) cm 3 molecule -1 s -1 . In addition, the pressure dependence of k(T) has been investigated at several temperatures between 21 K and 90 K. No pressure dependence of k(T) was observed in the investigated ranges. This may imply that this reaction is purely bimolecular or that the high-pressure limit is reached at the lowest total pressure experimentally accessible in our system. From our results, k(T) at usual IS temperatures (∼10-100 K) is confirmed to be very fast. Typical rate coefficients can be considered to range within about 4 × 10 -11 cm 3 molecule -1 s -1 at 100 K and around 1 × 10 -10 cm 3 molecule -1 s -1 at 20 K. The extrapolation of k at the lowest temperatures of the dense molecular clouds of ISM is also discussed in this paper.

Reductive amination of ethanol to ethylamines over Ni/Al_2O_3 catalysts

International Nuclear Information System (INIS)

Park, Jun Hyun; Hong, Eunpyo; An, Sang Hee; Shin, Chae-Ho; Lim, Dong-Hee

2017-01-01

Ni(x)/Al_2O_3 (x=wt%) catalysts with Ni loadings of 5-25 wt% were prepared via a wet impregnation method on an γ-Al_2O_3 support and subsequently applied in the reductive amination of ethanol to ethylamines. Among the various catalysts prepared, Ni(10)/Al2O3 exhibited the highest metal dispersion and the smallest Ni particle size, resulting in the highest catalytic performance. To reveal the effects of reaction parameters, a reductive amination process was performed by varying the reaction temperature (T), weight hourly space velocity (WHSV), and NH_3 and H_2 partial pressures in the reactions. In addition, on/off experiments for NH_3 and H_2 were also carried out. In the absence of NH_3 in the reactant stream, the ethanol conversion and selectivities towards the different ethylamine products were significantly reduced, while the selectivity to ethylene was dominant due to the dehydration of ethanol. In contrast, in the absence of H_2, the selectivity to acetonitrile significantly increased due to dehydrogenation of the imine intermediate. Although a small amount of catalyst deactivation was observed in the conversion of ethanol up to 10 h on stream due to the formation of nickel nitride, the Ni(10)/Al_2O_3 catalyst exhibited stable catalytic performance over 90 h under the optimized reaction conditions (i.e., T=190 .deg. C, WHSV=0.9 h"-"1, and EtOH/NH_3/H_2 molar ratio=1/1/6).

Surface chemistry of plasma-assisted atomic layer deposition of Al2O3 studied by infrared spectroscopy

NARCIS (Netherlands)

Langereis, E.; Keijmel, J.; Sanden, van de M.C.M.; Kessels, W.M.M.

2008-01-01

The surface groups created during plasma-assisted atomic layer deposition (ALD) of Al2O3 were studied by infrared spectroscopy. For temperatures in the range of 25–150 °C, –CH3 and –OH were unveiled as dominant surface groups after the Al(CH3)3precursor and O2 plasma half-cycles, respectively. At

Microstructure of two phases alloy Al3Ti/Al3Ti0.75Fe0.25

International Nuclear Information System (INIS)

Angeles, C.; Rosas, G.; Perez, R.

1998-01-01

The titanium-aluminium system presents three intermetallic compounds from those Al 3 Ti is what less attention has received. The objective of this work is to generate and characterize the microstructure of multiphase alloys nearby to Al 3 Ti compound through Fe addition as alloying. This is because it has been seen that little precipitates of Al 2 Ti phase over Al 3 Ti intermetallic compound increases its ductility. (Author)

Infrared and Raman spectroscopic characterization of the silicate mineral olmiite CaMn2+[SiO3(OH)](OH) - implications for the molecular structure

Science.gov (United States)

Frost, Ray L.; Scholz, Ricardo; López, Andrés; Xi, Yunfei; Granja, Amanda; Žigovečki Gobac, Željka; Lima, Rosa Malena Fernandes

2013-12-01

We have studied the mineral olmiite CaMn[SiO3(OH)](OH) which forms a series with its calcium analogue poldervaartite CaCa[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is pure and contains only calcium and manganese in the formula. Thermogravimetric analysis proves the mineral decomposes at 502 °C with a mass loss of 8.8% compared with the theoretical mass loss of 8.737%. A strong Raman band at 853 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations. Two intense Raman bands observed at 3511 and 3550 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of olmiite.

Global modelling of the total OH reactivity: investigations on the “missing” OH sink and its atmospheric implications

Directory of Open Access Journals (Sweden)

V. Ferracci

2018-05-01

Full Text Available The hydroxyl radical (OH plays a crucial role in the chemistry of the atmosphere as it initiates the removal of most trace gases. A number of field campaigns have observed the presence of a missing OH sink in a variety of regions across the planet. A comparison of direct measurements of the OH loss frequency, also known as total OH reactivity (kOH, with the sum of individual known OH sinks (obtained via the simultaneous detection of species such as volatile organic compounds and nitrogen oxides indicates that, in some cases, up to 80 % of kOH is unaccounted for. In this work, the UM-UKCA chemistry-climate model was used to investigate the wider implications of the missing reactivity on the oxidising capacity of the atmosphere. Simulations of the present-day atmosphere were performed and the model was evaluated against an array of field measurements to verify that the known OH sinks were reproduced well, with a resulting good agreement found for most species. Following this, an additional sink was introduced to simulate the missing OH reactivity as an emission of a hypothetical molecule, X, which undergoes rapid reaction with OH. The magnitude and spatial distribution of this sink were underpinned by observations of the missing reactivity. Model runs showed that the missing reactivity accounted for on average 6 % of the total OH loss flux at the surface and up to 50 % in regions where emissions of the additional sink were high. The lifetime of the hydroxyl radical was reduced by 3 % in the boundary layer, whilst tropospheric methane lifetime increased by 2 % when the additional OH sink was included. As no OH recycling was introduced following the initial oxidation of X, these results can be interpreted as an upper limit of the effects of the missing reactivity on the oxidising capacity of the troposphere. The UM-UKCA simulations also allowed us to establish the atmospheric implications of the newly characterised reactions of peroxy

Effect of CuO addition on the sintering temperature and microwave dielectric properties of CaSiO3–Al2O3 ceramics

Directory of Open Access Journals (Sweden)

Denghao Li

2014-06-01

Full Text Available CuO-doped CaSiO3–1 wt% Al2O3 ceramics were synthesized via a traditional solid-state reaction method, and their sintering behavior, microstructure and microwave dielectric properties were investigated. The results showed that appropriate CuO addition could accelerate the sintering process and assist the densification of CaSiO3–1 wt% Al2O3 ceramics, which could effectively lower the densification temperature from 1250 °C to 1050 °C. However, the addition of CuO undermined the microwave dielectric properties. The optimal amount of CuO addition was found to be 0.8 wt%, and the derived CaSiO3–Al2O3 ceramic sintered at 1100 °C presented good microwave dielectric properties of εr=7.27, Q×f=16,850 GHz and τf=−39.53 ppm/°C, which is much better than those of pure CaSiO3 ceramic sintered at 1340 oC (Q×f=13,109 GHz. The chemical compatibility of the above ceramic with 30 Pd/70 Ag during the cofiring process has also been investigated, and the result showed that there was no chemical reaction between palladium–silver alloys and ceramics.

An -OH group functionalized MOF for ratiometric Fe3+ sensing

Science.gov (United States)

Xu, Hui; Dong, Yingying; Wu, Yuhang; Ren, Wenjing; Zhao, Tao; Wang, Shunli; Gao, Junkuo

2018-02-01

Iron is one of the most important elements in the biochemical processes in all living system, both deficiency or excess of iron will lead to metabolism disorder diseases. However, Fe3+ is one of the most efficient fluorescence quenchers among the transition-metal ions because of its paramagnetic nature. The realization of Fe3+ ratiometric and self-calibrated fluorescent sensor is highly-challenging. We synthesized a novel luminescent -OH functionalized EuOHBDC (Eu2(OH-BDC)3, OH-BDC=2-hydroxyterephthalic acid) by hydrothermal reaction and in situ ligand synthesis, and used it as a rare ratiomatric luminescent sensor for Fe3+ ions. The -OH functional group facilitates both electron transfer and binding interaction between EuOHBDC and Fe3+, which lead to luminescent quenching of ligand-based emission while enhancement of a new peak emission, and thus enables ratiometric detection of Fe3+. The relative fluorescent intensity ratio (I375/I427) increased linearly with increasing Fe3+ concentration in the 10-50 μM range with 1.17 μM (65 ppb) detection limit. The EuOHBDC also shows excellent selectivity towards different metal ions, particularly can discriminate Fe3+ and Fe2+ through different luminescent responses. This result clearly demonstrates the superiority of -OH functionalized MOF for Fe3+ detection, which can contribute to develop high performance luminescent probe for detection of metal ions in environmental and biomedical applications.

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH+allene reaction

International Nuclear Information System (INIS)

Raman, Arjun S.; Justine Bell, M.; Lau, K.-C.; Butler, Laurie J.

2007-01-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH 2 CCH 2 OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193 nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl+CH 2 CCH 2 OH photofragments, a spin-orbit branching ratio for Cl( 2 P 1/2 ):Cl( 2 P 3/2 ) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH 2 CCH 2 OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH 2 CCH 2 OH radical intermediate to the three most important product channels for the OH+allene reaction expected from this radical intermediate: formaldehyde+C 2 H 3 , H+acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH 3 product channel. We compare our results to a previous theoretical study of the O+allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates

Photofragment imaging study of the CH2CCH2OH radical intermediate of the OH +allene reaction

Science.gov (United States)

Raman, Arjun S.; Justine Bell, M.; Lau, Kai-Chung; Butler, Laurie J.

2007-10-01

These velocity map imaging experiments characterize the photolytic generation of one of the two radical intermediates formed when OH reacts via an addition mechanism with allene. The CH2CCH2OH radical intermediate is generated photolytically from the photodissociation of 2-chloro-2-propen-1-ol at 193nm. Detecting the Cl atoms using [2+1] resonance-enhanced multiphoton ionization evidences an isotropic angular distribution for the Cl +CH2CCH2OH photofragments, a spin-orbit branching ratio for Cl(P1/22):Cl(P3/22) of 0.28, and a bimodal recoil kinetic energy distribution. Conservation of momentum and energy allows us to determine from this data the internal energy distribution of the nascent CH2CCH2OH radical cofragment. To assess the possible subsequent decomposition pathways of this highly vibrationally excited radical intermediate, we include electronic structure calculations at the G3//B3LYP level of theory. They predict the isomerization and dissociation transition states en route from the initial CH2CCH2OH radical intermediate to the three most important product channels for the OH +allene reaction expected from this radical intermediate: formaldehyde+C2H3, H +acrolein, and ethene+CHO. We also calculate the intermediates and transition states en route from the other radical adduct, formed by addition of the OH to the center carbon of allene, to the ketene+CH3 product channel. We compare our results to a previous theoretical study of the O +allyl reaction conducted at the CBS-QB3 level of theory, as the two reactions include several common intermediates.

Atmospheric Chemistry of cis-CF3CH=CHF: Kinetics of reactions with OH radicals and O3 and products of OH radical initiated oxidation

DEFF Research Database (Denmark)

Nilsson, Elna Johanna Kristina; Nielsen, Ole John; Johnson, Matthew Stanley

2009-01-01

Long path length FTIR-smog chamber techniques were used to measure k(OH + cis-CF3CH@CHF) = (1.20 ± 0.14) 1012 and k(O3 + cis-CF3CH@CHF) = (1.65 ± 0.16) 1021 cm3 molecule 1 s1 in 700 Torr of N2/O2 diluent at 296 K. The OH initiated oxidation of cis-CF3CH@CHF gives CF3CHO and HCOF in molar yields w...

Microstructural discovery of Al addition on Sn–0.5Cu-based Pb-free solder design

International Nuclear Information System (INIS)

Koo, Jahyun; Lee, Changsoo; Hong, Sung Jea; Kim, Keun-Soo; Lee, Hyuck Mo

2015-01-01

It is important to develop Pb-free solder alloys suitable for automotive use instead of traditional Sn–Pb solder due to environmental regulations (e.g., Restriction of Hazardous Substances (RoHS)). Al addition has been spotlighted to enhance solder properties. In this study, we investigated the microstructural change of Sn–0.5Cu wt.% based Pb-free solder alloys with Al addition (0.01–0.05 wt.%). The small amount of Al addition caused a remarkable microstructural change. The Al was favored to form Cu–Al intermetallic compounds inside the solder matrix. We identified the Cu–Al intermetallic compound as Cu_3_3Al_1_7, which has a rhombohedral structure, using EPMA and TEM analyses. This resulted in refined Cu_6Sn_5 networks in the Sn–0.5Cu based solder alloy. In addition, we conducted thermal analysis to confirm its stability at a high temperature of approximately 230 °C, which is the necessary temperature range for automotive applications. The solidification results were substantiated thermodynamically using the Scheil solidification model. We can provide criteria for the minimum aluminum content to modify the microstructure of Pb-free solder alloys. - Graphical abstract: The minor Al additions refined eutectic Cu_6Sn_5 IMC networks on the Sn–0.5Cu based solder alloys. The microstructure was dramatically changed with the minor Al addition. - Highlights: • We observed dramatic microstructure-change with Al additions. • We defined Cu_3_3Al_1_7 IMC with Al additions using TEM analysis. • We investigated grain refinement with Al additions using EBSD. • We discussed the refinement based on Scheil solidification model.

How to fill in your OHS-0-0-3 Safety Form

CERN Multimedia

HSE Unit

2014-01-01

The HSE Unit reminds all members of personnel that the OHS-0-0-3 Safety Form entitled “Identification of occupational risks” must be filled in on EDH at least once a year with their supervisor.   The form helps identify the occupational risks a person is exposed to in the course of his or her activities at CERN. In addition it provides information for the Medical Service database, which is used for personalized follow-up of employees. All persons who have only filled in the “paper” version of the form with their supervisor in previous years are required to complete the online form on EDH. Those who have already filled in the online OHS-0-0-3 form can find it on EDH or on their MARS form and clone it, verify it, update it if necessary and sign it. More information can be found on the CERN Admin e-guide.

Side-by-Side In(OH3 and In2O3 Nanotubes: Synthesis and Optical Properties

Directory of Open Access Journals (Sweden)

Tao Xiaojun

2009-01-01

Full Text Available Abstract A simple and mild wet-chemical approach was developed for the synthesis of one-dimensional (1D In(OH3 nanostructures. By calcining the 1D In(OH3 nanocrystals in air at 250 °C, 1D In2O3 nanocrystals with the same morphology were obtained. TEM results show that both 1D In(OH3 and 1D In2O3 are composed of uniform nanotube bundles. SAED and XRD patterns indicate that 1D In(OH3 and 1D In2O3 nanostructures are single crystalline and possess the same bcc crystalline structure as the bulk In(OH3 and In2O3, respectively. TGA/DTA analyses of the precursor In(OH3 and the final product In2O3 confirm the existence of CTAB molecules, and its content is about 6%. The optical absorption band edge of 1D In2O3 exhibits an evident blueshift with respect to that of the commercial In2O3 powders, which is caused by the increasing energy gap resulted from decreasing the grain size. A relatively strong and broad purple-blue emission band centered at 440 nm was observed in the room temperature PL spectrum of 1D In2O3 nanotube bundles, which was mainly attributed to the existence of the oxygen vacancies.

Dehydrogenation of Surface-Oxidized Mixtures of 2LiBH4 + Al/Additives (TiF3 or CeO2

Directory of Open Access Journals (Sweden)

Juan Luis Carrillo-Bucio

2017-11-01

Full Text Available Research for suitable hydrogen storage materials is an important ongoing subject. LiBH4–Al mixtures could be attractive; however, several issues must be solved. Here, the dehydrogenation reactions of surface-oxidized 2LiBH4 + Al mixtures plus an additive (TiF3 or CeO2 at two different pressures are presented. The mixtures were produced by mechanical milling and handled under welding-grade argon. The dehydrogenation reactions were studied by means of temperature programmed desorption (TPD at 400 °C and at 3 or 5 bar initial hydrogen pressure. The milled and dehydrogenated materials were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, and Fourier transformed infrared spectroscopy (FT-IR The additives and the surface oxidation, promoted by the impurities in the welding-grade argon, induced a reduction in the dehydrogenation temperature and an increase in the reaction kinetics, as compared to pure (reported LiBH4. The dehydrogenation reactions were observed to take place in two main steps, with onsets at 100 °C and 200–300 °C. The maximum released hydrogen was 9.3 wt % in the 2LiBH4 + Al/TiF3 material, and 7.9 wt % in the 2LiBH4 + Al/CeO2 material. Formation of CeB6 after dehydrogenation of 2LiBH4 + Al/CeO2 was confirmed.

Insight into the mechanism of methanol assistance with syngas conversion over partially hydroxylated γ-Al2O3(110D) surface in slurry bed.

Science.gov (United States)

Bai, Bing; Bai, Hui; Cao, Hao-Jie; Gao, Zhi-Hua; Zuo, Zhi-Jun; Huang, Wei

2018-04-27

Despite numerous studies devoted to the various properties of γ-Al2O3, the explorations of its catalytic activity remain scarce. In this study, density functional theory calculations are performed to study the elementary adsorption and reaction mechanisms for syngas conversion on partially hydroxylated γ-Al2O3(110D) surface in liquid paraffin. It is found that the partially hydroxylated γ-Al2O3(110D) surface with the hydroxyl coverage of 8.9 OH nm-2 is formed by two dissociative adsorptions of H2O on the dry γ-Al2O3(110D) surface. The hydroxyl coverage conditions play a key role in determining the dominant reaction mechanism on account of the existence of strong hydrogen bonds. The preferential pathway for syngas conversion with assistance of methanol over the partially hydroxylated γ-Al2O3(110D) surface in liquid paraffin has been proven to be CH3OH → CH3O + H → CH3 + OH, CH3 + CO → CH3CO. C2H5OH is then formed by successive hydrogenation via the pathway CH3CO + 3H → CH3CHO + 2H → CH3CH2O + H → C2H5OH. Here, CH3CHO formation by CH3CO hydrogenation is not inhibited. Actually, with the assistance of partially hydroxylated γ-Al2O3, CH3CHO has been synthesized with high selectivity in our previous experiment by the reaction of methanol and syngas, which provides favorable evidence for our results. The rate-limiting step is the formation of CH3O from CH3OH dehydrogenation with an activation barrier of 122.2 kJ mol-1. Moreover, the reaction barrier of CO insertion into the adsorbed CH3 group is at least 89.4 kJ mol-1, lower than those of CH4, C2H6, and CH3OCH3 formations. ADCH charge and ESP analyses indicate that the typical (Al, O) Lewis acid-base pair may have a significant effect upon the initial C-C chain formation. Thus, the present study provides a new approach for the rational tailoring and designing of new catalysts with superior reactivity involved in syngas conversion.

The influence of SiO2 Addition on 2MgO-Al2O3-3.3P2O5 Glass

DEFF Research Database (Denmark)

Larsen, P.H.; Poulsen, F.W.; Berg, Rolf W.

1999-01-01

2MgO-Al2O3-3.3P2O5 glasses with increasing amounts of SiO2 are considered for sealing applications in Solid Oxide Fuel Cells (SOFC). The change in chemical durability under SOFC anode conditions and the linear thermal expansion is measured as functions of the SiO2 concentration. Raman spectroscopy...... analysis of the glasses reveals no sign of important changes in the glass structure upon SiO2 addition. Some increase in glass durability with SiO2 concentration is reported and its cause is discussed....

Effect of Ce addition on microstructure of Al20Cu2Mn3 twin phase in an Al–Cu–Mn casting alloy

International Nuclear Information System (INIS)

Chen Zhongwei; Chen Pei; Li Shishun

2012-01-01

Highlights: ► Rare earth element Ce can retard the formation of the Al 20 Cu 2 Mn 3 twin phase in an Al–Cu–Mn casting alloy. ► Patterns of the particles of the Al 20 Cu 2 Mn 3 phase in Al–Cu–Mn free Ce alloy are more diverse. ► The symmetry of neighboring components of twins is characterized by glide reflection and reflection. ► The twins of Al 20 Cu 2 Mn 3 phase can enhance the mechanical properties of the Al–Cu–Mn casting alloys. - Abstract: Effects of Ce addition on microstructure of Al 20 Cu 2 Mn 3 twin phase and mechanical properties of an Al–Cu–Mn casting alloy were investigated by transmission electron microscopy, selected area electron diffraction, high resolution transmission electron microscopy and tensile test. The results show that rare earth element Ce can retard the formation of the Al 20 Cu 2 Mn 3 phase in the Al–Cu–Mn alloy. Compared with the Ce containing alloy, patterns of particles of the Al 20 Cu 2 Mn 3 phase in the Al–Cu–Mn free Ce alloy are more diverse. The symmetry of neighboring components of twins is characterized by glide reflection and reflection. In addition, twins of the Al 20 Cu 2 Mn 3 phase can enhance the mechanical properties of the Al–Cu–Mn alloy.

A coumarin based Schiff base probe for selective fluorescence detection of Al3 + and its application in live cell imaging

Science.gov (United States)

Sen, Bhaskar; Sheet, Sanjoy Kumar; Thounaojam, Romita; Jamatia, Ramen; Pal, Amarta Kumar; Aguan, Kripamoy; Khatua, Snehadrinarayan

2017-02-01

A new coumarin based Schiff base compound, CSB-1 has been synthesized to detect metal ion based on the chelation enhanced fluorescence (CHEF). The cation binding properties of CSB-1 was thoroughly examined in UV-vis and fluorescence spectroscopy. In fluorescence spectroscopy the compound showed high selectivity toward Al3 + ion and the Al3 + can be quantified in mixed aqueous buffer solution (MeOH: 0.01 M HEPES Buffer; 9:1; v/v) at pH 7.4 as well as in BSA media. The fluorescence intensity of CSB-1 was enhanced by 24 fold after addition of only five equivalents of Al3 +. The fluorescence titration of CSB-1 with Al3 + in mixed aqueous buffer afforded a binding constant, Ka = (1.06 ± 0.2) × 104 M- 1. The colour change from light yellow to colourless and the appearance of blue fluorescence, which can be observed by the naked eye, provides a real-time method for Al3 + sensing. Further the live cell imaging study indicated that the detection of intracellular Al3 + ions are also readily possible in living cell.

