840 research outputs found
Cation distribution in manganese cobaltite spinels Co3âxMnxO4 (0 †x †1) determined by thermal analysis
Thermogravimetric analysis was used in order to study the reduction in air of submicronic powders of Co3âx Mn x O4 spinels, with 0 †x †1. For x = 0 (i.e. Co3O4), cation reduction occurred in a single step. It involved the CoIII ions at the octahedral sites, which were reduced to Co2+ on producing CoO. For 0 < x †1, the reduction occurred in two stages at increasing temperature with increasing amounts of manganese. The first step corresponded to the reduction of octahedral CoIII ions and the second was attributed to the reduction of octahedral Mn4+ ions to Mn3+. From the individual weight losses and the electrical neutrality of the lattice, the CoIII and Mn4+ ion concentrations were calculated. The distribution of cobalt and manganese ions present on each crystallographic site of the spinel was determined. In contrast to most previous studies that took into account either CoIII and Mn3+ or Co2+, CoIII and Mn4+ only, our thermal analysis study showed that Co2+/CoIII and Mn3+/Mn4+ pairs occupy the octahedral sites. These results were used to explain the resistivity measurements carried out on dense ceramics prepared from our powders sintered at low temperature (700â750 °C) in a Spark Plasma Sintering apparatus
Formation of a cultivated spodosol in east-central Finland
The processes involved in Spodosol (Podzol) formation are still being debated. The pedogenic processes in a Spodosol, 10,700 years-old, at Sotkamo that has been cultivated for about 50 years were studied by characterizing the morphology and analyzing the major chemical properties, texture and mineralogy. Before cultivation, organic acids produced by decomposition of organic matter from pine litter in O and A horizons had weathered primary minerals in A and E horizons releasing Al and Fe. Percolating waters moved the organo-metallic complexes from A and E horizons to Bhsm and Bs horizons where the complexes coated and bridged sand grains eventually forming cemented ortstein. Because of the high biotite content of the parent material, the index of accumulation of Fe and Al in the Bhsm horizon (Al + 0.5 Fe = 4.1%) was the highest reported in Spodosols of Finland. The data support the theory of downward movement of Al and Fe as organo-metallic complexes with formation of some ferrihydrite but little or no formation of imogolite type materials. Little, if any, podzolization has likely occurred since the initiation of cultivation because, after agricultural liming and consequent increase of pH in the Ap horizon, organic compounds are likely to chelate Ca and Mg rather than Al and Fe.;Karkeille hietamaille syntyneet podsolit ovat Suomen kehittyneimpiÀ maannoksia. NiitÀ tutkimalla saadaan uutta tietoa tÀmÀn koko pohjoisella havumetsÀvyöhykkeellÀyleisen maannostyypin kehittymiseen johtaneista prosesseista, joista edelleenkin vallitsee erilaisia kÀsityksiÀ. TÀmÀn tutkimuksen kohteena oli Sotkamossa karkealla hietamaalla oleva noin 50 vuotta viljelty maa, joka on ollut kuivillaan noin 10 700 vuotta. Muokkauskerroksen alapuolella oli huuhtoutumiskerros (valkomaa), joka sisÀlsi lÀhes pelkkÀÀ kvartsihiekkaa. Sen alapuolella oli noin 10 cm paksu rautapalsi eli iskostunut horisontti, johon ylempÀÀ orgaanisina kompleksiyhdisteinÀ huuhtoutuneet rauta ja alumiini ovat saostuneet. Mikroskoopilla voidaan nÀhdÀ, miten nÀmÀ saostuneet ainesosat peittÀvÀt kvartsihiekan jyvÀset ja sitovat ne yhteen. TÀssÀ horisontissa oli erittÀin runsaasti heikosti kiteytynyttÀ rautaoksidia, joka on uutettavissa ammoniumoksalaattiliuoksella, kun taas valkomaassa tÀllaista rautaa oli erittÀin vÀhÀn. Rikastumiskerroksen alumiinista valtaosa oli pyrofosfaattiin uuttuvassa, oletettavasti orgaanisen aineksen sitomassa muodossa, mikÀ viittaa aineiden kulkeutuneen tÀhÀn horisonttiin nimenomaan kelaatteina eikÀ epÀorgaanisina kolloideina. SyvÀ kyntö on nostanut valkomaata ja kappaleita rikastumiskerroksen iskostumasta myös muokkauskerrokseen. Rikastumiskerroksen alapuolella kvartsihiekkajyvÀsten pinnoilla ei ollut paljonkaan rautasaostumia, mutta mikroskoopilla nÀkyi runsaasti rapautumatonta biotiittia. Rikastumiskerroksen rauta lienee suureksi osaksi perÀisin juuri biotiitista, joka on kokonaisuudessaan rapautunut pintamaasta. VÀhemmÀn biotiittia sisÀltÀviin maihin ei todennÀköisesti kehity nÀin vahvaa rikastumiskerrosta maan pienemmÀn rautapitoisuuden takia. Podsoloituminen on luultavasti pysÀhtynyt sen jÀlkeen, kun maa on otettu viljelyyn ja sen pintaosien pH on kalkituksen seurauksena noussut