Gas phase kinetics of the OH + CH3CH2OH reaction at temperatures of the interstellar medium (T = 21-10^7 K)

Science.gov (United States)

Ocaña, A. J.; Blázquez, S.; Ballesteros, B.; Canosa, A.; Antiñolo, M.; Albaladejoab, J.; Jiménez, E.

2018-02-01

Ethanol, CH3CH2OH, has been unveiled in the interstellar medium (ISM) by radioastronomy and it is thought to be released into the gas phase after the warm-up phase of the grain surface, where it is formed. Once in the gas phase, it can be destroyed by different reactions with atomic and radical species, such as hydroxyl (OH) radicals. The knowledge of the rate coefficients of all these processes at temperatures of the ISM is essential in the accurate interpretation of the observed abundances. In this work, we have determined the rate coefficient for the reaction of OH with CH3CH2OH (k(T)) between 21 and 10^7 K by employing the pulsed and continuous CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, which means Reaction Kinetics in a Uniform Supersonic Flow) technique. The pulsed laser photolysis technique was used for generating OH radicals, whose time evolution was monitored by laser induced fluorescence. An increase of approximately 4 times was observed for k(21 K) with respect to k(10^7 K). With respect to k(300 K), the OH-reactivity at 21 K is enhanced by two orders of magnitude. The obtained T-expression in the investigated temperature range is k(T) = (2.1 ± 0.5) × 10^-11 (T/300 K)-(0.71±0.10) cm^3 molecule^-1 s^-1. In addition, the pressure dependence of k(T) has been investigated at several temperatures between 21 K and 90 K. No pressure dependence of k(T) was observed in the investigated ranges. This may imply that this reaction is purely bimolecular or that the high-pressure limit is reached at the lowest total pressure experimentally accessible in our system. From our results, k(T) at usual IS temperatures (˜10-100 K) is confirmed to be very fast. Typical rate coefficients can be considered to range within about 4 × 10^-11 cm^3 molecule^-1 s^-1 at 100 K and around 1 × 10^-10 cm^3 molecule^-1 s^-1 at 20 K. The extrapolation of k at the lowest temperatures of the dense molecular clouds of ISM is also discussed in this paper.

Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

Directory of Open Access Journals (Sweden)

Zhenlei Cai

2016-03-01

Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

Crystal structure of vanuralite, Al[(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}](OH) . 8.5H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Plasil, Jakub [Czech Academy of Sciences, Praha (Czech Republic). Inst. of Physics

2017-07-01

Vanuralite, Al[(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}](OH) . 8.5H{sub 2}O, is a rare supergene uranyl vanadate that forms during hydration-oxidation weathering of uraninite in oxide zones of U deposits. On the basis of single-crystal X-ray diffraction data it is monoclinic, space group P2{sub 1}/n, with a = 10.4637(10), b = 8.4700(5), c = 20.527(2) Aa, β = 102.821(9) , V=1773.9(3) Aa{sup 3} and Z = 4, D{sub calc.} = 3.561 g cm{sup -3}. The structure of vanuralite (R = 0.058 for 2638 unique observed reflections) contains uranyl vanadate sheets of francevillite topology of the composition [(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}]{sup 2-}. Sheets are stacked perpendicular to c, and an interstitial complex {sup [6]}Al(OH)(H{sub 2}O){sub 4}(H{sub 2}O){sub 4.5}; adjacent structural sheets are linked through an extensive network of hydrogen bonds. Vanuralite is the most complex mineral among uranyl vanadates, with 961 bits/cell. The scarcity of occurrences is probably caused by the less common combination of elements present in the structure, as well as the relatively high complexity of the structure (compared to related minerals), arising namely from the complicated network of H-bonds.

Investigation into isomolar series of Al(NO/sub 3/)/sub 3/, Na/sub 3/VO/sub 4/ solution mixture and composition of solid phases

Energy Technology Data Exchange (ETDEWEB)

Chernysh, L F; Nakhodnova, A P; Makarova, R A [Donetskij Gosudarstvennyj Univ. (Ukrainian SSR)

1979-11-01

Conducted is investigation of properties of isomolar series of aluminium nitrate and sodium vanadate solutions at pH of the latter 12.5; 10.0; 7.0 and the temperature of 25 deg C using the methods of pH-metry, conductometry, ''seeming'' volume of precipitations, residual concentration of aluminium and vanadium. It is shown, that the composition property diagram of the system investigated does not reflect the true composition of solid-phase products of the reaction, which depends on the component ratio in solution. Bottom phases of isomolar series are mainly heterogeneous. At the excess of sodium vanadate solution and its high pH values conditions for the basic salt formation are created. At pH of the Na/sub 3/VO/sub 4/ solution of 12.5 and 10.0 and Al(NO/sub 3/)/sub 3/: Na/sub 3/VO/sub 4/ ratios 4:6 and 3:7 respectively obtained are the basic aluminium vanadates of the (AlOH)/sub 3/(VO/sub 4/)/sub 2/x 7.5H/sub 2/O and (AlOH)/sub 2/V/sub 2/O/sub 7/x5H/sub 2/O composition, some of their physicochemical properties being investigated.

Bifunctional behavior of Er3+ ions as the sintering additive and the fluorescent agent in Er3+ single doped γ-AlON transparent ceramics

International Nuclear Information System (INIS)

Wang, Ying; Xie, Xiumin; Qi, Jianqi; Wang, Shanshan; Wei, Nian; Lu, Zhongwen; Chen, Xingtao; Lu, Tiecheng

2016-01-01

We report on the sintering promoting and fluorescent activator roles of Er 3+ in AlON:Er 3+ transparent ceramics prepared by pressureless sintering with Er 2 O 3 and AlON powder. There shows that the transparency of samples varied with the content of Er 2 O 3 additive. The AlON:Er 3+ ceramics showed upconversion luminescence peaking at 546 nm, 662 nm and 840 nm under the 980 nm excitation due to transition of 4 S 3/2 / 2 H 11/2 → 4 I 15/2 , 4 F 9/2 → 4 I 15/2 and 4 S 3/2 / 2 H 11/2 → 4 I 13/2 of Er 3+ ions, respectively. The infrared spectra exhibited strong emission at 1534 nm corresponds to 4 I 13/2 → 4 I 15/2 transition. The mechanism of the IR and visible emission bands in AlON:Er 3+ ceramics are discussed, which suggest it should be attractive for lighting and display devices applications.

Ductility of Ni3Al doped with substitutional elements

International Nuclear Information System (INIS)

Hanada, S.; Chiba, A.; Guo, H.Z.; Watanabe, S.

1993-01-01

This paper reports on ductility of B-free Ni 3 Al alloys. Recrystallized Ni 3 Al binary alloys with Ni-rich compositions show appreciable ductility when an environmental effect is eliminated, while the alloys with stoichiometric and Al-rich compositions remain brittle. The ductility in the Ni-rich Ni 3 Al alloys is associated with low ordering energy. The additions of ternary elements, which are classified as γ formers, ductilize ternary Ni 3 Al alloys(Ni-23 at% Al-2 at% X, X = Pd, Pt, Cu and Co), whereas the additions of γ' formers embrittle ternary Ni 3 Al alloys(Ni-23 at% Al-2 at% X, X = Ta, Mo, Nb, Zr, Hf, V, Ti and Si). The additions of small amounts (less than 1 at%) of γ' formers such as Zr and Hf also ductilize as-cast ternary Ni 3 Al alloys. Ductility of Ni 3 Al alloys doped with substitutional elements is discussed in terms of ordering energy and microstructure

Morphology Controlled Synthesis of α-GaO(OH Nanoparticles: Thermal Conversion to Ga2O3 and Photocatalytic Properties

Directory of Open Access Journals (Sweden)

Ayse Dulda

2016-01-01

Full Text Available Morphology controlled α-GaO(OH particles have been synthesized via precipitation method which allows the tuning of relative growth rates of crystal facets. The effects of alkali addition rate and the type of alkali on the growth rates of the crystal facets during hydrolysis were also investigated. XRD and TG analysis confirmed that there was a phase transition from GaO(OH to Ga2O3 when precursor sample was calcined to 750°C. The single phase α-Ga2O3 was obtained after thermal treatment of NaOH precipitated precursor, while β-Ga2O3 was formed when the urea or NH4OH precipitated precursor was calcinated. Furthermore, the thermal, spectral, and photocatalytic properties connected to the crystal structure and morphology were discussed.

Rate Coefficient Measurements and Theoretical Analysis of the OH + ( E) CF3CH=CHCF3 Reaction.

Science.gov (United States)

Baasandorj, Munkhbayar; Marshall, Paul; Waterland, Robert L; Ravishankara, Akkihebbal R; Burkholder, James B

2018-04-25

Rate coefficients, k, for the gas-phase reaction of the OH radical with (E) CF3CH=CHCF3 ((E)-1,1,14,4,4-hexafluoro-2-butene, HFO-1336mzz(E)) were measured over a range of temperature (211-374 K) and bath gas pressure (20-300 Torr; He, N2) using a pulsed laser photolysis-laser induced fluorescence (PLP-LIF) technique. k1(T) was independent of pressure over this range of conditions with k1(296 K) = (1.31 ± 0.15) × 10 13 cm3 molecule 1 s 1 and k1(T) = (6.94 ± 0.80) × 10 13 exp[ (496 ± 10)/T] cm3 molecule 1 s 1, where the uncertainties are 2 and the pre-exponential term includes estimated systematic error. Rate coefficients for the OD reaction were also determined over a range of temperature (262-374 K) at 100 Torr (He). The OD rate coefficients were ~15% greater than the OH values and showed similar temperature dependent behavior with k2(T) = (7.52 ± 0.44) × 10 13 exp[ (476 ± 20)/T] and k2(296 K) = (1.53 ± 0.15) × 10 13 cm3 molecule 1 s 1. The rate coefficients for reaction 1 were also measured using a relative rate technique between 296 and 375 K with k1(296 K) measured to be (1.22 ± 0.1) × 10 13 cm3 molecule 1 s 1 in agreement with the PLP-LIF results. In addition, the 296 K rate coefficient for the O3 + (E) CF3CH=CHCF3 reaction was determined to be reaction and the significant decrease in OH reactivity compared to the (Z) CF3CH=CHCF3 stereoisomer reaction. The estimated atmospheric lifetime of (E) CF3CH=CHCF3, due to loss by reaction with OH, is estimated to be ~90 days, while the actual lifetime will depend on the location and season of its emission. Infrared absorption spectra of (E) CF3CH=CHCF3 were measured and used to estimate the 100-year time horizon global warming potentials (GWP) of 32 (atmospherically well-mixed) and 14 (lifetime-adjusted).

Synthesis of γ-Al2O3 nanowires through a boehmite precursor route

Indian Academy of Sciences (India)

has applications in absorbent, catalyst carrier and reinforce- ment of ceramic .... nia into the transparent solution, Al(OH)3 with colloidal form generates .... 99 1823. Zhou J, Deng S Z, Chen J, She J C and Xu N S 2002 Chem. Phys. Lett. 365 505.

In situ synthesis of 3D CoS nanoflake/Ni(OH)_2 nanosheet nanocomposite structure as a candidate supercapacitor electrode

International Nuclear Information System (INIS)

Li, Songzhan; Wen, Jian; Chen, Tian; Xiong, Liangbin; Wang, Jianbo; Fang, Guojia

2016-01-01

A three-dimensional (3D) CoS/Ni(OH)_2 nanocomposite structure based on CoS nanoflakes and two-dimensional (2D) Ni(OH)_2 nanosheets were in situ synthesized on Ni foam by a whole hydrothermal reaction and electrodeposition process. The 3D CoS/Ni(OH)_2 nanocomposite structures demonstrate the combined advantages of a sustained cycle stability of CoS and high specific capacitance from Ni(OH)_2. The obtained CoS/Ni(OH)_2 nanocomposite structures on Ni foam can directly serve as a binder-free electrode for a supercapacitor. For the 3D CoS/Ni(OH)_2 nanocomposite electrode, the high specific capacitance is 1837 F g"−"1 at a scan rate of 1 mV s"−"1, which is obviously higher than both the bare CoS electrode and Ni(OH)_2 electrode. The galvanostatic charge and discharge measurements illustrate that the 3D CoS/Ni(OH)_2 nanocomposite electrode possesses excellent cycle stability, and it keeps a 95.8% retention of the initial capacity after 5000 cycles. Electrochemical impedance spectroscopy measurements also confirm that the 3D CoS/Ni(OH)_2 nanocomposite electrode has better electrochemical characteristics. These remarkable performances can be attributed to the unique 3D nanoporous structure of CoS/Ni(OH)_2 which leads to a large accessible surface area and a high stability during long-term operation. In addition, 2D Ni(OH)_2 nanosheets in 3D nanocomposite structures can afford rapid mass transport and a strong synergistic effect of CoS and Ni(OH)_2 as individual compositions contribute to the high performance of the nanocomposite structure electrode. These results may promote the design and implementation of nanocomposite structures in advanced supercapacitors. (paper)

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O and anhydrous Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})

Energy Technology Data Exchange (ETDEWEB)

Yu, Na; Klepov, Vladislav V. [Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research (IEK-6), 52428 Jülich (Germany); Villa, Eric M. [Department of Chemistry, Creighton University, 2500 California Plaza, Omaha NE 68178 (United States); Bosbach, Dirk [Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research (IEK-6), 52428 Jülich (Germany); Suleimanov, Evgeny V. [Department of Chemistry, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Depmeier, Wulf [Institut für Geowissenschaften, Universität zu Kiel, 24118 Kiel (Germany); Albrecht-Schmitt, Thomas E., E-mail: albrecht-schmitt@chem.fsu.edu [Department of Chemistry and Biochemistry, Florida State University, 102 Varsity Way, Tallahassee, FL 32306-4390 (United States); Alekseev, Evgeny V., E-mail: e.alekseev@fz-juelich.de [Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research (IEK-6), 52428 Jülich (Germany); Institut für Kristallographie, RWTH Aachen University, 52066 Aachen (Germany)

2014-07-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O (α-, β-RbUAs) and the anhydrous phase Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions. - Graphical abstract: Three different layer geometries observed in the structures of Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})] and α- and β- Rb[UO{sub 2}(AsO{sub 3}OH)(AsO{sub 2}(OH){sub 2})]·H{sub 2}O. Two different coordination environments of uranium polyhedra (types I and II) are shown schematically on the top of the figure. - Highlights: • Three new uranyl arsenates were synthesized from the hydrothermal reactions. • The phases consist of the topologically identical but geometrically different layers. • Topotactic transitions were observed in the processes of mono-hyrates dehydration.

The Effects of Al and Ti Additions on the Structural Stability, Mechanical and Electronic Properties of D8m-Structured Ta5Si3

Directory of Open Access Journals (Sweden)

Linlin Liu

2016-05-01

Full Text Available In the present study, the influence of substitutional elements (Ti and Al on the structural stability, mechanical properties, electronic properties and Debye temperature of Ta5Si3 with a D8m structure were investigated by first principle calculations. The Ta5Si3 alloyed with Ti and Al shows negative values of formation enthalpies, indicating that these compounds are energetically stable. Based on the values of formation enthalpies, Ti exhibits a preferential occupying the Ta4b site and Al has a strong site preference for the Si8h site. From the values of the bulk modulus (B, shear modulus (G and Young’s modulus (E, we determined that both Ti and Al additions decrease both the shear deformation resistance and the elastic stiffness of D8m structured Ta5Si3. Using the shear modulus/bulk modulus ratio (G/B, Poisson’s ratio (υ and Cauchy’s pressure, the effect of Ti and Al additions on the ductility of D8m-structured Ta5Si3 are explored. The results show that Ti and Al additions reduce the hardness, resulting in solid solution softening, but improve the ductility of D8m-structured Ta5Si3. The electronic calculations reveal that Ti and Al additions change hybridization between Ta-Si and Si-Si atoms for the binary D8m-structured Ta5Si3. The new Ta-Al bond is weaker than the Ta-Si covalent bonds, reducing the covalent property of bonding in D8m-structured Ta5Si3, while the new strong Ti4b-Ti4b anti-bonding enhances the metallic behavior of the binary D8m-structured Ta5Si3. The change in the nature of bonding can well explain the improved ductility of D8m-structured Ta5Si3 doped by Ti and Al. Moreover, the Debye temperatures, ΘD, of D8m-structured Ta5Si3 alloying with Ti and Al are decreased as compared to the binary Ta5Si3.

Solid-state {sup 27}Al and {sup 29}Si NMR investigations on Si-substituted hydrogarnets

Energy Technology Data Exchange (ETDEWEB)

Rivas Mercury, J.M. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Pena, P. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain)]. E-mail: ppena@icv.csic.es; Aza, A.H. de [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Turrillas, X. [Instituto de Ciencias de la Construccion Eduardo Torroja, CSIC, Serrano Galvache, 4, 28033 Madrid (Spain); Sobrados, I. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain); Sanz, J. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain)

2007-02-15

Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} hydrates prepared by a reaction in the presence of D{sub 2}O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by {sup 29}Si and {sup 27}Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The {sup 29}Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} was followed by {sup 27}Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data.

Kinetic isotope effects in the gas phase reactions of OH and Cl with CH3Cl, CD3Cl, and 13CH3Cl

Directory of Open Access Journals (Sweden)

A. A. Gola

2005-01-01

Full Text Available The kinetic isotope effects in the reactions of CH3Cl, 13CH3Cl and CD3Cl with OH radicals and Cl atoms were studied in relative rate experiments at 298±2 K and 1013±10 mbar. The reactions were carried out in a smog chamber using long path FTIR detection and the spectroscopic data analyzed employing a non-linear least squares spectral fitting method using measured high-resolution infrared spectra as well as absorption cross sections from the HITRAN database. The reaction rates of 13CH3Cl and CD3Cl with OH and Cl were determined relative to CH3Cl as: kOH+CH3ClkOH+CH3Cl/kOH+13CH3Cl}kOH+13CH3Cl=1.059±0.008, kOH+CH3ClkOH+CH3Cl/kOH+CD3ClkOH+CD3Cl=3.9±0.4, kCl+CH3ClkCl+CH3Cl/kCl+13CH3ClkCl+13CH3Cl =1.070±0.010 and kCl+CH3ClkCl+CH3Cl/kCl+CD3ClkCl+CD3Cl=4.91±0.07. The uncertainties given are 2σ from the statistical analyses and do not include possible systematic errors. The unexpectedly large 13C kinetic isotope effect in the OH reaction of CH3Cl has important implications for the global emission inventory of CH3Cl.

Determining rotational temperatures from the OH(8-3 band, and a comparison with OH(6-2 rotational temperatures at Davis, Antarctica

Directory of Open Access Journals (Sweden)

F. Phillips

2004-04-01

Full Text Available Rotational temperatures derived from the OH(8–3 band may vary by ~18K depending on the choice of transition probabilities. This is of concern when absolute temperatures or trends determined in combination with measurements of other hydroxyl bands are important. In this paper, measurements of the OH(8–3 temperature-insensitive Q/P and R/P line intensity ratios are used to select the most appropriate transition probabilities for use with this band. Aurora, airglow and solar and telluric absorption in the OH(8–3 band are also investigated. Water vapour absorption of P₁(4, airglow or auroral contamination of P₁(2 and solar absorption in the vicinity of P₁(5 are concerns to be considered when deriving rotational temperatures from this band.

A comparison is made of temperatures derived from OH(6–2 and OH(8–3 spectra collected alternately at Davis (69° S, 78° E in 1990. An average difference of ~4K is found, with OH(8–3 temperatures being warmer, but a difference of this magnitude is within the two sigma uncertainty limit of the measurements.

Key words. Atmospheric composition and structure airglow and aurora; pressure, density, and temperature

Pb4(OH)4(BrO3)3(NO3): An Example of SHG Crystal in Metal Bromates Containing π-Conjugated Planar Triangle.

Science.gov (United States)

Kong, Fang; Hu, Chun-Li; Liang, Ming-Li; Mao, Jiang-Gao

2016-01-19

The first example of SHG crystal in the metal bromates containing π-conjugated planar triangle systems, namely, Pb4(OH)4(BrO3)3(NO3), was successfully synthesized via the hydrothermal method. Furthermore, a single crystal of centrosymmetric Pb8O(OH)6(BrO3)6(NO3)2·H2O was also obtained. Both compounds contain similar [Pb4(OH)4] cubane-like tetranuclear clusters, but they display different one-dimensional (1D) chain structures. Pb4(OH)4(BrO3)3(NO3) features a zigzag [Pb4(OH)4(BrO3)3](+) 1D chain, while Pb8O(OH)6(BrO3)6(NO3)2·H2O is composed of two different orthogonal chains: the linear [Pb4(OH)4(BrO3)2](2+) 1D chain along the b-axis and the zigzag [Pb4O2(OH)2(BrO3)4](2-) 1D chain along the a-axis. The NO3 planar triangles of the compounds are all isolated and located in the spaces of the structures. Pb4(OH)4(BrO3)3(NO3) exhibits the first example of SHG crystal in the metal bromates with π-conjugated planar triangle. The second-harmonic generation (SHG) efficiency of Pb4(OH)4(BrO3)3(NO3) is approximately equal to that of KDP and it is phase-matchable. Dipole moment and theory calculations indicate that BrO3, NO3, and PbO4 groups are the origin of its SHG efficiency, although some of the contributions cancel each other out.

The effect of boron additions on irradiation-induced order changes in Ni3Al intermetallic compounds

International Nuclear Information System (INIS)

Njah, N.; Gilbon, D.; Dimitrov, O.

1995-01-01

The effects of boron additions (0.1 wt%) on the kinetics of atomic order changes in a Ni 76 Al 24 intermetallic compound, under 1 MeV electron irradiation, were investigated at temperatures of 293 K and 410 K and displacement rates of 0.09 x 10 -3 to 4.7 x 10 -3 dpa.s -1 . In these irradiation conditions, a state of residual order was obtained for long irradiation times, characterized by a steady state order parameter S∞; it corresponds to a competition between two opposite features: irradiation disordering and thermal reordering enhanced by irradiation. Boron additions did not affect the efficiency of irradiation-induced disordering: the disordering cross-section (or, equivalently, the number of replacements per displacement var-epsilon) were comparable with and without a boron addition. By contrast, the S∞ values at 293 K were much lower in the alloy containing boron. Since boron does not change the disordering rate, the large difference between the values obtained in undoped and in boron-doped alloys shows that the reordering rate is strongly reduced by the presence of boron. Thus, boron modifies the mobility of the defects responsible for the irradiation-enhanced diffusion. The data on dislocation-loop size and the reordering kinetics suggest that vacancies are trapped by boron at low temperatures and immobilized, probably by the formation of a boron-vacancy complex. The effect becomes weaker at higher displacement rates and higher temperatures, probably due to the boron-vacancy complexes becoming unstable. It is proposed that two different reordering mechanisms may be operative at 293 K, according to the presence of boron: reordering is promoted by vacancy migration in the Ni 76 Al 24 alloy, whereas in the Ni 76 Al 24 (0.1 wt%B) alloy, it is promoted by the migration of split-interstitials or/and of low-mobility vacancy-boron complexes

Inhibition of ammonia poisoning by addition of platinum to Ru/α-Al2 O3 for preferential CO oxidation in fuel cells.

Science.gov (United States)

Sato, Katsutoshi; Yagi, Sho; Zaitsu, Shuhei; Kitayama, Godai; Kayada, Yuto; Teramura, Kentaro; Takita, Yusaku; Nagaoka, Katsutoshi

2014-12-01

In polymer electrolyte fuel cell (PEFC) systems, small amounts of ammonia (NH3 ) present in the reformate gas deactivate the supported ruthenium catalysts used for preferential oxidation (PROX) of carbon monoxide (CO). In this study, we investigated how the addition of a small amount of platinum to a Ru/α-Al2 O3 catalyst (Pt/Ru=1:9 w/w) affected the catalyst's PROX activity in both the absence and the presence of NH3 (130 ppm) under conditions mimicking the reformate conditions during steam reforming of natural gas. The activity of undoped Ru/α-Al2 O3 decreased sharply upon addition of NH3 , whereas Pt/Ru/α-Al2 O3 exhibited excellent PROX activity even in the presence of NH3 . Ruthenium K-edge X-ray absorption near-edge structure (XANES) spectra indicated that in the presence of NH3 , some of the ruthenium in the undoped catalyst was oxidized in the presence of NH3 , whereas ruthenium oxidation was not observed with Pt/Ru/α-Al2 O3 . These results suggest that ruthenium oxidation is retarded by the platinum, so that the catalyst shows high activity even in the presence of NH3 . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous measurements of the OH(8,3) band and 015577A airglow emissions

International Nuclear Information System (INIS)

Takahashi, H.; Sahai, Y.; Clemesha, B.R.; Simonich, D.M.; Batista, P.P.; Teixeira, N.R.

1981-01-01

Simultaneous measurements of the night airglow OH(8,3) band and OI 5577A have been made at Cachoeira Paulista (22.7 0 S, 45,2 0 W) during June-August 1976. Correlations between the nocturnal variations of these emissions and also with the OH rotational temperature are presented. It is found that OH (8,3) is correlated with the rotational temperature but with a time lag of about 1 hour. The variations of 5577A lead the OH (8,3) by about 2 to 3 hours. The rotational temperature co-varies with 5577A, rather than OH (8,3) and there is no significant time lag. Based on the correlation study, the nocturnal variations of the two emissions can be explained by the atmospheric density perturbation caused by solar tides and internal gravity waves. (Author) [pt

Processing of spent NiW/Al{sub 2}O{sub 3} catalysts

Energy Technology Data Exchange (ETDEWEB)

Paulino, Jessica Frontino; Afonso, Julio Carlos, E-mail: julio@iq.ufrj.br [Departamento de Quimica Analitica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, RJ (Brazil); Cunha, Jose Waldemar Silva Dias da [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), RJ (Brazil). Departamento de Quimica e Materiais Nucleares

2013-09-01

Spent oxidized (500 deg C, 5 h) commercial NiW/Al{sub 2}O{sub 3} catalysts were processed using two different routes: a) fusion with NaOH (650 deg C, 1 h), the roasted mass was leached in water; b) leaching with HCl or H{sub 2}SO{sub 4} (70 deg C, 1-3 h). HCl was the best leachant. In both routes, soluble tungsten was extracted at pH 1 with Alamine 336 (10 vol.% in kerosene) and stripped with 2 mol L{sup -1} NH{sub 4}OH (25 deg C, one stage, aqueous/organic ratio = 1 v/v). Tungsten was isolated as ammonium paratungstate at very high yield (> 97.5%). The elements were better separated using the acidic route. (author)

Microstructure and Properties of Fe3Al-Fe3AlC x Composite Prepared by Reactive Liquid Processing

Science.gov (United States)

Verona, Maria Nalu; Setti, Dalmarino; Paredes, Ramón Sigifredo Cortés

2018-04-01

A Fe3Al-Fe3AlC x composite was prepared using reactive liquid processing (RLP) through controlled mixture of carbon steel and aluminum in the liquid state. The microstructure and phases of the composite were assessed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, optical microscopy, and differential scanning calorimetry. In addition, the density, hardness, microhardness, and elastic modulus were evaluated. The Fe3Al-Fe3AlC x composite consisted of 65 vol pct Fe3Al and 35 vol pct Fe3AlC x ( κ). The κ phase contained 10.62 at. pct C, resulting in the stoichiometry Fe3AlC0.475. The elastic modulus of the Fe3Al-Fe3AlC0.475 composite followed the rule of mixtures. The RLP technique was shown to be capable of producing Fe3Al-Fe3AlC0.475 with a microstructure and properties similar to those achieved using other processing techniques reported in the literature.

Effect of the AlCr20 Addition on the Microstructure of Secondary AlSi7Mg0.3 Alloy

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2014-06-01

Full Text Available This paper deals with influence of chrome addition and heat treatment on segregation of iron based phases in the secondary alloy AlSi7Mg0.3 microstructure by chrome and heat treatment. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type or by heat treatment. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases.

Electrodeposition of Al from a 1-butylpyrrolidine-AlCl3 ionic liquid

Directory of Open Access Journals (Sweden)

Giridhar Pulletikurthi

2015-12-01

Full Text Available The addition of 1-butylpyrrolidine to AlCl3 results in the formation of an electrolyte that is suited to Al deposition. The feasibility of electrodepositing Al from the synthesized electrolyte was investigated. Several compositions of AlCl3 and 1-butylpyrrolidine were prepared for this purpose. These mixtures show a different phase behavior at various compositions of AlCl3 and 1-butylpyrrolidine. IR, Raman and NMR spectroscopy were employed to characterize the synthesized liquids. Among the prepared compositions, 1:1.2 mol ratio of 1-butylpyrrolidine:AlCl3 and the upper phase of 1:1.3 mol ratio of 1-butylpyrrolidine:AlCl3 were found to be suitable for Al electrodeposition at room temperature (RT. Uniform and thick (~µm thick layers of Al were obtained on copper at RT. Al deposition occured from the cationic species of AlCl3−xLy+ (where x≤2, y=1–2, and L=1-butylpyrrolidine in this electrolyte. This behavior is contrary to the well investigated classic AlCl3 based ionic liquids, where the deposition of Al occurs mainly from anionic Al2Cl7− ions.

The vitamin D analogue ED71 but Not 1,25(OH2D3 targets HIF1α protein in osteoclasts.

Directory of Open Access Journals (Sweden)

Yuiko Sato

Full Text Available Although both an active form of the vitamin D metabolite, 1,25(OH2D3, and the vitamin D analogue, ED71 have been used to treat osteoporosis, anti-bone resorbing activity is reportedly seen only in ED71- but not in 1,25(OH2D3 -treated patients. In addition, how ED71 inhibits osteoclast activity in patients has not been fully characterized. Recently, HIF1α expression in osteoclasts was demonstrated to be required for development of post-menopausal osteoporosis. Here we show that ED71 but not 1,25(OH2D3, suppress HIF1α protein expression in osteoclasts in vitro. We found that 1,25(OH2D3 or ED71 function in osteoclasts requires the vitamin D receptor (VDR. ED71 was significantly less effective in inhibiting M-CSF and RANKL-stimulated osteoclastogenesis than was 1,25(OH2D3 in vitro. Downregulation of c-Fos protein and induction of Ifnβ mRNA in osteoclasts, both of which reportedly block osteoclastogenesis induced by 1,25(OH2D3 in vitro, were both significantly higher following treatment with 1,25(OH2D3 than with ED71. Thus, suppression of HIF1α protein activity in osteoclasts in vitro, which is more efficiently achieved by ED71 rather than by 1,25(OH2D3, could be a reliable read-out in either developing or screening reagents targeting osteoporosis.

The Effects of Dy Addition on Microstructure and Mechanical Properties of the As-Cast Mg-5Al-3Ca-2Nd Alloys.

Science.gov (United States)

Son, Hyeon-Taek; Kim, Yong-Ho; Yoo, Hyo-Sang

2018-03-01

The microstructure of the as-cast Mg-5Al-3Ca-2Nd-xDy alloys consists of α-Mg matrix, (Mg, Al)2Ca eutectic phase, Al-Nd and Al-Dy intermetallic compounds. α-Mg matrix morphology was changed from dendritic to equiaxed with the increase Dy addition. And grain size was remarkably refined. As Dy content was increased, yield strength was improved due to the refined grains and the homogeneous distribution of Al-Dy phase.

Experimental cation redistribution in the tourmaline lucchesiite, CaFe2 + 3Al6(Si6O18)(BO3)3(OH)3O

Science.gov (United States)

Bosi, Ferdinando; Skogby, Henrik; Hålenius, Ulf; Ciriotti, Marco E.

2018-02-01

Natural Mg-rich lucchesiite was thermally treated in air and hydrogen atmosphere up to 800 °C to study potential changes in Fe-, Mg- and Al ordering over the octahedrally coordinated Y- and Z-sites, and to explore possible applications to intracrystalline geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that thermal treatment of lucchesiite results in an increase of Fetot contents at Z balanced by an increase of Mg and Al at Y. This process is accompanied by a significant deprotonation of the O3 anion site. The Fe order-disorder reaction depends more on temperature, than on redox conditions. During heat treatment in H2, reduction of Fe3+ to Fe2+ was not observed despite strongly reducing conditions, indicating that the f O2 conditions do not exclusively control the Fe oxidation state at the present experimental conditions. On the basis of this and previous studies, the intersite order-disorder process induced by thermal treatment indicates that Fe redistribution is an important factor for Fe-Mg-Al-exchange and is significant at temperatures around 800 °C. As a result, Fe-Mg-Al intersite order-disorder is sensitive to temperature variations, whereas geothermometers based solely on Mg-Al order-disorder appear insensitive and involve large uncertainties. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks, and indicate that successful tourmaline geothermometers may be developed by thermal calibration of the Fe-Mg-Al order-disorder reaction.

OH yields from the CH3CO+O-2 reaction using an internal standard\\ud

OpenAIRE

Carr, S.A.; Baeza-Romero, M.T.; Blitz, M.A.; Pilling, M.J.; Heard, D.E.; Seakins, P.W.

2007-01-01

Laser flash photolysis of CH3C(O)OH at 248 nm was used to create equal zero time yields of CH3CO and OH. The absolute OH yield from the CH3CO + O2 (+M) reaction was determined by following the OH temporal profile using the zero time\\ud OH concentration as an internal standard. The OH yield from CH3CO + O2 (+M) was observed to decrease with increasing pressure with an extrapolated zero pressure yield\\ud close to unity (1.1 ± 0.2, quoted uncertainties correspond to 95% confidence limits). The r...

Observations of OH and HO2 radicals in coastal Antarctica

Directory of Open Access Journals (Sweden)

S. J.-B. Bauguitte

2007-08-01

Full Text Available OH and HO2 radical concentrations have been measured in the boundary layer of coastal Antarctica for a six-week period during the austral summer of 2005. The measurements were performed at the British Antarctic Survey's Halley Research Station (75° 35' S, 26° 19' W, using the technique of on-resonance laser-induced fluorescence to detect OH, with HO2 measured following chemical conversion through addition of NO. The mean radical levels were 3.9×105 molecule cm−3 for OH, and 0.76 ppt for HO2 (ppt denotes parts per trillion, by volume. Typical maximum (local noontime levels were 7.9×105 molecule cm−3 and 1.50 ppt for OH and HO2 respectively. The main sources of HOx were photolysis of O3 and HCHO, with potentially important but uncertain contributions from HONO and higher aldehydes. Of the measured OH sinks, reaction with CO and CH4 dominated, however comparison of the observed OH concentrations with those calculated via the steady state approximation indicated that additional co-reactants were likely to have been present. Elevated levels of NOx resulting from snowpack photochemistry contributed to HOx cycling and enhanced levels of OH, however the halogen oxides IO and BrO dominated the CH3O2 – HO2 – OH conversion in this environment, with associated ozone destruction.

Oxalate molecule as the trap for gamma-irradiation energy in the amorphous aluminosilicate Al2(OH)6H4SiO4

International Nuclear Information System (INIS)

Nothig-Laslo, V.; Horvath, L.; Bilinski, H.

1990-01-01

Paramagnetic species which were the products of gamma irradiation at 77 K and at room temperature were studied by ESR spectroscopy in the amorphous aluminosilicate, Al2(OH)6H4SiO4, prepared in the presence and in the absence of oxalate ion. The aluminosilicate precipitated from the solution containing the oxalate ion in 10(-4) mol dm-3 concentration contained the oxalate only in trace amounts. When gamma-irradiated at 77 K and at room temperature, this compound gave the stable paramagnetic species represented by the single ESR line centered at g = 2.000. We ascribe this spectrum to the CO2- radical formed from the oxalate ion. The same aluminosilicate prepared in the absence of the oxalate either produced no stable paramagnetic product after gamma irradiation at room temperature or resulted in composite ESR spectra, indicating the presence of several paramagnetic species if irradiated at 77 K. Complex ESR spectra were transformed by heating to the stable paramagnetic centers which differed from the one obtained from oxalate ion. We conclude that in Al2(OH)6H4SiO4 oxalate acts as a trap for the gamma-radiation energy

Upconversion luminescence of Er3+/Yb3+ doped Sr5(PO4)3OH phosphor powders

Science.gov (United States)

Mokoena, P. P.; Swart, H. C.; Ntwaeaborwa, O. M.

2018-04-01

Sr5(PO4)3OH co-doped with Er3+and Yb3+ powder phosphors were synthesized by urea combustion method. The crystal structure was analyzed using X-ray diffraction (XRD). Particle morphology was analyzed using a Jeol JSM 7800F thermal field emission scanning electron microscope (FE-SEM) and the chemical composition analysis was carried out using an Oxford Instruments AzTEC energy dispersive spectrometer (EDS) attached to the FE-SEM. Upconversion emission was measured by using a FLS980 Spectrometer equipped with a 980 nm NIR laser as the excitation source, and a photomultiplier (PMT) detector. The XRD data of the Sr5(PO4)3OH powder exhibited characteristic diffraction patterns of the hexagonal structure referenced in the standard JCPDS card number 00-033-1348. The sharp peaks revealed the formation of crystalline Sr5(PO4)3OH. The powders were made up of hexagonal nanospheres. The enhanced red emission due to the 4F9/2 → 4I15/2 transitions of Er3+ was observed and was attributed to up conversion (UC) energy transfer from Yb3+. The upconversion energy transfer mechanism from Yb3+ to Er3+ is discussed.

Secondary organic aerosol formation from in situ OH, O3, and NO3 oxidation of ambient forest air in an oxidation flow reactor

Science.gov (United States)

Palm, Brett B.; Campuzano-Jost, Pedro; Day, Douglas A.; Ortega, Amber M.; Fry, Juliane L.; Brown, Steven S.; Zarzana, Kyle J.; Dube, William; Wagner, Nicholas L.; Draper, Danielle C.; Kaser, Lisa; Jud, Werner; Karl, Thomas; Hansel, Armin; Gutiérrez-Montes, Cándido; Jimenez, Jose L.

2017-04-01

Ambient pine forest air was oxidized by OH, O3, or NO3 radicals using an oxidation flow reactor (OFR) during the BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen - Rocky Mountain Biogenic Aerosol Study) campaign to study biogenic secondary organic aerosol (SOA) formation and organic aerosol (OA) aging. A wide range of equivalent atmospheric photochemical ages was sampled, from hours up to days (for O3 and NO3) or weeks (for OH). Ambient air processed by the OFR was typically sampled every 20-30 min, in order to determine how the availability of SOA precursor gases in ambient air changed with diurnal and synoptic conditions, for each of the three oxidants. More SOA was formed during nighttime than daytime for all three oxidants, indicating that SOA precursor concentrations were higher at night. At all times of day, OH oxidation led to approximately 4 times more SOA formation than either O3 or NO3 oxidation. This is likely because O3 and NO3 will only react with gases containing C = C bonds (e.g., terpenes) to form SOA but will not react appreciably with many of their oxidation products or any species in the gas phase that lacks a C = C bond (e.g., pinonic acid, alkanes). In contrast, OH can continue to react with compounds that lack C = C bonds to produce SOA. Closure was achieved between the amount of SOA formed from O3 and NO3 oxidation in the OFR and the SOA predicted to form from measured concentrations of ambient monoterpenes and sesquiterpenes using published chamber yields. This is in contrast to previous work at this site (Palm et al., 2016), which has shown that a source of SOA from semi- and intermediate-volatility organic compounds (S/IVOCs) 3.4 times larger than the source from measured VOCs is needed to explain the measured SOA formation from OH oxidation. This work suggests that those S/IVOCs typically do not contain C = C bonds. O3 and NO3 oxidation produced SOA with elemental O : C and H : C

Low 25(OH)D3 levels are associated with total adiposity, metabolic syndrome, and hypertension in Caucasian children and adolescents.

Science.gov (United States)

Pacifico, L; Anania, C; Osborn, J F; Ferraro, F; Bonci, E; Olivero, E; Chiesa, C

2011-10-01

Evidence of the association between vitamin D and cardiovascular risk factors in the young is limited. We therefore assessed the relationships between circulating 25-hydroxyvitamin D(3) (25(OH)D(3)) and metabolic syndrome (MetS), its components, and early atherosclerotic changes in 452 (304 overweight/obese and 148 healthy, normal weight) Caucasian children. We determined serum 25(OH)D(3) concentrations in relation to MetS, its components (central obesity, hypertension, low high-density lipoprotein (HDL)-cholesterol, hypertriglyceridemia, glucose impairment, and/or insulin resistance (IR)), and impairment of flow-mediated vasodilatation (FMD) and increased carotid intima-media thickness (cIMT) - two markers of subclinical atherosclerosis. Higher 25(OH)D(3) was significantly associated with a reduced presence of MetS. Obesity, central obesity, hypertension, hypertriglyceridemia, low HDL-cholesterol, IR, and MetS were all associated with increased odds of having low 25(OH)D(3) levels, after adjustment for age, sex, and Tanner stage. After additional adjustment for SDS-body mass index, elevated blood pressure (BP) and MetS remained significantly associated with low vitamin D status. The adjusted odds ratio (95% confidence interval) for those in the lowest (27 ng/ml) of 25(OH)D(3) for hypertension was 1.72 (1.02-2.92), and for MetS, it was 2.30 (1.20-4.40). A similar pattern of association between 25(OH)D(3), high BP, and MetS was observed when models were adjusted for waist circumference. No correlation was found between 25(OH)D(3) concentrations and either FMD or cIMT. Low 25(OH)D(3) levels in Caucasian children are inversely related to total adiposity, MetS, and hypertension.

Microstructure of two phases alloy Al{sub 3}Ti/Al{sub 3}Ti{sub 0.75}Fe{sub 0.25}; Microestructura de una aleacion de dos fases Al{sub 3}Ti/Al{sub 3}Ti{sub 0.75}Fe{sub 0.25}

Energy Technology Data Exchange (ETDEWEB)

Angeles, C; Rosas, G; Perez, R [Instituto Nacional de Investigaciones Nucleares, Departamento de Sintesis y Caracterizacion de Materiales, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1998-07-01

The titanium-aluminium system presents three intermetallic compounds from those Al{sub 3}Ti is what less attention has received. The objective of this work is to generate and characterize the microstructure of multiphase alloys nearby to Al{sub 3}Ti compound through Fe addition as alloying. This is because it has been seen that little precipitates of Al{sub 2}Ti phase over Al{sub 3}Ti intermetallic compound increases its ductility. (Author)

A combined high-temperature experimental and theoretical kinetic study of the reaction of dimethyl carbonate with OH radicals

KAUST Repository

Khaled, Fathi; Giri, Binod; Szőri, Milá n; Mai, Tam V.-T.; Huynh, Lam K.; Farooq, Aamir

2017-01-01

The reaction kinetics of dimethyl carbonate (DMC) and OH radicals were investigated behind reflected shock waves over the temperature range of 872-1295 K and at pressures near 1.5 atm. Reaction progress was monitored by detecting OH radicals at 306.69 nm using a UV laser absorption technique. The rate coefficients for the reaction of DMC with OH radicals were extracted using a detailed kinetic model developed by Glaude et al. (Proc. Combust. Inst. 2005, 30(1), 1111-1118). The experimental rate coefficients can be expressed in Arrhenius form as: kexpt'l = 5.15 × 10(13) exp(-2710.2/T) cm(3) mol(-1) s(-1). To explore the detailed chemistry of the DMC + OH reaction system, theoretical kinetic analyses were performed using high-level ab initio and master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) calculations. Geometry optimization and frequency calculations were carried out at the second-order Møller-Plesset (MP2) perturbation level of theory using Dunning's augmented correlation consistent-polarized valence double-ζ basis set (aug-cc-pVDZ). The energy was extrapolated to the complete basis set using single point calculations performed at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory. For comparison purposes, additional ab initio calculations were also carried out using composite methods such as CBS-QB3, CBS-APNO, G3 and G4. Our calculations revealed that the H-abstraction reaction of DMC by OH radicals proceeds via an addition elimination mechanism in an overall exothermic process, eventually forming dimethyl carbonate radicals and H2O. Theoretical rate coefficients were found to be in excellent agreement with those determined experimentally. Rate coefficients for the DMC + OH reaction were combined with literature rate coefficients of four straight chain methyl ester + OH reactions to extract site-specific rates of H-abstraction from methyl esters by OH radicals.