Effect of reinforcing submicron SiC particles on the wear of electrolytic NiP coatings Part 1. Uni-directional sliding
As-plated and annealed NiP coatings and composite NiP-SiC coatings were investigated in uni-directional ball-on-disc sliding tests. Abrasive wear was noticed in the case of composite NiP coatings containing submicron SiC particles, whereas in NiP coatings oxidational wear was active. The addition of submicron SiC particles not only increases the hardness of these electrolytic coatings but also hinders the formation of an oxide film in the sliding wear track. As a consequence, the wear loss on as-plated NiP coatings is not markedly reduced by the addition of SiC particles. On the contrary, a heat treatment at 420 °C for 1 h decreases the wear loss on both pure NiP and composite NiP-SiC coatings. During that heat treatment, Ni3P precipitates are formed in the NiP matrix and owing to this fact, the hardness of both pure NiP and composite NiP-SiC coatings increases. However, the heat treatment of composite NiP-SiC coatings induces the sensitivity for crack formation in the NiP matrix around these SiC particles. As a result, the pull out of SiC particles in the wear track occurs easily during sliding, and the wear loss of composite NiP-SiC coatings remains above the wear loss on NiP coatings
Gas-liquid mass transfer : a comparison of down-and up-pumping axial flow impellers with radial impellers
The performance of a down- and up-pumping pitched blade turbine and A315 for gas-liquid dispersion and mass
transfer was evaluated and then compared with that of Rushton and Scaba turbines in a small laboratory scale
vessel. The results show that when the axial flow impellers are operated in the up-pumping mode, the overall
performance is largely improved compared with the down-pumping configuration. Compared with the radial
turbines, the up-pumping A315 has a high gas handling capacity, equivalent to the Scaba turbine and is
economically much more efficient in terms of mass transfer than both turbines. On the other hand, the uppumping
pitched blade turbine is not as well adapted to such applications. Finally, the axial flow impellers in the
down-pumping mode have the lowest performance of all the impellers studied, although the A315 is preferred of
the pitched blade turbine
Computing the Weight Distribution of the Binary Reed-Muller Code
We compute the weight distribution of the by combining
the approach described in D. V. Sarwate's Ph.D. thesis from 1973 with knowledge
on the affine equivalence classification of Boolean functions. To solve this
problem posed, e.g., in the MacWilliams and Sloane book [p. 447], we apply a
refined approach based on the classification of Boolean quartic forms in
variables due to Ph. Langevin and G. Leander, and recent results on the
classification of the quotient space
due to V. Gillot and Ph. Langevin
Perkembangan Hidup Dan Daya Memangsa Curinus Coeruleus Mulsant Pada Beberapa Kutu Tanaman
The biological development and feeding ability of Curinus coeruleus Mulsant on several phytophthires. The research was conducted to investigate the survival and feeding capability of Curinus coeruleus Mulsant on Heteropsylla Cubana, Aleurocanthus spiniferus, Planococcus citri, and Aspidiotus destructor. The research was done in completely randomized design with eight replications. The result showed that C. coeruleus could not survive on A. spiniferus. The head width of C. coeruleus larvae did not differ significantly in A. destructor, P. citri, or H. Cubana. The head width increase of C. coeruleus larvae feeding on A. destructor followed Dyar\u27s law with growth ratio of 1,4. Larval stadium of C. coeruleus, imago stadium, longevity, and the number of consumed preys were affected by phytophthires species. C. coeruleus could feed on more H. Cubana than A. destructor, or P. citri