Mechanism and kinetic properties for the OH-initiated atmospheric oxidation degradation of 9,10-Dichlorophenanthrene.

Science.gov (United States)

Dang, Juan; Shi, Xiangli; Zhang, Qingzhu; Hu, Jingtian; Wang, Wenxing

2015-02-01

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) have become a serious environmental concern due to their widespread occurrence and dioxin-like toxicities. In this work, the mechanism of the OH-initiated atmospheric oxidation degradation of 9,10-dichlorophenanthrene (9,10-Cl₂Phe) was investigated by using high-accuracy quantum chemistry calculations. The rate constants of the crucial elementary reactions were determined by the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The theoretical results were compared with the available experimental data. The main oxidation products are a group of ring-retaining and ring-opening compounds including chlorophenanthrols, 9,10-dichlorophenanthrene-3,4-dione, dialdehydes, chlorophenanthrenequinones, nitro-9,10-Cl₂Phe and epoxides et al. The overall rate constant of the OH addition reaction is 2.35 × 10(-12)cm(3) molecule(-1)s(-1) at 298 K and 1 atm. The atmospheric lifetime of 9,10-Cl₂Phe determined by OH radicals is about 5.05 days. This study provides a comprehensive investigation of the OH-initiated oxidation degradation of 9,10-Cl₂Phe and should contribute to clarifying its atmospheric fate. Copyright © 2014 Elsevier B.V. All rights reserved.

CF3CH(ONO)CF3: Synthesis, IR spectrum, and use as OH radical source for kinetic and mechanistic studies

DEFF Research Database (Denmark)

Andersen, Mads Peter Sulbæk; Hurley, MD; Ball, JC

2003-01-01

The synthesis, IR spectrum, and first-principles characterization of CF3CH(ONO)CF3 as well as its use as an OH radical source in kinetic and mechanistic studies are reported. CF3CH(ONO)CF3 exists in two conformers corresponding to rotation about the RCO-NO bond. The more prevalent trans conformer......C(O)CF3 and, by implication, OH radicals in 100% yield. CF3CH(ONO)CF3 photolysis is a convenient source of OH radicals in the studies of the yields of CO, CO2, HCHO, and HC(O)OH products which can be difficult to measure using more conventional OH radical sources (e.g., CH3ONO photolysis). CF3CH...

Direct observation of unimolecular decay of CH{sub 3}CH{sub 2}CHOO Criegee intermediates to OH radical products

Energy Technology Data Exchange (ETDEWEB)

Fang, Yi; Liu, Fang; Lester, Marsha I., E-mail: milester@sas.upenn.edu [Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Klippenstein, Stephen J. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2016-07-28

The unimolecular decay of carbonyl oxide intermediates, known as Criegee intermediates, produced in alkene ozonolysis is a significant source of OH radicals in the troposphere. Here, the rate of appearance of OH radical products is examined directly in the time-domain for a prototypical alkyl-substituted Criegee intermediate, CH{sub 3}CH{sub 2}CHOO, following vibrational activation under collision-free conditions. Complementary statistical Rice–Ramsperger–Kassel–Marcus calculations of the microcanonical unimolecular decay rate for CH{sub 3}CH{sub 2}CHOO are also carried out at energies in the vicinity of the barrier for 1,4 hydrogen atom transfer that leads to OH products. Tunneling through the barrier, derived from high level electronic structure calculations, contributes significantly to the decay rate. Infrared transitions of CH{sub 3}CH{sub 2}CHOO are identified in the CH stretch overtone region, which are detected by ultraviolet laser-induced fluorescence of the resultant OH products. The features observed are attributed to CH vibrational excitations and conformational forms utilizing insights from theory. Both experiment and theory yield unimolecular decay rates for CH{sub 3}CH{sub 2}CHOO of ca. 10{sup 7} s{sup −1}, which are slower than those obtained for syn-CH{sub 3}CHOO or (CH{sub 3}){sub 2}COO reported previously [Fang et al., J. Chem. Phys. 144, 061102 (2016)] at similar energies. Master equation modeling is also utilized to predict the thermal decay rate of CH{sub 3}CH{sub 2}CHOO under atmospheric conditions, giving a rate of 279 s{sup −1} at 298 K.

Control of interfacial intermetallic compounds in Fe–Al joining by Zn addition

Energy Technology Data Exchange (ETDEWEB)

Yang, J. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Li, Y.L., E-mail: liyulong1112ster@gmail.com [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Zhang, H. [Key Laboratory of Robot and Welding Automation of Jiangxi Province, School of Mechanical and Electrical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Guo, W. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); School of Mechanical Engineering and Automation, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Zhou, Y. [Center for Advanced Materials Joining, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada)

2015-10-01

By Zn addition to the fusion zone, the interfacial intermetallic compounds (IMCs) of laser Al/steel joint changed from layered Fe{sub 2}Al{sub 5} and needle-like FeAl{sub 3} to layered Fe{sub 2}Al{sub 5−x}Zn{sub x} and dispersed FeZn{sub 10} with minor Al-rich amorphous phase. This resulted in an improvement in the joint strength and the change of failure mode.

A magneto-optically modulated CH3OH laser for Faraday rotation measurements in tokamaks

International Nuclear Information System (INIS)

Mansfield, D.K.; Johnson, L.C.

1981-01-01

Distortion-free intracavity polarization modulation of an optically pumped CH3OH laser is shown to be viable. The possible use of this modulation technique to make a multichannel Faraday rotation measurement on a tokamak device is discussed. In addition, the CdTe Faraday modulator employed in this study is shown to have an anomalously large Verdet constant

The influence of chromium additions on order and ductility in Fe3Al intermetallic

International Nuclear Information System (INIS)

Morris, D.G.; Dadras, M.; Morris, M.A.

1993-01-01

It has previously been shown that the addition of Cr to the Fe 3 Al alloy can lead to improvements in ductility. Initial interpretations of this effect were based on changes in the fault energies and dislocation configurations, but recently the influence of environmental attack has been invoked. In the present study the role of Cr and other elemental additions on the state of order, dislocation dissociations and configurations, and on ductility has been examined under conditions where environmental attack should not be important. The addition of Cr is shown to have only a minor affect on ordering kinetics, fault energies and dislocation configurations. However, for the alloys generally considered, containing 28% Al, it is shown that the ordered state and microstructure depends sensitively on the precise composition and heat treatments given. In particular, small amounts of solute elements such as B can lead to the appearance of two-phase ordered-disordered microstructures over a wide temperature range, to the appearance of imperfect long range and short range order, and to major changes in the kinetics of ordering and disordering. The mechanical properties achieved are shown to depend critically on the extent and distribution of disorder (the long range order parameter, the extent of short range order, the presence and distribution of thick disordered domain walls) and this factor may explain much of the variability in properties reported between similar alloys. By way of example, the presence of short range order will confine dislocations to well-defined shear planes, concentrating shear and inducing early failure; disordered domain walls will dissociate superdislocations thereby spreading shear homogeneously; the ordered domains/disordered walls morphology will lead to particle-dispersion hardening. (orig.)

Effect of Al_2O_3 Nanoparticles Additives on the Density, Saturated Vapor Pressure, Surface Tension and Viscosity of Isopropyl Alcohol

Science.gov (United States)

Zhelezny, Vitaly; Geller, Vladimir; Semenyuk, Yury; Nikulin, Artem; Lukianov, Nikolai; Lozovsky, Taras; Shymchuk, Mykola

2018-03-01

This paper presents results of an experimental study of the density, saturated vapor pressure, surface tension and viscosity of Al_2O_3 nanoparticle colloidal solutions in isopropyl alcohol. Studies of the thermophysical properties of nanofluids were performed at various temperatures and concentrations of Al_2O_3 nanoparticles. The paper gives considerable attention to a turbidimetric analysis of the stability of nanofluid samples. Samples of nanofluids remained stable over the range of parameters of the experiments, ensuring the reliability of the thermophysical property data for the Al_2O_3 nanoparticle colloidal solutions in isopropyl alcohol. The studies show that the addition of Al_2O_3 nanoparticles leads to an increase of the density, saturated vapor pressure and viscosity, as well as a decrease for the surface tension of isopropyl alcohol. The information reported in this paper on the various thermophysical properties for the isopropyl alcohol/Al_2O_3 nanoparticle model system is useful for the development of thermodynamically consistent models for predicting properties of nanofluids and correct modeling of the heat exchange processes.

Peptide Fraction pOh2 Exerts Antiadipogenic Activity through Inhibition of C/EBP-α and PPAR-γ Expression in 3T3-L1 Adipocytes

Directory of Open Access Journals (Sweden)

Thi Tuyet Nhung Nguyen

2017-01-01

Full Text Available Many studies have comprehensively examined the venom of Ophiophagus hannah snake. Its venom comprises different compounds exhibiting a wide range of pharmacological activities. In this investigation, four peptide fractions (PFs, ranging from 3 kDa to 10 kDa, isolated from the Vietnamese snake venom of O. hannah were separated by HPLC and investigated for their inhibitory activity on adipogenesis in 3T3-L1 adipocytes. The most effective PF was then further purified, generating two peptides, pOh1 and pOh2. Upon investigation of these two peptides on 3T3-L1 adipocytes, it was revealed that, at 10 μg/mL, pOh2 was able to inhibit the lipid accumulation in 3T3-L1 adipocytes by up to 56%, without affecting cell viability. Furthermore, the pOh2 downregulated the gene expression of important transcription factors C/EBP-α and PPAR-γ. In addition, aP2 and GPDH adipocyte-specific markers were also significantly reduced compared to untreated differentiated cells. Taken together, pOh2 inhibited the expression of key transcription factors C/EBP-α and PPAR-γ and their target genes, aP2 and GPDH, thereby blocking the adipocyte differentiation. In conclusion, this novel class of peptide might have potential for in vivo antiobesity effects.

Effects of Be additions on microstructures of TiAl intermetallic compounds

International Nuclear Information System (INIS)

Nonaka, Katsuhiko; Tanosaki, Kazuo; Kawabata, Takeshi; Nakajima, Hideo

1997-01-01

TiAl-0.1-3.0 mol%Be alloys made by the argon arc melting method were investigated to characterize microstructures in cast and annealed conditions using optical microscopy, SEM, EPMA and X-ray diffractometer. The addition of Be to TiAl resulted in a decrease of α 2 phase, thereby coarsening grains and a shift of γ/(γ+α 2 ) phase boundary to Ti-rich side. Two types of Be compound were observed: one was a few micron size of particles which contain a large amount of oxygen and the other was a coarse and eutectic-like phase (θ) which has an atomic ratio of Ti:Al:Be=41:30:29. The solubility limit of Be in TiAl was less than 0.1 mol%. In the (γ+θ) two phase and (γ+α 2 +θ) three phase regions, an increase of Be addition beyond the solubility limit resulted in a small increase of Ti/Al compositional ratio in γ phase. A volume fraction of lamellar structure in TiAl-Be ternary alloys was smaller in the cast structure but was larger in the annealed structure than that in TiAl binary alloys which have nearly the same Ti/Al ratio as that in the ternary alloys, because the Be addition may increase the stacking fault energy and will stabilize the lamellar twin boundaries, respectively. (author)

Effects of flux additives on the characteristics of Y2.95Al5O12:0.05Ce3+ phosphor: Particle growth mechanism and luminescence

International Nuclear Information System (INIS)

Chiang, Chung-Hao; Liu, Te-Hsing; Lin, Han-Yu; Kuo, Hung-Yi; Chu, Sheng-Yuan

2013-01-01

The dependence of the amount of the BaF 2 flux additive on the luminescence of Y 2.95 Al 5 O 12 :0.05Ce 3+ phosphors was investigated. The integrated emission intensity of Y 2.95 Al 5 O 12 :0.05Ce 3+ prepared without the flux was enhanced by 29% with the addition of BaF 2 flux at the optimum amount of 6 wt. %. Such an enhancement can be attributed to the purer phase of Y 3 Al 5 O 12 and the morphology change from the irregular shape to spherical shape with the smoother surface due to the flux. The morphology and luminescence of Y 2.95 Al 5 O 12 :0.05Ce 3+ prepared with the 6 wt. % BaF 2 flux additive (Sample II) were further compared with those of Y 2.95 Al 5 O 12 :0.05Ce 3+ prepared with the 7 wt. % H 3 BO 3 flux additive (Sample I). The particle size, particle shape, and integrated emission intensity (λ ex  = 450 nm) of the former were found to be larger, more regular, and 6% higher than those of the latter. The difference in the morphology of Samples I and II, which led to the difference in the emission intensity and the external quantum efficiency, were well explained by the particle growth mechanism

Replacement of Oxygen by Sulfur in Small Organic Molecules. 3. Theoretical Studies on the Tautomeric Equilibria of the 2OH and 4OH-Substituted Oxazole and Thiazole and the 3OH and 4OH-Substituted Isoxazole and Isothiazole in the Isolated State and in Solution

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Peter I. Nagy

2016-07-01

Full Text Available This follow-up paper completes the author’s investigations to explore the in-solution structural preferences and relative free energies of all OH-substituted oxazole, thiazole, isoxazole, and isothiazole systems. The polarizable continuum dielectric solvent method calculations in the integral-equation formalism (IEF-PCM were performed at the DFT/B97D/aug-cc-pv(q+(dz level for the stable neutral tautomers with geometries optimized in dichloromethane and aqueous solution. With the exception of the predictions for the predominant tautomers of the 3OH isoxazole and isothiazole, the results of the IEF-PCM calculations for identifying the most stable tautomer of the given species in the two selected solvents agreed with those from experimental investigations. The calculations predict that the hydroxy proton, with the exception for the 4OH isoxazole and 4OH isothiazole, moves preferentially to the ring nitrogen or to a ring carbon atom in parallel with the development of a C=O group. The remaining, low-fraction OH tautomers will not be observable in the equilibrium compositions. Relative solvation free energies obtained by the free energy perturbation method implemented in Monte Carlo simulations are in moderate accord with the IEF-PCM results, but consideration of the ΔGsolv/MC values in calculating ΔGstot maintains the tautomeric preferences. It was revealed from the Monte Carlo solution structure analyses that the S atom is not a hydrogen-bond acceptor in any OH-substituted thiazole or isothiazole, and the OH-substituted isoxazole and oxazole ring oxygens may act as a weak hydrogen-bond acceptor at most. The molecules form 1.0−3.4 solute−water hydrogen bonds in generally unexplored numbers at some specific solute sites. Nonetheless, hydrogen-bond formation is favorable with the NH, C=O and OH groups.

Formation of AlFeSi phase in AlSi12 alloy with Ce addition

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S. Kores

2012-04-01

Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

[Co(NH3)6]3[Cu4(OH)(CO3)8].2H2O--a new carbonato-copper(II) anion stabilized by extensive hydrogen bonding.

Science.gov (United States)

Abrahams, Brendan F; Haywood, Marissa G; Robson, Richard

2004-04-21

Addition of Co(NH3)6(3+) to aqueous solutions of Cu(II) in excess carbonate promotes the assembly of a new highly charged carbonato-copper(II) anion, [Cu4(OH)(CO3)8](9-), which contains an unusual mu4 hydroxo-bridged square Cu4 arrangement, stabilised in the crystal by no less than forty hydrogen bonds (< 3 Angstrom) to hexammine cations.

Microstructures and Properties Evolution of Al-Cu-Mn Alloy with Addition of Vanadium

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Fansheng Meng

2016-12-01

Full Text Available The effect of the vanadium addition on the microstructure, the precipitation behavior, and the mechanical properties of the Al-5.0Cu-0.4Mn alloy has been studied. The as-cast Al-5.0Cu-0.4Mn alloy was produced by squeeze casting and the heat treatment was carried out following the standard T6 treatment. It is shown that, with the addition of V, grain refinement of aluminum occurred. During heat treatment, the addition of V accelerates the precipitation kinetics of θ′ (Al2Cu phase along the grain boundaries, and promotes the growth rate of the θ′ in the α(Al matrix. Meanwhile, the addition of V retards the precipitation of T (Al20Cu2Mn3 phase. The tensile strength of the Al-5.0Cu-0.4Mn alloy increases with the increase of V content, which can be explained by combined effects of the solid solution strengthening and precipitate strengthening. However, excessively high V addition deteriorates the mechanical properties by forming brittle coarse intermetallic phases.

Synthesis and investigation of aluminium uranium-containing compounds of Al[B5UO6]2[OH]·nH2O (B5=P, As) composition

International Nuclear Information System (INIS)

Chernorukov, N.G.; Sulejmanov, E.V.; Barch, S.V.

2001-01-01

The technique of synthesis of hydroxyuranophosphate and hydroxyuranoarsenate of aluminium is developed. Hydroxyuranophosphates and hydroxyuranoarsenates of aluminium are prepared by reaction of interaction of aqueous solutions of orthophosphoric (orthoarsenic) acid (0.05 mol/l), uranyl nitrate (0.05 mol/l) and aluminium nitrate (0.1 mol/l) at 20 Deg C. Peculiarities of the structure and thermal degradation reactions are studied by the methods of x-ray diffraction, IR spectroscopy, thermography. It is shown that in dependence on outer conditions in the systems Al[PUO 6 ] 2 ·[OH]·nH 2 O and Al[AsUO 6 ] 2 ·[OH]·nH 2 O crystal hydrates with hydrate numbers n=3-11(13) and anhydrous compounds form. The compounds have laminated type of lattice. Two-dimensional layers of [P(As)UO 6 ] ∞ n- are the basis of anion sublattice of these compounds. Aluminium in coordination surrounding of hydroxy groups and water molecules forms cationic sublattice [ru

Measuring the Distribution and Excitation of Cometary CH3OH Using ALMA

Science.gov (United States)

Cordiner, M. A.; Charnley, S. B.; Mumma, M. J.; Bockelée-Morvan, D.; Biver, N.; Villanueva, G.; Paganini, L.; Milam, S. N.; Remijan, A. J.; Lis, D. C.; Crovisier, J.; Boissier, J.; Kuan, Y.-J.; Coulson, I. M.

2016-10-01

The Atacama Large Millimeter/submillimeter Array (ALMA) was used to obtain measurements of spatially and spectrally resolved CH3OH emission from comet C/2012 K1 (PanSTARRS) on 28-29 June 2014. Detection of 12-14 emission lines of CH3OH on each day permitted the derivation of spatially-resolved rotational temperature profiles (averaged along the line of sight), for the innermost 5000 km of the coma. On each day, the CH3OH distribution was centrally peaked and approximately consistent with spherically symmetric, uniform outflow. The azimuthally-averaged CH3OH rotational temperature (T rot) as a function of sky-projected nucleocentric distance (ρ), fell by about 40 K between ρ= 0 and 2500 km on 28 June, whereas on 29 June, T rot fell by about 50 K between ρ =0 km and 1500 km. A remarkable (~50 K) rise in T rot at ρ = 1500-2500 km on 29 June was not present on 28 June. The observed variations in CH3OH rotational temperature are interpreted primarily as a result of variations in the coma kinetic temperature due to adiabatic cooling, and heating through Solar irradiation, but collisional and radiative non-LTE excitation processes also play a role.

Acid indium strontium phosphate SrIn2[PO3(OH)]4: synthesis and crystal structure

International Nuclear Information System (INIS)

Rusakov, D.A.; Bobylev, A.P.; Komissarova, L.N.; Filaretov, A.A.; Danilov, V.P.

2007-01-01

Acid indium-strontium phosphate SrIn 2 [PO 3 (OH)] 4 is synthesized and characterized. Crystal structure and lattice parameters ate determined. In atoms in SrIn 2 [PO 3 (OH)] 4 structure are in distorted InO 6 octahedrons and form with PO 3 (OH) tetrahedrons mixed paraskeleton {In 2 [PO 3 (OH)] 4 } 3∞ 2- with emptinesses occupied by big Sr 2+ cations. The compound is thermally stable up to 400 Deg C [ru

Reductive amination of ethanol to ethylamines over Ni/Al{sub 2}O{sub 3} catalysts

Energy Technology Data Exchange (ETDEWEB)

Park, Jun Hyun [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Hong, Eunpyo; An, Sang Hee; Shin, Chae-Ho; Lim, Dong-Hee [Chungbuk National University, Chungju (Korea, Republic of)

2017-10-15

Ni(x)/Al{sub 2}O{sub 3} (x=wt%) catalysts with Ni loadings of 5-25 wt% were prepared via a wet impregnation method on an γ-Al{sub 2}O{sub 3} support and subsequently applied in the reductive amination of ethanol to ethylamines. Among the various catalysts prepared, Ni(10)/Al2O3 exhibited the highest metal dispersion and the smallest Ni particle size, resulting in the highest catalytic performance. To reveal the effects of reaction parameters, a reductive amination process was performed by varying the reaction temperature (T), weight hourly space velocity (WHSV), and NH{sub 3} and H{sub 2} partial pressures in the reactions. In addition, on/off experiments for NH{sub 3} and H{sub 2} were also carried out. In the absence of NH{sub 3} in the reactant stream, the ethanol conversion and selectivities towards the different ethylamine products were significantly reduced, while the selectivity to ethylene was dominant due to the dehydration of ethanol. In contrast, in the absence of H{sub 2}, the selectivity to acetonitrile significantly increased due to dehydrogenation of the imine intermediate. Although a small amount of catalyst deactivation was observed in the conversion of ethanol up to 10 h on stream due to the formation of nickel nitride, the Ni(10)/Al{sub 2}O{sub 3} catalyst exhibited stable catalytic performance over 90 h under the optimized reaction conditions (i.e., T=190 .deg. C, WHSV=0.9 h{sup -1}, and EtOH/NH{sub 3}/H{sub 2} molar ratio=1/1/6).

Characterization of Ti6Al7Nb alloy foams surface treated in aqueous NaOH and CaCl2 solutions.

Science.gov (United States)

Bütev, Ezgi; Esen, Ziya; Bor, Şakir

2016-07-01

Ti6Al7Nb alloy foams having 53-73% porosity were manufactured via evaporation of magnesium space holders. A bioactive 1µm thick sodium hydrogel titanate layer, NaxH2-xTiyO2y+1, formed after 5M NaOH treatment, was converted to crystalline sodium titanate, Na2TiyO2y+1, as a result of post-heat treatment. On the other hand, subsequent CaCl2 treatment of NaOH treated specimens induced calcium titanate formation. However, heat treatment of NaOH-CaCl2 treated specimens led to the loss of calcium and disappearance of the titanate phase. All of the aforementioned surface treatments reduced yield strengths due to the oxidation of the cell walls of the foams, while elastic moduli remained mostly unchanged. Accordingly, equiaxed dimples seen on the fracture surfaces of as-manufactured foams turned into relatively flat and featureless fracture surfaces after surface treatments. On the other hand, Ca- and Na-rich coating preserved their mechanical stabilities and did not spall during fracture. The relation between mechanical properties of foams and macro-porosity fraction were found to obey a power law. The foams with 63 and 73% porosity met the desired biocompatibility requirements with fully open pore structures and elastic moduli similar to that of bone. In vitro tests conducted in simulated body fluid (SBF) showed that NaOH-heat treated surfaces exhibit the highest bioactivity and allow the formation of Ca-P rich phases having Ca/P ratio of 1.3 to form within 5 days. Although Ca-P rich phases formed only after 15 days on NaOH-CaCl2 treated specimens, the Ca/P ratio was closer to that of apatite found in bone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

International Nuclear Information System (INIS)

Qin, Gaowu W.; Ren Yuping; Huang Wei; Li Song; Pei Wenli

2010-01-01

Graphical abstract: Display Omitted Research highlights: The ε-AlMn phase acts as the heterogeneous nucleus of α-Mg phase during the solidification of the AZ31 Mg alloy, not the γ-Al 8 Mn 5 phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure ε-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 o C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure ε-AlMn, γ 2 -Al 8 Mn 5 or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the ε-AlMn phase in the Mn-Al alloys, not the γ 2 -Al 8 Mn 5 phase. The grain size of AZ31 Mg alloy is about 91 μm without any addition of Mn-Al alloys, but remarkably decreases to ∼55 μm with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to ∼53 μm, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 o C.

Magneto-optically modulated CH/sub 3/OH laser For faraday rotation measurements in tokamaks

International Nuclear Information System (INIS)

Mansfield, D.K.; Johnson, L.C.

1981-01-01

Distortion-free intracavity polarization modulation of an optically pumped CH/sub 3/OH laser is shown to be viable. The possible use of this modulation technique to make a multichannel Faraday rotation measurement on a Tokamak device is discussed. In addition, the CdTe Faraday modulator employed in this study is shown to have an anomalously large Verdet constant. 12 refs

Field ion microscopy and 3-D atom probe analysis of Al3Zr particles in 7050 Al alloy

International Nuclear Information System (INIS)

Sha, G.; Cerezo, A.

2004-01-01

Full text: For high strength 7xxx series Al alloys, Zr is an important trace alloy element which is often added to optimise properties, having effects such as refining grain size, inhibiting recrystallization, and improving stress corrosion cracking resistance and quench sensitivity. In addition, it has been reported recently that Zr addition also has a significant influence on early stage ageing behaviour of a 7xxx series Al alloy. Zr equilibrium solubility in solid Al is extremely low. After solution or ageing treatment, most Zr is present as small spherical Ai 3 Zr dispersoids approximately 20 nm in diameter, distributed at grain boundaries as well as within the Al matrix. The crystallographic nature of intermetallic phase Al 3 Zr has been well studied in the literatures. So far, no direct measurement of the chemistry of the Al 3 Zr particles in 7xxx series Al alloys has been published. It is unclear if there is significant Zn, Mg or Cu included in the particles. In this research, 3DAP has been employed for the first time to investigate ionisation behaviour of Al 3 Zr particles and determine the chemistry of the particles in 7050 Al alloy. Using field ion microscopy, the local evaporation radius of the Al 3 Zr particle has been measured to be equivalent to 36 nm for a 10 kV tip, less than the equivalent tip radius for the Al matrix of ∼68 nm. Using the matrix Al evaporation field (19 V/nm) as a reference, this allows the evaporation field of Al 3 Zr to be calculated as 35 V/nm, the same as the field calculated for evaporation of Al as Al 2+ (35 V/nm), and that of Zr as Zr 3+ (35 V/nm). This result is consistent with Al 2+ and Zr 3+ being the main species observed in the mass spectrum during analysis of Al 3 Zr particles. Using 3DAP, the chemical compositions of Al 3 Zr particles are determined to be 64.8∼67.7 at% Al, 23.6∼24.8 at% Zr, 6.9∼9.1 at% Zn, 0.4∼0.7 at% Cu, 0.5∼1.2 at% Mg, with a (Al+Zn)/Zr ratio close to 3. Choice of specimen temperature of

Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

Energy Technology Data Exchange (ETDEWEB)

Qin, Gaowu W., E-mail: qingw@smm.neu.edu.c [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China); Ren Yuping; Huang Wei; Li Song; Pei Wenli [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China)

2010-10-08

Graphical abstract: Display Omitted Research highlights: The {epsilon}-AlMn phase acts as the heterogeneous nucleus of {alpha}-Mg phase during the solidification of the AZ31 Mg alloy, not the {gamma}-Al{sub 8}Mn{sub 5} phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure {epsilon}-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 {sup o}C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure {epsilon}-AlMn, {gamma}{sub 2}-Al{sub 8}Mn{sub 5} or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the {epsilon}-AlMn phase in the Mn-Al alloys, not the {gamma}{sub 2}-Al{sub 8}Mn{sub 5} phase. The grain size of AZ31 Mg alloy is about 91 {mu}m without any addition of Mn-Al alloys, but remarkably decreases to {approx}55 {mu}m with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to {approx}53 {mu}m, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 {sup o}C.

Corrosion behavior of die-cast Mg-4Al-2Sn-xCa alloy

Energy Technology Data Exchange (ETDEWEB)

Park, Kyung Chul; Kim, Byeong Ho; Kim, Kyung Ro [Defence Agency for Technology and Quality, Jinju (Korea, Republic of); Cho, Dae Hyun; Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

2016-05-15

In the present work, the effect of Ca additions on microstructure and corrosion characteristics of high pressure die-cast Mg-4Al-2Sn alloy has been investigated. Mg-4Al-2Sn-xCa (x= 0, 0.3 and 0.7wt.%) alloy was prepared by using a high pressure die-casting method. Results indicated that the microstructure of Mg-4Al-2Sn alloy consisted of α-Mg, Mg{sub 17}Al{sub 12} and Mg{sub 2}Sn phase. With increase of Ca additions, CaMgSn phase was newly formed and grain size was sharply decreased. From the test results, the corrosion resistance of die-cast Mg-4Al-2Sn alloy was significantly improved by Ca addition. It is considered that stabilization of Mg(OH){sub 2} layer and refinements of microstructure with increase of Ca additions.

Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

Science.gov (United States)

Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

2018-05-01

Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

25 (OH) D3 levels, incidence and recurrence of different clinical forms of BPPV.

Science.gov (United States)

Maslovara, Sinisa; Butkovic Soldo, Silva; Sestak, Anamarija; Milinkovic, Katarina; Rogic-Namacinski, Jasna; Soldo, Anamarija

2017-06-11

Benign Paroxysmal Positional Vertigo (BPPV) is the most common cause of dizziness in the general population. It is a condition with potential impact of reduced levels of vitamin D on its recurrent attacks. The aim of this study was to measure the serum levels of 25-hydroxyvitamin D3 (25-OH D3) in patients with BPPV and determine whether there is a difference in the serum levels of vitamin D3 between patients with and without recurrence, as well as between the different clinical forms of BPPV. The study included 40 patients who came to the regular medical examination, diagnosed with PC-BPPV based on the positive Dix-Hallpike's test. All patients underwent Epley manoeuvre after the diagnosis. Patients were classified according to current guidelines for levels of vitamin D3 in the serum in three groups: the deficiency, insufficiency and adequate level. The average serum level of 25-OH D3 among respondents was 20.78ng/mL, indicating a lack or insufficiency of the aforementioned 25-OH D3. According to the levels of 25-OH D3, most patients suffer from deficiency (47.5%). 7 (17.5%) respondents had adequate blood level of 25-OH D3, and 14 (35%) respondents suffer from insufficiency. A significant difference was not found in the serum level of 25-OH D3 between patients with and without BPPV recurrence. There was a significant difference in the serum levels of 25-OH D3 in comparison to the clinical form of the disease. Lower 25-OH D3 values were found in patients with canalithiasis compared to those with cupulolithiasis. There were no significant differences in the vitamin D3 serum level in patients with and without recurrence. The study showed a low level of serum vitamin D3 in most patients, indicating the need for supplemental therapy. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Comparison of Efficiencies and Mechanisms of Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce, Mg, and Ce-Mg Oxides Loaded Al2O3

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Chunmao Chen

2017-02-01

Full Text Available The use of catalytic ozonation processes (COPs for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW is rapidly expanding. In this study, magnesium (Mg, cerium (Ce, and Mg-Ce oxide-loaded alumina (Al2O3 were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al2O3 support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al2O3 (Mg-Ce/Al2O3-COP reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al2O3-COP, Ce/Al2O3-COP, Al2O3-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs are the dominant catalytic active sites on Al2O3. These active surface –OHs along with the deposited metal oxides (Mg2+ and/or Ce4+ increased the catalytic activity. The Mg-Ce/Al2O3 catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions.

Crystal structure of (Al,V)4(P4O12)3, archetype of double cubic ring tetraphosphate

International Nuclear Information System (INIS)

Yakubovich, O. V.; Biralo, G. V.; Dimitrova, O. V.

2012-01-01

The crystal structure of the (Al,V) 4 (P 4 O 12 ) 3 solid solution, obtained in the single-crystal form by hydrothermal synthesis in the Al(OH) 3 -VO 2 -NaCl-H 3 PO 4 -H 2 O system, has been solved by X-ray diffraction analysis (Xcalibur-S-CCD diffractometer, R = 0.0257): a = 13.7477(2) Å, sp. gr. I 4 bar 3d, Z = 4, and ρ calcd = 2.736 g/cm 3 . It is shown that the crystal structure of the parent cubic Al 4 (P 4 O 12 ) 3 modification can formally be considered an archetype for the formation of double isosymmetric tetraphosphates on its basis.

Al2O3-Cact-(CuO, Cr2O3, Co3O4 Adsorbents-Catalysts: Preparation and Characterization

Directory of Open Access Journals (Sweden)

Gitana DABRILAITĖ-KUDŽMIENĖ

2013-03-01

Full Text Available Al2O3-Cact-(CuO, Cr2O3 Co3O4 adsorbents-catalysts were prepared using Al2O3-Cact (alumina gel–activated carbon adsorbent and different amount of CuO, Cr2O3 and Co3O4. The active components were incorporated into wet alumina gel–carbon mixture using different conditions (by sol-gel method and mixing a milled metal oxides. Equilibrium adsorptive capacity measurements of alcohol vapours were carried out in order to determine the influence of preparation conditions on the stability of prepared adsorbents–catalysts. Specific surface area of the prepared adsorbents-catalysts were measured by BET method. It was established that for adsorbent-catalyst produced by sol-gel method SBET = 244.7 m2/g. Surface area SBET = 29.32 m2/g was obtained for adsorbent-catalyst with metal oxides. On the basis of these results it was assumed that active carbon was lost in this adsorbent-catalyst during the preparation process. Sol-gel derived adsorbent–catalyst was tested for the oxidation of methanol vapours. Catalytic oxidation was carried out in fixed-bed reactor. Experimental data indicate that adsorptive capacity of the adsorbent–catalyst is (3.232 – 3.259 mg/m3 CH3OH at relative air humidity is 40 % – 50 %. During a fast heating of CH3OH – saturated adsorbent-catalyst a part of adsorbate is converted to CO2 and H2O. Methanol conversion increases with increasing of adsorbent-catalyst heating rate.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3832

Computational Study of Ethanol Conversion on Al ₈ O ₁₂ as a Model for γ-Al ₂ O ₃

Energy Technology Data Exchange (ETDEWEB)

Fang, Zongtang; Wang, Yong; Dixon, David A.

2015-10-15

Correlated molecular orbital theory at the coupled cluster CCSD(T) level with density functional theory geometries is used to study ethanol dehydration, dehydrogenation, and condensation reactions on an the Al8O12 cluster which is a model for γ-Al2O3. The Al in the active site on the cluster is a strong Lewis acid. The reactions begin with formation of a very stable Lewis acid–base ethanol–cluster adduct. Dehydration proceeds by β-H transfer to a bicoordinate oxygen leading to the direct formation of ethylene and two OH groups following an E2 mechanism. Dehydrogenation proceeds directly by α-H transfer to the active metal center and a proton transfer to a bicoordinate bridge O to form acetaldehyde plus a metal hydride and a hydroxyl, again an E2 mechanism. After addition of a second ethanol, diethyl ether is generated by an α-C transfer from the first to the second ethanol, an acid-driven SN2 mechanism. Condensation and dehydration with two alcohols have comparable energy barriers. The addition of a second ethanol or a water molecule raises the energy barriers. Condensation and dehydration are predicted to be more likely than dehydrogenation. The computational results for the mechanism and the energetics agree well with the available experimental data.

In(OH){sub 3} and In{sub 2}O{sub 3} nanorice and microflowers: morphology transformation and optical properties

Energy Technology Data Exchange (ETDEWEB)

Ren Weian; Liu Ying; Mei Zongwei; Wen Xiaogang, E-mail: wenxg2001@163.com [Sichuan University, School of Materials Science and Engineering (China); Wang Suhua [Chinese Academy of Sciences, Institute of Intelligent Machines (China)

2013-02-15

In this work, In(OH){sub 3} and In{sub 2}O{sub 3} nanostructures with controllable complex morphologies were successfully synthesized through a simple hydrothermal process followed by annealing. The In(OH){sub 3} nanostructures were synthesized using urea as the alkaline source at a relatively low temperature without any templates or surfactants. The morphology transformation of In(OH){sub 3} from nanorice to microflowers was observed. The In(OH){sub 3} nanorice are 180 nm in diameter and 550 nm in length, the microflowers are about 3 {mu}m in diameter and composed of thin nanoflakes with 4-nm thickness. In{sub 2}O{sub 3} with similar morphology was formed by annealing In(OH){sub 3} precursors. The nanostructures were characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Our results suggest that a new nucleation-growth-etching-regrowth mechanism can explain the morphology transformation from nanorice to flower-like frameworks. Raman spectrum and photoluminescence (PL) properties of In{sub 2}O{sub 3} were also measured, and a 3-nm blue-shift of PL spectrum was observed due to the thinness of the nanostructures.

Evolution of Mg-5Al-0.4Mn microstructure after rare earth elements addition

Directory of Open Access Journals (Sweden)

A. Żydek

2011-04-01

Full Text Available Mg-5Al-0.4Mn-xRE (x = 0, 1, 2, 3 wt.% magnesium alloys were prepared successfully by casting method. The microstructure wasinvestigated by light microscopy. The influence of rare earth (RE elements on the area fraction of eutectic was analysed. The obtainedresults revealed that the as-cast Mg-5Al-0.4Mn alloy consist of α - Mg matrix and eutectic α + γ (where γ is Mg17Al12. However, whilerare earth elements were added to the Mg-Al type alloy, Al11RE3 precipitates were formed. The amount of the Al11RE3 precipitatesincreased with increasing addition of RE, but the amount of γ - Mg17Al12 decreased.

Ni Foam-Ni3 S2 @Ni(OH)2 -Graphene Sandwich Structure Electrode Materials: Facile Synthesis and High Supercapacitor Performance.

Science.gov (United States)

Wang, Xiaobing; Hu, Jiangjiang; Su, Yichang; Hao, Jin; Liu, Fanggang; Han, Shuang; An, Jian; Lian, Jianshe

2017-03-23

A novel Ni foam-Ni 3 S 2 @Ni(OH) 2 -graphene sandwich-structured electrode (NF-NN-G) with high areal mass loading (8.33 mg cm -2 ) has been developed by sulfidation and hydrolysis reactions. The conductivity of Ni 3 S 2 and Ni(OH) 2 were both improved. The upper layer of Ni(OH) 2 , covered with a thin graphene film, is formed in situ from the surface of the lower layer of Ni 3 S 2 , whereas the Ni 3 S 2 grown on Ni foam substrate mainly acts as a rough support bridging the Ni(OH) 2 and Ni foam. The graphene stabilized the Ni(OH) 2 and the electrochemical properties were effectively enhanced. The as-synthesized NF-NN-G-5mg electrode shows a high specific capacitance (2258 F g -1 at 1 A g -1 or 18.81 F cm -2 at 8.33 mA cm -2 ) and an outstanding rate property (1010 F g -1 at 20 Ag -1 or 8.413 F cm -2 at 166.6 mA cm -2 ). This result is around double the capacitance achieved in previous research on Ni 3 S 2 @Ni(OH) 2 /3DGN composites (3DGN=three-dimensional graphene network). In addition, the as-fabricated NF-NN-G-5mg composite electrode has an excellent cycle life with no capacitance loss after 3000 cycles, indicating a potential application as an efficient electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

MICROSTRUCTURE AND TENSILE PROPERTIES OF Fe3Al-BASED ALLOYS WITH VC AND TiC ADDITIONS

Institute of Scientific and Technical Information of China (English)

W.L.Xu; Y.S.Sun; S.S.Ding

2001-01-01

Microstructure and tensile properties of Fe3Al-based alloys with additions of TiC andVC particles have been investigated.Results show that the formation of TiC particlesresults in the refinement of the macrostructure of as-cast ingots.Although the additionof VC particles does not cause significant change of the as-cast microstructure,themicrostructure of the alloy after hot-working and recrystallization has been found tobe refined.The formation of both VC and TiC particles results in the increase of yieldstrength,especially at high temperature of 600℃.

Knudsen cell--mass spectrometer studies of cesium--urania interactions. [Cs/sub 2/CO/sub 3/ or CsOH

Energy Technology Data Exchange (ETDEWEB)

Collins, J.L.; Osborne, M.F.; Malinauskas, A.P.; Lorenz, R.A.; Manning, S.R.

1976-06-01

Limited Knudsen cell--mass spectrometer studies were made of the partial pressures of cesium-containing species (assumed to be primarily Cs(g)) over Cs/sub 2/CO/sub 3/ and over phase equilibria involving UO/sub 2/ and probable Cs-U-O compounds formed from mixtures that initially contained either Cs/sub 2/CO/sub 3/-UO/sub 2/ or CsOH-UO/sub 2/. Although additional work is required to further define the equilibria involved, the data demonstrate unambiguously a significant reduction in cesium partial pressures due to probable Cs-U-O compound formation and indicate essentially identical behavior with either CsOH or Cs/sub 2/CO/sub 3/ as the starting material with UO/sub 2/.

A roadmap for OH reactivity research

Science.gov (United States)

Williams, Jonathan; Brune, William

2015-04-01

A fundamental property of the atmosphere is the frequency of gas-phase reactions with the OH radical, the atmosphere's primary oxidizing agent. This reaction frequency is called the OH reactivity and is the inverse the lifetime of the OH radical itself, which varies from a few seconds in the clean upper troposphere to below 10 ms in forests and polluted city environments. Ever since the discovery of the OH radical's importance to tropospheric chemistry, the characterization of its overall loss rate (OH reactivity) has remained a key question. At first, this property was assessed by summing the reactivity contributions of individually measured compounds; however, as improving analytical technology revealed ever more reactive species in ambient air, it became clear that this approach could provide only a lower limit. Approximately 15 years ago, the direct measurement of total OH reactivity was conceived independently by two groups. The first publications demonstrated direct OH reactivity measurements in the laboratory (Calpini et al., 1999) based on LIDAR and in the ambient air (Kovacs and Brune, 2001) based on in situ laser induced fluorescence detection of OH.

Temperature-programmed reaction of CO2 reduction in the presence of hydrogen over Fe/Al2O3, Re/Al2O3 and Cr-Mn-O/Al2O3 catalysts

International Nuclear Information System (INIS)

Mirzabekova, S.R.; Mamedov, A.B.; Krylov, O.V.

1996-01-01

Regularities in CO 2 reduction have been studied using the systems Fe/Al 2 O 3 , Re/Al 2 O 3 and Cr-Mn-O/Al 2 O 3 under conditions of thermally programmed reaction by way of example. A sharp increase in the reduction rate in the course of CO 2 interaction with reduced Fe/Al 2 O 3 and Re/Al 2 O 3 , as well as with carbon fragments with addition in CO 2 flow of 1-2%H 2 , has been revealed. The assumption is made on intermediate formation of a formate in the process and on initiating effect of hydrogen on CO 2 reduction by the catalyst. Refs. 26, figs. 10

DFT investigation on the selective complexation of Fe3+ and Al3+ with hydroxypyridinones used for treatment of the aluminium and iron overload diseases.

Science.gov (United States)

Kaviani, Sadegh; Izadyar, Mohammad; Housaindokht, Mohammad Reza

2018-03-01

The chelating agents for Al 3+ and Fe 3+ metal cations with therapeutic applications have been considered in the recent years. In designing of the hydroxypyridinones (HPOs) as the therapeutic chelating agents for iron and aluminium overload pathologies, quantum mechanical (QM) calculations are necessary for predicting the binding energies and thermodynamic parameters of the metal-HPO complexes. Three derivatives of the HPOs called 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (DFP), 3-hydroxy-4(1H)-pyridinone (HOPO) and 5-hydroxy-2-(hydroxymethyl)pyridin-4(1H)-one (P1) were investigated for complexation with Fe 3+ and Al 3+ metal ions. Because of the maximum interaction between Fe 3+ and HPOs, all HPOs form stable complexes with Fe 3+ metal ion. Moreover, it was found that [Fe-P1] 2+ is a more stable complex than [Fe-DFP] 2+ and [Fe-3,4-HOPO] 2+ in the gas phase and water, confirming that P1 is the strongest selective iron chelator. The more stability of [Fe-P1] 2+ was attributed to an intramolecular hydrogen bond formation between the hydrogen atom of NH group and the oxygen atom of CH 2 OH chain. All complexes of the HPOs with Fe 3+ and Al 3+ were formed through the oxygen atoms of the CO and OH groups of the HPO. Natural bond orbital analysis showed that the interaction of the lone pair electrons of the oxygen atom of the chelator and antibonding orbitals of the Al 3+ and Fe 3+ are important in the complex formation. Topological parameters at the bond critical points confirmed the effective interaction between the Al 3+ and Fe 3+ metal ions and HPO as well as the nature of the metal-oxygen bonds. Copyright © 2018 Elsevier Inc. All rights reserved.