CCM.G-K2 key comparison
open55sĂŹIn November 2013 an International Key Comparison, CCM.G-K2, was organized in the Underground Laboratory for Geodynamics in Walferdange. The comparison has assembled 25 participants coming from 19 countries and four different continents. The comparison was divided into two parts: the key comparison that included 10 NMIs or DIs, and the pilot study including all participants. The global result given by the pilot study confirms that all instruments are absolutely coherent to each other. The results obtained for the key comparison confirm a good agreement between the NMI instrumentsopenO. Francis; H. Baumann; C. Ullrich; S. Castelein; M. Van Camp; M. Andrade de Sousa; R. Lima Melhorato; C. Li; J. Xu; D. Su; S. Wu; H. Hu; K. Wu; G. Li; Z. Li; W. Hsieh; V. PĂĄlinkĂĄs; J. KosteleckĂœ; J. MĂ€kinen; J. NĂ€rĂ€nen; S. Merlet; F. Pereira Dos Santos; P. Gillot; J. Hinderer; J. D. Bernard; N. Le Moigne; B. Fores; O. Gitlein; M. Schilling; R. Falk; H. Wilmes; Germak A.; E. Biolcati; C. Origlia; D. Iacovone; F. Baccaro; S. Mizushima; R. De Plaen; G. Klein; M. Seil; R. Radinovic; M. Sekowski; P. Dykowski; I. M. Choi; M. S. Kim; A. Borreguero; S. Sainz-Maza; M. Calvo; A. Engfeldt; J. Agren; R. Reudink; M. Eckl; D. van Westrum; R. Billson; B. EllisFrancis, O.; Baumann, H.; Ullrich, C.; Castelein, S.; Van Camp, M.; Andrade de Sousa, M.; Lima Melhorato, R.; Li, C.; Xu, J.; Su, D.; Wu, S.; Hu, H.; Wu, K.; Li, G.; Li, Z.; Hsieh, W.; PĂĄlinkĂĄs, V.; KosteleckĂœ, J.; MĂ€kinen, J.; NĂ€rĂ€nen, J.; Merlet, S.; Pereira Dos Santos, F.; Gillot, P.; Hinderer, J.; Bernard, J. D.; Le Moigne, N.; Fores, B.; Gitlein, O.; Schilling, M.; Falk, R.; Wilmes, H.; Germak, ALESSANDRO FRANCO LIDIA; Biolcati, E.; Origlia, C.; Iacovone, D.; Baccaro, F.; Mizushima, S.; De Plaen, R.; Klein, G.; Seil, M.; Radinovic, R.; Sekowski, M.; Dykowski, P.; Choi, I. M.; Kim, M. S.; Borreguero, A.; Sainz Maza, S.; Calvo, M.; Engfeldt, A.; Agren, J.; Reudink, R.; Eckl, M.; van Westrum, D.; Billson, R.; Ellis, B
Matter-wave laser Interferometric Gravitation Antenna (MIGA): New perspectives for fundamental physics and geosciences
The MIGA project aims at demonstrating precision measurements of gravity with
cold atom sensors in a large scale instrument and at studying the associated
applications in geosciences and fundamental physics. The first stage of the
project (2013-2018) will consist in building a 300-meter long optical cavity to
interrogate atom interferometers and will be based at the low noise underground
laboratory LSBB in Rustrel, France. The second stage of the project (2018-2023)
will be dedicated to science runs and data analyses in order to probe the
spatio-temporal structure of the local gravity field of the LSBB region, a site
of high hydrological interest. MIGA will also assess future potential
applications of atom interferometry to gravitational wave detection in the
frequency band Hz hardly covered by future long baseline optical
interferometers. This paper presents the main objectives of the project, the
status of the construction of the instrument and the motivation for the
applications of MIGA in geosciences. Important results on new atom
interferometry techniques developed at SYRTE in the context of MIGA and paving
the way to precision gravity measurements are also reported.Comment: Proceedings of the 50th Rencontres de Moriond "100 years after GR",
La Thuile (Italy), 21-28 March 2015 - 10 pages, 5 figures, 23 references
version2: added references, corrected typo
Diamondlike flake composites
A carbon coating is vacuum arc deposited on a smooth surface of a target which is simultaneously ion beam sputtered. The bombarding ions have sufficient energy to create diamond bonds. Spalling occurs as the carbon deposit thickens. The resulting diamond-like carbon flakes are mixed with a binder or matrix material to form a composite material having improved thermal, electrical, mechanical, and tribological properties when used in aerospace structures and components
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