A combined high-temperature experimental and theoretical kinetic study of the reaction of dimethyl carbonate with OH radicals

KAUST Repository

Khaled, Fathi

2017-02-08

The reaction kinetics of dimethyl carbonate (DMC) and OH radicals were investigated behind reflected shock waves over the temperature range of 872-1295 K and at pressures near 1.5 atm. Reaction progress was monitored by detecting OH radicals at 306.69 nm using a UV laser absorption technique. The rate coefficients for the reaction of DMC with OH radicals were extracted using a detailed kinetic model developed by Glaude et al. (Proc. Combust. Inst. 2005, 30(1), 1111-1118). The experimental rate coefficients can be expressed in Arrhenius form as: kexpt\\'l = 5.15 × 10(13) exp(-2710.2/T) cm(3) mol(-1) s(-1). To explore the detailed chemistry of the DMC + OH reaction system, theoretical kinetic analyses were performed using high-level ab initio and master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) calculations. Geometry optimization and frequency calculations were carried out at the second-order Møller-Plesset (MP2) perturbation level of theory using Dunning\\'s augmented correlation consistent-polarized valence double-ζ basis set (aug-cc-pVDZ). The energy was extrapolated to the complete basis set using single point calculations performed at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory. For comparison purposes, additional ab initio calculations were also carried out using composite methods such as CBS-QB3, CBS-APNO, G3 and G4. Our calculations revealed that the H-abstraction reaction of DMC by OH radicals proceeds via an addition elimination mechanism in an overall exothermic process, eventually forming dimethyl carbonate radicals and H2O. Theoretical rate coefficients were found to be in excellent agreement with those determined experimentally. Rate coefficients for the DMC + OH reaction were combined with literature rate coefficients of four straight chain methyl ester + OH reactions to extract site-specific rates of H-abstraction from methyl esters by OH radicals.

Phase constituents and microstructure of laser cladding Al2O3/Ti3Al reinforced ceramic layer on titanium alloy

International Nuclear Information System (INIS)

Li Jianing; Chen Chuanzhong; Lin Zhaoqing; Squartini, Tiziano

2011-01-01

Research highlights: → In this study, Fe 3 Al has been chosen as cladding powder due to its excellent properties of wear resistance and high strength, etc. → Laser cladding of Fe 3 Al + TiB 2 /Al 2 O 3 pre-placed alloy powder on Ti-6Al-4V alloy substrate can form the Ti 3 Al/Fe 3 Al + TiB 2 /Al 2 O 3 ceramic layer, which can increase wear resistance of substrate. → In cladding process, Al 2 O 3 can react with TiB 2 leading to formation of Ti 3 Al and B. → This principle can be used to improve the Fe 3 Al + TiB 2 laser-cladded coating. - Abstract: Laser cladding of the Fe 3 Al + TiB 2 /Al 2 O 3 pre-placed alloy powder on Ti-6Al-4V alloy can form the Ti 3 Al/Fe 3 Al + TiB 2 /Al 2 O 3 ceramic layer, which can greatly increase wear resistance of titanium alloy. In this study, the Ti 3 Al/Fe 3 Al + TiB 2 /Al 2 O 3 ceramic layer has been researched by means of electron probe, X-ray diffraction, scanning electron microscope and micro-analyzer. In cladding process, Al 2 O 3 can react with TiB 2 leading to formation of amount of Ti 3 Al and B. This principle can be used to improve the Fe 3 Al + TiB 2 laser cladded coating, it was found that with addition of Al 2 O 3 , the microstructure performance and micro-hardness of the coating was obviously improved due to the action of the Al-Ti-B system and hard phases.

Interactions between kaolinite Al−OH surface and sodium hexametaphosphate

Energy Technology Data Exchange (ETDEWEB)

Han, Yonghua, E-mail: hyh19891102@163.com [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Liu, Wenli; Zhou, Jia [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chen, Jianhua [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China)

2016-11-30

Highlights: • Sodium hexametaphosphate (NaHMP) can adsorb on kaolinite Al−OH terminated (001) surface easily. • The oxygen atoms of hexametaphosphate form strong hydrogen bonds with the hydrogen atoms of kaolinite Al−OH surface. • The electrostatic force is the main interaction between NaHMP and Al−OH surface. • The linear hexaphosphate −[PO{sub 3}]{sub m}− chains adsorb stably than −[HPO{sub 3}]{sub m}− chains. - Abstract: To investigate the dispersion mechanism of sodium hexametaphosphate on kaolinite particles, we simulated the interaction between linear polyphosphate chains and kaolinite Al−OH terminated surface by molecular dynamics, as well as the interaction between the [HPO{sub 4}]{sup 2−} anion and kaolinite Al−OH surface by density functional theory (DFT). The calculated results demonstrate that hexametaphosphate can be adsorbed by the kaolinite Al−OH surface. The oxygen atoms of hexametaphosphate anions may receive many electrons from the Al−OH surface and form hydrogen bonds with the hydrogen atoms of surface hydroxyl groups. Moreover, electrostatic force dominates the interactions between hexametaphosphate anions and kaolinite Al−OH surface. Therefore, after the adsorption of hexametaphosphate on kaolinite Al−OH surface, the kaolinite particles carry more negative charge and the electrostatic repulsion between particles increases. In addition, the adsorption of −[PO{sub 3}]{sub m}− species on the Al−OH surface should be more stable than the adsorption of −[HPO{sub 3}]{sub m}− species.

Solid-State Synthesis and Structure of the Enigmatic Ammonium Octaborate: (NH4)2[B7O9(OH)5]·3/4B(OH)3·5/4H2O.

Science.gov (United States)

Neiner, Doinita; Sevryugina, Yulia V; Schubert, David M

2016-09-06

The compound known since the 19th century as ammonium octaborate was structurally characterized revealing the ammonium salt of the ribbon isomer of the heptaborate anion, [B7O9(OH)5](2-), with boric acid and water molecules. Of composition (NH4)2B7.75O12.63·4.88H2O, it approximates the classical ammonium octaborate composition (NH4)2B8O13·6H2O and has the structural formula {(NH4)2[B7O9(OH)5]}4·3B(OH)3·5H2O. It spontaneously forms at room temperature in solid-state mixtures of ammonium tetraborate and ammonium pentaborate. It crystallizes in the monoclinic space group P21/c with a = 11.4137(2) Å, b = 11.8877(2) Å, c = 23.4459(3) Å, β = 90.092(1)°, V = 3181.19(8) Å(3), and Z = 2 and contains well-ordered ammonium cations and [B7O9(OH)5](2-) anions and disordered B(OH)3 and H2O molecules linked by extensive H bonding. Expeditious solid-state formation of the heptaborate anion under ambient conditions has important implications for development of practical syntheses of industrially useful borates.

Influence of annealing temperature on passivation performance of thermal atomic layer deposition Al2O3 films

International Nuclear Information System (INIS)

Zhang Xiang; Liu Bang-Wu; Li Chao-Bo; Xia Yang; Zhao Yan

2013-01-01

Chemical and field-effect passivation of atomic layer deposition (ALD) Al 2 O 3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Passivation performance is improved remarkably by annealing at temperatures of 450 °C and 500 °C, while the improvement is quite weak at 600 °C, which can be attributed to the poor quality of chemical passivation. An increase of fixed negative charge density in the films during annealing can be explained by the Al 2 O 3 /Si interface structural change. The Al—OH groups play an important role in chemical passivation, and the Al—OH concentration in an as-deposited film subsequently determines the passivation quality of that film when it is annealed, to a certain degree. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Improvement of photoluminescence intensity of Ce-doped Y{sub 3}Al{sub 5}O{sub 12} phosphor by Si{sub 3}N{sub 4} addition

Energy Technology Data Exchange (ETDEWEB)

Shyu, Jiin-Jyh, E-mail: jjshyu@ttu.edu.tw; Yang, Chia-Wei

2017-06-01

Yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, YAG) has been widely used as a host for luminescent ions. The present paper describes the effects of Si{sub 3}N{sub 4} addition on the formation and photoluminescence properties of the Ce-doped YAG yellow phosphors. Phosphor powders with the nominal compositions of Y{sub 2.95}Ce{sub 0.05}Al{sub 5-m}Si{sub m}O{sub 12-m}N{sub m} (m = 0–0.6) were prepared by calcining the mixed raw materials at 1500 °C in nitrogen atmosphere. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscopy equipped with an energy dispersive x-ray spectrometer were used to characterize the structure of the calcined powders. The photoluminescence properties were measured with fluorescence spectrophotometry. It was found that in the range of m = 0–0.27, single phase YAG solid solution (s.s.) in which the Y, Al, and O sites are partially occupied by Ce, Si, and N ions, respectively. The nitrogen ions do not distribute homogeneously over the YAG lattice. The tendency to bond with nitrogen ion for the cations is (Y, Ce) > Si > Al. With the increase in the Si{sub 3}N{sub 4} content, the increase in both the Ce{sup 3+}/(Ce{sup 3+} + Ce{sup 4+}) ratio and the Ce-N bonds improve the intensity of the photoluminescent emission. At m = 0.27, the emission intensity reaches a maximum which is about 2.5 and 1.6 times of that for the Si{sub 3}N{sub 4}-free composition (m = 0) calcined in air and nitrogen, respectively. When the Si{sub 3}N{sub 4} content (m) is higher than 0.27, the emission intensity decreases due to the existence of residual Si{sub 3}N{sub 4} phase. - Highlights: • Addition of Si{sub 3}N{sub 4} can increase the emission intensity of YAG:Ce up to 2.5 times. • Increase in the Ce{sup 3+}/Ce{sup 4+} ratio and the number of Ce-N bonds improve the emission. • The tendency to bond with nitrogen ion for cations in YAG:Ce is (Y, Ce) > Si > Al. • The incomplete dissolution

Adsorption of cadmium onto Al{sub 13}-pillared acid-activated montmorillonite

Energy Technology Data Exchange (ETDEWEB)

Yan Liangguo [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Shan Xiaoquan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)], E-mail: xiaoquan@rcees.ac.cn; Wen Bei [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Owens, Gary [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes Campus, Mawson Lakes, Boulevard, South Australia 5095 (Australia)

2008-08-15

The optimal preparation conditions for Al{sub 13}-pillared acid-activated Na{sup +}-montmorillonite (Al{sub 13}-PAAMt) were (1) an acid-activated Na{sup +}-montmorillonite (Na{sup +}-Mt) solution of pH 3.0, (2) a OH{sup -}/Al{sup 3+} molar ratio of 2.4 and (3) Al{sup 3+}/Na{sup +}-Mt ratio of 1.0 mmol g{sup -1}. The effects of OH{sup -}/Al{sup 3+} and Al{sup 3+}/Na{sup +}-Mt ratios on the adsorption of Cd{sup 2+} onto Al{sub 13}-PAAMt were studied. A comparison of the adsorption of Cd{sup 2+} onto Al{sub 13}-PAAMt, Al{sub 13}-pillared Na{sup +}-montmorillonite (Al{sub 13}-PMt) and Na{sup +}-Mt suggested that Al{sub 13}-PAAMt had higher adsorption affinity for Cd{sup 2+} than the other two adsorbents. A pseudo-second-order model described the adsorption kinetics well. Cadmium adsorption followed the Langmuir two-site equation, while desorption was hysteretic.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) Signaling Capacity and the Epithelial-Mesenchymal Transition in Non-Small Cell Lung Cancer (NSCLC): Implications for Use of 1,25(OH)2D3 in NSCLC Treatment

International Nuclear Information System (INIS)

Upadhyay, Santosh Kumar; Verone, Alissa; Shoemaker, Suzanne; Qin, Maochun; Liu, Song; Campbell, Moray; Hershberger, Pamela A.

2013-01-01

1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) exerts anti-proliferative activity by binding to the vitamin D receptor (VDR) and regulating gene expression. We previously reported that non-small cell lung cancer (NSCLC) cells which harbor epidermal growth factor receptor (EGFR) mutations display elevated VDR expression (VDR high ) and are vitamin D-sensitive. Conversely, those with K-ras mutations are VDR low and vitamin D-refractory. Because EGFR mutations are found predominately in NSCLC cells with an epithelial phenotype and K-ras mutations are more common in cells with a mesenchymal phenotype, we investigated the relationship between vitamin D signaling capacity and the epithelial mesenchymal transition (EMT). Using NSCLC cell lines and publically available lung cancer cell line microarray data, we identified a relationship between VDR expression, 1,25(OH) 2 D 3 sensitivity, and EMT phenotype. Further, we discovered that 1,25(OH) 2 D 3 induces E-cadherin and decreases EMT-related molecules SNAIL, ZEB1, and vimentin in NSCLC cells. 1,25(OH) 2 D 3 -mediated changes in gene expression are associated with a significant decrease in cell migration and maintenance of epithelial morphology. These data indicate that 1,25(OH) 2 D 3 opposes EMT in NSCLC cells. Because EMT is associated with increased migration, invasion, and chemoresistance, our data imply that 1,25(OH) 2 D 3 may prevent lung cancer progression in a molecularly defined subset of NSCLC patients

Mechanism and kinetic properties for the OH-initiated atmospheric oxidation degradation of 9,10-Dichlorophenanthrene

Energy Technology Data Exchange (ETDEWEB)

Dang, Juan; Shi, Xiangli; Zhang, Qingzhu, E-mail: zqz@sdu.edu.cn; Hu, Jingtian; Wang, Wenxing

2015-02-01

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) have become a serious environmental concern due to their widespread occurrence and dioxin-like toxicities. In this work, the mechanism of the OH-initiated atmospheric oxidation degradation of 9,10-dichlorophenanthrene (9,10-Cl{sub 2}Phe) was investigated by using high-accuracy quantum chemistry calculations. The rate constants of the crucial elementary reactions were determined by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The theoretical results were compared with the available experimental data. The main oxidation products are a group of ring-retaining and ring-opening compounds including chlorophenanthrols, 9,10-dichlorophenanthrene-3,4-dione, dialdehydes, chlorophenanthrenequinones, nitro-9,10-Cl{sub 2}Phe and epoxides et al. The overall rate constant of the OH addition reaction is 2.35 × 10{sup −12} cm{sup 3} molecule{sup −1} s{sup −1} at 298 K and 1 atm. The atmospheric lifetime of 9,10-Cl{sub 2}Phe determined by OH radicals is about 5.05 days. This study provides a comprehensive investigation of the OH-initiated oxidation degradation of 9,10-Cl{sub 2}Phe and should contribute to clarifying its atmospheric fate. - Highlights: • We studied a comprehensive mechanism of OH-initiated degradation of 9,10-Cl{sub 2}Phe. • The atmospheric lifetime of 9,10-Cl{sub 2}Phe determined by OH radical is about 5.05 d. • The rate constants of the crucial elementary steps were evaluated. • Water plays an important role in the formation of nitro-9,10-Cl{sub 2}Phe.

Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH.

Science.gov (United States)

Walrafen, George E; Douglas, Rudolph T W

2006-03-21

High-temperature, high-pressure Raman spectra were obtained from aqueous NaOH solutions up to 2NaOHH2O, with X(NaOH)=0.667 at 480 K. The spectra corresponding to the highest compositions, X(NaOH)> or =0.5, are dominated by H3O2-. An IR xi-function dispersion curve for aqueous NaOH, at 473 K and 1 kbar, calculated from the data of Franck and Charuel indicates that the OH- ion forms H3O2- by preferential H bonding with nonhydrogen-bonded OH groups. Raman spectra from wet to anhydrous, solid LiOH, NaOH, and KOH yield sharp, symmetric OH- stretching peaks at 3664, 3633, and 3596 cm(-1), respectively, plus water-related, i.e., H3O2-, peaks near LiOH, 3562 cm(-1), NaOH, 3596 cm(-1), and, KOH, 3500 cm(-1). Absence of H3O2- peaks from the solid assures that the corresponding melt is anhydrous. Raman spectra from the anhydrous melts yield OH- stretching peak frequencies: LiOH, 3614+/-4 cm(-1), 873 K; NaOH, 3610+/-2 cm(-1), 975 K; and, KOH, 3607+/-2 cm(-1), 773 K, but low-frequency asymmetry due to ion-pair interactions is present which is centered near 3550 cm(-1). The ion-pair-related asymmetry corresponds to the sole IR maximum near 3550 cm(-1) from anhydrous molten NaOH, at 623 K. Bose-Einstein correction of published low-frequency Raman data from molten LiOH revealed an acoustic phonon, near 205 cm(-1), related to restricted translation of OH- versus Li+, and an optical phonon, at 625 cm(-1) and tau approximately 0.05 ps, due to protonic precession and/or pendular motion. Strong H bonding between water and the O atom of OH- forms H3O2-, but the proton of OH- does not bond with H significantly. Large Raman bandwidths (aqueous solutions) are explained in terms of inhomogeneous broadening due to proton transfer in a double well. Vibrational assignments are presented for H3O2-.

Corrosion resistance of micro-arc oxidation coatings formed on aluminum alloy with addition of Al2O3

Science.gov (United States)

Zhang, Y.; Chen, Y.; Du, H. Q.; Zhao, YW

2018-03-01

Micro-arc oxidation (MAO) coatings were formed on the aluminum alloy in silicate-based electrolyte without and with the addition of Al2O3. It is showed that the coating produced in 7 g l‑1 Al2O3-containing electrolyte was of the most superior corrosion resistance. Besides, the corrosion properties of the coatings were studied by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test in both 0.5 M and 1 M NaCl solution. The results proved that the coating is capable to protect the substrate from the corrosion of aggressive Cl‑ in 0.5 M NaCl after 384 h immersion. However, it can not offer protection to the aluminum alloy substrate after 384 h immersion in 1 M NaCl solution. The schematic diagrams illustrate the corrosion process and matched well with the corrosion test results.

Recycling of cobalt from spent Li-ion batteries as β-Co(OH)2 and the application of Co3O4 as a pseudocapacitor

Science.gov (United States)

Barbieri, E. M. S.; Lima, E. P. C.; Lelis, M. F. F.; Freitas, M. B. J. G.

2014-12-01

This work has investigated recycling cobalt from the cathodes of spent Li-ion batteries as β-Co(OH)2, obtaining Co3O4. β-Co(OH)2 with a hexagonal structure by using chemical precipitation (CP) or electrochemical precipitation (EP). In addition, the study has investigated whether the charge density applied directly affects the β-Co(OH)2 morphology. Co3O4 is formed by heat-treating β-Co(OH)2 at 450 °C for 3 h (h) in an air atmosphere. After calcining, the Co3O4 shows a cubic structure and satisfactory purity grade, regardless of the route used for preparation via which it was obtained. Cyclic voltammetry (CV) is then used for electrochemical characterization of the Co3O4 composite electrodes. In the cathodic process, CoO2 undergoes reduction to CoOOH, which undergoes further reduction to Co3O4. In the anodic process, Co3O4 undergoes oxidation to CoOOH, which simultaneously undergoes further oxidation to CoO2. The composite electrodes containing Co3O4, carbon black, and epoxy resin show great reversibility, charge efficiency, and a specific capacitance of 13.0 F g-1 (1.0 mV s-1). The synthesis method of Co(OH)2 influences the charge efficiency of Co3O4 composite electrodes at a scan rate of 10.0 mV s-1. Therefore, in addition to presenting an alternative use for exhausted batteries, Co3O4 composites exhibit favorable characteristics for use as pseudocapacitors.

A shock tube and laser absorption study of ignition delay times and OH reaction rates of ketones: 2-Butanone and 3-buten-2-one

KAUST Repository

Badra, Jihad

2014-03-01

Ketones are potential biofuel candidates and are also formed as intermediate products during the oxidation of large hydrocarbons or oxygenated fuels, such as alcohols and esters. This paper presents shock tube ignition delay times and OH reaction rates of 2-butanone (C2H5COCH3) and 3-buten-2-one (C2H3COCH3). Ignition delay measurements were carried out over temperatures of 1100-1400K, pressures of 3-6.5atm, and at equivalence ratios (F{cyrillic}) of 0.5 and 1. Ignition delay times were monitored using two different techniques: pressure time history and OH absorption near 306nm. The reaction rates of hydroxyl radicals (OH) with these two ketones were measured over the temperature range of 950-1400K near 1.5atm. The OH profiles were monitored by the narrow-line-width ring-dye laser absorption of the well-characterized R1(5) line in the OH A-X (0, 0) band near 306.69nm. We found that the ignition delay times of 2-butanone and 3-buten-2-one mixtures scale with pressure as P-0.42 and P-0.52, respectively. The ignition delay times of 3-buten-2-one were longer than that of 2-butanone for stoichiometric mixtures, however, for lean mixtures (F{cyrillic}=0.5), 2-butanone had longer ignition delay times. The chemical kinetic mechanism of Serinyel et al. [1] over-predicted the ignition delay times of 2-butanone at all tested conditions, however, the discrepancies were smaller at higher pressures. The mechanism was updated with recent rate measurements to decrease discrepancy with the experimental data. A detailed chemistry for the oxidation of 3-buten-2-one was developed using rate estimation method and reasonable agreements were obtained with the measured ignition delay data. The measured reaction rate of 2-butanone with OH agreed well with the literature data, while we present the first high-temperature measurements for the reaction of OH with 3-buten-2-one. The following Arrhenius expressions are suggested over the temperature range of 950-1450K: kC2H5COCH3+OH=6.78×1013exp

Adsorption and reaction mechanism of arsenic vapors over γ-Al2O3 in the simulated flue gas containing acid gases.

Science.gov (United States)

Hu, Hongyun; Chen, Dunkui; Liu, Huan; Yang, Yuhan; Cai, Hexun; Shen, Junhao; Yao, Hong

2017-08-01

Arsenic emission from fuel combustion and metal smelting flue gas causes serious pollution. Addition of sorbents is a promising way for the arsenic capture from high temperature flue gas. However, it is difficult to remove arsenic from SO 2 /HCl-rich flue gas due to the competitive reaction of the sorbents with arsenic and these acid gases. To solve this problem, arsenic adsorption over γ-Al 2 O 3 was studied in this work to evaluate its adsorption mechanism, resistance to acid gases as well as regeneration behavior. The results show that γ-Al 2 O 3 had good resistance to acid gases and the arsenic adsorption by γ-Al 2 O 3 could be effectively carried out at a wide temperature range between 573 and 1023 K. Nevertheless, adsorption at higher-temperature (like 1173 K) leaded to the decrease of surface area and the rearrangement of crystal structure of γ-Al 2 O 3 , reducing the active sites for arsenic adsorption. The adsorption of arsenic was confirmed to occur at different active sites in γ-Al 2 O 3 by forming various adsorbed species. Increasing temperature facilitated arsenic transformation into more stable chemisorbed As 3+ and As 5+ which were difficult to remove through thermal treatment regeneration. Fortunately, the regeneration of spent γ-Al 2 O 3 could be well performed using NaOH solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of CeLa addition on the microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy

International Nuclear Information System (INIS)

Du, Jiandi; Ding, Dongyan; Xu, Zhou; Zhang, Junchao; Zhang, Wenlong; Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua; Chen, Renzong; Huang, Yuanwei; Tang, Jinsong

2017-01-01

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 8 Cu 4 Ce and Al 6 Cu 6 La phases formed due to CeLa addition. Addition of 0.25 wt.% CeLa could promote the formation of denser precipitation of Al 20 Cu 2 Mn 3 and Al 6 (Mn, Fe) phases, which improved the mechanical properties of the alloy at room temperature. However, up to 0.50 wt.% CeLa addition could promote the formation of coarse Al 8 Cu 4 Ce phase, Al 6 Cu 6 La phase and Al 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 8 Cu 4 Ce and Al 6 Cu 6 La phases formed after CeLa addition. •Addition of 0.25 wt.% CeLa promoted formation of denser precipitates of Al 20 Cu 2 Mn 3 and Al 6 (Mn, Fe). •Mechanical properties of the alloy was improved after 0.25 wt.% CeLa addition.

Facile fabrication of carbon microspheres decorated with B(OH) 3 and α-Fe 2 O 3 nanoparticles: superior microwave absorption

KAUST Repository

Zhong, Bo

2017-06-02

We demonstrate that novel three-dimensional (3D) B(OH)3 and α-Fe2O3 nanoparticles decorated carbon microspheres (B(OH)3/α-Fe2O3-CMSs) can be fabricated via a facile thermal treatment process. The carbon microspheres with diameter of 1 to 3 μm and decorated B(OH)3 and α-Fe2O3 nanoparticles with diameters of several to tens of nanometers are successfully fabricated. These novel 3D B(OH)3/α-Fe2O3-CMS composites exhibit enhanced microwave absorption with tunable strong absorption wavebands in the frequency range of 2–18 GHz. They have a minimum reflection loss (RL) value of -52.69 dB at a thickness of 3.0 mm, and the effective absorption bandwidth for RL less than -10 dB is as large as 5.64 GHz. The enhanced microwave absorption performance arises from the synergy of the impedance matching caused by the B(OH)3 nanoparticles, dielectric loss as well as the enhancement of multiple reflection among 3D α-Fe2O3 nanocrystals. These results provide a new strategy to tune electromagnetic properties and enhance the capacity of high-efficient microwave absorbers.

Facile fabrication of carbon microspheres decorated with B(OH) 3 and α-Fe 2 O 3 nanoparticles: superior microwave absorption

KAUST Repository

Zhong, Bo; Wang, Chaojun; Yu, Yuanlie; Xia, Long; Wen, Guangwu

2017-01-01

We demonstrate that novel three-dimensional (3D) B(OH)3 and α-Fe2O3 nanoparticles decorated carbon microspheres (B(OH)3/α-Fe2O3-CMSs) can be fabricated via a facile thermal treatment process. The carbon microspheres with diameter of 1 to 3 μm and decorated B(OH)3 and α-Fe2O3 nanoparticles with diameters of several to tens of nanometers are successfully fabricated. These novel 3D B(OH)3/α-Fe2O3-CMS composites exhibit enhanced microwave absorption with tunable strong absorption wavebands in the frequency range of 2–18 GHz. They have a minimum reflection loss (RL) value of -52.69 dB at a thickness of 3.0 mm, and the effective absorption bandwidth for RL less than -10 dB is as large as 5.64 GHz. The enhanced microwave absorption performance arises from the synergy of the impedance matching caused by the B(OH)3 nanoparticles, dielectric loss as well as the enhancement of multiple reflection among 3D α-Fe2O3 nanocrystals. These results provide a new strategy to tune electromagnetic properties and enhance the capacity of high-efficient microwave absorbers.

ON THE ORIGIN OF C_4H AND CH_3OH IN PROTOSTELLAR ENVELOPES

International Nuclear Information System (INIS)

Lindberg, Johan E.; Charnley, Steven B.; Cordiner, Martin A.

2016-01-01

The formation pathways of different types of organic molecules in protostellar envelopes and other regions of star formation are subjects of intense current interest. We present here observations of C_4H and CH_3OH, tracing two distinct groups of interstellar organic molecules, toward 16 protostars in the Ophiuchus and Corona Australis molecular clouds. Together with observations in the literature, we present C_4H and CH_3OH data from single-dish observations of 40 embedded protostars. We find no correlation between the C_4H and CH_3OH column densities in this large sample. Based on this lack of correlation, a difference in line profiles between C_4H and CH_3OH, and previous interferometric observations of similar sources, we propose that the emission from these two molecules is spatially separated, with the CH_3OH tracing gas that has been transiently heated to high (∼70–100 K) temperatures and the C_4H tracing the cooler large-scale envelope where CH_4 molecules have been liberated from ices. These results provide insight in the differentiation between hot corino and warm carbon-chain chemistry in embedded protostars.

Promoting Effect of CeO2 Addition on Activity and Catalytic Stability in Steam Reforming of Methane over Ni/Al2O3

International Nuclear Information System (INIS)

Rakib, A.; Gennequin, C.; Ringot, S.; Aboukais, A.; Abi-Aad, E.; Dhainaut, T.

2011-01-01

Hydrogen production by steam reforming of methane was studied over Ni catalysts supported on CeO 2 , Al 2 O 3 and CeO 2 -Al 2 O 3 . These catalysts were prepared using the impregnation method and characterized by XRD. The effect of CeO2 promoter on the catalytic performance of Ni/Al 2 O 3 catalyst for methane steam reforming reaction was investigated. In fact, CeO 2 had a positive effect on the catalytic activity in this reaction. Experimental results demonstrated that Ni/CeO 2 -Al 2 O 3 catalyst showed excellent catalytic activity and high reaction performance. In addition, the effects of reaction temperature and metal content on the conversion of CH 4 and H 2 /CO ratio were also investigated. Results indicated that CH4 conversion increased significantly with the increase of the reaction temperature and metal content. (author)

Atomistic calculations of hydrogen interactions with Ni3Al grain boundaries and Ni/Ni3Al interfaces

International Nuclear Information System (INIS)

Baskes, M.I.; Angelo, J.E.; Moody, N.R.

1995-01-01

Embedded Atom Method (EAM) potentials have been developed for the Ni/Al/H system. The potentials have been fit to numerous properties of this system. For example, these potentials represent the structural and elastic properties of bulk Ni, Al, Ni 3 Al, and NiAl quite well. In addition the potentials describe the solution and migration behavior of hydrogen in both nickel and aluminum. A number of calculations using these potentials have been performed. It is found that hydrogen strongly prefers sites in Ni 3 Al that are surrounded by 6 Ni atoms. Calculations of the trapping of hydrogen to a number of grain boundaries in Ni 3 Al have been performed as a function of hydrogen chemical potential at room temperature. The failure of these bicrystals under tensile stress has been examined and will be compared to the failure of pure Ni 3 Al boundaries. Boundaries containing a preponderance of nickel are severely weakened by hydrogen. In order to investigate the potential embrittlement of γ/γ' alloys, trapping of hydrogen to a spherical Ni 3 Al precipate in nickel as a function of chemical potential at room temperature has been calculated. It appears that the boundary is not a strong trap for hydrogen, hence embrittlement in these alloys is not primarily due to interactions of hydrogen with the γ/γ interface

Effects of samarium (Sm) additions on the microstructure and mechanical properties of as-cast and hot-extruded Mg-5 wt%Al-3 wt%Ca-based alloys

International Nuclear Information System (INIS)

Son, Hyeon-Taek; Lee, Jae-Seol; Kim, Dae-Guen; Yoshimi, Kyosuke; Maruyama, Kouichi

2009-01-01

Samarium (Sm) additions to as-cast Mg-5Al-3Ca-based alloys result in changes, such as equiaxed grains and a refined grain size. The microstructure of as-cast Mg-5Al-3Ca-xSm alloys consists of an α-Mg matrix, a (Mg, Al) 2 Ca eutectic phase, and an Al 2 Sm intermetallic compound. In as-cast alloys, the (Mg, Al) 2 Ca eutectic phase was located at grain boundaries with a chain structure, and the Al 2 Sm intermetallic compounds were homogeneously distributed at the α-Mg matrix and grain boundaries. The eutectic phase of the extruded alloys was elongated in the extrusion direction and crushed into fine particles because of severe deformation during hot extrusion, and the grain size was refined with an increased amount of Sm addition. The maximum values of the yield strength and tensile strength were 313 MPa and 330 MPa at 2 wt%Sm alloy content, respectively

OH detection by Ford Motor Company

Science.gov (United States)

Wang, Charles C.

1986-12-01

Two different methods for detection of OH are presented: a low pressure flow cell system and a frequency modulation absorption measurement. Using conventional absorption spectroscopy, detection limits were quoted of 1,000,000 OH molecules per cu cm using a 30-minute averaging time on the ground, and a 3-hour averaging time in the air for present apparatus in use. With the addition of FM spectroscopy at 1 GHz, a double-beam machine should permit detectable absorption of and an OH limit of 100,000 per cu cm in a 30-minute averaging time. In the low pressure system on which experiments are ongoing nonexponential time behavior was observed after the decay had progressed to about 0.3 of its original level; this was attributed to ion emission in the photomultiplier. A flame source with OH present at high concentration levels was used as a calibration. It was estimated that within the sampling chamber, 400,000 OH could be measured. With a factor-of-2 loss at the sampling orifice, this means detectability of 5 to 8 x 100,000 cu cm at the present time. This could be reduced by a factor of 2 in one hour averaging time; improvements in laser bandwidth and energy should provide another factor of 2 in sensitivity.

Topotactic synthesis of Co3O4 nanoboxes from Co(OH)2 nanoflakes

International Nuclear Information System (INIS)

Tian Li; Huang Kelong; Liu Younian; Liu Suqin

2011-01-01

Hollow nanocubes of spinel Co 3 O 4 with the dimension of 20 nm were successfully prepared via a facile and reproducible solvothermal route. The structure and morphology of Co 3 O 4 nanoboxes were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HRTEM) techniques. And a possible growth mechanism of Co 3 O 4 nanoboxes were suggested that solid Co 3 O 4 nanocubes nucleate in-situ and grow epitaxially from hexagonal β-Co(OH) 2 precursors with the structural matching relationship of [0 0 1] β-Co(OH) 2 //[1 1 1] Co 3 O 4 , and then solid Co 3 O 4 nanocubes gradually hollow and convert to single-crystal nanoboxes owing to Ostwald ripening. - Graphical abstract: The formation mechanism of Co 3 O 4 nanoboxes can be expressed as epitaxial growth of Co 3 O 4 nanocubes from β-Co(OH) 2 nanoflakes due to a topotactic transformation and hollowing process owing to Ostwald ripening. Highlights: → Co 3 O 4 nanoboxes were prepared by a convenient, economical and controllable hydrothermal route. → Morphology and structure of Co 3 O 4 nanoboxes were characterized by XRD, SEM, and TEM techniques. → Co 3 O 4 nanoboxes grow epitaxially from Co(OH) 2 by topotactic transformation was suggested.

Addition of iron for the removal of the {beta}-AlFeSi intermetallic by refining of {alpha}-AlFeSi phase in an Al-7.5Si-3.6Cu alloy

Energy Technology Data Exchange (ETDEWEB)

Belmares-Perales, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Zaldivar-Cadena, A.A., E-mail: azaldiva70@hotmail.com [Facultad de Ingenieria Civil, Departamento de Ecomateriales y Energia, Instituto de Ingenieria Civil, Av. Fidel Velasquez and Av. Universidad S/N, Cd. Universitaria, San Nicolas de los Garza, N.L. 66450 (Mexico)

2010-10-25

Addition of iron into the molten metal for the removal of the {beta}-AlFeSi intermetallic by refining of {alpha}-AlFeSi phase has been studied. Solidification conditions and composition determine the final microstructure and mechanical properties of a casting piece. It is known that increasing the iron content will produce an increasing of the {alpha}-AlFeSi and {beta}-AlFeSi phases. This phenomenon was confirmed with calculations made by Thermo-Calc{sup TM} software and validated with experimental results, however, the technique of iron addition in this study plays an important role on the solidification kinetics of these iron phases because the refining of {alpha}-AlFeSi and removal of {beta}-AlFeSi phases can be improved. Final results showed an improvement in mechanical properties by removal and refining of {beta}-AlFeSi and {alpha}-AlFeSi phases, respectively. This study shows a new method of removal of {beta}-AlFeSi that could be adopted in the aluminum smelting industry in aluminum alloys with a low cooling rate with a secondary dendritic spacing of about 37 {mu}m.

Addition of iron for the removal of the β-AlFeSi intermetallic by refining of α-AlFeSi phase in an Al-7.5Si-3.6Cu alloy

International Nuclear Information System (INIS)

Belmares-Perales, S.; Zaldivar-Cadena, A.A.

2010-01-01

Addition of iron into the molten metal for the removal of the β-AlFeSi intermetallic by refining of α-AlFeSi phase has been studied. Solidification conditions and composition determine the final microstructure and mechanical properties of a casting piece. It is known that increasing the iron content will produce an increasing of the α-AlFeSi and β-AlFeSi phases. This phenomenon was confirmed with calculations made by Thermo-Calc TM software and validated with experimental results, however, the technique of iron addition in this study plays an important role on the solidification kinetics of these iron phases because the refining of α-AlFeSi and removal of β-AlFeSi phases can be improved. Final results showed an improvement in mechanical properties by removal and refining of β-AlFeSi and α-AlFeSi phases, respectively. This study shows a new method of removal of β-AlFeSi that could be adopted in the aluminum smelting industry in aluminum alloys with a low cooling rate with a secondary dendritic spacing of about 37 μm.

Effect of CeLa addition on the microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy

Energy Technology Data Exchange (ETDEWEB)

Du, Jiandi [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ding, Dongyan, E-mail: dyding@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Xu, Zhou; Zhang, Junchao; Zhang, Wenlong [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua [Huafon NLM Al Co., Ltd, Shanghai 201506 (China); Chen, Renzong; Huang, Yuanwei; Tang, Jinsong [Shanghai Huafon Materials Technology Institute, Shanghai 201203 (China)

2017-01-15

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. 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.

Vitamina D y cáncer: acción antineoplásica de la 1α, 25(OH2 -vitamina D3

Directory of Open Access Journals (Sweden)

Verónica González Pardo

2012-04-01

Full Text Available La forma hormonalmente activa de la vitamina D, 1α,25(OH2-vitamina D3 (1α,25(OH2D3, además de desempeñar un rol crucial en el mantenimiento de la homeostasis de calcio en el cuerpo, también regula el crecimiento y la diferenciación de diferentes tipos celulares, incluyendo células cancerosas. Actualmente hay numerosos estudios que investigan los efectos de la hormona en estas células, debido al interés en el uso terapéutico del 1α,25(OH2D3 y de análogos con menor actividad calcémica para el tratamiento o prevención del cáncer. En este trabajo de revisión se describe el sistema endocrino de la vitamina D, su mecanismo de acción, su acción antineoplásica y se provee información sobre los últimos avances en el estudio de nuevos análogos de la hormona con menos actividad calcémica para el tratamiento del cáncer.

Structural diversity of a family of aluminophosphates with Al/P ratio of non-unity

Science.gov (United States)

Yu, Jihong; Xu, Ruren; Li, Jiyang

2000-05-01

A family of organically templated aluminophosphates (denoted AlPOs) with an Al/P ratio of non-unity has been prepared with 1-D chain, 2-D layer and 3-D open-framework architectures. Their inorganic parts are constructed from alternating Al-centered polyhedra (AlO 4, AlO 5, AlO 4(OH 2) 2) and P-centered tetrahedra P(OAl) nO 4- n ( n=0, 1, 2, 3). The existence of terminal POH and/or PO groups in the structures results in the deviation of Al/P ratio from unity, and the commonly encountered Al/P ratios are 1/2, 3/5, 2/3, 3/4, 4/5 and 5/6. This review will discuss the structural features of these AlPOs with various dimensionalities and stoichiometries.

Effect of titanium and calcium oxide additions on Zr2O2 polymorphism during Al2O3+Zr2O2 mixture fusion

International Nuclear Information System (INIS)

Gladkov, V.E.; Zhekhanova, N.B.; Fotiev, A.A.; Viktorov, V.V.; Ivashinnikov, V.T.; Zubov, A.S.

1985-01-01

The effect of titanium and calcium containing additions introduced into the Al 2 O 3 +ZrO 2 melt on the phase composition and temperature ranges of ZrO 2 polymorphous transformation in the material is investigated. It is shown that introducing sponge titanium into the 70Al 2 O 3 +30ZrO 2 prepared composition melt (mass. %) with its subsequent intensive cooling one can conserve upto room temperatures 50-70% of ZrO 2 metastable tetragonal modification and therefore reduce the volume changes causing metal cracking. Calcium oxide doping stabilizes the ZrO 2 cubic modification and reduces α-Al 2 O 3 content due to formation of aluminates

Laboratory Study of the OH + Permethylsiloxane (L2, L3, D3, and D4) Reaction Rate Coefficients Between 240 and 370 K

Science.gov (United States)

Burkholder, J. B.; Bernard, F.; Papadimitriou, V. C.

2016-12-01

The atmospheric chemistry of organosiloxanes has recently been implicated in the formation of new particles as well as regional and indoor air quality. Methylsiloxanes with Sitextiles, health care and household products and in industrial applications as solvents and lubricants. They are released into the atmosphere during manufacturing, use, and disposal and have been observed in the atmosphere in ppb levels in certain locations. However, the fundamental chemical properties of this class of compounds, particularly their reactivity with the OH radical, are presently not fully characterized. In this work, the temperature dependence of the rate coefficients for the OH radical reaction with the simplest linear (L2 and L3) and cyclic (D3 and D4) siloxanes were measured: OH + (CH3)3SiOSi(CH3)3 = Products L2OH + [(CH3)3SiO]2Si(CH3)2 = Products L3OH + [-Si(CH3)2O-]3 = Products D3OH + [-Si(CH3)2O-]4 = Products D4OH rate coefficients were measured under pseudo-first conditions in OH over the temperature range 240-370 K using a pulsed laser photolysis-laser induced fluorescence (PLP-LIF) technique and at 296 K using a relative rate method. The present results are compared with available literature data where possible and discrepancies are discussed. The results from this work will be discussed in terms of the atmospheric lifetimes of these methylsiloxanes and the reactivity trends for this class of compound.

Ab Initio Chemical Kinetics for the CH3 + O((3)P) Reaction and Related Isomerization-Decomposition of CH3O and CH2OH Radicals.

Science.gov (United States)

Xu, Z F; Raghunath, P; Lin, M C

2015-07-16

The kinetics and mechanism of the CH3 + O reaction and related isomerization-decomposition of CH3O and CH2OH radicals have been studied by ab initio molecular orbital theory based on the CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVTZ, CCSD/aug-cc-pVDZ, and G2M//B3LYP/6-311+G(3df,2p) levels of theory. The predicted potential energy surface of the CH3 + O reaction shows that the CHO + H2 products can be directly generated from CH3O by the TS3 → LM1 → TS7 → LM2 → TS4 path, in which both LM1 and LM2 are very loose and TS7 is roaming-like. The result for the CH2O + H reaction shows that there are three low-energy barrier processes including CH2O + H → CHO + H2 via H-abstraction and CH2O + H → CH2OH and CH2O + H → CH3O by addition reactions. The predicted enthalpies of formation of the CH2OH and CH3O radicals at 0 K are in good agreement with available experimental data. Furthermore, the rate constants for the forward and some key reverse reactions have been predicted at 200-3000 K under various pressures. Based on the new reaction pathway for CH3 + O, the rate constants for the CH2O + H and CHO + H2 reactions were predicted with the microcanonical variational transition-state/Rice-Ramsperger-Kassel-Marcus (VTST/RRKM) theory. The predicted total and individual product branching ratios (i.e., CO versus CH2O) are in good agreement with experimental data. The rate constant for the hydrogen abstraction reaction of CH2O + H has been calculated by the canonical variational transition-state theory with quantum tunneling and small-curvature corrections to be k(CH2O + H → CHO + H2) = 2.28 × 10(-19) T(2.65) exp(-766.5/T) cm(3) molecule(-1) s(-1) for the 200-3000 K temperature range. The rate constants for the addition giving CH3O and CH2OH and the decomposition of the two radicals have been calculated by the microcanonical RRKM theory with the time-dependent master equation solution of the multiple quantum well system in the 200-3000 K temperature range at 1 Torr to

Integrated nanophotonic hubs based on ZnO-Tb(OH3/SiO2 nanocomposites

Directory of Open Access Journals (Sweden)

Lin Yu

2011-01-01

Full Text Available Abstract Optical integration is essential for practical application, but it remains unexplored for nanoscale devices. A newly designed nanocomposite based on ZnO semiconductor nanowires and Tb(OH3/SiO2 core/shell nanospheres has been synthesized and studied. The unique sea urchin-type morphology, bright and sharply visible emission bands of lanthanide, and large aspect ratio of ZnO crystalline nanotips make this novel composite an excellent signal receiver, waveguide, and emitter. The multifunctional composite of ZnO nanotips and Tb(OH3/SiO2 nanoparticles therefore can serve as an integrated nanophotonics hub. Moreover, the composite of ZnO nanotips deposited on a Tb(OH3/SiO2 photonic crystal can act as a directional light fountain, in which the confined radiation from Tb ions inside the photonic crystal can be well guided and escape through the ZnO nanotips. Therefore, the output emission arising from Tb ions is truly directional, and its intensity can be greatly enhanced. With highly enhanced lasing emissions in ZnO-Tb(OH3/SiO2 as well as SnO2-Tb(OH3/SiO2 nanocomposites, we demonstrate that our approach is extremely beneficial for the creation of low threshold and high-power nanolaser.

Growth and characterization of Al{sub 2}O{sub 3} films on fluorine functionalized epitaxial graphene

Energy Technology Data Exchange (ETDEWEB)

Robinson, Zachary R., E-mail: ZRobinso@Brockport.edu [Department of Physics, The College at Brockport, Brockport, New York 14420 (United States); Jernigan, Glenn G.; Wheeler, Virginia D.; Hernández, Sandra C.; Eddy, Charles R. [U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Mowll, Tyler R.; Ong, Eng Wen [College of Nanoscale Science and Engineering, University at Albany-SUNY, Albany, New York 12203 (United States); Ventrice, Carl A. [College of Nanoscale Science, SUNY Polytechnic Institute, Albany, New York 12203 (United States); Geisler, Heike [Department of Chemistry and Biochemistry, SUNY Oneonta, Oneonta, New York 13820 (United States); Pletikosic, Ivo; Yang, Hongbo; Valla, Tonica [Brookhaven National Laboratory, Brookhaven, New York 11973 (United States)

2016-08-21

Intelligent engineering of graphene-based electronic devices on SiC(0001) requires a better understanding of processes used to deposit gate-dielectric materials on graphene. Recently, Al{sub 2}O{sub 3} dielectrics have been shown to form conformal, pinhole-free thin films by functionalizing the top surface of the graphene with fluorine prior to atomic layer deposition (ALD) of the Al{sub 2}O{sub 3} using a trimethylaluminum (TMA) precursor. In this work, the functionalization and ALD-precursor adsorption processes have been studied with angle-resolved photoelectron spectroscopy, low energy electron diffraction, and X-ray photoelectron spectroscopy. It has been found that the functionalization process has a negligible effect on the electronic structure of the graphene, and that it results in a twofold increase in the adsorption of the ALD-precursor. In situ TMA-dosing and XPS studies were also performed on three different Si(100) substrates that were terminated with H, OH, or dangling Si-bonds. This dosing experiment revealed that OH is required for TMA adsorption. Based on those data along with supportive in situ measurements that showed F-functionalization increases the amount of oxygen (in the form of adsorbed H{sub 2}O) on the surface of the graphene, a model for TMA-adsorption on graphene is proposed that is based on a reaction of a TMA molecule with OH.

Identification and determination of D3 vitamine, D3 vitamine 25 (OH) and D3 vitamine 1,25(OH)2 in plasma of animals treated with solanum glaucophyllum (Sg)

International Nuclear Information System (INIS)

Pawlak, Eva

1997-01-01

The enzootic calcinosis is a disease produced in the bovines by the ingestion of the toxic plant Sg, which contains vitamine D 3 glycosides and its active metabolites. This disease is characterized by the loss of weight and physical condition, motor disorders and alteration of phosphocalcic metabolism with deposition of calcium compounds in soft tissues. To contribute to the advanced diagnostic of the disease, analytic techniques to determine D vitamine, D vitamine 25 (OH) and D vitamine 1,25 (OH) 2 in plasma, by high resolution liquid chromatography and radio receptor essay are used

Synthesis and Application of One-Dimensional La(OH3 Nanostructures: An Overview

Directory of Open Access Journals (Sweden)

Xiang Xiao

2014-01-01

Full Text Available One-dimensional (1D semiconductor nanomaterials are of particular importance owing to their unique properties and potential applications. This review attempts to provide a comprehensive introduction of 1D La(OH3 nanostructures including nanowires, nanoneedles, nanobelts, and nanorods. Firstly, various strategies developed to fabricate the 1D La(OH3 nanostructures are discussed, such as precipitation and composite-hydroxide-mediated, hydrothermal, and solvothermal methods, accompanying the description of the corresponding growth mechanisms. Then, the unique properties such as novel physical properties of 1D La(OH3 nanostructures resulting from their unique electronic structures and numerous transition modes involving the 4f shells of these ions are represented in detail. Also, the wide applications in photocatalyst, capacitors, and photoluminescence based on the unique properties are discussed. Finally, the paper ends with a summary and some perspectives on the challenges and new directions in this emerging area.

Molecular-cloud-scale Chemical Composition. II. Mapping Spectral Line Survey toward W3(OH) in the 3 mm Band

Energy Technology Data Exchange (ETDEWEB)

Nishimura, Yuri [Institute of Astronomy, The University of Tokyo, 2-21-1, Osawa, Mitaka, Tokyo 181-0015 (Japan); Watanabe, Yoshimasa; Yamamoto, Satoshi [Department of Physics, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Harada, Nanase [Academia Sinica Institute of Astronomy and Astrophysics, No.1, Sec. 4, Roosevelt Road, 10617 Taipei, Taiwan, R.O.C. (China); Shimonishi, Takashi [Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramakiazaaoba 6-3, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Sakai, Nami [RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Aikawa, Yuri [Department of Astronomy, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kawamura, Akiko [Chile Observatory, National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)

2017-10-10

To study a molecular-cloud-scale chemical composition, we conducted a mapping spectral line survey toward the Galactic molecular cloud W3(OH), which is one of the most active star-forming regions in the Perseus arm. We conducted our survey through the use of the Nobeyama Radio Observatory 45 m telescope, and observed the area of 16′ × 16′, which corresponds to 9.0 pc × 9.0 pc. The observed frequency ranges are 87–91, 96–103, and 108–112 GHz. We prepared the spectrum averaged over the observed area, in which eight molecular species (CCH, HCN, HCO{sup +}, HNC, CS, SO, C{sup 18}O, and {sup 13}CO) are identified. On the other hand, the spectrum of the W3(OH) hot core observed at a 0.17 pc resolution shows the lines of various molecules such as OCS, H{sub 2}CS CH{sub 3}CCH, and CH{sub 3}CN in addition to the above species. In the spatially averaged spectrum, emission of the species concentrated just around the star-forming core, such as CH{sub 3}OH and HC{sub 3}N, is fainter than in the hot core spectrum, whereas emission of the species widely extended over the cloud such as CCH is relatively brighter. We classified the observed area into five subregions according to the integrated intensity of {sup 13}CO, and evaluated the contribution to the averaged spectrum from each subregion. The CCH, HCN, HCO{sup +}, and CS lines can be seen even in the spectrum of the subregion with the lowest {sup 13}CO integrated intensity range (<10 K km s{sup −1}). Thus, the contributions of the spatially extended emission is confirmed to be dominant in the spatially averaged spectrum.

Electrochemical reduction approach-based 3D graphene/Ni(OH)2 electrode for high-performance supercapacitors

International Nuclear Information System (INIS)

Yan, Huijun; Bai, Jianwei; Wang, Bin; Yu, Lei; Zhao, Lin; Wang, Jun; Liu, Qi; Liu, Jingyuan; Li, Zhanshuang

2015-01-01

Highlights: • 3D graphene foam is synthesized by a simple electrochemical reduction method. • The 3D graphene/Ni(OH) 2 composite is used as a monolithic free-standing electrode material. • The 3D conductive graphene network improves the contact between electrode and electrolyte. • Compositing graphene with Ni(OH) 2 sheets take full advantage of the synergistic effects. • Results show that the as-synthesized products have good electrochemical property. - Abstract: Using a simple electrochemical reduction approach, we have produced three-dimensional (3D) graphene foam having high conductivity and well-defined macroporous structure. Through a hydrothermal process, Ni(OH) 2 sheets are grown in-situ onto the graphene surface. This monolithic 3D graphene/Ni(OH) 2 composite is used as the free-standing electrode for supercapacitor application; it shows a high specific capacitance of 183.1 F g −1 (based on the total mass of the electrode), along with excellent rate capability and cycle performance. The asymmetric supercapacitor based on the 3D graphene/Ni(OH) 2 as a positive electrode and active carbon (AC) as a negative electrode is also assembled and it exhibits a specific capacitance of 148.3 F g −1 at 0.56 A g −1 and a high energy density of 52.7 W h kg −1 at a power density of 444.4 W kg −1 . Moreover, 3D graphene/Ni(OH) 2 //AC has a good cycle stability (87.9% capacitance retention after 1000 cycles), making it promising as one of the most attractive candidates for electrochemical energy storage. This excellent electrochemical performance results from the multiplexed 3D graphene network facilitating electron transport; the interlaced Ni(OH) 2 sheets shorten ion diffusion paths and facilitate the rapid migration of electrolyte ions

Synthesis of Ti3AlC2 by spark plasma sintering of mechanically milled 3Ti/xAl/2C powder mixtures

International Nuclear Information System (INIS)

Yang Chen; Jin Songzhe; Liang Baoyan; Liu Guojun; Duan Lianfeng; Jia Shusheng

2009-01-01

Elemental powders of Ti, Al and C were mechanically milled as starting materials for the fabrication of ternary carbide Ti 3 AlC 2 by spark plasma sintering (SPS) technique. The effect of Al content in the starting materials on the Ti 3 AlC 2 synthesis was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to determine the phase identification and observe the microstructure of the synthesized samples. With increasing proper Al content, it was found that the purity of Ti 3 AlC 2 increased and the sintering temperature reduced. The dense and high-purity Ti 3 AlC 2 could be successfully fabricated from 3Ti/1.2Al/2C powders at a lower sintering temperature of 1050 deg. C, holding for 10 min. In addition, the reaction path for the formation of Ti 3 AlC 2 in the present study was proposed

Effects of La and Ce Addition on the Modification of Al-Si Based Alloys

Directory of Open Access Journals (Sweden)

Emad M. Elgallad

2016-01-01

Full Text Available This study focuses on the effects of the addition of rare earth metals (mainly lanthanum and cerium on the eutectic Si characteristics in Al-Si based alloys. Based on the solidification curves and microstructural examination of the corresponding alloys, it was found that addition of La or Ce increases the alloy melting temperature and the Al-Si eutectic temperature, with an Al-Si recalescence of 2-3°C, and the appearance of post-α-Al peaks attributed to precipitation of rare earth intermetallics. Addition of La or Ce to Al-(7–13% Si causes only partial modification of the eutectic Si particles. Lanthanum has a high affinity to react with Sr, which weakens the modification efficiency of the latter. Cerium, however, has a high affinity for Ti, forming a large amount of sludge. Due to the large difference in the length of the eutectic Si particles in the same sample, the normal use of standard deviation in this case is meaningless.

A DFT study of ethanol adsorption and decomposition on α-Al2O3(0 0 0 1) surface

International Nuclear Information System (INIS)

Chiang, Hsin-Ni; Nachimuthu, Santhanamoorthi; Cheng, Ya-Chin; Damayanti, Nur Pradani; Jiang, Jyh-Chiang

2016-01-01

Graphical abstract: - Highlights: • Ethanol decomposition has been studied over α-Al 2 O 3 (0 0 0 1) surface. • EDD and DOS results confirm the stable adsorption of ethanol on the surface. • DFT calculations favor ethylene formation via C β −H bond scission. • The formation of acetaldehyde has higher energy barrier. - Abstract: Ethanol adsorption and decomposition on the clean α-Al 2 O 3 (0 0 0 1) surface have been systematically investigated by density functional theory calculations. The nature of the surface-ethanol bonding has studied through the density of states (DOS) and the electron density difference (EDD) contour plots. The DOS patterns confirm that the lone pair electrons of EtOH are involved in the formation of a surface Al−O dative bond and the EDD plots provide evidences for the bond weakening/forming, which are consistent with the DOS analysis. Our ethanol decomposition results indicate that ethanol dehydration to ethylene (CH 3 CH 2 OH (a) → C 2 H 4(g) + OH (a) + H (a) ), is the main reaction pathway with the energy barrier of 1.46 eV. Although the cleavage of the hydroxyl group of ethanol has lower energy barrier, the further decomposition of ethoxy owns much higher energy barrier.

Effects of Oxcarbazepine and Levetiracetam on Calcium, Ionized Calcium, and 25-OH Vitamin-D3 Levels in Patients with Epilepsy.

Science.gov (United States)

Aksoy, Duygu; Güveli, Betül Tekin; Ak, Pelin Doğan; Sarı, Hüseyin; Ataklı, Dilek; Arpacı, Baki

2016-02-29

The primary objective of the present study was to further elucidate the effects of oxcarbazepine (OXC) and levetiracetam (LEV) monotherapies on the bone health status of patients with epilepsy. This study included 48 patients who attended our epilepsy outpatient clinic, had a diagnosis of epilepsy, and were undergoing either OXC or LEV monotherapy and 42 healthy control subjects. The demographic and clinical features of the patients, including gender, age, onset of disease, daily drug dosage, and duration of disease, were noted. Additionally, the calcium, ionized calcium, and 25-OH vitamin-D3 levels of the participants were prospectively evaluated. The 25-OH vitamin-D3, calcium, and ionized calcium levels of the patients taking OXC were significantly lower than those of the control group. These levels did not significantly differ between the patients taking LEV and the control group, but there was a significant negative relationship between daily drug dose and ionized calcium levels in the LEV patients. In the present study, anti-epileptic drugs altered the calcium, ionized calcium, and 25-OH vitamin-D3 levels of epilepsy patients and resulted in bone loss, abnormal mineralization, and fractures. These findings suggest that the calcium, ionized calcium, and 25-OH vitamin-D3 levels of patients with epilepsy should be regularly assessed.

Electronic Structures and Bonding Properties of Ti2AlC and Ti3AlC2

Institute of Scientific and Technical Information of China (English)

MIN Xinmin; REN Yi

2007-01-01

The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SixAl1-x C has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al3p.

The Effect of Mg Addition and Manufacturing Conditions on the Interfacial Reactions between Al and CNT in Al-CNT Pellets

International Nuclear Information System (INIS)

Lim, Jung-Kyu; Choi, Soon-Yool; Choe, Kyong-Hwan; Cho, Gue-Serb; Kim, Sang-Sub

2013-01-01

In the present study, Al-CNT pellets were investigated to understand the effect of Mg addition and manufacturing conditions on the interfacial reactions between Al and CNTs in Al-CNT pellets. The pellets were heated and held at 700 °C and 800 °C for 2 hours under nitrogen (N_2) atmosphere. To confirm the reactions between Al and CNT in the pellets under different manufacturing conditions, the microstructures were observed by optical microscopy (OM) and field emission scanning electro microscopy (FESEM). And, the composition and reaction phases were analyzed by energy dispersive X-ray spectroscory (EDXS) and X-ray diffractometry (XRD). The presence of oxidation products and Mg on the surface of Al powder in the pellets appeared to prevent the formation of Al_4C_3. But, Al_4C_3 reaction products were increased due to the high temperature of 800 °C, which produced a high amount of reduced aluminium and increased the reaction areas between Al and CNT. The Al-CNT pellets compacted under air atmosphere prohibited the reaction between Al and CNT because of the high amount of oxidation products, such as MgO and MgAl_2O_4.

Synchronous exfoliation and assembly of graphene on 3D Ni(OH)2 for supercapacitors.

Science.gov (United States)

Ma, Liguo; Zheng, Maojun; Liu, Shaohua; Li, Qiang; You, Yuxiu; Wang, Faze; Ma, Li; Shen, Wenzhong

2016-11-08

Nowadays, new approaches to fabricate high-performance electrode materials are of vital importance in the renewable energy field. Here, we present a facile synthesis procedure of 3D Ni(OH) 2 /graphene hybrids for supercapacitors via synchronous electrochemical-assisted exfoliation and assembly of graphene on 3D Ni(OH) 2 networks. With the assistance of an electric field, the electrochemically exfoliated high-quality graphene can be readily, uniformly assembled on the surfaces of 3D Ni(OH) 2 . When serving as electrode materials for supercapacitors, the resulting 3D Ni(OH) 2 /graphene composites exhibited excellent specific capacitance (263 mF cm -2 at 2 mA cm -2 ), remarkable rate capability and super-long cycle life (retention of 94.1% even after 10 000 continuous charge-discharge cycles), which may be attributed to their highly porous, stable 3D architecture as well as uniform, firm anchoring of ultrathin graphene on their surfaces. Therefore, our approach provides a facile strategy for the large-scale synthesis of high-quality graphene based composites towards various applications.

Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

International Nuclear Information System (INIS)

Qu, Jun; He, Xiaoman; Chen, Min; Hu, Huimin; Zhang, Qiwu; Liu, Xinzhong

2017-01-01

In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu_2(OH)_2CO_3) and aluminum hydroxide (Al(OH)_3) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

Energy Technology Data Exchange (ETDEWEB)

Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

2017-04-15

In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

The first study of antiferromagnetic eosphorite-childrenite series (Mn{sub 1−x}Fe{sub x})AlP(OH){sub 2}H{sub 2}O (x=0.5)

Energy Technology Data Exchange (ETDEWEB)

Behal, D. [Sektion Kristallographie, Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München (LMU), Theresienstrasse 41, D-80333 Munich (Germany); Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München (TUM), Lichtenbergstrasse 1, D-85748 Garching (Germany); Röska, B. [Sektion Kristallographie, Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München (LMU), Theresienstrasse 41, D-80333 Munich (Germany); Park, S.-H., E-mail: sohyun.park@lmu.de [Sektion Kristallographie, Department für Geo- und Umweltwissenschaften, Ludwig-Maximilians-Universität München (LMU), Theresienstrasse 41, D-80333 Munich (Germany); Pedersen, B. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München (TUM), Lichtenbergstrasse 1, D-85748 Garching (Germany); Benka, G.; Pfleiderer, Ch. [Chair E21, Physik-Department, Technische Universität München (TUM), James-Franck-Strasse 1, D-85748 Garching (Germany); Wakabayashi, Y.; Kimura, T. [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531 (Japan)

2017-04-15

This study presents for the first time the antiferromagnetic structure of the eosphorite-childrenite series (Mn{sub 1-x}Fe{sub x})AlPO{sub 4}(OH){sub 2}H{sub 2}O (x=0.5), based on neutron single crystal diffraction at 3 K in combination with group theoretical representation analysis. The new magnetic structure is described in the magnetic space group P{sub C}mnb, maintaining the atomistic unit cell size (a×b×c) with a ~6.9 Å, b ~10.4 Å, c ~13.4 Å. Mn-rich and Fe-rich zones within solid solution crystals are expanded up to several hundred micrometers, as seen in electron microprobe and polarisation microscopy. Magnetic susceptibility and specific heat measurements on two different eosphorite-childrenite crystals show the magnetic transition temperature between 6.5 K and 6.8 K as the Mn{sup 2+}/Fe{sup 2+} ratio varies over single compositional zones. Below the Néel temperature, a magnetic field between 1.5 T and 2 T parallel to the a-axis causes a 180° spin-flip, reaching the saturation (5.25 μ{sub B} pfu) toward high magnetic fields. - Highlights: • New magnetic structure of (Mn{sub 1-x}Fe{sub x})AlPO{sub 4}(OH){sub 2}H{sub 2}O (x=0.5). • Magnetic phase transition at 6.5–6.6 K. • Magnetic interaction anisotropy in (Mn{sub 0.5}Fe{sub 0.5})AlPO{sub 4}(OH){sub 2}H{sub 2}O. • Compositional zones in the eosphorite-childrenite series.

Chemisorption of carbon dioxide and ethene on eta-Al2O3

International Nuclear Information System (INIS)

Schubart, W.; Knoezinger, H.

1985-01-01

The chemisorption of ethene on eta-Al 2 O 3 has been studied by thermal desorption spectroscopy (TDS) as a function of the degree of surface hydroxylation. The effect of CO 2 poisoning and the D 2 exchange with chemisorbed C 2 H 4 was investigated. While CO 2 shows a broad distribution of interaction energies, three (or four) distinct chemisorption states can be detected for C 2 H 4 . It is suggested that C 2 H 4 forms vinyl species via heterolytic cleavage of C-H bonds on acid-base pair sites. These presumably contain strong defects (ensembles of anion vacanies) and OH-groups coordinated to tetrahedral Al 3+ in immediate vicinity. Differences in coordination and local environment are assumed to be responsible for the formation of the three (or four) distinct chemisorption states. (orig.) [de

Corrosion behavior of Mg–5Al based magnesium alloy with 1 wt.% Sn, Mn and Zn additions in 3.5 wt.% NaCl solution

Directory of Open Access Journals (Sweden)

Nguyen Dang Nam

2014-06-01

Full Text Available The corrosion properties of four Mg–5Al alloys with M-alloying elements (tin, manganese and zinc in a 3.5 wt.% NaCl solution were examined using electrochemical tests and surface analyses. The electrochemical results indicated that the addition of 1 wt.% M metal decreased the corrosion rate and hydrogen evolution rate of the Mg–5Al specimens. Moreover, the addition of 1Zn resulted in having the best corrosion resistance due to the interaction of Zn oxide with Mg and Al oxides which acted as a corrosion barrier.

Vibrational Dynamics of Interfacial Water by Free Induction Decay Sum Frequency Generation (FID-SFG) at the Al2O3(1120)/H2O Interface.

Science.gov (United States)

Boulesbaa, Abdelaziz; Borguet, Eric

2014-02-06

The dephasing dynamics of a vibrational coherence may reveal the interactions of chemical functional groups with their environment. To investigate this process at a surface, we employ free induction decay sum frequency generation (FID-SFG) to measure the time that it takes for free OH stretch oscillators at the charged (pH ≈ 13, KOH) interface of alumina/water (Al2O3/H2O) to lose their collective coherence. By employing noncollinear optical parametric amplification (NOPA) technology and nonlinear vibrational spectroscopy, we showed that the single free OH peak actually corresponds to two distinct oscillators oriented opposite to each other and measured the total dephasing time, T2, of the free OH stretch modes at the Al2O3/H2O interface with a sub-40 fs temporal resolution. Our results suggested that the free OH oscillators associated with interfacial water dephase on the time scale of 89.4 ± 6.9 fs, whereas the homogeneous dephasing of interfacial alumina hydroxyls is an order of magnitude slower.

Sorption of microamounts of Cesup(3+), Pmsup(3+), Gdsup(3+) and Ybsup(3+) on aluminium hydroxide